Improved command sync

Fix: Skull texture out of bounds error

build.gradle.kts

@@ -158,6 +158,7 @@ allprojects {
             relocate("org.litote", "com.willfp.eco.libs.litote")
             relocate("org.reactivestreams", "com.willfp.eco.libs.reactivestreams")
             relocate("reactor.", "com.willfp.eco.libs.reactor.") // Dot in name to be safe
+            relocate("com.moandjiezana.toml", "com.willfp.eco.libs.toml")
 
             /*
             Kotlin and caffeine are not shaded so that they can be accessed directly by eco plugins.

eco-api/src/main/java/com/willfp/eco/core/Eco.java

@@ -1,82 +1,560 @@
 package com.willfp.eco.core;
 
+import com.willfp.eco.core.config.ConfigType;
+import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.config.interfaces.LoadableConfig;
+import com.willfp.eco.core.config.updating.ConfigHandler;
+import com.willfp.eco.core.data.ExtendedPersistentDataContainer;
+import com.willfp.eco.core.data.PlayerProfile;
+import com.willfp.eco.core.data.ServerProfile;
+import com.willfp.eco.core.data.keys.PersistentDataKey;
+import com.willfp.eco.core.drops.DropQueue;
+import com.willfp.eco.core.entities.ai.EntityController;
+import com.willfp.eco.core.events.EventManager;
+import com.willfp.eco.core.extensions.ExtensionLoader;
+import com.willfp.eco.core.factory.MetadataValueFactory;
+import com.willfp.eco.core.factory.NamespacedKeyFactory;
+import com.willfp.eco.core.factory.RunnableFactory;
+import com.willfp.eco.core.fast.FastItemStack;
+import com.willfp.eco.core.gui.menu.Menu;
+import com.willfp.eco.core.gui.menu.MenuBuilder;
+import com.willfp.eco.core.gui.menu.MenuType;
+import com.willfp.eco.core.gui.slot.SlotBuilder;
+import com.willfp.eco.core.gui.slot.functional.SlotProvider;
+import com.willfp.eco.core.items.TestableItem;
+import com.willfp.eco.core.math.MathContext;
+import com.willfp.eco.core.proxy.ProxyFactory;
+import com.willfp.eco.core.scheduling.Scheduler;
+import net.kyori.adventure.platform.bukkit.BukkitAudiences;
 import org.apache.commons.lang.Validate;
+import org.bukkit.Location;
+import org.bukkit.NamespacedKey;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.entity.Entity;
+import org.bukkit.entity.Mob;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.meta.SkullMeta;
+import org.bukkit.persistence.PersistentDataContainer;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
-import java.lang.annotation.Documented;
-import java.lang.annotation.ElementType;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.annotation.Target;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+import java.util.logging.Logger;
 
 /**
- * Holds the instance of the eco handler for bridging between the frontend
+ * Holds the instance of eco for bridging between the frontend
  * and backend.
+ * <p>
+ * <strong>Do not use this in your plugins!</strong> It can and will contain
+ * breaking changes between minor versions and even patches, and you will create
+ * compatibility issues by. All parts of this have been abstracted
+ * into logically named API components that you can use.
  *
- * @see Eco#getHandler()
- * @see Handler
+ * @see Eco#get()
  */
 @ApiStatus.Internal
-public final class Eco {
+public interface Eco {
     /**
-     * Instance of eco handler.
-     */
-    @ApiStatus.Internal
-    private static Handler handler;
-
-    /**
-     * Set the handler.
+     * Create a scheduler.
      *
-     * @param handler The handler.
+     * @param plugin The plugin.
+     * @return The scheduler.
      */
-    @ApiStatus.Internal
-    public static void setHandler(@NotNull final Handler handler) {
-        Validate.isTrue(Eco.handler == null, "Already initialized!");
-
-        Eco.handler = handler;
-    }
+    @NotNull
+    Scheduler createScheduler(@NotNull EcoPlugin plugin);
 
     /**
-     * Get the instance of the eco handler; the bridge between the api frontend
-     * and the implementation backend.
-     * <p>
-     * <strong>Do not use the handler in your plugins!</strong> It can and will contain
-     * breaking changes between minor versions and even patches, and you will create
-     * compatibility issues by using the handler. All parts of the handler have been abstracted
-     * into logically named API components that you can use.
-     * <p>
-     * Prior to version 6.12.0, the handler was considered as an API component, but it has
-     * since been moved into an internal component, and in 6.17.0, the first breaking change
-     * was introduced to {@link com.willfp.eco.core.config.wrapper.ConfigFactory}. This means
-     * that any usages of the handler can now cause problems in your plugins.
+     * Create an event manager.
      *
+     * @param plugin The plugin.
+     * @return The event manager.
+     */
+    @NotNull
+    EventManager createEventManager(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a NamespacedKey factory.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    NamespacedKeyFactory createNamespacedKeyFactory(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a MetadataValue factory.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    MetadataValueFactory createMetadataValueFactory(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a Runnable factory.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    RunnableFactory createRunnableFactory(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create an ExtensionLoader.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    ExtensionLoader createExtensionLoader(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a config handler.
+     *
+     * @param plugin The plugin.
      * @return The handler.
      */
+    @NotNull
+    ConfigHandler createConfigHandler(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a logger.
+     *
+     * @param plugin The plugin.
+     * @return The logger.
+     */
+    @NotNull
+    Logger createLogger(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a PAPI integration.
+     *
+     * @param plugin The plugin.
+     */
+    void createPAPIIntegration(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a proxy factory.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    ProxyFactory createProxyFactory(@NotNull EcoPlugin plugin);
+
+    /**
+     * Get eco Spigot plugin.
+     *
+     * @return The plugin.
+     */
+    @NotNull
+    EcoPlugin getEcoPlugin();
+
+    /**
+     * Updatable config.
+     *
+     * @param configName            The name of the config
+     * @param plugin                The plugin.
+     * @param subDirectoryPath      The subdirectory path.
+     * @param source                The class that owns the resource.
+     * @param removeUnused          Whether keys not present in the default config should be removed on update.
+     * @param type                  The config type.
+     * @param updateBlacklist       Substring of keys to not add/remove keys for.
+     * @param requiresChangesToSave If the config must be changed in order to save the config.
+     * @return The config implementation.
+     */
+    @NotNull
+    LoadableConfig createUpdatableConfig(@NotNull String configName,
+                                         @NotNull PluginLike plugin,
+                                         @NotNull String subDirectoryPath,
+                                         @NotNull Class<?> source,
+                                         boolean removeUnused,
+                                         @NotNull ConfigType type,
+                                         boolean requiresChangesToSave,
+                                         @NotNull String... updateBlacklist);
+
+    /**
+     * Loadable config.
+     *
+     * @param configName            The name of the config
+     * @param plugin                The plugin.
+     * @param subDirectoryPath      The subdirectory path.
+     * @param source                The class that owns the resource.
+     * @param type                  The config type.
+     * @param requiresChangesToSave If the config must be changed in order to save the config.
+     * @return The config implementation.
+     */
+    @NotNull
+    LoadableConfig createLoadableConfig(@NotNull String configName,
+                                        @NotNull PluginLike plugin,
+                                        @NotNull String subDirectoryPath,
+                                        @NotNull Class<?> source,
+                                        @NotNull ConfigType type,
+                                        boolean requiresChangesToSave);
+
+    /**
+     * Create config.
+     *
+     * @param config The handle.
+     * @return The config implementation.
+     */
+    @NotNull
+    Config wrapConfigurationSection(@NotNull ConfigurationSection config);
+
+    /**
+     * Create config.
+     *
+     * @param values The values.
+     * @param type   The config type.
+     * @return The config implementation.
+     */
+    @NotNull
+    Config createConfig(@NotNull Map<String, Object> values,
+                        @NotNull ConfigType type);
+
+    /**
+     * Create config.
+     *
+     * @param contents The file contents.
+     * @param type     The type.
+     * @return The config implementation.
+     */
+    @NotNull
+    Config createConfig(@NotNull String contents,
+                        @NotNull ConfigType type);
+
+    /**
+     * Create a Drop Queue.
+     *
+     * @param player The player.
+     * @return The drop queue.
+     */
+    @NotNull
+    DropQueue createDropQueue(@NotNull Player player);
+
+    /**
+     * Create slot builder.
+     *
+     * @param provider The provider.
+     * @return The builder.
+     */
+    @NotNull
+    SlotBuilder createSlotBuilder(@NotNull SlotProvider provider);
+
+    /**
+     * Create menu builder.
+     *
+     * @param rows The amount of rows.
+     * @param type The type.
+     * @return The builder.
+     */
+    @NotNull
+    MenuBuilder createMenuBuilder(int rows,
+                                  @NotNull MenuType type);
+
+    /**
+     * Combine the state of two menus together.
+     *
+     * @param base       The base menu.
+     * @param additional The additional state.
+     * @return The menu.
+     */
+    @NotNull
+    Menu blendMenuState(@NotNull Menu base,
+                        @NotNull Menu additional);
+
+    /**
+     * Clean up ClassLoader (etc.) to allow PlugMan support.
+     *
+     * @param plugin The plugin to clean up.
+     */
+    void clean(@NotNull EcoPlugin plugin);
+
+    /**
+     * Add new plugin.
+     *
+     * @param plugin The plugin.
+     */
+    void addNewPlugin(@NotNull EcoPlugin plugin);
+
+    /**
+     * Get plugin by name.
+     *
+     * @param name The name.
+     * @return The plugin.
+     */
+    @Nullable
+    EcoPlugin getPluginByName(@NotNull String name);
+
+    /**
+     * Get all loaded eco plugins.
+     *
+     * @return A list of plugin names in lowercase.
+     */
+    @NotNull
+    List<String> getLoadedPlugins();
+
+    /**
+     * Create a FastItemStack.
+     *
+     * @param itemStack The base ItemStack.
+     * @return The FastItemStack.
+     */
+    @NotNull
+    FastItemStack createFastItemStack(@NotNull ItemStack itemStack);
+
+    /**
+     * Register bStats metrics.
+     *
+     * @param plugin The plugin.
+     */
+    void registerBStats(@NotNull EcoPlugin plugin);
+
+    /**
+     * Get Adventure audiences.
+     *
+     * @return The audiences.
+     */
+    @Nullable
+    BukkitAudiences getAdventure();
+
+    /**
+     * Register a persistent data key to be stored.
+     *
+     * @param key The key.
+     */
+    void registerPersistentKey(@NotNull PersistentDataKey<?> key);
+
+    /**
+     * Get all registered keys.
+     *
+     * @return The keys.
+     */
+    @NotNull
+    Set<PersistentDataKey<?>> getRegisteredPersistentDataKeys();
+
+    /**
+     * Load a player profile.
+     *
+     * @param uuid The UUID.
+     * @return The profile.
+     */
+    @NotNull
+    PlayerProfile loadPlayerProfile(@NotNull UUID uuid);
+
+    /**
+     * Load the server profile.
+     *
+     * @return The profile.
+     */
+    @NotNull
+    ServerProfile getServerProfile();
+
+    /**
+     * Unload a player profile from memory.
+     * <p>
+     * This will not save the profile first.
+     *
+     * @param uuid The uuid.
+     */
+    void unloadPlayerProfile(@NotNull UUID uuid);
+
+    /**
+     * Create dummy entity - never spawned, exists purely in code.
+     *
+     * @param location The location.
+     * @return The entity.
+     */
+    @NotNull
+    Entity createDummyEntity(@NotNull Location location);
+
+    /**
+     * Create a {@link NamespacedKey} quickly
+     * <p>
+     * Bypasses the constructor, allowing for the creation of invalid keys,
+     * therefore this is considered unsafe and should only be called after
+     * the key has been confirmed to be valid.
+     *
+     * @param namespace The namespace.
+     * @param key       The key.
+     * @return The key.
+     */
+    @NotNull
+    NamespacedKey createNamespacedKey(@NotNull String namespace,
+                                      @NotNull String key);
+
+    /**
+     * Return or get props for a plugin.
+     *
+     * @param existing The existing constructor props.
+     * @param plugin   The plugin.
+     * @return The props.
+     */
+    @NotNull
+    PluginProps getProps(@Nullable PluginProps existing,
+                         @NotNull Class<? extends EcoPlugin> plugin);
+
+    /**
+     * Format a string with MiniMessage.
+     *
+     * @param message The message.
+     * @return The formatted string.
+     */
+    @NotNull
+    String formatMiniMessage(@NotNull String message);
+
+    /**
+     * Create controlled entity from a mob.
+     *
+     * @param mob The mob.
+     * @param <T> The mob type.
+     * @return The controlled entity.
+     */
+    @NotNull <T extends Mob> EntityController<T> createEntityController(@NotNull T mob);
+
+    /**
+     * Adapt base PDC to extended PDC.
+     *
+     * @param container The container.
+     * @return The extended container.
+     */
+    @NotNull
+    ExtendedPersistentDataContainer adaptPdc(@NotNull PersistentDataContainer container);
+
+    /**
+     * Create new PDC.
+     *
+     * @return The container.
+     */
+    @NotNull
+    PersistentDataContainer newPdc();
+
+    /**
+     * Get item from SNBT.
+     *
+     * @param snbt The NBT string.
+     * @return The ItemStack, or null if invalid.
+     */
+    @Nullable
+    ItemStack fromSNBT(@NotNull String snbt);
+
+    /**
+     * Convert item to SNBT.
+     *
+     * @param itemStack The item.
+     * @return The NBT string.
+     */
+    @NotNull
+    String toSNBT(@NotNull ItemStack itemStack);
+
+    /**
+     * Make TestableItem from SNBT.
+     *
+     * @param snbt The NBT string.
+     * @return The TestableItem.
+     */
+    @NotNull
+    TestableItem testableItemFromSNBT(@NotNull String snbt);
+
+    /**
+     * Get the texture of a skull.
+     *
+     * @param meta The skull meta.
+     * @return The texture, or null if not found.
+     */
+    @Nullable
+    String getSkullTexture(@NotNull SkullMeta meta);
+
+    /**
+     * Set the texture of a skull.
+     *
+     * @param meta   The skull meta.
+     * @param base64 The texture.
+     */
+    void setSkullTexture(@NotNull SkullMeta meta,
+                         @NotNull String base64);
+
+    /**
+     * Get the current server TPS.
+     *
+     * @return The TPS.
+     */
+    double getTPS();
+
+    /**
+     * Evaluate an expression.
+     *
+     * @param expression The expression.
+     * @param context    The context.
+     * @return The value of the expression, or zero if invalid.
+     */
+    double evaluate(@NotNull String expression,
+                    @NotNull MathContext context);
+
+    /**
+     * Get the menu a player currently has open.
+     *
+     * @param player The player.
+     * @return The menu, or null if no menu open.
+     */
+    @Nullable
+    Menu getOpenMenu(@NotNull Player player);
+
+    /**
+     * Sync commands.
+     */
+    void syncCommands();
+
+    /**
+     * Get the instance of eco; the bridge between the api frontend
+     * and the implementation backend.
+     *
+     * @return The instance of eco.
+     */
     @ApiStatus.Internal
-    public static Handler getHandler() {
-        return handler;
+    static Eco get() {
+        return Instance.get();
     }
 
     /**
-     * Eco Handler components are internals, so if a class is marked as a handler component,
-     * then it should be treated the same as if it was marked with {@link ApiStatus.Internal}.
-     * <p>
-     * If a class is marked with {@link HandlerComponent}, <strong>Do not reference it in
-     * your code!</strong> It can and will contain breaking changes between minor versions and
-     * even patches, and you will create compatibility issues by using them.
-     * <p>
-     * Handler components should also be marked with {@link ApiStatus.Internal} in order to
-     * cause compiler / IDE warnings.
+     * Manages the internal frontend -> backend communication.
      */
-    @Documented
-    @Retention(RetentionPolicy.CLASS)
-    @Target({ElementType.TYPE})
-    public @interface HandlerComponent {
+    @ApiStatus.Internal
+    final class Instance {
+        /**
+         * Instance of eco.
+         */
+        @ApiStatus.Internal
+        private static Eco eco;
 
-    }
+        /**
+         * Initialize eco.
+         *
+         * @param eco The instance of eco.
+         */
+        @ApiStatus.Internal
+        static void set(@NotNull final Eco eco) {
+            Validate.isTrue(Instance.eco == null, "Already initialized!");
 
-    private Eco() {
-        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+            Instance.eco = eco;
+        }
+
+        /**
+         * Get eco.
+         *
+         * @return eco.
+         */
+        static Eco get() {
+            return eco;
+        }
+
+        private Instance() {
+            throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+        }
     }
 }

eco-api/src/main/java/com/willfp/eco/core/EcoPlugin.java

@@ -13,15 +13,16 @@ import com.willfp.eco.core.factory.MetadataValueFactory;
 import com.willfp.eco.core.factory.NamespacedKeyFactory;
 import com.willfp.eco.core.factory.RunnableFactory;
 import com.willfp.eco.core.integrations.IntegrationLoader;
-import com.willfp.eco.core.integrations.placeholder.PlaceholderManager;
 import com.willfp.eco.core.proxy.ProxyFactory;
 import com.willfp.eco.core.scheduling.Scheduler;
 import com.willfp.eco.core.web.UpdateChecker;
 import org.apache.commons.lang.Validate;
 import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
 import org.bukkit.Bukkit;
+import org.bukkit.NamespacedKey;
 import org.bukkit.configuration.file.FileConfiguration;
 import org.bukkit.event.Listener;
+import org.bukkit.metadata.FixedMetadataValue;
 import org.bukkit.plugin.Plugin;
 import org.bukkit.plugin.java.JavaPlugin;
 import org.jetbrains.annotations.NotNull;
@@ -79,12 +80,12 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
     private final Set<String> loadedIntegrations = new HashSet<>();
 
     /**
-     * The internal plugin scheduler.
+     * The plugin scheduler.
      */
     private final Scheduler scheduler;
 
     /**
-     * The internal plugin Event Manager.
+     * The plugin Event Manager.
      */
     private final EventManager eventManager;
 
@@ -99,17 +100,17 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
     private final LangYml langYml;
 
     /**
-     * The internal factory to produce {@link org.bukkit.NamespacedKey}s.
+     * The factory to produce {@link org.bukkit.NamespacedKey}s.
      */
     private final NamespacedKeyFactory namespacedKeyFactory;
 
     /**
-     * The internal factory to produce {@link org.bukkit.metadata.FixedMetadataValue}s.
+     * The factory to produce {@link org.bukkit.metadata.FixedMetadataValue}s.
      */
     private final MetadataValueFactory metadataValueFactory;
 
     /**
-     * The internal factory to produce {@link com.willfp.eco.core.scheduling.RunnableTask}s.
+     * The factory to produce {@link com.willfp.eco.core.scheduling.RunnableTask}s.
      */
     private final RunnableFactory runnableFactory;
 
@@ -151,6 +152,31 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
     @Nullable
     private final ProxyFactory proxyFactory;
 
+    /**
+     * The tasks to run on enable.
+     */
+    private final List<Runnable> onEnable = new ArrayList<>();
+
+    /**
+     * The tasks to run on disable.
+     */
+    private final List<Runnable> onDisable = new ArrayList<>();
+
+    /**
+     * The tasks to run on reload.
+     */
+    private final List<Runnable> onReload = new ArrayList<>();
+
+    /**
+     * The tasks to run on load.
+     */
+    private final List<Runnable> onLoad = new ArrayList<>();
+
+    /**
+     * The tasks to run after load.
+     */
+    private final List<Runnable> afterLoad = new ArrayList<>();
+
     /**
      * Create a new plugin.
      * <p>
@@ -258,42 +284,42 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
      */
     protected EcoPlugin(@Nullable final PluginProps pluginProps) {
         /*
-        The handler must be initialized before any plugin's constructors
-        are called, as the constructors call Eco#getHandler().
+        Eco must be initialized before any plugin's constructors
+        are called, as the constructors call Eco#get().
 
         To fix this, EcoSpigotPlugin an abstract class and the 'actual'
-        plugin class is EcoHandler - that way I can create the handler
+        plugin class is EcoImpl - that way I can initialize eco
         before any plugins are loaded while still having a separation between
-        the plugin class and the handler class (for code clarity).
+        the plugin class and the implementation class (for code clarity).
 
-        I don't really like the fact that the handler class *is* the
+        I don't really like the fact that the implementation class *is* the
         spigot plugin, but it is what it is.
 
         There is probably a better way of doing it - maybe with
-        some sort of HandlerCreator interface in order to still have
-        a standalone handler class, but then there would be an interface
+        some sort of EcoCrater interface in order to still have
+        a standalone eco class, but then there would be an interface
         left in the API that doesn't really help anything.
 
-        The other alternative would be to use reflection to get a 'createHandler'
+        The other alternative would be to use reflection to get a 'createEco'
         method that only exists in EcoSpigotPlugin - but that feels filthy,
         and I'd rather only use reflection where necessary.
         */
 
-        if (Eco.getHandler() == null && this instanceof Handler) {
+        if (Eco.get() == null && this instanceof Eco) {
             /*
-            This code is only ever called by EcoSpigotPlugin (EcoHandler)
-            as it's the first plugin to load, and it is a handler.
+            This code is only ever called by EcoSpigotPlugin (EcoImpl)
+            as it's the first plugin to load, and it's an instance of eco.
 
-            Any other plugins will never call this code as the handler
-            will have already been initialized.
+            Any other plugins will never call this code as eco will have already
+            been initialized.
              */
 
-            Eco.setHandler((Handler) this);
+            Eco.Instance.set((Eco) this);
         }
 
-        assert Eco.getHandler() != null;
+        assert Eco.get() != null;
 
-        PluginProps generatedProps = Eco.getHandler().getProps(pluginProps, this.getClass());
+        PluginProps generatedProps = Eco.get().getProps(pluginProps, this.getClass());
         generatedProps.validate();
         PluginProps props = this.mutateProps(generatedProps);
         props.validate();
@@ -304,23 +330,23 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         this.color = props.getColor();
         this.supportingExtensions = props.isSupportingExtensions();
 
-        this.proxyFactory = this.proxyPackage.equalsIgnoreCase("") ? null : Eco.getHandler().createProxyFactory(this);
-        this.logger = Eco.getHandler().createLogger(this);
+        this.proxyFactory = this.proxyPackage.equalsIgnoreCase("") ? null : Eco.get().createProxyFactory(this);
+        this.logger = Eco.get().createLogger(this);
 
         this.getLogger().info("Initializing " + this.getColor() + this.getName());
 
-        this.scheduler = Eco.getHandler().createScheduler(this);
-        this.eventManager = Eco.getHandler().createEventManager(this);
-        this.namespacedKeyFactory = Eco.getHandler().createNamespacedKeyFactory(this);
-        this.metadataValueFactory = Eco.getHandler().createMetadataValueFactory(this);
-        this.runnableFactory = Eco.getHandler().createRunnableFactory(this);
-        this.extensionLoader = Eco.getHandler().createExtensionLoader(this);
-        this.configHandler = Eco.getHandler().createConfigHandler(this);
+        this.scheduler = Eco.get().createScheduler(this);
+        this.eventManager = Eco.get().createEventManager(this);
+        this.namespacedKeyFactory = Eco.get().createNamespacedKeyFactory(this);
+        this.metadataValueFactory = Eco.get().createMetadataValueFactory(this);
+        this.runnableFactory = Eco.get().createRunnableFactory(this);
+        this.extensionLoader = Eco.get().createExtensionLoader(this);
+        this.configHandler = Eco.get().createConfigHandler(this);
 
         this.langYml = this.createLangYml();
         this.configYml = this.createConfigYml();
 
-        Eco.getHandler().addNewPlugin(this);
+        Eco.get().addNewPlugin(this);
 
         /*
         The minimum eco version check was moved here because it's very common
@@ -329,7 +355,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         they have an outdated version of eco installed.
          */
 
-        DefaultArtifactVersion runningVersion = new DefaultArtifactVersion(Eco.getHandler().getEcoPlugin().getDescription().getVersion());
+        DefaultArtifactVersion runningVersion = new DefaultArtifactVersion(Eco.get().getEcoPlugin().getDescription().getVersion());
         DefaultArtifactVersion requiredVersion = new DefaultArtifactVersion(this.getMinimumEcoVersion());
         if (!(runningVersion.compareTo(requiredVersion) > 0 || runningVersion.equals(requiredVersion))) {
             this.getLogger().severe("You are running an outdated version of eco!");
@@ -350,7 +376,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         this.getLogger().info("");
         this.getLogger().info("Loading " + this.getColor() + this.getName());
 
-        if (this.getResourceId() != 0 && !Eco.getHandler().getEcoPlugin().getConfigYml().getBool("no-update-checker")) {
+        if (this.getResourceId() != 0 && !Eco.get().getEcoPlugin().getConfigYml().getBool("no-update-checker")) {
             new UpdateChecker(this).getVersion(version -> {
                 DefaultArtifactVersion currentVersion = new DefaultArtifactVersion(this.getDescription().getVersion());
                 DefaultArtifactVersion mostRecentVersion = new DefaultArtifactVersion(version);
@@ -364,7 +390,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         }
 
         if (this.getBStatsId() != 0) {
-            Eco.getHandler().registerBStats(this);
+            Eco.get().registerBStats(this);
         }
 
         Set<String> enabledPlugins = Arrays.stream(Bukkit.getPluginManager().getPlugins())
@@ -373,8 +399,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
                 .collect(Collectors.toSet());
 
         if (enabledPlugins.contains("PlaceholderAPI".toLowerCase())) {
-            this.loadedIntegrations.add("PlaceholderAPI");
-            PlaceholderManager.addIntegration(Eco.getHandler().createPAPIIntegration(this));
+            Eco.get().createPAPIIntegration(this);
         }
 
         this.loadIntegrationLoaders().forEach(integrationLoader -> {
@@ -384,6 +409,8 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
             }
         });
 
+        this.loadedIntegrations.removeIf(pl -> pl.equalsIgnoreCase(this.getName()));
+
         this.getLogger().info("Loaded integrations: " + String.join(", ", this.getLoadedIntegrations()));
 
         Prerequisite.update();
@@ -412,10 +439,20 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         }
 
         this.handleEnable();
+        this.onEnable.forEach(Runnable::run);
 
         this.getLogger().info("");
     }
 
+    /**
+     * Add new task to run on enable.
+     *
+     * @param task The task.
+     */
+    public final void onEnable(@NotNull final Runnable task) {
+        this.onEnable.add(task);
+    }
+
     /**
      * Default code to be executed on plugin disable.
      */
@@ -427,13 +464,23 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         this.getScheduler().cancelAll();
 
         this.handleDisable();
+        this.onDisable.forEach(Runnable::run);
 
         if (this.isSupportingExtensions()) {
             this.getExtensionLoader().unloadExtensions();
         }
 
         this.getLogger().info("Cleaning up...");
-        Eco.getHandler().getCleaner().clean(this);
+        Eco.get().clean(this);
+    }
+
+    /**
+     * Add new task to run on disable.
+     *
+     * @param task The task.
+     */
+    public final void onDisable(@NotNull final Runnable task) {
+        this.onDisable.add(task);
     }
 
     /**
@@ -444,6 +491,16 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         super.onLoad();
 
         this.handleLoad();
+        this.onLoad.forEach(Runnable::run);
+    }
+
+    /**
+     * Add new task to run on load.
+     *
+     * @param task The task.
+     */
+    public final void onLoad(@NotNull final Runnable task) {
+        this.onLoad.add(task);
     }
 
     /**
@@ -476,6 +533,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         }
 
         this.handleAfterLoad();
+        this.afterLoad.forEach(Runnable::run);
 
         this.reload();
 
@@ -486,6 +544,15 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         this.getLogger().info("Loaded " + this.color + this.getName());
     }
 
+    /**
+     * Add new task to run after load.
+     *
+     * @param task The task.
+     */
+    public final void afterLoad(@NotNull final Runnable task) {
+        this.afterLoad.add(task);
+    }
+
     /**
      * Reload the plugin.
      */
@@ -497,12 +564,22 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         this.getConfigHandler().callUpdate(); // Call twice to fix issues
 
         this.handleReload();
+        this.onReload.forEach(Runnable::run);
 
         for (Extension extension : this.extensionLoader.getLoadedExtensions()) {
             extension.handleReload();
         }
     }
 
+    /**
+     * Add new task to run on enable.
+     *
+     * @param task The task.
+     */
+    public final void onReload(@NotNull final Runnable task) {
+        this.onReload.add(task);
+    }
+
     /**
      * Reload the plugin and return the time taken to reload.
      *
@@ -746,7 +823,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
      * @return The plugin.
      */
     public static EcoPlugin getPlugin(@NotNull final String pluginName) {
-        return Eco.getHandler().getPluginByName(pluginName);
+        return Eco.get().getPluginByName(pluginName);
     }
 
     /**
@@ -755,7 +832,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
      * @return The set of names.
      */
     public static Set<String> getPluginNames() {
-        return new HashSet<>(Eco.getHandler().getLoadedPlugins());
+        return new HashSet<>(Eco.get().getLoadedPlugins());
     }
 
     /**
@@ -921,4 +998,26 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
     public ProxyFactory getProxyFactory() {
         return this.proxyFactory;
     }
+
+    /**
+     * Create a NamespacedKey.
+     *
+     * @param key The key.
+     * @return The namespaced key.
+     */
+    @NotNull
+    public NamespacedKey createNamespacedKey(@NotNull final String key) {
+        return this.getNamespacedKeyFactory().create(key);
+    }
+
+    /**
+     * Create a metadata value.
+     *
+     * @param value The value.
+     * @return The metadata value.
+     */
+    @NotNull
+    public FixedMetadataValue createMetadataValue(@NotNull final Object value) {
+        return this.getMetadataValueFactory().create(value);
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/Handler.java

@@ -1,312 +0,0 @@
-package com.willfp.eco.core;
-
-import com.willfp.eco.core.config.updating.ConfigHandler;
-import com.willfp.eco.core.config.wrapper.ConfigFactory;
-import com.willfp.eco.core.data.ExtendedPersistentDataContainer;
-import com.willfp.eco.core.data.ProfileHandler;
-import com.willfp.eco.core.data.keys.KeyRegistry;
-import com.willfp.eco.core.drops.DropQueueFactory;
-import com.willfp.eco.core.entities.ai.EntityController;
-import com.willfp.eco.core.events.EventManager;
-import com.willfp.eco.core.extensions.ExtensionLoader;
-import com.willfp.eco.core.factory.MetadataValueFactory;
-import com.willfp.eco.core.factory.NamespacedKeyFactory;
-import com.willfp.eco.core.factory.RunnableFactory;
-import com.willfp.eco.core.fast.FastItemStack;
-import com.willfp.eco.core.gui.GUIFactory;
-import com.willfp.eco.core.integrations.placeholder.PlaceholderIntegration;
-import com.willfp.eco.core.items.SNBTHandler;
-import com.willfp.eco.core.proxy.Cleaner;
-import com.willfp.eco.core.proxy.ProxyFactory;
-import com.willfp.eco.core.scheduling.Scheduler;
-import net.kyori.adventure.platform.bukkit.BukkitAudiences;
-import org.bukkit.Location;
-import org.bukkit.NamespacedKey;
-import org.bukkit.entity.Entity;
-import org.bukkit.entity.Mob;
-import org.bukkit.inventory.ItemStack;
-import org.bukkit.persistence.PersistentDataContainer;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.List;
-import java.util.logging.Logger;
-
-/**
- * @see Eco#getHandler()
- */
-@ApiStatus.Internal
-public interface Handler {
-    /**
-     * Create a scheduler.
-     *
-     * @param plugin The plugin.
-     * @return The scheduler.
-     */
-    @NotNull
-    Scheduler createScheduler(@NotNull EcoPlugin plugin);
-
-    /**
-     * Create an event manager.
-     *
-     * @param plugin The plugin.
-     * @return The event manager.
-     */
-    @NotNull
-    EventManager createEventManager(@NotNull EcoPlugin plugin);
-
-    /**
-     * Create a NamespacedKey factory.
-     *
-     * @param plugin The plugin.
-     * @return The factory.
-     */
-    @NotNull
-    NamespacedKeyFactory createNamespacedKeyFactory(@NotNull EcoPlugin plugin);
-
-    /**
-     * Create a MetadataValue factory.
-     *
-     * @param plugin The plugin.
-     * @return The factory.
-     */
-    @NotNull
-    MetadataValueFactory createMetadataValueFactory(@NotNull EcoPlugin plugin);
-
-    /**
-     * Create a Runnable factory.
-     *
-     * @param plugin The plugin.
-     * @return The factory.
-     */
-    @NotNull
-    RunnableFactory createRunnableFactory(@NotNull EcoPlugin plugin);
-
-    /**
-     * Create an ExtensionLoader.
-     *
-     * @param plugin The plugin.
-     * @return The factory.
-     */
-    @NotNull
-    ExtensionLoader createExtensionLoader(@NotNull EcoPlugin plugin);
-
-    /**
-     * Create a config handler.
-     *
-     * @param plugin The plugin.
-     * @return The handler.
-     */
-    @NotNull
-    ConfigHandler createConfigHandler(@NotNull EcoPlugin plugin);
-
-    /**
-     * Create a logger.
-     *
-     * @param plugin The plugin.
-     * @return The logger.
-     */
-    @NotNull
-    Logger createLogger(@NotNull EcoPlugin plugin);
-
-    /**
-     * Create a PAPI integration.
-     *
-     * @param plugin The plugin.
-     * @return The integration.
-     */
-    @NotNull
-    PlaceholderIntegration createPAPIIntegration(@NotNull EcoPlugin plugin);
-
-    /**
-     * Create a proxy factory.
-     *
-     * @param plugin The plugin.
-     * @return The factory.
-     */
-    @NotNull
-    ProxyFactory createProxyFactory(@NotNull EcoPlugin plugin);
-
-    /**
-     * Get eco Spigot plugin.
-     *
-     * @return The plugin.
-     */
-    @NotNull
-    EcoPlugin getEcoPlugin();
-
-    /**
-     * Get config factory.
-     *
-     * @return The factory.
-     */
-    @NotNull
-    ConfigFactory getConfigFactory();
-
-    /**
-     * Get drop queue factory.
-     *
-     * @return The factory.
-     */
-    @NotNull
-    DropQueueFactory getDropQueueFactory();
-
-    /**
-     * Get GUI factory.
-     *
-     * @return The factory.
-     */
-    @NotNull
-    GUIFactory getGUIFactory();
-
-    /**
-     * Get cleaner.
-     *
-     * @return The cleaner.
-     */
-    @NotNull
-    Cleaner getCleaner();
-
-    /**
-     * Add new plugin.
-     *
-     * @param plugin The plugin.
-     */
-    void addNewPlugin(@NotNull EcoPlugin plugin);
-
-    /**
-     * Get plugin by name.
-     *
-     * @param name The name.
-     * @return The plugin.
-     */
-    @Nullable
-    EcoPlugin getPluginByName(@NotNull String name);
-
-    /**
-     * Get all loaded eco plugins.
-     *
-     * @return A list of plugin names in lowercase.
-     */
-    @NotNull
-    List<String> getLoadedPlugins();
-
-    /**
-     * Create a FastItemStack.
-     *
-     * @param itemStack The base ItemStack.
-     * @return The FastItemStack.
-     */
-    @NotNull
-    FastItemStack createFastItemStack(@NotNull ItemStack itemStack);
-
-    /**
-     * Register bStats metrics.
-     *
-     * @param plugin The plugin.
-     */
-    void registerBStats(@NotNull EcoPlugin plugin);
-
-    /**
-     * Get Adventure audiences.
-     *
-     * @return The audiences.
-     */
-    @Nullable
-    BukkitAudiences getAdventure();
-
-    /**
-     * Get the key registry.
-     *
-     * @return The registry.
-     */
-    @NotNull
-    KeyRegistry getKeyRegistry();
-
-    /**
-     * Get the PlayerProfile handler.
-     *
-     * @return The handler.
-     */
-    @NotNull
-    ProfileHandler getProfileHandler();
-
-    /**
-     * Create dummy entity - never spawned, exists purely in code.
-     *
-     * @param location The location.
-     * @return The entity.
-     */
-    @NotNull
-    Entity createDummyEntity(@NotNull Location location);
-
-    /**
-     * Create a {@link NamespacedKey} quickly
-     * <p>
-     * Bypasses the constructor, allowing for the creation of invalid keys,
-     * therefore this is considered unsafe and should only be called after
-     * the key has been confirmed to be valid.
-     *
-     * @param namespace The namespace.
-     * @param key       The key.
-     * @return The key.
-     */
-    @NotNull
-    NamespacedKey createNamespacedKey(@NotNull String namespace,
-                                      @NotNull String key);
-
-    /**
-     * Return or get props for a plugin.
-     *
-     * @param existing The existing constructor props.
-     * @param plugin   The plugin.
-     * @return The props.
-     */
-    @NotNull
-    PluginProps getProps(@Nullable PluginProps existing,
-                         @NotNull Class<? extends EcoPlugin> plugin);
-
-    /**
-     * Format a string with MiniMessage.
-     *
-     * @param message The message.
-     * @return The formatted string.
-     */
-    @NotNull
-    String formatMiniMessage(@NotNull String message);
-
-    /**
-     * Create controlled entity from a mob.
-     *
-     * @param mob The mob.
-     * @param <T> The mob type.
-     * @return The controlled entity.
-     */
-    @NotNull <T extends Mob> EntityController<T> createEntityController(@NotNull T mob);
-
-    /**
-     * Adapt base PDC to extended PDC.
-     *
-     * @param container The container.
-     * @return The extended container.
-     */
-    @NotNull
-    ExtendedPersistentDataContainer adaptPdc(@NotNull PersistentDataContainer container);
-
-    /**
-     * Create new PDC.
-     *
-     * @return The container.
-     */
-    @NotNull
-    PersistentDataContainer newPdc();
-
-    /**
-     * Get SNBT handler.
-     *
-     * @return The SNBT handler.
-     */
-    @NotNull
-    SNBTHandler getSNBTHandler();
-}

eco-api/src/main/java/com/willfp/eco/core/PluginDependent.java

@@ -13,7 +13,9 @@ import org.jetbrains.annotations.NotNull;
  * in the constructor.
  *
  * @param <T> The eco plugin type.
+ * @deprecated Leaky inheritance, shouldn't exist.
  */
+@Deprecated(since = "6.43.0", forRemoval = true)
 public abstract class PluginDependent<T extends EcoPlugin> {
     /**
      * The {@link EcoPlugin} that is stored.

eco-api/src/main/java/com/willfp/eco/core/command/CommandBase.java

@@ -1,7 +1,9 @@
 package com.willfp.eco.core.command;
 
+import com.google.common.collect.ImmutableList;
 import com.willfp.eco.core.EcoPlugin;
 import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
@@ -43,8 +45,6 @@ public interface CommandBase {
 
     /**
      * Handle command execution.
-     * <p>
-     * Marked as default void with no implementation for backwards compatibility.
      *
      * @param sender The sender.
      * @param args   The args.
@@ -54,20 +54,43 @@ public interface CommandBase {
         // Do nothing.
     }
 
+    /**
+     * Handle command execution from players.
+     *
+     * @param sender The sender.
+     * @param args   The args.
+     */
+    default void onExecute(@NotNull Player sender,
+                           @NotNull List<String> args) {
+        // Do nothing.
+    }
+
     /**
      * Handle tab completion.
-     * <p>
-     * Marked as default void with no implementation for backwards compatibility.
      *
      * @param sender The sender.
      * @param args   The args.
      * @return The results.
      */
+    @NotNull
     default List<String> tabComplete(@NotNull CommandSender sender,
                                      @NotNull List<String> args) {
         return new ArrayList<>();
     }
 
+    /**
+     * Handle tab completion.
+     *
+     * @param sender The sender.
+     * @param args   The args.
+     * @return The results.
+     */
+    @NotNull
+    default List<String> tabComplete(@NotNull Player sender,
+                                     @NotNull List<String> args) {
+        return new ArrayList<>();
+    }
+
     /**
      * Get the plugin.
      *
@@ -83,7 +106,11 @@ public interface CommandBase {
      * @deprecated Use {@link CommandBase#onExecute(CommandSender, List)} instead.
      */
     @Deprecated(forRemoval = true)
-    CommandHandler getHandler();
+    default CommandHandler getHandler() {
+        return (a, b) -> {
+
+        };
+    }
 
     /**
      * Set the handler.
@@ -93,7 +120,9 @@ public interface CommandBase {
      * @deprecated Handlers have been deprecated.
      */
     @Deprecated(forRemoval = true)
-    void setHandler(@NotNull CommandHandler handler);
+    default void setHandler(@NotNull final CommandHandler handler) {
+        // Do nothing.
+    }
 
     /**
      * Get the tab completer.
@@ -103,7 +132,9 @@ public interface CommandBase {
      * @deprecated Use {@link CommandBase#tabComplete(CommandSender, List)} instead.
      */
     @Deprecated(forRemoval = true)
-    TabCompleteHandler getTabCompleter();
+    default TabCompleteHandler getTabCompleter() {
+        return (a, b) -> ImmutableList.of();
+    }
 
     /**
      * Set the tab completer.
@@ -113,5 +144,7 @@ public interface CommandBase {
      * @deprecated Handlers have been deprecated.
      */
     @Deprecated(forRemoval = true)
-    void setTabCompleter(@NotNull TabCompleteHandler handler);
+    default void setTabCompleter(@NotNull final TabCompleteHandler handler) {
+        // Do nothing.
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/command/impl/DelegatedBukkitCommand.java

@@ -0,0 +1,71 @@
+package com.willfp.eco.core.command.impl;
+
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.command.PluginIdentifiableCommand;
+import org.bukkit.command.TabCompleter;
+import org.bukkit.plugin.Plugin;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+
+/**
+ * Delegates a bukkit command to an eco command (for registrations).
+ */
+public final class DelegatedBukkitCommand extends Command implements TabCompleter, PluginIdentifiableCommand {
+    /**
+     * The delegate command.
+     */
+    private final PluginCommand delegate;
+
+    /**
+     * Create a new delegated command.
+     *
+     * @param delegate The delegate.
+     */
+    public DelegatedBukkitCommand(@NotNull final PluginCommand delegate) {
+        super(delegate.getName());
+
+        this.delegate = delegate;
+    }
+
+    @Override
+    public boolean execute(@NotNull final CommandSender commandSender,
+                           @NotNull final String label,
+                           @NotNull final String[] args) {
+        return delegate.onCommand(commandSender, this, label, args);
+    }
+
+    @Override
+    public List<String> onTabComplete(@NotNull final CommandSender commandSender,
+                                      @NotNull final Command command,
+                                      @NotNull final String label,
+                                      @NotNull final String[] args) {
+        return delegate.onTabComplete(commandSender, command, label, args);
+    }
+
+    @NotNull
+    @Override
+    public Plugin getPlugin() {
+        return this.delegate.getPlugin();
+    }
+
+    @Nullable
+    @Override
+    public String getPermission() {
+        return this.delegate.getPermission();
+    }
+
+    @NotNull
+    @Override
+    public String getDescription() {
+        return this.delegate.getDescription() == null ? "" : this.delegate.getDescription();
+    }
+
+    @NotNull
+    @Override
+    public List<String> getAliases() {
+        return this.delegate.getAliases();
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/command/impl/HandledCommand.java

@@ -145,6 +145,9 @@ abstract class HandledCommand implements CommandBase {
             this.getHandler().onExecute(sender, Arrays.asList(args));
         } else {
             this.onExecute(sender, Arrays.asList(args));
+            if (sender instanceof Player player) {
+                this.onExecute(player, Arrays.asList(args));
+            }
         }
     }
 
@@ -202,7 +205,11 @@ abstract class HandledCommand implements CommandBase {
         if (this.getTabCompleter() != null) {
             return this.getTabCompleter().tabComplete(sender, Arrays.asList(args));
         } else {
-            return this.tabComplete(sender, Arrays.asList(args));
+            List<String> completions = this.tabComplete(sender, Arrays.asList(args));
+            if (sender instanceof Player player) {
+                completions.addAll(this.tabComplete(player, Arrays.asList(args)));
+            }
+            return completions;
         }
     }
 

eco-api/src/main/java/com/willfp/eco/core/command/impl/PluginCommand.java

@@ -1,14 +1,18 @@
 package com.willfp.eco.core.command.impl;
 
+import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.EcoPlugin;
 import org.bukkit.Bukkit;
 import org.bukkit.command.Command;
 import org.bukkit.command.CommandExecutor;
+import org.bukkit.command.CommandMap;
 import org.bukkit.command.CommandSender;
 import org.bukkit.command.TabCompleter;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.lang.reflect.Field;
+import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -38,14 +42,63 @@ public abstract class PluginCommand extends HandledCommand implements CommandExe
 
     /**
      * Registers the command with the server,
-     * <p>
-     * Requires the command name to exist, defined in plugin.yml.
      */
     public final void register() {
         org.bukkit.command.PluginCommand command = Bukkit.getPluginCommand(this.getName());
-        assert command != null;
-        command.setExecutor(this);
-        command.setTabCompleter(this);
+        if (command != null) {
+            command.setExecutor(this);
+            command.setTabCompleter(this);
+
+            if (this.getDescription() != null) {
+                command.setDescription(this.getDescription());
+            }
+
+            List<String> aliases = new ArrayList<>(command.getAliases());
+            aliases.addAll(this.getAliases());
+            command.setAliases(aliases);
+        } else {
+            this.unregister();
+
+            CommandMap commandMap = getCommandMap();
+
+            commandMap.register(this.getPlugin().getName().toLowerCase(), new DelegatedBukkitCommand(this));
+        }
+
+        Eco.get().syncCommands();
+    }
+
+    /**
+     * Unregisters the command from the server.
+     */
+    public final void unregister() {
+        CommandMap commandMap = getCommandMap();
+
+        Command found = commandMap.getCommand(this.getName());
+        if (found != null) {
+            found.unregister(commandMap);
+        }
+
+        Eco.get().syncCommands();
+    }
+
+    /**
+     * Get aliases. Leave null if this command is from plugin.yml.
+     *
+     * @return The aliases.
+     */
+    @NotNull
+    public List<String> getAliases() {
+        return new ArrayList<>();
+    }
+
+    /**
+     * Get description.
+     *
+     * @return The description.
+     */
+    @Nullable
+    public String getDescription() {
+        return null;
     }
 
     /**
@@ -93,4 +146,19 @@ public abstract class PluginCommand extends HandledCommand implements CommandExe
 
         return this.handleTabCompletion(sender, args);
     }
+
+    /**
+     * Get the internal server CommandMap.
+     *
+     * @return The CommandMap.
+     */
+    public static CommandMap getCommandMap() {
+        try {
+            Field field = Bukkit.getServer().getClass().getDeclaredField("commandMap");
+            field.setAccessible(true);
+            return (CommandMap) field.get(Bukkit.getServer());
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            throw new NullPointerException("Command map wasn't found!");
+        }
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/config/BaseConfig.java

@@ -40,7 +40,7 @@ public abstract class BaseConfig extends LoadableConfigWrapper {
                          final boolean removeUnused,
                          @NotNull final ConfigType type,
                          final boolean requiresChangeToSave) {
-        super(Eco.getHandler().getConfigFactory().createUpdatableConfig(
+        super(Eco.get().createUpdatableConfig(
                 configName,
                 plugin,
                 "",

eco-api/src/main/java/com/willfp/eco/core/config/BuildableConfig.java

@@ -6,12 +6,12 @@ import org.jetbrains.annotations.Nullable;
 /**
  * Builder for configs to create them programmatically.
  */
-public class BuildableConfig extends TransientConfig {
+public class BuildableConfig extends GenericConfig {
     /**
      * Create a new empty config builder.
      */
     public BuildableConfig() {
-        super();
+
     }
 
     /**

eco-api/src/main/java/com/willfp/eco/core/config/ConfigType.java

@@ -14,7 +14,12 @@ public enum ConfigType {
     /**
      * .yml config.
      */
-    YAML("yml");
+    YAML("yml"),
+
+    /**
+     * .toml config.
+     */
+    TOML("toml");
 
     /**
      * The file extension.

eco-api/src/main/java/com/willfp/eco/core/config/Configs.java

@@ -0,0 +1,157 @@
+package com.willfp.eco.core.config;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.config.interfaces.Config;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.file.Files;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Utilities / API methods for configs.
+ */
+public final class Configs {
+    /**
+     * Load a Config from a bukkit {@link ConfigurationSection}.
+     *
+     * @param config The ConfigurationSection.
+     * @return The config.
+     */
+    @NotNull
+    public static Config fromBukkit(@Nullable final ConfigurationSection config) {
+        return config == null ? empty() : Eco.get().wrapConfigurationSection(config);
+    }
+
+    /**
+     * Load a config from an {@link InputStream}.
+     * <p>
+     * Only for yaml configs.
+     *
+     * @param stream The InputStream.
+     * @return The config.
+     */
+    @NotNull
+    public static Config fromStream(@Nullable final InputStream stream) {
+        return stream != null ? fromBukkit(YamlConfiguration.loadConfiguration(
+                new InputStreamReader(stream)
+        )) : empty();
+    }
+
+    /**
+     * Load a config from a file.
+     *
+     * @param file The file.
+     * @return The config.
+     */
+    @NotNull
+    public static Config fromFile(@Nullable final File file) {
+        if (file == null) {
+            return empty();
+        }
+
+        int lastIndex = file.getName().lastIndexOf(".");
+
+        if (lastIndex < 0) {
+            return empty();
+        }
+
+        for (ConfigType type : ConfigType.values()) {
+            if (file.getName().substring(lastIndex + 1).equalsIgnoreCase(type.getExtension())) {
+                return fromFile(file, type);
+            }
+        }
+
+        return empty();
+    }
+
+    /**
+     * Load a config from a file.
+     *
+     * @param file The file.
+     * @param type The type.
+     * @return The config.
+     */
+    @NotNull
+    public static Config fromFile(@Nullable final File file,
+                                  @NotNull final ConfigType type) {
+        if (file == null) {
+            return empty();
+        }
+
+        try {
+            return Eco.get().createConfig(Files.readString(file.toPath()), type);
+        } catch (IOException e) {
+            return empty();
+        }
+    }
+
+    /**
+     * Load config from map (uses {@link ConfigType#JSON}).
+     *
+     * @param values The values.
+     * @return The config.
+     */
+    @NotNull
+    public static Config fromMap(@NotNull final Map<String, Object> values) {
+        return fromMap(values, ConfigType.JSON);
+    }
+
+    /**
+     * Load config from map.
+     *
+     * @param values The values.
+     * @param type   The type.
+     * @return The config.
+     */
+    @NotNull
+    public static Config fromMap(@NotNull final Map<String, Object> values,
+                                 @NotNull final ConfigType type) {
+        return Eco.get().createConfig(values, type);
+    }
+
+    /**
+     * Create empty config (uses {@link ConfigType#JSON}).
+     *
+     * @return An empty config.
+     */
+    @NotNull
+    public static Config empty() {
+        return fromMap(new HashMap<>(), ConfigType.JSON);
+    }
+
+    /**
+     * Create empty config.
+     *
+     * @param type The type.
+     * @return An empty config.
+     */
+    @NotNull
+    public static Config empty(@NotNull final ConfigType type) {
+        return fromMap(new HashMap<>(), type);
+    }
+
+    /**
+     * Load config from string.
+     *
+     * @param contents The contents of the config.
+     * @param type     The config type.
+     * @return The config.
+     */
+    @NotNull
+    public static Config fromString(@NotNull final String contents,
+                                    @NotNull final ConfigType type) {
+        return Eco.get().createConfig(contents, type);
+    }
+
+    private Configs() {
+        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/config/ExtendableConfig.java

@@ -31,7 +31,7 @@ public abstract class ExtendableConfig extends LoadableConfigWrapper {
                                @NotNull final String subDirectoryPath,
                                @NotNull final ConfigType type,
                                @NotNull final String... updateBlacklist) {
-        super(Eco.getHandler().getConfigFactory().createUpdatableConfig(
+        super(Eco.get().createUpdatableConfig(
                 configName,
                 plugin,
                 subDirectoryPath,

eco-api/src/main/java/com/willfp/eco/core/config/GenericConfig.java

@@ -0,0 +1,27 @@
+package com.willfp.eco.core.config;
+
+import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.config.wrapper.ConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Generic config to simplify creating custom configs without having
+ * to meddle with delegation.
+ */
+public abstract class GenericConfig extends ConfigWrapper<Config> {
+    /**
+     * Create a new generic config.
+     */
+    protected GenericConfig() {
+        super(Configs.empty());
+    }
+
+    /**
+     * Create a new generic config.
+     *
+     * @param type The config type.
+     */
+    protected GenericConfig(@NotNull final ConfigType type) {
+        super(Configs.empty(type));
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/config/StaticBaseConfig.java

@@ -21,7 +21,7 @@ public abstract class StaticBaseConfig extends LoadableConfigWrapper {
     protected StaticBaseConfig(@NotNull final String configName,
                                @NotNull final PluginLike plugin,
                                @NotNull final ConfigType type) {
-        super(Eco.getHandler().getConfigFactory().createLoadableConfig(
+        super(Eco.get().createLoadableConfig(
                 configName,
                 plugin,
                 "",

eco-api/src/main/java/com/willfp/eco/core/config/TransientConfig.java

@@ -20,13 +20,16 @@ import java.util.Map;
  * Config that exists purely in the code, not linked to any file.
  * <p>
  * Use for inline configs to move data around or to add subsections to other configs.
+ *
+ * @deprecated Poorly named class, makes the config system seem needlessly complicated.
  */
+@Deprecated(since = "6.44.0", forRemoval = true)
 public class TransientConfig extends ConfigWrapper<Config> {
     /**
      * @param config The ConfigurationSection handle.
      */
     public TransientConfig(@NotNull final ConfigurationSection config) {
-        super(Eco.getHandler().getConfigFactory().createConfig(config));
+        super(Eco.get().wrapConfigurationSection(config));
     }
 
     /**
@@ -42,7 +45,7 @@ public class TransientConfig extends ConfigWrapper<Config> {
      * @param stream The InputStream.
      */
     public TransientConfig(@Nullable final InputStream stream) {
-        super(stream != null ? Eco.getHandler().getConfigFactory().createConfig(YamlConfiguration.loadConfiguration(
+        super(stream != null ? Eco.get().wrapConfigurationSection(YamlConfiguration.loadConfiguration(
                 new InputStreamReader(stream)
         )) : new TransientConfig());
     }
@@ -62,7 +65,7 @@ public class TransientConfig extends ConfigWrapper<Config> {
      */
     public TransientConfig(@Nullable final File file,
                            @NotNull final ConfigType type) {
-        super(file != null ? Eco.getHandler().getConfigFactory().createConfig(readFile(file), type)
+        super(file != null ? Eco.get().createConfig(readFile(file), type)
                 : new TransientConfig());
     }
 
@@ -72,7 +75,7 @@ public class TransientConfig extends ConfigWrapper<Config> {
      * @param values The values.
      */
     public TransientConfig(@NotNull final Map<String, Object> values) {
-        super(Eco.getHandler().getConfigFactory().createConfig(values, ConfigType.YAML));
+        super(Eco.get().createConfig(values, ConfigType.YAML));
     }
 
     /**
@@ -83,7 +86,7 @@ public class TransientConfig extends ConfigWrapper<Config> {
      */
     public TransientConfig(@NotNull final Map<String, Object> values,
                            @NotNull final ConfigType type) {
-        super(Eco.getHandler().getConfigFactory().createConfig(values, type));
+        super(Eco.get().createConfig(values, type));
     }
 
     /**
@@ -99,7 +102,7 @@ public class TransientConfig extends ConfigWrapper<Config> {
      */
     public TransientConfig(@NotNull final String contents,
                            @NotNull final ConfigType type) {
-        super(Eco.getHandler().getConfigFactory().createConfig(contents, type));
+        super(Eco.get().createConfig(contents, type));
     }
 
     /**

eco-api/src/main/java/com/willfp/eco/core/config/interfaces/Config.java

@@ -2,7 +2,7 @@ package com.willfp.eco.core.config.interfaces;
 
 import com.willfp.eco.core.config.BuildableConfig;
 import com.willfp.eco.core.config.ConfigType;
-import com.willfp.eco.core.config.TransientConfig;
+import com.willfp.eco.core.config.Configs;
 import com.willfp.eco.core.placeholder.AdditionalPlayer;
 import com.willfp.eco.core.placeholder.InjectablePlaceholder;
 import com.willfp.eco.core.placeholder.PlaceholderInjectable;
@@ -103,7 +103,7 @@ public interface Config extends Cloneable, PlaceholderInjectable {
      */
     @NotNull
     default Config getSubsection(@NotNull String path) {
-        return Objects.requireNonNullElse(getSubsectionOrNull(path), new TransientConfig());
+        return Objects.requireNonNullElse(getSubsectionOrNull(path), Configs.empty());
     }
 
     /**

eco-api/src/main/java/com/willfp/eco/core/config/wrapper/ConfigFactory.java

@@ -1,87 +0,0 @@
-package com.willfp.eco.core.config.wrapper;
-
-import com.willfp.eco.core.Eco;
-import com.willfp.eco.core.PluginLike;
-import com.willfp.eco.core.config.ConfigType;
-import com.willfp.eco.core.config.interfaces.Config;
-import com.willfp.eco.core.config.interfaces.LoadableConfig;
-import org.bukkit.configuration.ConfigurationSection;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Map;
-
-/**
- * Internal component to create backend config implementations.
- */
-@ApiStatus.Internal
-@Eco.HandlerComponent
-public interface ConfigFactory {
-    /**
-     * Updatable config.
-     *
-     * @param configName            The name of the config
-     * @param plugin                The plugin.
-     * @param subDirectoryPath      The subdirectory path.
-     * @param source                The class that owns the resource.
-     * @param removeUnused          Whether keys not present in the default config should be removed on update.
-     * @param type                  The config type.
-     * @param updateBlacklist       Substring of keys to not add/remove keys for.
-     * @param requiresChangesToSave If the config must be changed in order to save the config.
-     * @return The config implementation.
-     */
-    LoadableConfig createUpdatableConfig(@NotNull String configName,
-                                         @NotNull PluginLike plugin,
-                                         @NotNull String subDirectoryPath,
-                                         @NotNull Class<?> source,
-                                         boolean removeUnused,
-                                         @NotNull ConfigType type,
-                                         boolean requiresChangesToSave,
-                                         @NotNull String... updateBlacklist);
-
-    /**
-     * Loadable config.
-     *
-     * @param configName            The name of the config
-     * @param plugin                The plugin.
-     * @param subDirectoryPath      The subdirectory path.
-     * @param source                The class that owns the resource.
-     * @param type                  The config type.
-     * @param requiresChangesToSave If the config must be changed in order to save the config.
-     * @return The config implementation.
-     */
-    LoadableConfig createLoadableConfig(@NotNull String configName,
-                                        @NotNull PluginLike plugin,
-                                        @NotNull String subDirectoryPath,
-                                        @NotNull Class<?> source,
-                                        @NotNull ConfigType type,
-                                        boolean requiresChangesToSave);
-
-    /**
-     * Create config.
-     *
-     * @param config The handle.
-     * @return The config implementation.
-     */
-    Config createConfig(@NotNull ConfigurationSection config);
-
-    /**
-     * Create config.
-     *
-     * @param values The values.
-     * @param type   The config type.
-     * @return The config implementation.
-     */
-    Config createConfig(@NotNull Map<String, Object> values,
-                        @NotNull ConfigType type);
-
-    /**
-     * Create config.
-     *
-     * @param contents The file contents.
-     * @param type     The type.
-     * @return The config implementation.
-     */
-    Config createConfig(@NotNull String contents,
-                        @NotNull ConfigType type);
-}

eco-api/src/main/java/com/willfp/eco/core/data/ExtendedPersistentDataContainer.java

@@ -87,7 +87,7 @@ public interface ExtendedPersistentDataContainer {
      * @return The extended container.
      */
     static ExtendedPersistentDataContainer extend(@NotNull PersistentDataContainer base) {
-        return Eco.getHandler().adaptPdc(base);
+        return Eco.get().adaptPdc(base);
     }
 
     /**
@@ -96,6 +96,6 @@ public interface ExtendedPersistentDataContainer {
      * @return The extended container.
      */
     static ExtendedPersistentDataContainer create() {
-        return extend(Eco.getHandler().newPdc());
+        return extend(Eco.get().newPdc());
     }
 }

eco-api/src/main/java/com/willfp/eco/core/data/PlayerProfile.java

@@ -31,6 +31,6 @@ public interface PlayerProfile extends Profile {
      */
     @NotNull
     static PlayerProfile load(@NotNull final UUID uuid) {
-        return Eco.getHandler().getProfileHandler().load(uuid);
+        return Eco.get().loadPlayerProfile(uuid);
     }
 }

eco-api/src/main/java/com/willfp/eco/core/data/ProfileHandler.java

@@ -1,94 +0,0 @@
-package com.willfp.eco.core.data;
-
-import com.willfp.eco.core.Eco;
-import com.willfp.eco.core.data.keys.PersistentDataKey;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Set;
-import java.util.UUID;
-
-/**
- * API to handle profiles.
- */
-@ApiStatus.Internal
-@Eco.HandlerComponent
-public interface ProfileHandler {
-    /**
-     * Load a player profile.
-     *
-     * @param uuid The UUID.
-     * @return The profile.
-     */
-    PlayerProfile load(@NotNull UUID uuid);
-
-    /**
-     * Load the server profile.
-     *
-     * @return The profile.
-     */
-    ServerProfile loadServerProfile();
-
-    /**
-     * Unload a player profile from memory.
-     * <p>
-     * This will not save the profile first.
-     *
-     * @param uuid The uuid.
-     */
-    void unloadPlayer(@NotNull UUID uuid);
-
-    /**
-     * Save a player profile.
-     * <p>
-     * Can run async if using MySQL.
-     *
-     * @param uuid The uuid.
-     * @deprecated Saving changes is faster and should be used. Saving a player manually is not recommended.
-     */
-    @Deprecated
-    default void savePlayer(@NotNull UUID uuid) {
-        this.saveKeysFor(uuid, PersistentDataKey.values());
-    }
-
-    /**
-     * Save keys for a player.
-     * <p>
-     * Can run async if using MySQL.
-     *
-     * @param uuid The uuid.
-     * @param keys The keys.
-     */
-    void saveKeysFor(@NotNull UUID uuid,
-                     @NotNull Set<PersistentDataKey<?>> keys);
-
-    /**
-     * Save all player data.
-     *
-     * @param async If the saving should be done asynchronously.
-     * @deprecated async is now handled automatically depending on implementation.
-     */
-    @Deprecated(forRemoval = true)
-    default void saveAll(boolean async) {
-        saveAll();
-    }
-
-    /**
-     * Save all player data.
-     * <p>
-     * Can run async if using MySQL.
-     *
-     * @deprecated Never used.
-     */
-    @Deprecated(since = "6.36.0", forRemoval = true)
-    default void saveAll() {
-        // Do nothing.
-    }
-
-    /**
-     * Commit all changes to the file.
-     * <p>
-     * Does nothing if using MySQL.
-     */
-    void save();
-}

eco-api/src/main/java/com/willfp/eco/core/data/ServerProfile.java

@@ -16,6 +16,6 @@ public interface ServerProfile extends Profile {
      */
     @NotNull
     static ServerProfile load() {
-        return Eco.getHandler().getProfileHandler().loadServerProfile();
+        return Eco.get().getServerProfile();
     }
 }

eco-api/src/main/java/com/willfp/eco/core/data/keys/KeyRegistry.java

@@ -1,39 +0,0 @@
-package com.willfp.eco.core.data.keys;
-
-import com.willfp.eco.core.Eco;
-import org.bukkit.NamespacedKey;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.Set;
-
-/**
- * API to register persistent data keys.
- */
-@ApiStatus.Internal
-@Eco.HandlerComponent
-public interface KeyRegistry {
-    /**
-     * Register a persistent data key to be stored.
-     *
-     * @param key The key.
-     */
-    void registerKey(@NotNull PersistentDataKey<?> key);
-
-    /**
-     * Get all registered keys.
-     *
-     * @return The keys.
-     */
-    Set<PersistentDataKey<?>> getRegisteredKeys();
-
-    /**
-     * Get persistent data key from namespaced key.
-     *
-     * @param namespacedKey The key.
-     * @return The key, or null if not found.
-     */
-    @Nullable
-    PersistentDataKey<?> getKeyFrom(@NotNull NamespacedKey namespacedKey);
-}

eco-api/src/main/java/com/willfp/eco/core/data/keys/PersistentDataKey.java

@@ -43,7 +43,7 @@ public final class PersistentDataKey<T> {
         this.defaultValue = defaultValue;
         this.type = type;
 
-        Eco.getHandler().getKeyRegistry().registerKey(this);
+        Eco.get().registerPersistentKey(this);
     }
 
     @Override
@@ -126,7 +126,7 @@ public final class PersistentDataKey<T> {
      * @return The keys.
      */
     public static Set<PersistentDataKey<?>> values() {
-        return Eco.getHandler().getKeyRegistry().getRegisteredKeys();
+        return Eco.get().getRegisteredPersistentDataKeys();
     }
 
     @Override

eco-api/src/main/java/com/willfp/eco/core/data/keys/PersistentDataKeyType.java

@@ -1,5 +1,6 @@
 package com.willfp.eco.core.data.keys;
 
+import com.willfp.eco.core.config.interfaces.Config;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -43,6 +44,11 @@ public final class PersistentDataKeyType<T> {
      */
     public static final PersistentDataKeyType<List<String>> STRING_LIST = new PersistentDataKeyType<>(null, "STRING_LIST");
 
+    /**
+     * Config.
+     */
+    public static final PersistentDataKeyType<Config> CONFIG = new PersistentDataKeyType<>(Config.class, "CONFIG");
+
     /**
      * The class of the type.
      */

eco-api/src/main/java/com/willfp/eco/core/display/Display.java

@@ -1,11 +1,21 @@
 package com.willfp.eco.core.display;
 
+import com.willfp.eco.core.fast.FastItemStack;
+import com.willfp.eco.util.NamespacedKeyUtils;
+import org.bukkit.NamespacedKey;
 import org.bukkit.entity.Player;
+import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.ItemStack;
-import org.jetbrains.annotations.ApiStatus;
+import org.bukkit.persistence.PersistentDataType;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
 /**
  * Utility class to manage client-side item display.
  */
@@ -16,9 +26,14 @@ public final class Display {
     public static final String PREFIX = "§z";
 
     /**
-     * The display handler.
+     * All registered modules.
      */
-    private static DisplayHandler handler = null;
+    private static final Map<Integer, List<DisplayModule>> REGISTERED_MODULES = new TreeMap<>();
+
+    /**
+     * The finalize key.
+     */
+    private static final NamespacedKey FINALIZE_KEY = NamespacedKeyUtils.createEcoKey("finalized");
 
     /**
      * Display on ItemStacks.
@@ -39,7 +54,49 @@ public final class Display {
      */
     public static ItemStack display(@NotNull final ItemStack itemStack,
                                     @Nullable final Player player) {
-        return handler.display(itemStack, player);
+        Map<String, Object[]> pluginVarArgs = new HashMap<>();
+
+        for (List<DisplayModule> modules : REGISTERED_MODULES.values()) {
+            for (DisplayModule module : modules) {
+                pluginVarArgs.put(module.getPluginName(), module.generateVarArgs(itemStack));
+            }
+        }
+
+        Display.revert(itemStack);
+
+        if (!itemStack.hasItemMeta()) {
+            return itemStack;
+        }
+
+        ItemStack original = itemStack.clone();
+        Inventory inventory = player == null ? null : player.getOpenInventory().getTopInventory();
+        boolean inInventory = inventory != null && inventory.contains(original);
+        boolean inGui = inventory != null && inventory.getHolder() == null;
+
+        DisplayProperties properties = new DisplayProperties(
+                inInventory,
+                inGui,
+                original
+        );
+
+        for (List<DisplayModule> modules : REGISTERED_MODULES.values()) {
+            for (DisplayModule module : modules) {
+                Object[] varargs = pluginVarArgs.get(module.getPluginName());
+
+                if (varargs == null) {
+                    continue;
+                }
+
+                module.display(itemStack, varargs);
+
+                if (player != null) {
+                    module.display(itemStack, player, varargs);
+                    module.display(itemStack, player, properties, varargs);
+                }
+            }
+        }
+
+        return itemStack;
     }
 
     /**
@@ -71,7 +128,25 @@ public final class Display {
      * @return The ItemStack.
      */
     public static ItemStack revert(@NotNull final ItemStack itemStack) {
-        return handler.revert(itemStack);
+        if (Display.isFinalized(itemStack)) {
+            Display.unfinalize(itemStack);
+        }
+
+        FastItemStack fast = FastItemStack.wrap(itemStack);
+
+        List<String> lore = fast.getLore();
+
+        if (!lore.isEmpty() && lore.removeIf(line -> line.startsWith(Display.PREFIX))) {
+            fast.setLore(lore);
+        }
+
+        for (List<DisplayModule> modules : REGISTERED_MODULES.values()) {
+            for (DisplayModule module : modules) {
+                module.revert(itemStack);
+            }
+        }
+
+        return itemStack;
     }
 
     /**
@@ -81,7 +156,15 @@ public final class Display {
      * @return The ItemStack.
      */
     public static ItemStack finalize(@NotNull final ItemStack itemStack) {
-        return handler.finalize(itemStack);
+        if (itemStack.getType().getMaxStackSize() > 1) {
+            return itemStack;
+        }
+
+        FastItemStack.wrap(itemStack)
+                .getPersistentDataContainer()
+                .set(FINALIZE_KEY, PersistentDataType.INTEGER, 1);
+
+        return itemStack;
     }
 
     /**
@@ -91,7 +174,11 @@ public final class Display {
      * @return The ItemStack.
      */
     public static ItemStack unfinalize(@NotNull final ItemStack itemStack) {
-        return handler.unfinalize(itemStack);
+        FastItemStack.wrap(itemStack)
+                .getPersistentDataContainer()
+                .remove(FINALIZE_KEY);
+
+        return itemStack;
     }
 
     /**
@@ -101,7 +188,9 @@ public final class Display {
      * @return If finalized.
      */
     public static boolean isFinalized(@NotNull final ItemStack itemStack) {
-        return handler.isFinalized(itemStack);
+        return FastItemStack.wrap(itemStack)
+                .getPersistentDataContainer()
+                .has(FINALIZE_KEY, PersistentDataType.INTEGER);
     }
 
     /**
@@ -110,23 +199,15 @@ public final class Display {
      * @param module The module.
      */
     public static void registerDisplayModule(@NotNull final DisplayModule module) {
-        handler.registerDisplayModule(module);
-    }
+        List<DisplayModule> modules = REGISTERED_MODULES.getOrDefault(
+                module.getWeight(),
+                new ArrayList<>()
+        );
 
-    /**
-     * Set the display handler.
-     * <p>
-     * Internal API component, you will cause bugs if you create your own handler.
-     *
-     * @param handler The handler.
-     */
-    @ApiStatus.Internal
-    public static void setHandler(@NotNull final DisplayHandler handler) {
-        if (Display.handler != null) {
-            throw new IllegalStateException("Display already initialized!");
-        }
+        modules.removeIf(it -> it.getPluginName().equalsIgnoreCase(module.getPluginName()));
+        modules.add(module);
 
-        Display.handler = handler;
+        REGISTERED_MODULES.put(module.getWeight(), modules);
     }
 
     private Display() {

eco-api/src/main/java/com/willfp/eco/core/display/DisplayHandler.java

@@ -1,64 +0,0 @@
-package com.willfp.eco.core.display;
-
-import com.willfp.eco.core.Eco;
-import org.bukkit.entity.Player;
-import org.bukkit.inventory.ItemStack;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-/**
- * Interface for display implementations.
- */
-@ApiStatus.Internal
-@Eco.HandlerComponent
-public interface DisplayHandler {
-    /**
-     * Register display module.
-     *
-     * @param module The module.
-     */
-    void registerDisplayModule(@NotNull DisplayModule module);
-
-    /**
-     * Display on ItemStacks.
-     *
-     * @param itemStack The item.
-     * @param player    The player.
-     * @return The ItemStack.
-     */
-    ItemStack display(@NotNull ItemStack itemStack,
-                      @Nullable Player player);
-
-    /**
-     * Revert on ItemStacks.
-     *
-     * @param itemStack The item.
-     * @return The ItemStack.
-     */
-    ItemStack revert(@NotNull ItemStack itemStack);
-
-    /**
-     * Finalize an ItemStacks.
-     *
-     * @param itemStack The item.
-     * @return The ItemStack.
-     */
-    ItemStack finalize(@NotNull ItemStack itemStack);
-
-    /**
-     * Unfinalize an ItemStacks.
-     *
-     * @param itemStack The item.
-     * @return The ItemStack.
-     */
-    ItemStack unfinalize(@NotNull ItemStack itemStack);
-
-    /**
-     * If an item is finalized.
-     *
-     * @param itemStack The item.
-     * @return If finalized.
-     */
-    boolean isFinalized(@NotNull ItemStack itemStack);
-}

eco-api/src/main/java/com/willfp/eco/core/display/DisplayModule.java

@@ -1,7 +1,6 @@
 package com.willfp.eco.core.display;
 
 import com.willfp.eco.core.EcoPlugin;
-import com.willfp.eco.core.PluginDependent;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
@@ -10,12 +9,17 @@ import org.jetbrains.annotations.Nullable;
 /**
  * Class for all plugin-specific client-side item display modules.
  */
-public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
+public abstract class DisplayModule {
     /**
      * The priority of the module.
      */
     private final int weight;
 
+    /**
+     * The plugin.
+     */
+    private final EcoPlugin plugin;
+
     /**
      * Create a new display module.
      *
@@ -24,8 +28,7 @@ public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
      */
     protected DisplayModule(@NotNull final EcoPlugin plugin,
                             @NotNull final DisplayPriority priority) {
-        super(plugin);
-        this.weight = priority.getWeight();
+        this(plugin, priority.getWeight());
     }
 
     /**
@@ -36,7 +39,7 @@ public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
      */
     protected DisplayModule(@NotNull final EcoPlugin plugin,
                             final int weight) {
-        super(plugin);
+        this.plugin = plugin;
         this.weight = weight;
     }
 
@@ -104,7 +107,7 @@ public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
      * @return The plugin name.
      */
     public final String getPluginName() {
-        return super.getPlugin().getName();
+        return this.getPlugin().getName();
     }
 
     /**
@@ -132,4 +135,13 @@ public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
     public int getWeight() {
         return this.weight;
     }
+
+    /**
+     * Get the plugin.
+     *
+     * @return The plugin.
+     */
+    public EcoPlugin getPlugin() {
+        return plugin;
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/drops/DropQueue.java

@@ -21,13 +21,25 @@ public class DropQueue {
     /**
      * The internally used {@link DropQueue}.
      */
-    private final InternalDropQueue handle;
+    private final DropQueue delegate;
 
     /**
+     * Create a new DropQueue.
+     *
      * @param player The player.
      */
     public DropQueue(@NotNull final Player player) {
-        handle = Eco.getHandler().getDropQueueFactory().create(player);
+        this.delegate = Eco.get().createDropQueue(player);
+    }
+
+    /**
+     * Create a new DropQueue with no delegate.
+     * <p>
+     * Call this constructor if you're creating custom DropQueue
+     * implementations.
+     */
+    protected DropQueue() {
+        this.delegate = null;
     }
 
     /**
@@ -37,7 +49,11 @@ public class DropQueue {
      * @return The DropQueue.
      */
     public DropQueue addItem(@NotNull final ItemStack item) {
-        handle.addItem(item);
+        if (delegate == null) {
+            return this;
+        }
+
+        delegate.addItem(item);
         return this;
     }
 
@@ -48,7 +64,11 @@ public class DropQueue {
      * @return The DropQueue.
      */
     public DropQueue addItems(@NotNull final Collection<ItemStack> itemStacks) {
-        handle.addItems(itemStacks);
+        if (delegate == null) {
+            return this;
+        }
+
+        delegate.addItems(itemStacks);
         return this;
     }
 
@@ -59,7 +79,11 @@ public class DropQueue {
      * @return The DropQueue.
      */
     public DropQueue addXP(final int amount) {
-        handle.addXP(amount);
+        if (delegate == null) {
+            return this;
+        }
+
+        delegate.addXP(amount);
         return this;
     }
 
@@ -70,7 +94,11 @@ public class DropQueue {
      * @return The DropQueue.
      */
     public DropQueue setLocation(@NotNull final Location location) {
-        handle.setLocation(location);
+        if (delegate == null) {
+            return this;
+        }
+
+        delegate.setLocation(location);
         return this;
     }
 
@@ -80,7 +108,11 @@ public class DropQueue {
      * @return The DropQueue.
      */
     public DropQueue forceTelekinesis() {
-        handle.forceTelekinesis();
+        if (delegate == null) {
+            return this;
+        }
+
+        delegate.forceTelekinesis();
         return this;
     }
 
@@ -88,6 +120,10 @@ public class DropQueue {
      * Push the queue.
      */
     public void push() {
-        handle.push();
+        if (delegate == null) {
+            return;
+        }
+
+        delegate.push();
     }
 }

eco-api/src/main/java/com/willfp/eco/core/drops/DropQueueFactory.java

@@ -1,21 +0,0 @@
-package com.willfp.eco.core.drops;
-
-import com.willfp.eco.core.Eco;
-import org.bukkit.entity.Player;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-
-/**
- * Internal component to create backend DropQueue implementations.
- */
-@ApiStatus.Internal
-@Eco.HandlerComponent
-public interface DropQueueFactory {
-    /**
-     * Create a DropQueue.
-     *
-     * @param player The player.
-     * @return The Queue.
-     */
-    InternalDropQueue create(@NotNull Player player);
-}

eco-api/src/main/java/com/willfp/eco/core/drops/InternalDropQueue.java

@@ -1,60 +0,0 @@
-package com.willfp.eco.core.drops;
-
-import com.willfp.eco.core.Eco;
-import org.bukkit.Location;
-import org.bukkit.inventory.ItemStack;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Collection;
-
-/**
- * Internal interface for backend DropQueue implementations.
- */
-@ApiStatus.Internal
-@Eco.HandlerComponent
-public interface InternalDropQueue {
-    /**
-     * Add item to queue.
-     *
-     * @param item The item to add.
-     * @return The DropQueue.
-     */
-    InternalDropQueue addItem(@NotNull ItemStack item);
-
-    /**
-     * Add multiple items to queue.
-     *
-     * @param itemStacks The items to add.
-     * @return The DropQueue.
-     */
-    InternalDropQueue addItems(@NotNull Collection<ItemStack> itemStacks);
-
-    /**
-     * Add xp to queue.
-     *
-     * @param amount The amount to add.
-     * @return The DropQueue.
-     */
-    InternalDropQueue addXP(int amount);
-
-    /**
-     * Set location of the origin of the drops.
-     *
-     * @param location The location.
-     * @return The DropQueue.
-     */
-    InternalDropQueue setLocation(@NotNull Location location);
-
-    /**
-     * Force the queue to act as if player is telekinetic.
-     *
-     * @return The DropQueue.
-     */
-    InternalDropQueue forceTelekinesis();
-
-    /**
-     * Push the queue.
-     */
-    void push();
-}

eco-api/src/main/java/com/willfp/eco/core/entities/ai/EntityController.java

@@ -101,6 +101,6 @@ public interface EntityController<T extends Mob> {
      * @return The entity controller.
      */
     static <T extends Mob> EntityController<T> getFor(@NotNull final T entity) {
-        return Eco.getHandler().createEntityController(entity);
+        return Eco.get().createEntityController(entity);
     }
 }

eco-api/src/main/java/com/willfp/eco/core/entities/impl/EmptyTestableEntity.java

@@ -28,6 +28,6 @@ public class EmptyTestableEntity implements TestableEntity {
     public Entity spawn(@NotNull final Location location) {
         Validate.notNull(location.getWorld());
 
-        return Eco.getHandler().createDummyEntity(location);
+        return Eco.get().createDummyEntity(location);
     }
 }

eco-api/src/main/java/com/willfp/eco/core/extensions/ExtensionLoader.java

@@ -3,7 +3,7 @@ package com.willfp.eco.core.extensions;
 import java.util.Set;
 
 /**
- * Internal component to manage loading and unloading extensions.
+ * Manages the loading and unloading of extensions for a particular plugin.
  */
 public interface ExtensionLoader {
     /**

eco-api/src/main/java/com/willfp/eco/core/fast/FastItemStack.java

@@ -72,6 +72,7 @@ public interface FastItemStack extends PersistentDataHolder {
      * @deprecated Poorly named method. Use getEnchantmentLevel instead.
      */
     @Deprecated(since = "6.34.0", forRemoval = true)
+    @SuppressWarnings("DeprecatedIsStillUsed")
     default int getLevelOnItem(@NotNull Enchantment enchantment,
                                boolean checkStored) {
         return getEnchantmentLevel(enchantment, checkStored);
@@ -271,6 +272,6 @@ public interface FastItemStack extends PersistentDataHolder {
      * @return The FastItemStack.
      */
     static FastItemStack wrap(@Nullable final ItemStack itemStack) {
-        return Eco.getHandler().createFastItemStack(Objects.requireNonNullElseGet(itemStack, () -> new ItemStack(Material.AIR)));
+        return Eco.get().createFastItemStack(Objects.requireNonNullElseGet(itemStack, () -> new ItemStack(Material.AIR)));
     }
 }

eco-api/src/main/java/com/willfp/eco/core/gui/GUIComponent.java

@@ -0,0 +1,82 @@
+package com.willfp.eco.core.gui;
+
+import com.willfp.eco.core.gui.menu.Menu;
+import com.willfp.eco.core.gui.slot.Slot;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * A GUI Component is a 2-dimensional set of slots that can be
+ * placed in a menu.
+ */
+public interface GUIComponent {
+    /**
+     * Get the amount of rows in the component.
+     *
+     * @return The rows.
+     */
+    int getRows();
+
+    /**
+     * Get the amount of columns in the component.
+     *
+     * @return The columns.
+     */
+    int getColumns();
+
+    /**
+     * Initialize the component.
+     * <p>
+     * This is called before getRows / getColumns is queried,
+     * and allows for dynamically sized components.
+     * <p>
+     * getRows and getColumns can return values bigger than this,
+     * it will simply prevent the component from being added at
+     * this position (for minimum-sized components).
+     *
+     * @param maxRows    The maximum number of rows.
+     * @param maxColumns The maximum number of columns.
+     */
+    default void init(final int maxRows,
+                      final int maxColumns) {
+        // Most components will not require initialization.
+    }
+
+    /**
+     * Get the slot at a certain position in the component.
+     * <p>
+     * It's safe to assume to the row and column will always be in bounds.
+     *
+     * @param row    The row (1-indexed).
+     * @param column The column (1-indexed).
+     * @return The slot, or null if no slot at the location.
+     */
+    @Nullable
+    default Slot getSlotAt(final int row,
+                           final int column) {
+        return null;
+    }
+
+    /**
+     * Get the slot at a certain position in the component.
+     * <p>
+     * If your component doesn't use context data (player, menu),
+     * then it will default to the raw slot.
+     * <p>
+     * It's safe to assume to the row and column will always be in bounds.
+     *
+     * @param row    The row (1-indexed).
+     * @param column The column (1-indexed).
+     * @param player The player.
+     * @param menu   The menu.
+     * @return The slot, or null if no slot at the location.
+     */
+    @Nullable
+    default Slot getSlotAt(final int row,
+                           final int column,
+                           @NotNull final Player player,
+                           @NotNull final Menu menu) {
+        return getSlotAt(row, column);
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/gui/GUIFactory.java

@@ -1,33 +0,0 @@
-package com.willfp.eco.core.gui;
-
-import com.willfp.eco.core.Eco;
-import com.willfp.eco.core.gui.menu.MenuBuilder;
-import com.willfp.eco.core.gui.slot.SlotBuilder;
-import com.willfp.eco.core.gui.slot.functional.SlotProvider;
-import org.bukkit.inventory.ItemStack;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-
-/**
- * Internal component used by {@link com.willfp.eco.core.gui.menu.Menu#builder(int)}
- * and {@link com.willfp.eco.core.gui.slot.Slot#builder(ItemStack)}.
- */
-@ApiStatus.Internal
-@Eco.HandlerComponent
-public interface GUIFactory {
-    /**
-     * Create slot builder.
-     *
-     * @param provider The provider.
-     * @return The builder.
-     */
-    SlotBuilder createSlotBuilder(@NotNull SlotProvider provider);
-
-    /**
-     * Create menu builder.
-     *
-     * @param rows The amount of rows.
-     * @return The builder.
-     */
-    MenuBuilder createMenuBuilder(int rows);
-}

eco-api/src/main/java/com/willfp/eco/core/gui/menu/Menu.java

@@ -1,7 +1,9 @@
 package com.willfp.eco.core.gui.menu;
 
 import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.gui.page.Page;
 import com.willfp.eco.core.gui.slot.Slot;
+import com.willfp.eco.util.NamespacedKeyUtils;
 import org.bukkit.NamespacedKey;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.Inventory;
@@ -12,7 +14,9 @@ import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 /**
  * GUI version of {@link Inventory}.
@@ -28,7 +32,19 @@ public interface Menu {
     int getRows();
 
     /**
-     * Get slot at given row and column.
+     * Get the amount of columns.
+     *
+     * @return The amount of columns.
+     */
+    default int getColumns() {
+        return 9;
+    }
+
+    /**
+     * Get a static slot at a given row and column.
+     * <p>
+     * If the slot at the location is reactive, this will return
+     * an empty slot.
      *
      * @param row    The row.
      * @param column The column.
@@ -37,6 +53,24 @@ public interface Menu {
     Slot getSlot(int row,
                  int column);
 
+    /**
+     * Get a slot at a given row and column.
+     * <p>
+     * Defaults to static slot if no reactive slot exists.
+     *
+     * @param row    The row.
+     * @param column The column.
+     * @param player The player
+     * @param menu   The menu.
+     * @return The slot.
+     */
+    default Slot getSlot(int row,
+                         int column,
+                         @NotNull Player player,
+                         @NotNull Menu menu) {
+        return this.getSlot(row, column);
+    }
+
     /**
      * Get the menu title.
      *
@@ -61,15 +95,47 @@ public interface Menu {
     List<ItemStack> getCaptiveItems(@NotNull Player player);
 
     /**
-     * Add state for a player.
+     * Get a captive item at a specific position.
+     *
+     * @param player The player.
+     * @param row    The row.
+     * @param column The column.
+     * @return The captive item.
+     */
+    @Nullable
+    default ItemStack getCaptiveItem(@NotNull final Player player,
+                                     final int row,
+                                     final int column) {
+        return null;
+    }
+
+    /**
+     * Set state for a player.
      *
      * @param player The player.
      * @param key    The key.
      * @param value  The state.
      */
-    void addState(@NotNull Player player,
-                  @NotNull String key,
-                  @Nullable Object value);
+    default void setState(@NotNull Player player,
+                          @NotNull String key,
+                          @Nullable Object value) {
+        // Blank method for backwards compatibility.
+    }
+
+    /**
+     * Add state for a player.
+     *
+     * @param player The player.
+     * @param key    The key.
+     * @param value  The state.
+     * @deprecated Poorly named, use setState instead.
+     */
+    @Deprecated(since = "6.44.0", forRemoval = true)
+    default void addState(@NotNull Player player,
+                          @NotNull String key,
+                          @Nullable Object value) {
+        this.setState(player, key, value);
+    }
 
     /**
      * Remove state for a player.
@@ -107,6 +173,55 @@ public interface Menu {
      */
     Map<String, Object> getState(@NotNull Player player);
 
+    /**
+     * Re-render the menu for a player.
+     *
+     * @param player The player.
+     */
+    void refresh(@NotNull Player player);
+
+    /**
+     * If the menu allows changing the held item.
+     *
+     * @return If allowed.
+     */
+    default boolean allowsChangingHeldItem() {
+        return false;
+    }
+
+    /**
+     * Call a menu event.
+     *
+     * @param player    The player.
+     * @param menuEvent The event.
+     */
+    default void callEvent(@NotNull final Player player,
+                           @NotNull final MenuEvent menuEvent) {
+        // Override when needed.
+    }
+
+    /**
+     * Get the current page a player is on.
+     *
+     * @param player The player.
+     * @return The page.
+     */
+    default int getPage(@NotNull final Player player) {
+        Integer pageState = this.getState(player, Page.PAGE_KEY);
+        return Objects.requireNonNullElse(pageState, 1);
+    }
+
+    /**
+     * Get the max page for a player.
+     *
+     * @param player The player.
+     * @return The page.
+     */
+    default int getMaxPage(@NotNull final Player player) {
+        Integer pageState = this.getState(player, Page.MAX_PAGE_KEY);
+        return Objects.requireNonNullElse(pageState, Integer.MAX_VALUE);
+    }
+
     /**
      * Write data.
      *
@@ -119,10 +234,12 @@ public interface Menu {
      * @deprecated Use addState instead.
      */
     @Deprecated(since = "6.35.0", forRemoval = true)
-    <T, Z> void writeData(@NotNull Player player,
-                          @NotNull NamespacedKey key,
-                          @NotNull PersistentDataType<T, Z> type,
-                          @NotNull Z value);
+    default <T, Z> void writeData(@NotNull final Player player,
+                                  @NotNull final NamespacedKey key,
+                                  @NotNull final PersistentDataType<T, Z> type,
+                                  @NotNull final Z value) {
+        this.setState(player, key.toString(), value);
+    }
 
     /**
      * Read data.
@@ -136,9 +253,11 @@ public interface Menu {
      * @deprecated Use getState instead.
      */
     @Deprecated(since = "6.35.0", forRemoval = true)
-    @Nullable <T, Z> T readData(@NotNull Player player,
-                                @NotNull NamespacedKey key,
-                                @NotNull PersistentDataType<T, Z> type);
+    default @Nullable <T, Z> T readData(@NotNull final Player player,
+                                        @NotNull final NamespacedKey key,
+                                        @NotNull final PersistentDataType<T, Z> type) {
+        return this.getState(player, key.toString());
+    }
 
     /**
      * Get all data keys for a player.
@@ -148,14 +267,12 @@ public interface Menu {
      * @deprecated Use getState instead.
      */
     @Deprecated(since = "6.35.0", forRemoval = true)
-    Set<NamespacedKey> getKeys(@NotNull Player player);
-
-    /**
-     * Re-render the menu for a player.
-     *
-     * @param player The player.
-     */
-    void refresh(@NotNull Player player);
+    default Set<NamespacedKey> getKeys(@NotNull final Player player) {
+        return this.getState(player).keySet().stream()
+                .map(NamespacedKeyUtils::fromStringOrNull)
+                .filter(Objects::nonNull)
+                .collect(Collectors.toSet());
+    }
 
     /**
      * Create a builder with a given amount of rows.
@@ -164,6 +281,19 @@ public interface Menu {
      * @return The builder.
      */
     static MenuBuilder builder(final int rows) {
-        return Eco.getHandler().getGUIFactory().createMenuBuilder(rows);
+        return Eco.get().createMenuBuilder(
+                rows,
+                MenuType.NORMAL
+        );
+    }
+
+    /**
+     * Create a builder with a given type.
+     *
+     * @param type The menu type.
+     * @return The builder.
+     */
+    static MenuBuilder builder(@NotNull final MenuType type) {
+        return Eco.get().createMenuBuilder(type.getDefaultRows(), type);
     }
 }

eco-api/src/main/java/com/willfp/eco/core/gui/menu/MenuBuilder.java

@@ -1,5 +1,8 @@
 package com.willfp.eco.core.gui.menu;
 
+import com.willfp.eco.core.gui.GUIComponent;
+import com.willfp.eco.core.gui.page.Page;
+import com.willfp.eco.core.gui.page.PageBuilder;
 import com.willfp.eco.core.gui.slot.FillerMask;
 import com.willfp.eco.core.gui.slot.Slot;
 import org.bukkit.entity.Player;
@@ -8,11 +11,12 @@ import org.jetbrains.annotations.NotNull;
 
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
+import java.util.function.Function;
 
 /**
  * Builder to create menus.
  */
-public interface MenuBuilder {
+public interface MenuBuilder extends PageBuilder {
     /**
      * Set the menu title.
      *
@@ -21,6 +25,15 @@ public interface MenuBuilder {
      */
     MenuBuilder setTitle(@NotNull String title);
 
+    /**
+     * Get the menu title.
+     *
+     * @return The builder.
+     */
+    default String getTitle() {
+        return "";
+    }
+
     /**
      * Set a slot.
      *
@@ -29,9 +42,44 @@ public interface MenuBuilder {
      * @param slot   The slot.
      * @return The builder.
      */
-    MenuBuilder setSlot(int row,
-                        int column,
-                        @NotNull Slot slot);
+    @Override
+    default MenuBuilder setSlot(final int row,
+                                final int column,
+                                @NotNull final Slot slot) {
+        return this.addComponent(row, column, slot);
+    }
+
+
+    /**
+     * Add a component.
+     *
+     * @param layer     The layer.
+     * @param row       The row of the top left corner.
+     * @param column    The column of the top left corner.
+     * @param component The component.
+     * @return The builder.
+     */
+    @Override
+    MenuBuilder addComponent(@NotNull MenuLayer layer,
+                             int row,
+                             int column,
+                             @NotNull GUIComponent component);
+
+
+    /**
+     * Add a component.
+     *
+     * @param row       The row of the top left corner.
+     * @param column    The column of the top left corner.
+     * @param component The component.
+     * @return The builder.
+     */
+    @Override
+    default MenuBuilder addComponent(final int row,
+                                     final int column,
+                                     @NotNull final GUIComponent component) {
+        return this.addComponent(MenuLayer.MIDDLE, row, column, component);
+    }
 
     /**
      * Run function to modify the builder.
@@ -47,21 +95,65 @@ public interface MenuBuilder {
      * @param mask The mask.
      * @return The builder.
      */
-    MenuBuilder setMask(@NotNull FillerMask mask);
+    @Override
+    default MenuBuilder setMask(@NotNull final FillerMask mask) {
+        return this.addComponent(MenuLayer.BACKGROUND, 1, 1, mask);
+    }
 
     /**
-     * Set the menu close handler.
+     * Add a page.
+     *
+     * @param page The page.
+     * @return The builder.
+     */
+    default MenuBuilder addPage(@NotNull final Page page) {
+        return this.addComponent(MenuLayer.UPPER, 1, 1, page);
+    }
+
+    /**
+     * Add a page.
+     *
+     * @param pageNumber The page number.
+     * @param builder    The page builder.
+     * @return The builder.
+     */
+    default MenuBuilder addPage(final int pageNumber,
+                                @NotNull final PageBuilder builder) {
+        return this.addPage(new Page(pageNumber, ((MenuBuilder) builder).build()));
+    }
+
+    /**
+     * Set the max pages.
+     *
+     * @param pages The max pages.
+     * @return The builder.
+     */
+    default MenuBuilder maxPages(final int pages) {
+        return this.maxPages(player -> pages);
+    }
+
+    /**
+     * Set the max pages dynamically for a player.
+     *
+     * @param pages The max pages.
+     * @return The builder.
+     */
+    default MenuBuilder maxPages(@NotNull final Function<Player, Integer> pages) {
+        return onRender((player, menu) -> menu.setState(player, Page.MAX_PAGE_KEY, pages.apply(player)));
+    }
+
+    /**
+     * Add a menu close handler.
      *
      * @param action The handler.
      * @return The builder.
      */
-    default MenuBuilder onClose(@NotNull Consumer<InventoryCloseEvent> action) {
-        onClose((event, menu) -> action.accept(event));
-        return this;
+    default MenuBuilder onClose(@NotNull final Consumer<InventoryCloseEvent> action) {
+        return this.onClose((event, menu) -> action.accept(event));
     }
 
     /**
-     * Set the menu close handler.
+     * Add a menu close handler.
      *
      * @param action The handler.
      * @return The builder.
@@ -69,7 +161,7 @@ public interface MenuBuilder {
     MenuBuilder onClose(@NotNull CloseHandler action);
 
     /**
-     * Set the menu open handler.
+     * Add a menu open handler.
      *
      * @param action The handler.
      * @return The builder.
@@ -77,13 +169,32 @@ public interface MenuBuilder {
     MenuBuilder onOpen(@NotNull OpenHandler action);
 
     /**
-     * Set the action to run on render.
+     * Add an action to run on render.
      *
      * @param action The action.
      * @return The builder.
      */
     MenuBuilder onRender(@NotNull BiConsumer<Player, Menu> action);
 
+    /**
+     * Add an action to run on an event.
+     *
+     * @param action The action.
+     * @return The builder.
+     */
+    default MenuBuilder onEvent(@NotNull final MenuEventHandler<?> action) {
+        return this;
+    }
+
+    /**
+     * Allow the player to change their held item.
+     *
+     * @return The builder.
+     */
+    default MenuBuilder allowChangingHeldItem() {
+        return this;
+    }
+
     /**
      * Build the menu.
      *

eco-api/src/main/java/com/willfp/eco/core/gui/menu/MenuEvent.java

@@ -0,0 +1,8 @@
+package com.willfp.eco.core.gui.menu;
+
+/**
+ * Represents an event sent to a menu.
+ */
+public interface MenuEvent {
+
+}

eco-api/src/main/java/com/willfp/eco/core/gui/menu/MenuEventHandler.java

@@ -0,0 +1,45 @@
+package com.willfp.eco.core.gui.menu;
+
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Handles menu events.
+ */
+public abstract class MenuEventHandler<T extends MenuEvent> {
+    /**
+     * The class of the event.
+     */
+    private final Class<T> eventClass;
+
+    /**
+     * Create a new menu event handler.
+     *
+     * @param eventClass The class of event to handle.
+     */
+    protected MenuEventHandler(@NotNull final Class<T> eventClass) {
+        this.eventClass = eventClass;
+    }
+
+
+    /**
+     * Performs this operation on the given arguments.
+     *
+     * @param player The player.
+     * @param menu   The menu.
+     * @param event  The event.
+     */
+    public abstract void handle(@NotNull Player player,
+                                @NotNull Menu menu,
+                                @NotNull T event);
+
+    /**
+     * Get if this handler can handle a certain event.
+     *
+     * @param menuEvent The event
+     * @return If the event can be handled.
+     */
+    public boolean canHandleEvent(@NotNull final MenuEvent menuEvent) {
+        return eventClass.isAssignableFrom(menuEvent.getClass());
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/gui/menu/MenuLayer.java

@@ -0,0 +1,31 @@
+package com.willfp.eco.core.gui.menu;
+
+/**
+ * Different layers of the menu.
+ */
+public enum MenuLayer {
+    /**
+     * Right at the back.
+     */
+    BACKGROUND,
+
+    /**
+     * Second from the back.
+     */
+    LOWER,
+
+    /**
+     * In the middle (default).
+     */
+    MIDDLE,
+
+    /**
+     * Near the top.
+     */
+    UPPER,
+
+    /**
+     * At the absolute top.
+     */
+    TOP
+}

eco-api/src/main/java/com/willfp/eco/core/gui/menu/MenuType.java

@@ -0,0 +1,56 @@
+package com.willfp.eco.core.gui.menu;
+
+/**
+ * The type of menu.
+ */
+public enum MenuType {
+    /**
+     * Normal menu (1x9, 2x9, 3x9, etc).
+     */
+    NORMAL(9, 6),
+
+    /**
+     * Dispenser menu (3x3).
+     */
+    DISPENSER(3, 3);
+
+    /**
+     * The amount of columns.
+     */
+    private final int columns;
+
+    /**
+     * The default amount of rows.
+     */
+    private final int defaultRows;
+
+    /**
+     * Create a new menu type.
+     *
+     * @param columns     The number of columns.
+     * @param defaultRows The default number of rows.
+     */
+    MenuType(final int columns,
+             final int defaultRows) {
+        this.columns = columns;
+        this.defaultRows = defaultRows;
+    }
+
+    /**
+     * Get the amount of columns.
+     *
+     * @return The columns.
+     */
+    public int getColumns() {
+        return columns;
+    }
+
+    /**
+     * Get the default amount of rows.
+     *
+     * @return The default amount of rows.
+     */
+    public int getDefaultRows() {
+        return defaultRows;
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/gui/page/Page.java

@@ -0,0 +1,115 @@
+package com.willfp.eco.core.gui.page;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.gui.GUIComponent;
+import com.willfp.eco.core.gui.menu.Menu;
+import com.willfp.eco.core.gui.menu.MenuBuilder;
+import com.willfp.eco.core.gui.slot.Slot;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * A page is a component representing another menu.
+ * This allows full component support in pagination.
+ */
+public final class Page implements GUIComponent {
+    /**
+     * The Menu state key for the current page.
+     */
+    public static final String PAGE_KEY = "page";
+
+    /**
+     * The Menu state key for the amount of pages.
+     */
+    public static final String MAX_PAGE_KEY = "max_page";
+
+    /**
+     * The page number.
+     */
+    private final int pageNumber;
+
+    /**
+     * The base menu.
+     */
+    private final Menu page;
+
+    /**
+     * The delegate menu.
+     */
+    private Menu delegate = null;
+
+    /**
+     * The rows for the page to have.
+     */
+    private int rows = 6;
+
+    /**
+     * The columns for the page to have.
+     */
+    private int columns = 9;
+
+    /**
+     * Create a new page.
+     *
+     * @param pageNumber The page number.
+     * @param page       The base menu.
+     */
+    public Page(final int pageNumber,
+                @NotNull final Menu page) {
+        this.pageNumber = pageNumber;
+        this.page = page;
+    }
+
+    /**
+     * Get the current page number.
+     *
+     * @return The page number.
+     */
+    public int getPageNumber() {
+        return this.pageNumber;
+    }
+
+    @Override
+    public @Nullable Slot getSlotAt(final int row,
+                                    final int column,
+                                    @NotNull final Player player,
+                                    @NotNull final Menu menu) {
+        if (menu.getPage(player) != pageNumber) {
+            return null;
+        }
+
+        if (delegate == null) {
+            delegate = Eco.get().blendMenuState(page, menu);
+        }
+
+        return page.getSlot(row, column, player, delegate);
+    }
+
+    @Override
+    public void init(final int maxRows,
+                     final int maxColumns) {
+        this.rows = maxRows;
+        this.columns = maxColumns;
+    }
+
+    @Override
+    public int getRows() {
+        return rows;
+    }
+
+    @Override
+    public int getColumns() {
+        return columns;
+    }
+
+    /**
+     * Create a new page builder.
+     *
+     * @param context The context to create the page for.
+     * @return The page builder.
+     */
+    public static PageBuilder builder(@NotNull final MenuBuilder context) {
+        return Menu.builder(context.getRows());
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/gui/page/PageBuilder.java

@@ -0,0 +1,92 @@
+package com.willfp.eco.core.gui.page;
+
+import com.willfp.eco.core.gui.GUIComponent;
+import com.willfp.eco.core.gui.menu.Menu;
+import com.willfp.eco.core.gui.menu.MenuLayer;
+import com.willfp.eco.core.gui.slot.FillerMask;
+import com.willfp.eco.core.gui.slot.Slot;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.function.BiConsumer;
+
+/**
+ * Builder to create pages.
+ */
+public interface PageBuilder {
+    /**
+     * Get the amount of rows.
+     *
+     * @return The amount of rows.
+     */
+    int getRows();
+
+    /**
+     * Get the amount of columns.
+     *
+     * @return The amount of columns.
+     */
+    int getColumns();
+
+    /**
+     * Set a slot.
+     *
+     * @param row    The row.
+     * @param column The column.
+     * @param slot   The slot.
+     * @return The builder.
+     */
+    default PageBuilder setSlot(final int row,
+                                final int column,
+                                @NotNull final Slot slot) {
+        return this.addComponent(row, column, slot);
+    }
+
+
+    /**
+     * Add a component.
+     *
+     * @param layer     The layer.
+     * @param row       The row of the top left corner.
+     * @param column    The column of the top left corner.
+     * @param component The component.
+     * @return The builder.
+     */
+    PageBuilder addComponent(@NotNull MenuLayer layer,
+                             int row,
+                             int column,
+                             @NotNull GUIComponent component);
+
+
+    /**
+     * Add a component.
+     *
+     * @param row       The row of the top left corner.
+     * @param column    The column of the top left corner.
+     * @param component The component.
+     * @return The builder.
+     */
+    default PageBuilder addComponent(final int row,
+                                     final int column,
+                                     @NotNull final GUIComponent component) {
+        return this.addComponent(MenuLayer.MIDDLE, row, column, component);
+    }
+
+    /**
+     * Set the menu mask.
+     *
+     * @param mask The mask.
+     * @return The builder.
+     */
+    default PageBuilder setMask(@NotNull final FillerMask mask) {
+        return this.addComponent(MenuLayer.BACKGROUND, 1, 1, mask);
+    }
+
+    /**
+     * Set the action to run on render.
+     *
+     * @param action The action.
+     * @return The builder.
+     */
+    PageBuilder onRender(@NotNull BiConsumer<Player, Menu> action);
+}

eco-api/src/main/java/com/willfp/eco/core/gui/page/PageChangeEvent.java

@@ -0,0 +1,16 @@
+package com.willfp.eco.core.gui.page;
+
+import com.willfp.eco.core.gui.menu.MenuEvent;
+
+/**
+ * Represents a page change.
+ *
+ * @param newPage The new page.
+ * @param oldPage The old page.
+ */
+public record PageChangeEvent(
+        int newPage,
+        int oldPage
+) implements MenuEvent {
+
+}

eco-api/src/main/java/com/willfp/eco/core/gui/page/PageChanger.java

@@ -0,0 +1,126 @@
+package com.willfp.eco.core.gui.page;
+
+import com.willfp.eco.core.gui.GUIComponent;
+import com.willfp.eco.core.gui.menu.Menu;
+import com.willfp.eco.core.gui.slot.Slot;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * A slot loaded in from config.
+ */
+public final class PageChanger implements GUIComponent {
+    /**
+     * The slot to be shown.
+     */
+    private final Slot slot;
+
+    /**
+     * The direction to turn the page.
+     */
+    private final Direction direction;
+
+    /**
+     * Create a new page change slot.
+     *
+     * @param itemStack The ItemStack.
+     * @param direction The direction.
+     */
+    public PageChanger(@NotNull final ItemStack itemStack,
+                       @NotNull final Direction direction) {
+        this.direction = direction;
+
+        slot = Slot.builder(itemStack)
+                .onLeftClick((event, slot, menu) -> {
+                    Player player = (Player) event.getWhoClicked();
+                    int page = menu.getPage(player);
+                    int newPage = Math.max(
+                            1,
+                            Math.min(
+                                    page + direction.getChange(),
+                                    menu.getMaxPage(player)
+                            )
+                    );
+
+                    if (newPage == page) {
+                        return;
+                    }
+
+                    menu.setState(player, Page.PAGE_KEY, newPage);
+                    menu.callEvent(player, new PageChangeEvent(
+                            newPage,
+                            page
+                    ));
+                })
+                .build();
+    }
+
+    @Override
+    public int getRows() {
+        return 1;
+    }
+
+    @Override
+    public int getColumns() {
+        return 1;
+    }
+
+    @Override
+    public @Nullable Slot getSlotAt(final int row,
+                                    final int column,
+                                    @NotNull final Player player,
+                                    @NotNull final Menu menu) {
+        int page = menu.getPage(player);
+        int maxPage = menu.getMaxPage(player);
+
+        if (page <= 1 && this.direction == Direction.BACKWARDS) {
+            return null;
+        }
+
+        if (page >= maxPage && this.direction == Direction.FORWARDS) {
+            return null;
+        }
+
+        return slot;
+    }
+
+    /**
+     * The direction to change the page.
+     */
+    public enum Direction {
+        /**
+         * Increment the page by 1.
+         */
+        FORWARDS(1),
+
+        /**
+         * Decrement the page by 1.
+         */
+        BACKWARDS(-1);
+
+        /**
+         * The amount of pages to change by.
+         */
+        private final int change;
+
+        /**
+         * Create a new direction.
+         *
+         * @param change The amount of pages to change by.
+         */
+        Direction(final int change) {
+            this.change = change;
+        }
+
+        /**
+         * Get the amount of pages to change by.
+         *
+         * @return The change.
+         */
+        public int getChange() {
+            return change;
+        }
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/gui/slot/ConfigSlot.java

@@ -0,0 +1,123 @@
+package com.willfp.eco.core.gui.slot;
+
+import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.gui.slot.functional.SlotHandler;
+import com.willfp.eco.core.items.Items;
+import com.willfp.eco.util.StringUtils;
+import org.bukkit.Bukkit;
+import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.ClickType;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+
+/**
+ * A slot loaded in from config.
+ */
+public class ConfigSlot extends CustomSlot {
+    /**
+     * The config of the slot.
+     */
+    private final Config config;
+
+    /**
+     * Cached handlers, for performance.
+     */
+    private final Map<String, List<CommandToDispatch>> handlers = new HashMap<>();
+
+    /**
+     * Create a new config slot.
+     *
+     * @param config The config.
+     */
+    public ConfigSlot(@NotNull final Config config) {
+        this.config = config;
+
+        SlotBuilder builder = Slot.builder(Items.lookup(config.getString("item")));
+
+        for (ClickType clickType : ClickType.values()) {
+            builder.onClick(
+                    clickType,
+                    dispatchCommandHandler(
+                            clickType.name().toLowerCase(Locale.ROOT)
+                                    .replace("_", "-")
+                                    + "-click"
+                    )
+            );
+        }
+
+        init(builder.build());
+    }
+
+    /**
+     * Create a slot handler for dispatching commands.
+     *
+     * @param configKey The config key.
+     * @return The handler.
+     */
+    private SlotHandler dispatchCommandHandler(@NotNull final String configKey) {
+        if (!handlers.containsKey(configKey)) {
+            List<CommandToDispatch> commands = new ArrayList<>();
+
+            for (String command : config.getStrings(configKey)) {
+                if (command.startsWith("console:")) {
+                    commands.add(new CommandToDispatch(
+                            StringUtils.removePrefix("console:", command),
+                            true
+                    ));
+                } else {
+                    commands.add(new CommandToDispatch(
+                            command,
+                            false
+                    ));
+                }
+            }
+
+            handlers.put(configKey, commands);
+        }
+
+        List<CommandToDispatch> toDispatch = handlers.get(configKey);
+
+        return (event, slot, menu) -> {
+            Player player = (Player) event.getWhoClicked();
+
+            for (CommandToDispatch dispatch : toDispatch) {
+                dispatch.dispatch(player);
+            }
+        };
+    }
+
+    /**
+     * Signifies a command to dispatch.
+     *
+     * @param command The command.
+     * @param console If the command should be run as console.
+     */
+    private record CommandToDispatch(
+            @NotNull String command,
+            boolean console
+    ) {
+        /**
+         * Dispatch command.
+         *
+         * @param player The player.
+         */
+        void dispatch(@NotNull final Player player) {
+            if (console()) {
+                Bukkit.dispatchCommand(
+                        Bukkit.getConsoleSender(),
+                        command().replace("%player%", player.getName())
+                );
+            } else {
+                Bukkit.dispatchCommand(
+                        player,
+                        command().replace("%player%", player.getName())
+                );
+            }
+        }
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/gui/slot/CustomSlot.java

@@ -0,0 +1,94 @@
+package com.willfp.eco.core.gui.slot;
+
+import com.willfp.eco.core.gui.menu.Menu;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Base class for custom slot implementations.
+ */
+public abstract class CustomSlot implements Slot {
+    /**
+     * The internal slot to delegate to.
+     */
+    private Slot delegate = null;
+
+    /**
+     * Create a new custom slot.
+     */
+    protected CustomSlot() {
+
+    }
+
+    /**
+     * Initialize the slot with the delegate.
+     *
+     * @param slot The slot to delegate to.
+     */
+    protected void init(@NotNull final Slot slot) {
+        this.delegate = slot;
+    }
+
+    @Override
+    public @NotNull ItemStack getItemStack(@NotNull final Player player) {
+        if (delegate == null) {
+            throw new IllegalStateException("Custom Slot was not initialized!");
+        }
+
+        return delegate.getItemStack(player);
+    }
+
+    @Override
+    public boolean isCaptive(@NotNull final Player player,
+                             @NotNull final Menu menu) {
+        if (delegate == null) {
+            throw new IllegalStateException("Custom Slot was not initialized!");
+        }
+
+        return delegate.isCaptive(player, menu);
+    }
+
+    @Override
+    public boolean isCaptiveFromEmpty() {
+        if (delegate == null) {
+            throw new IllegalStateException("Custom Slot was not initialized!");
+        }
+
+        return delegate.isCaptiveFromEmpty();
+    }
+
+    @Override
+    public final Slot getActionableSlot(@NotNull final Player player,
+                                        @NotNull final Menu menu) {
+        return delegate;
+    }
+
+    @Override
+    public final int getRows() {
+        return Slot.super.getRows();
+    }
+
+    @Override
+    public final int getColumns() {
+        return Slot.super.getColumns();
+    }
+
+    @Override
+    public final Slot getSlotAt(int row, int column) {
+        return Slot.super.getSlotAt(row, column);
+    }
+
+    /**
+     * Get the delegate slot.
+     * <p>
+     * This is not required to add the slot to a menu, but is instead used internally.
+     *
+     * @return The slot.
+     * @deprecated Replaced with {@link Slot#getActionableSlot(Player, Menu)}
+     */
+    @Deprecated(since = "6.43.0", forRemoval = true)
+    public Slot getDelegate() {
+        return this.delegate;
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/gui/slot/FillerMask.java

@@ -1,5 +1,6 @@
 package com.willfp.eco.core.gui.slot;
 
+import com.willfp.eco.core.gui.GUIComponent;
 import com.willfp.eco.core.items.builder.ItemStackBuilder;
 import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
 import com.willfp.eco.core.recipe.parts.MaterialTestableItem;
@@ -7,6 +8,7 @@ import com.willfp.eco.util.ListUtils;
 import org.bukkit.Material;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.Arrays;
 import java.util.List;
@@ -26,12 +28,17 @@ import java.util.List;
  * "11111111"
  * );
  */
-public class FillerMask {
+public class FillerMask implements GUIComponent {
     /**
      * Mask.
      */
     private final List<List<Slot>> mask;
 
+    /**
+     * Rows.
+     */
+    private final int rows;
+
     /**
      * Create a new filler mask.
      *
@@ -71,7 +78,8 @@ public class FillerMask {
             throw new IllegalArgumentException("Items cannot be empty!");
         }
 
-        mask = ListUtils.create2DList(6, 9);
+        rows = pattern.length;
+        mask = ListUtils.create2DList(rows, 9);
 
         for (int i = 0; i < items.items().length; i++) {
             ItemStack itemStack = new ItemStackBuilder(items.items()[i])
@@ -82,9 +90,6 @@ public class FillerMask {
 
             for (String patternRow : pattern) {
                 int column = 0;
-                if (patternRow.length() != 9) {
-                    throw new IllegalArgumentException("Invalid amount of columns in pattern!");
-                }
                 for (char c : patternRow.toCharArray()) {
                     if (c == '0') {
                         mask.get(row).set(column, null);
@@ -107,4 +112,20 @@ public class FillerMask {
     public List<List<Slot>> getMask() {
         return this.mask;
     }
+
+    @Override
+    public int getRows() {
+        return rows;
+    }
+
+    @Override
+    public int getColumns() {
+        return 9;
+    }
+
+    @Override
+    public @Nullable Slot getSlotAt(final int row,
+                                    final int column) {
+        return mask.get(row - 1).get(column - 1);
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/gui/slot/FillerSlot.java

@@ -1,6 +1,5 @@
 package com.willfp.eco.core.gui.slot;
 
-import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
 
@@ -9,37 +8,16 @@ import org.jetbrains.annotations.NotNull;
  * <p>
  * Useful for backgrounds.
  */
-public class FillerSlot implements Slot {
-    /**
-     * The ItemStack.
-     */
-    private final ItemStack itemStack;
-
+public class FillerSlot extends CustomSlot {
     /**
      * Create new filler slot.
      *
      * @param itemStack The ItemStack.
      */
     public FillerSlot(@NotNull final ItemStack itemStack) {
-        this.itemStack = itemStack;
-    }
-
-    @Override
-    public ItemStack getItemStack(@NotNull final Player player) {
-        return itemStack;
-    }
-
-    @Override
-    public boolean isCaptive() {
-        return false;
-    }
-
-    /**
-     * Get the ItemStack.
-     *
-     * @return The ItemStack.
-     */
-    public ItemStack getItemStack() {
-        return this.itemStack;
+        init(
+                Slot.builder(itemStack)
+                        .build()
+        );
     }
 }

eco-api/src/main/java/com/willfp/eco/core/gui/slot/ReactiveSlot.java

@@ -0,0 +1,62 @@
+package com.willfp.eco.core.gui.slot;
+
+import com.willfp.eco.core.gui.menu.Menu;
+import org.bukkit.Material;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Base class for custom slot implementations.
+ */
+public abstract class ReactiveSlot implements Slot {
+    /**
+     * Create a new reactive slot.
+     */
+    protected ReactiveSlot() {
+
+    }
+
+    /**
+     * Get the actual slot to be shown.
+     *
+     * @param player The player.
+     * @param menu   The menu.
+     * @return The slot.
+     */
+    @NotNull
+    public abstract Slot getSlot(@NotNull final Player player,
+                                 @NotNull final Menu menu);
+
+    @Override
+    public @NotNull ItemStack getItemStack(@NotNull final Player player) {
+        return new ItemStack(Material.STONE);
+    }
+
+    @Override
+    public boolean isCaptive(@NotNull final Player player,
+                             @NotNull final Menu menu) {
+        return getSlot(player, menu).isCaptive(player, menu);
+    }
+
+    @Override
+    public final Slot getActionableSlot(@NotNull final Player player,
+                                        @NotNull final Menu menu) {
+        return getSlot(player, menu);
+    }
+
+    @Override
+    public final int getRows() {
+        return Slot.super.getRows();
+    }
+
+    @Override
+    public final int getColumns() {
+        return Slot.super.getColumns();
+    }
+
+    @Override
+    public final Slot getSlotAt(int row, int column) {
+        return Slot.super.getSlotAt(row, column);
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/gui/slot/Slot.java

@@ -1,7 +1,10 @@
 package com.willfp.eco.core.gui.slot;
 
 import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.gui.GUIComponent;
+import com.willfp.eco.core.gui.menu.Menu;
 import com.willfp.eco.core.gui.slot.functional.SlotProvider;
+import com.willfp.eco.core.items.TestableItem;
 import org.bukkit.Material;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
@@ -11,31 +14,57 @@ import java.util.function.Function;
 
 /**
  * A slot is an item in a GUI that can handle clicks.
+ * <p>
+ * While you can create custom Slot implementations directly from this class,
+ * it's heavily encouraged to extend {@link CustomSlot}, which will abstract
+ * internal functionality away.
+ * <p>
+ * A lot of methods here are marked as default as in 6.43.0 the GUI system
+ * was overhauled, but to preserve backwards compatibility, the new methods
+ * had to be marked default, and many old methods became deprecated.
  */
-public interface Slot {
+public interface Slot extends GUIComponent {
     /**
      * Get the ItemStack that would be shown to a player.
      *
      * @param player The player.
      * @return The ItemStack.
      */
+    @NotNull
     ItemStack getItemStack(@NotNull Player player);
 
     /**
      * If the slot is captive. (Can items be placed in it).
      *
+     * @param player The player.
+     * @param menu   The menu.
      * @return If captive.
      */
-    boolean isCaptive();
+    default boolean isCaptive(@NotNull final Player player,
+                              @NotNull final Menu menu) {
+        return false;
+    }
 
     /**
-     * If the slot is not captive for a player.
+     * Get the actionable slot to be shown.
+     * <p>
+     * This is mostly internal, if you want to implement custom slots you should
+     * turn to {@link CustomSlot} or {@link ReactiveSlot}, which abstract this
+     * behaviour away.
+     * <p>
+     * **Never** return {@code this} from this method. Always make sure that your
+     * slots eventually delegate to a slot created by {@link Slot#builder()}.
+     * <p>
+     * {@code this} is returned by default for backwards-compatibility.
      *
      * @param player The player.
-     * @return If not captive for the player.
+     * @param menu   The menu.
+     * @return The slot.
      */
-    default boolean isNotCaptiveFor(@NotNull Player player) {
-        return false;
+    @NotNull
+    default Slot getActionableSlot(@NotNull final Player player,
+                                   @NotNull final Menu menu) {
+        return this;
     }
 
     /**
@@ -48,13 +77,29 @@ public interface Slot {
         return false;
     }
 
+    @Override
+    default int getRows() {
+        return 1;
+    }
+
+    @Override
+    default int getColumns() {
+        return 1;
+    }
+
+    @Override
+    default Slot getSlotAt(final int row,
+                           final int column) {
+        return this;
+    }
+
     /**
      * Create a builder for an ItemStack.
      *
      * @return The builder.
      */
     static SlotBuilder builder() {
-        return Eco.getHandler().getGUIFactory().createSlotBuilder((player, menu) -> new ItemStack(Material.AIR));
+        return Eco.get().createSlotBuilder((player, menu) -> new ItemStack(Material.AIR));
     }
 
     /**
@@ -64,7 +109,17 @@ public interface Slot {
      * @return The builder.
      */
     static SlotBuilder builder(@NotNull final ItemStack itemStack) {
-        return Eco.getHandler().getGUIFactory().createSlotBuilder((player, menu) -> itemStack);
+        return Eco.get().createSlotBuilder((player, menu) -> itemStack);
+    }
+
+    /**
+     * Create a builder for a TestableItem.
+     *
+     * @param item The item.
+     * @return The builder.
+     */
+    static SlotBuilder builder(@NotNull final TestableItem item) {
+        return Eco.get().createSlotBuilder((player, menu) -> item.getItem());
     }
 
     /**
@@ -72,9 +127,11 @@ public interface Slot {
      *
      * @param provider The provider.
      * @return The builder.
+     * @deprecated This method was written incorrectly, should have been a Player + Menu function.
      */
+    @Deprecated(since = "6.45.0", forRemoval = true)
     static SlotBuilder builder(@NotNull final Function<Player, ItemStack> provider) {
-        return Eco.getHandler().getGUIFactory().createSlotBuilder((player, menu) -> provider.apply(player));
+        return Eco.get().createSlotBuilder((player, menu) -> provider.apply(player));
     }
 
     /**
@@ -84,6 +141,29 @@ public interface Slot {
      * @return The builder.
      */
     static SlotBuilder builder(@NotNull final SlotProvider provider) {
-        return Eco.getHandler().getGUIFactory().createSlotBuilder(provider);
+        return Eco.get().createSlotBuilder(provider);
+    }
+
+    /**
+     * If the slot is not captive for a player.
+     *
+     * @param player The player.
+     * @return If not captive for the player.
+     * @deprecated Captivity is now reactive, this method can produce incorrect results.
+     */
+    @Deprecated(since = "6.43.0", forRemoval = true)
+    default boolean isNotCaptiveFor(@NotNull Player player) {
+        return false;
+    }
+
+    /**
+     * If the slot is captive. (Can items be placed in it).
+     *
+     * @return If captive.
+     * @deprecated Captivity is now reactive, this method can produce incorrect results.
+     */
+    @Deprecated(since = "6.43.0", forRemoval = true)
+    default boolean isCaptive() {
+        return false;
     }
 }

eco-api/src/main/java/com/willfp/eco/core/gui/slot/SlotBuilder.java

@@ -4,6 +4,7 @@ import com.willfp.eco.core.gui.slot.functional.SlotHandler;
 import com.willfp.eco.core.gui.slot.functional.SlotModifier;
 import com.willfp.eco.core.gui.slot.functional.SlotUpdater;
 import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.ClickType;
 import org.bukkit.event.inventory.InventoryClickEvent;
 import org.jetbrains.annotations.NotNull;
 
@@ -14,6 +15,28 @@ import java.util.function.Predicate;
  * Builder to create slots.
  */
 public interface SlotBuilder {
+    /**
+     * Set click handler.
+     *
+     * @param type    The click type.
+     * @param handler The handler.
+     * @return The builder.
+     */
+    SlotBuilder onClick(@NotNull ClickType type,
+                        @NotNull SlotHandler handler);
+
+    /**
+     * Set click handler.
+     *
+     * @param type   The click type.
+     * @param action The handler.
+     * @return The builder.
+     */
+    default SlotBuilder onClick(@NotNull final ClickType type,
+                                @NotNull final BiConsumer<InventoryClickEvent, Slot> action) {
+        return onClick(type, (event, slot, menu) -> action.accept(event, slot));
+    }
+
     /**
      * Set click handler.
      *
@@ -30,7 +53,9 @@ public interface SlotBuilder {
      * @param handler The handler.
      * @return The builder.
      */
-    SlotBuilder onLeftClick(@NotNull SlotHandler handler);
+    default SlotBuilder onLeftClick(@NotNull final SlotHandler handler) {
+        return onClick(ClickType.LEFT, handler);
+    }
 
     /**
      * Set click handler.
@@ -48,7 +73,9 @@ public interface SlotBuilder {
      * @param handler The handler.
      * @return The builder.
      */
-    SlotBuilder onRightClick(@NotNull SlotHandler handler);
+    default SlotBuilder onRightClick(@NotNull final SlotHandler handler) {
+        return onClick(ClickType.RIGHT, handler);
+    }
 
     /**
      * Set click handler.
@@ -66,7 +93,9 @@ public interface SlotBuilder {
      * @param handler The handler.
      * @return The builder.
      */
-    SlotBuilder onShiftLeftClick(@NotNull SlotHandler handler);
+    default SlotBuilder onShiftLeftClick(@NotNull final SlotHandler handler) {
+        return onClick(ClickType.SHIFT_LEFT, handler);
+    }
 
     /**
      * Set click handler.
@@ -84,7 +113,9 @@ public interface SlotBuilder {
      * @param handler The handler.
      * @return The builder.
      */
-    SlotBuilder onShiftRightClick(@NotNull SlotHandler handler);
+    default SlotBuilder onShiftRightClick(@NotNull final SlotHandler handler) {
+        return onClick(ClickType.SHIFT_RIGHT, handler);
+    }
 
     /**
      * Set click handler.
@@ -102,7 +133,9 @@ public interface SlotBuilder {
      * @param handler The handler.
      * @return The builder.
      */
-    SlotBuilder onMiddleClick(@NotNull SlotHandler handler);
+    default SlotBuilder onMiddleClick(@NotNull final SlotHandler handler) {
+        return onClick(ClickType.MIDDLE, handler);
+    }
 
     /**
      * Prevent captive for players that match a predicate.
@@ -112,21 +145,6 @@ public interface SlotBuilder {
      */
     SlotBuilder notCaptiveFor(@NotNull Predicate<Player> predicate);
 
-    /**
-     * Modify the ItemStack.
-     *
-     * @param modifier The modifier.
-     * @return The builder.
-     * @deprecated Use {@link SlotBuilder#setUpdater(SlotUpdater)} instead.
-     */
-    @Deprecated
-    default SlotBuilder setModifier(@NotNull SlotModifier modifier) {
-        return setUpdater((player, menu, previous) -> {
-            modifier.modify(player, menu, previous);
-            return previous;
-        });
-    }
-
     /**
      * Set the ItemStack updater.
      *
@@ -158,4 +176,19 @@ public interface SlotBuilder {
      * @return The slot.
      */
     Slot build();
+
+    /**
+     * Modify the ItemStack.
+     *
+     * @param modifier The modifier.
+     * @return The builder.
+     * @deprecated Use {@link SlotBuilder#setUpdater(SlotUpdater)} instead.
+     */
+    @Deprecated
+    default SlotBuilder setModifier(@NotNull SlotModifier modifier) {
+        return setUpdater((player, menu, previous) -> {
+            modifier.modify(player, menu, previous);
+            return previous;
+        });
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/gui/slot/functional/SlotProvider.java

@@ -4,6 +4,7 @@ import com.willfp.eco.core.gui.menu.Menu;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Interface to run on slot display.
@@ -17,6 +18,7 @@ public interface SlotProvider {
      * @param menu   The menu.
      * @return The ItemStack.
      */
+    @Nullable
     ItemStack provide(@NotNull Player player,
                       @NotNull Menu menu);
 }

eco-api/src/main/java/com/willfp/eco/core/gui/slot/functional/SlotUpdater.java

@@ -4,6 +4,7 @@ import com.willfp.eco.core.gui.menu.Menu;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Interface to run on slot update.
@@ -18,6 +19,7 @@ public interface SlotUpdater {
      * @param previous The previous ItemStack.
      * @return The new ItemStack.
      */
+    @Nullable
     ItemStack update(@NotNull Player player,
                      @NotNull Menu menu,
                      @NotNull ItemStack previous);

eco-api/src/main/java/com/willfp/eco/core/integrations/anticheat/AnticheatManager.java

@@ -38,7 +38,7 @@ public final class AnticheatManager {
      */
     public static void register(@NotNull final AnticheatIntegration anticheat) {
         if (anticheat instanceof Listener) {
-            Eco.getHandler().getEcoPlugin().getEventManager().registerListener((Listener) anticheat);
+            Eco.get().getEcoPlugin().getEventManager().registerListener((Listener) anticheat);
         }
         ANTICHEATS.removeIf(it -> it.getPluginName().equalsIgnoreCase(anticheat.getPluginName()));
         ANTICHEATS.add(anticheat);

eco-api/src/main/java/com/willfp/eco/core/integrations/economy/EconomyIntegration.java

@@ -8,7 +8,19 @@ import java.math.BigDecimal;
 
 /**
  * Wrapper class for economy integrations.
+ * <p>
+ * If you're adding your economy to be supported in eco,
+ * it's recommended to override the {@link BigDecimal} methods
+ * as opposed to the {@code double} methods.
+ * <p>
+ * <strong>You must override at least one of all methods</strong>,
+ * i.e. one {@code hasAmount}, one {@code giveMoney}, etc.,
+ * otherwise your integration will cause {@link StackOverflowError}.
+ * <p>
+ * All methods are marked as default to preserve compatibility with
+ * integrations made before 6.43.0.
  */
+@SuppressWarnings("DeprecatedIsStillUsed")
 public interface EconomyIntegration extends Integration {
     /**
      * Get if a player has a certain amount.
@@ -16,9 +28,39 @@ public interface EconomyIntegration extends Integration {
      * @param player The player.
      * @param amount The amount.
      * @return If the player has the amount.
+     * @deprecated Use {@link BigDecimal} methods instead.
      */
-    boolean hasAmount(@NotNull OfflinePlayer player,
-                      double amount);
+    @Deprecated(since = "6.43.0")
+    default boolean hasAmount(@NotNull OfflinePlayer player,
+                              double amount) {
+        return hasAmount(player, BigDecimal.valueOf(amount));
+    }
+
+    /**
+     * Get if a player has a certain amount.
+     *
+     * @param player The player.
+     * @param amount The amount
+     * @return If the player has the amount.
+     */
+    default boolean hasAmount(@NotNull OfflinePlayer player,
+                              @NotNull BigDecimal amount) {
+        return hasAmount(player, amount.doubleValue());
+    }
+
+    /**
+     * Give money to a player.
+     *
+     * @param player The player.
+     * @param amount The amount to give.
+     * @return If the transaction was a success.
+     * @deprecated Use {@link BigDecimal} methods instead.
+     */
+    @Deprecated(since = "6.43.0")
+    default boolean giveMoney(@NotNull OfflinePlayer player,
+                              double amount) {
+        return giveMoney(player, BigDecimal.valueOf(amount));
+    }
 
     /**
      * Give money to a player.
@@ -27,8 +69,24 @@ public interface EconomyIntegration extends Integration {
      * @param amount The amount to give.
      * @return If the transaction was a success.
      */
-    boolean giveMoney(@NotNull OfflinePlayer player,
-                      double amount);
+    default boolean giveMoney(@NotNull OfflinePlayer player,
+                              @NotNull BigDecimal amount) {
+        return giveMoney(player, amount.doubleValue());
+    }
+
+    /**
+     * Remove money from a player.
+     *
+     * @param player The player.
+     * @param amount The amount to remove.
+     * @return If the transaction was a success.
+     * @deprecated Use {@link BigDecimal} methods instead.
+     */
+    @Deprecated(since = "6.43.0")
+    default boolean removeMoney(@NotNull OfflinePlayer player,
+                                double amount) {
+        return removeMoney(player, BigDecimal.valueOf(amount));
+    }
 
     /**
      * Remove money from a player.
@@ -37,16 +95,23 @@ public interface EconomyIntegration extends Integration {
      * @param amount The amount to remove.
      * @return If the transaction was a success.
      */
-    boolean removeMoney(@NotNull OfflinePlayer player,
-                        double amount);
+    default boolean removeMoney(@NotNull OfflinePlayer player,
+                                @NotNull BigDecimal amount) {
+        return removeMoney(player, amount.doubleValue());
+    }
+
 
     /**
      * Get the balance of a player.
      *
      * @param player The player.
      * @return The balance.
+     * @deprecated Use {@link BigDecimal} methods instead.
      */
-    double getBalance(@NotNull OfflinePlayer player);
+    @Deprecated(since = "6.43.0")
+    default double getBalance(@NotNull OfflinePlayer player) {
+        return getExactBalance(player).doubleValue();
+    }
 
     /**
      * Get the balance of a player.

eco-api/src/main/java/com/willfp/eco/core/integrations/economy/EconomyManager.java

@@ -44,6 +44,18 @@ public final class EconomyManager {
      */
     public static boolean hasAmount(@NotNull final OfflinePlayer player,
                                     final double amount) {
+        return hasAmount(player, BigDecimal.valueOf(amount));
+    }
+
+    /**
+     * Get if a player has a certain amount.
+     *
+     * @param player The player.
+     * @param amount The amount.
+     * @return If the player has the amount.
+     */
+    public static boolean hasAmount(@NotNull final OfflinePlayer player,
+                                    final BigDecimal amount) {
         for (EconomyIntegration integration : REGISTERED) {
             return integration.hasAmount(player, amount);
         }
@@ -60,6 +72,18 @@ public final class EconomyManager {
      */
     public static boolean giveMoney(@NotNull final OfflinePlayer player,
                                     final double amount) {
+        return giveMoney(player, BigDecimal.valueOf(amount));
+    }
+
+    /**
+     * Give money to a player.
+     *
+     * @param player The player.
+     * @param amount The amount to give.
+     * @return If the transaction was a success.
+     */
+    public static boolean giveMoney(@NotNull final OfflinePlayer player,
+                                    @NotNull final BigDecimal amount) {
         for (EconomyIntegration integration : REGISTERED) {
             return integration.giveMoney(player, amount);
         }
@@ -76,6 +100,18 @@ public final class EconomyManager {
      */
     public static boolean removeMoney(@NotNull final OfflinePlayer player,
                                       final double amount) {
+        return removeMoney(player, BigDecimal.valueOf(amount));
+    }
+
+    /**
+     * Remove money from a player.
+     *
+     * @param player The player.
+     * @param amount The amount to remove.
+     * @return If the transaction was a success.
+     */
+    public static boolean removeMoney(@NotNull final OfflinePlayer player,
+                                      @NotNull final BigDecimal amount) {
         for (EconomyIntegration integration : REGISTERED) {
             return integration.removeMoney(player, amount);
         }
@@ -90,11 +126,7 @@ public final class EconomyManager {
      * @return The balance.
      */
     public static double getBalance(@NotNull final OfflinePlayer player) {
-        for (EconomyIntegration integration : REGISTERED) {
-            return integration.getBalance(player);
-        }
-
-        return 0;
+        return getExactBalance(player).doubleValue();
     }
 
     /**

eco-api/src/main/java/com/willfp/eco/core/integrations/placeholder/PlaceholderEntry.java

@@ -158,13 +158,13 @@ public class PlaceholderEntry {
     Placeholder toModernPlaceholder() {
         if (this.requiresPlayer) {
             return new PlayerPlaceholder(
-                    Objects.requireNonNullElse(plugin, Eco.getHandler().getEcoPlugin()),
+                    Objects.requireNonNullElse(plugin, Eco.get().getEcoPlugin()),
                     identifier,
                     function
             );
         } else {
             return new PlayerlessPlaceholder(
-                    Objects.requireNonNullElse(plugin, Eco.getHandler().getEcoPlugin()),
+                    Objects.requireNonNullElse(plugin, Eco.get().getEcoPlugin()),
                     identifier,
                     () -> function.apply(null)
             );

eco-api/src/main/java/com/willfp/eco/core/integrations/placeholder/PlaceholderManager.java

@@ -51,10 +51,15 @@ public final class PlaceholderManager {
             .expireAfterWrite(50, TimeUnit.MILLISECONDS)
             .build(key -> key.entry.getValue(key.player));
 
+    /**
+     * The default PlaceholderAPI pattern; brought in for compatibility.
+     */
+    private static final Pattern PATTERN = Pattern.compile("[%]([^% ]+)[%]");
+
     /**
      * Empty injectable object.
      */
-    private static final PlaceholderInjectable EMPTY_INJECTABLE = new PlaceholderInjectable() {
+    public static final PlaceholderInjectable EMPTY_INJECTABLE = new PlaceholderInjectable() {
         @Override
         public void clearInjectedPlaceholders() {
             // Do nothing.
@@ -67,11 +72,6 @@ public final class PlaceholderManager {
         }
     };
 
-    /**
-     * The default PlaceholderAPI pattern; brought in for compatibility.
-     */
-    private static final Pattern PATTERN = Pattern.compile("[%]([^%]+)[%]");
-
     /**
      * Register a new placeholder integration.
      *
@@ -92,7 +92,7 @@ public final class PlaceholderManager {
             throw new IllegalArgumentException("Static placeholders cannot be registered!");
         }
 
-        EcoPlugin plugin = placeholder.getPlugin() == null ? Eco.getHandler().getEcoPlugin() : placeholder.getPlugin();
+        EcoPlugin plugin = placeholder.getPlugin() == null ? Eco.get().getEcoPlugin() : placeholder.getPlugin();
         Map<String, Placeholder> pluginPlaceholders = REGISTERED_PLACEHOLDERS
                 .getOrDefault(plugin, new HashMap<>());
         pluginPlaceholders.put(placeholder.getIdentifier(), placeholder);
@@ -136,11 +136,11 @@ public final class PlaceholderManager {
     public static String getResult(@Nullable final Player player,
                                    @NotNull final String identifier,
                                    @Nullable final EcoPlugin plugin) {
-        EcoPlugin owner = plugin == null ? Eco.getHandler().getEcoPlugin() : plugin;
+        EcoPlugin owner = plugin == null ? Eco.get().getEcoPlugin() : plugin;
         Placeholder placeholder = REGISTERED_PLACEHOLDERS.getOrDefault(owner, new HashMap<>()).get(identifier.toLowerCase());
 
         if (placeholder == null && plugin != null) {
-            Placeholder alternate = REGISTERED_PLACEHOLDERS.getOrDefault(Eco.getHandler().getEcoPlugin(), new HashMap<>())
+            Placeholder alternate = REGISTERED_PLACEHOLDERS.getOrDefault(Eco.get().getEcoPlugin(), new HashMap<>())
                     .get(identifier.toLowerCase());
             if (alternate != null) {
                 placeholder = alternate;

eco-api/src/main/java/com/willfp/eco/core/integrations/shop/ShopManager.java

@@ -1,10 +1,7 @@
 package com.willfp.eco.core.integrations.shop;
 
-import com.willfp.eco.core.EcoPlugin;
 import org.bukkit.entity.Player;
-import org.bukkit.event.Listener;
 import org.bukkit.inventory.ItemStack;
-import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -30,22 +27,6 @@ public final class ShopManager {
         REGISTERED.add(integration);
     }
 
-    /**
-     * Register the events with eco.
-     *
-     * @param plugin Instance of eco.
-     */
-    @ApiStatus.Internal
-    public static void registerEvents(@NotNull final EcoPlugin plugin) {
-        for (ShopIntegration integration : REGISTERED) {
-            Listener listener = integration.getSellEventAdapter();
-
-            if (listener != null) {
-                plugin.getEventManager().registerListener(listener);
-            }
-        }
-    }
-
     /**
      * Register eco item provider for shop plugins.
      */
@@ -89,6 +70,15 @@ public final class ShopManager {
         return 0.0;
     }
 
+    /**
+     * Get all registered integrations.
+     *
+     * @return The integrations.
+     */
+    public static Set<ShopIntegration> getRegisteredIntegrations() {
+        return new HashSet<>(REGISTERED);
+    }
+
     private ShopManager() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

eco-api/src/main/java/com/willfp/eco/core/items/CustomItem.java

@@ -53,7 +53,7 @@ public class CustomItem implements TestableItem {
         immediately after due to registration order; so eco waits until the item should be
         working in order to check.
          */
-        Eco.getHandler().getEcoPlugin().getScheduler().runLater(() -> {
+        Eco.get().getEcoPlugin().getScheduler().runLater(() -> {
             if (!matches(getItem())) {
                 Bukkit.getLogger().severe("Item with key " + key + " is invalid!");
             }

eco-api/src/main/java/com/willfp/eco/core/items/Items.java

@@ -25,6 +25,7 @@ import org.jetbrains.annotations.Nullable;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -81,6 +82,16 @@ public final class Items {
      */
     private static final ItemsLookupHandler ITEMS_LOOKUP_HANDLER = new ItemsLookupHandler(Items::doParse);
 
+    /**
+     * Instance of EmptyTestableItem.
+     */
+    private static final TestableItem EMPTY_TESTABLE_ITEM = new EmptyTestableItem();
+
+    /**
+     * Friendly material names (without underscores, etc.)
+     */
+    private static final Map<String, Material> FRIENDLY_MATERIAL_NAMES = new HashMap<>();
+
     /**
      * Register a new custom item.
      *
@@ -187,7 +198,7 @@ public final class Items {
     @NotNull
     public static TestableItem lookup(@NotNull final String key) {
         if (key.startsWith("{")) {
-            return Eco.getHandler().getSNBTHandler().createTestable(key);
+            return Eco.get().testableItemFromSNBT(key);
         }
 
         return ITEMS_LOOKUP_HANDLER.parseKey(key);
@@ -211,7 +222,7 @@ public final class Items {
             if (isWildcard) {
                 itemType = itemType.substring(1);
             }
-            Material material = Material.getMaterial(itemType.toUpperCase());
+            Material material = FRIENDLY_MATERIAL_NAMES.get(itemType.toLowerCase());
             if (material == null || material == Material.AIR) {
                 return new EmptyTestableItem();
             }
@@ -533,7 +544,7 @@ public final class Items {
      */
     @NotNull
     public static String toSNBT(@NotNull final ItemStack itemStack) {
-        return Eco.getHandler().getSNBTHandler().toSNBT(itemStack);
+        return Eco.get().toSNBT(itemStack);
     }
 
     /**
@@ -544,10 +555,41 @@ public final class Items {
      */
     @Nullable
     public static ItemStack fromSNBT(@NotNull final String snbt) {
-        return Eco.getHandler().getSNBTHandler().fromSNBT(snbt);
+        return Eco.get().fromSNBT(snbt);
+    }
+
+    /**
+     * Get if an item is empty.
+     *
+     * @param itemStack The item.
+     * @return If empty.
+     */
+    public static boolean isEmpty(@Nullable final ItemStack itemStack) {
+        return EMPTY_TESTABLE_ITEM.matches(itemStack);
     }
 
     private Items() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }
+
+    static {
+        for (Material material : Material.values()) {
+            FRIENDLY_MATERIAL_NAMES.put(material.name().toLowerCase(), material);
+
+            String oneWord = material.name().toLowerCase().replace("_", "");
+            if (!FRIENDLY_MATERIAL_NAMES.containsKey(oneWord)) {
+                FRIENDLY_MATERIAL_NAMES.put(oneWord, material);
+            }
+
+            String plural = material.name().toLowerCase() + "s";
+            if (!FRIENDLY_MATERIAL_NAMES.containsKey(plural)) {
+                FRIENDLY_MATERIAL_NAMES.put(plural, material);
+            }
+
+            String oneWordPlural = oneWord + "s";
+            if (!FRIENDLY_MATERIAL_NAMES.containsKey(oneWordPlural)) {
+                FRIENDLY_MATERIAL_NAMES.put(oneWordPlural, material);
+            }
+        }
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/items/SNBTHandler.java

@@ -1,41 +0,0 @@
-package com.willfp.eco.core.items;
-
-import com.willfp.eco.core.Eco;
-import org.bukkit.inventory.ItemStack;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-/**
- * API to handle SNBT conversion.
- */
-@ApiStatus.Internal
-@Eco.HandlerComponent
-public interface SNBTHandler {
-    /**
-     * Get item from SNBT.
-     *
-     * @param snbt The NBT string.
-     * @return The ItemStack, or null if invalid.
-     */
-    @Nullable
-    ItemStack fromSNBT(@NotNull String snbt);
-
-    /**
-     * Convert item to SNBT.
-     *
-     * @param itemStack The item.
-     * @return The NBT string.
-     */
-    @NotNull
-    String toSNBT(@NotNull ItemStack itemStack);
-
-    /**
-     * Make TestableItem from SNBT.
-     *
-     * @param snbt The NBT string.
-     * @return The TestableItem.
-     */
-    @NotNull
-    TestableItem createTestable(@NotNull String snbt);
-}

eco-api/src/main/java/com/willfp/eco/core/items/builder/AbstractItemStackBuilder.java

@@ -1,5 +1,6 @@
 package com.willfp.eco.core.items.builder;
 
+import com.willfp.eco.core.fast.FastItemStack;
 import com.willfp.eco.core.items.TestableItem;
 import com.willfp.eco.util.StringUtils;
 import org.apache.commons.lang.Validate;
@@ -13,7 +14,6 @@ import org.bukkit.persistence.PersistentDataType;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Supplier;
 
@@ -28,7 +28,7 @@ public abstract class AbstractItemStackBuilder<T extends ItemMeta, U extends Abs
     /**
      * The ItemMeta used while building.
      */
-    private final T meta;
+    private T meta;
 
     /**
      * The ItemStack.
@@ -113,10 +113,15 @@ public abstract class AbstractItemStackBuilder<T extends ItemMeta, U extends Abs
 
     @Override
     public U addLoreLine(@NotNull final String line) {
-        List<String> lore = meta.hasLore() ? meta.getLore() : new ArrayList<>();
-        assert lore != null;
+        base.setItemMeta(meta);
+
+        FastItemStack fis = FastItemStack.wrap(base);
+
+        List<String> lore = fis.getLore();
         lore.add(StringUtils.format(line));
-        meta.setLore(lore);
+        fis.setLore(lore);
+
+        meta = (T) base.getItemMeta();
 
         return (U) this;
     }
@@ -130,12 +135,19 @@ public abstract class AbstractItemStackBuilder<T extends ItemMeta, U extends Abs
 
     @Override
     public U addLoreLines(@NotNull final List<String> lines) {
-        List<String> lore = meta.hasLore() ? meta.getLore() : new ArrayList<>();
-        assert lore != null;
+        base.setItemMeta(meta);
+
+        FastItemStack fis = FastItemStack.wrap(base);
+
+        List<String> lore = fis.getLore();
+
         for (String line : lines) {
             lore.add(StringUtils.format(line));
         }
-        meta.setLore(lore);
+
+        fis.setLore(lore);
+
+        meta = (T) base.getItemMeta();
 
         return (U) this;
     }

eco-api/src/main/java/com/willfp/eco/core/math/MathContext.java

@@ -0,0 +1,63 @@
+package com.willfp.eco.core.math;
+
+import com.willfp.eco.core.integrations.placeholder.PlaceholderManager;
+import com.willfp.eco.core.placeholder.AdditionalPlayer;
+import com.willfp.eco.core.placeholder.PlaceholderInjectable;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Collection;
+import java.util.Collections;
+
+/**
+ * Represents a context to do math in.
+ *
+ * @param injectableContext The PlaceholderInjectable context.
+ * @param player            The player.
+ * @param additionalPlayers The additional players.
+ */
+public record MathContext(
+        @NotNull PlaceholderInjectable injectableContext,
+        @Nullable Player player,
+        @NotNull Collection<AdditionalPlayer> additionalPlayers
+) {
+    /**
+     * Empty math context.
+     */
+    public static final MathContext EMPTY = new MathContext(
+            PlaceholderManager.EMPTY_INJECTABLE,
+            null,
+            Collections.emptyList()
+    );
+
+    /**
+     * Create MathContext of a PlaceholderInjectable context.
+     *
+     * @param injectableContext The PlaceholderInjectable context.
+     * @return The MathContext.
+     */
+    public static MathContext of(@NotNull final PlaceholderInjectable injectableContext) {
+        return new MathContext(
+                injectableContext,
+                null,
+                Collections.emptyList()
+        );
+    }
+
+    /**
+     * Copy a MathContext with a player.
+     *
+     * @param context The context.
+     * @param player  The player.
+     * @return The new MathContext.
+     */
+    public static MathContext copyWithPlayer(@NotNull final MathContext context,
+                                             @Nullable final Player player) {
+        return new MathContext(
+                context.injectableContext(),
+                player,
+                context.additionalPlayers()
+        );
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/particle/ParticleFactory.java

@@ -0,0 +1,28 @@
+package com.willfp.eco.core.particle;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+
+/**
+ * Create particles.
+ */
+public interface ParticleFactory {
+    /**
+     * Get the names (how the particle looks in lookup strings).
+     * <p>
+     * For example, for RGB particles this would be 'rgb', 'color', etc.
+     *
+     * @return The allowed names.
+     */
+    @NotNull List<String> getNames();
+
+    /**
+     * Create the particle
+     *
+     * @param key The key.
+     * @return The particle.
+     */
+    @Nullable SpawnableParticle create(@NotNull String key);
+}

eco-api/src/main/java/com/willfp/eco/core/particle/Particles.java

@@ -0,0 +1,83 @@
+package com.willfp.eco.core.particle;
+
+import com.willfp.eco.core.particle.impl.EmptyParticle;
+import com.willfp.eco.core.particle.impl.SimpleParticle;
+import com.willfp.eco.util.StringUtils;
+import org.bukkit.Particle;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Class to manage particles.
+ */
+public final class Particles {
+    /**
+     * All factories.
+     */
+    private static final Map<String, ParticleFactory> FACTORIES = new ConcurrentHashMap<>();
+
+    /**
+     * Register a new particle factory.
+     *
+     * @param factory The factory.
+     */
+    public static void registerParticleFactory(@NotNull final ParticleFactory factory) {
+        for (String name : factory.getNames()) {
+            FACTORIES.put(name.toLowerCase(), factory);
+        }
+    }
+
+    /**
+     * Lookup a particle from a string.
+     * <p>
+     * A particle string should look like {@code magic}, {@code rgb:00ff00}
+     *
+     * @param key The key.
+     * @return The particle, or an {@link EmptyParticle} if invalid.
+     */
+    @NotNull
+    public static SpawnableParticle lookup(@NotNull final String key) {
+        String[] args = StringUtils.parseTokens(key.toLowerCase());
+
+        if (args.length == 0) {
+            return new EmptyParticle();
+        }
+
+        SpawnableParticle spawnableParticle;
+
+        String[] split = args[0].split(":");
+
+        if (split.length == 1) {
+            try {
+                Particle particle = Particle.valueOf(args[0].toUpperCase());
+                spawnableParticle = new SimpleParticle(particle);
+            } catch (IllegalArgumentException e) {
+                spawnableParticle = new EmptyParticle();
+            }
+        } else if (split.length == 2) {
+            String name = split[0];
+            String factoryKey = split[1];
+
+            ParticleFactory factory = FACTORIES.get(name);
+            if (factory == null) {
+                spawnableParticle = new EmptyParticle();
+            } else {
+                spawnableParticle = factory.create(factoryKey);
+            }
+        } else {
+            return new EmptyParticle();
+        }
+
+        if (spawnableParticle == null || spawnableParticle instanceof EmptyParticle) {
+            return new EmptyParticle();
+        }
+
+        return spawnableParticle;
+    }
+
+    private Particles() {
+        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/particle/SpawnableParticle.java

@@ -0,0 +1,27 @@
+package com.willfp.eco.core.particle;
+
+import org.bukkit.Location;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A particle that can be spawned.
+ */
+public interface SpawnableParticle {
+    /**
+     * Spawn the particle at a location.
+     *
+     * @param location The location.
+     * @param amount   The amount to spawn.
+     */
+    void spawn(@NotNull Location location,
+               int amount);
+
+    /**
+     * Spawn the particle at a location.
+     *
+     * @param location The location.
+     */
+    default void spawn(@NotNull Location location) {
+        spawn(location, 1);
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/particle/impl/EmptyParticle.java

@@ -0,0 +1,16 @@
+package com.willfp.eco.core.particle.impl;
+
+import com.willfp.eco.core.particle.SpawnableParticle;
+import org.bukkit.Location;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Empty (invalid) particle that is spawned when an invalid key is provided.
+ */
+public final class EmptyParticle implements SpawnableParticle {
+    @Override
+    public void spawn(@NotNull final Location location,
+                      final int amount) {
+        // Do nothing.
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/particle/impl/SimpleParticle.java

@@ -0,0 +1,38 @@
+package com.willfp.eco.core.particle.impl;
+
+import com.willfp.eco.core.particle.SpawnableParticle;
+import org.bukkit.Location;
+import org.bukkit.Particle;
+import org.bukkit.World;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Empty (invalid) particle that is spawned when an invalid key is provided.
+ */
+public final class SimpleParticle implements SpawnableParticle {
+    /**
+     * The particle to be spawned.
+     */
+    private final Particle particle;
+
+    /**
+     * Create a new spawnable particle.
+     *
+     * @param particle The particle.
+     */
+    public SimpleParticle(@NotNull final Particle particle) {
+        this.particle = particle;
+    }
+
+    @Override
+    public void spawn(@NotNull final Location location,
+                      final int amount) {
+        World world = location.getWorld();
+
+        if (world == null) {
+            return;
+        }
+
+        world.spawnParticle(particle, location, amount, 0, 0, 0, 0, null);
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/placeholder/InjectablePlaceholder.java

@@ -9,6 +9,6 @@ import com.willfp.eco.core.EcoPlugin;
 public sealed interface InjectablePlaceholder extends Placeholder permits PlayerStaticPlaceholder, StaticPlaceholder {
     @Override
     default EcoPlugin getPlugin() {
-        return Eco.getHandler().getEcoPlugin();
+        return Eco.get().getEcoPlugin();
     }
 }

eco-api/src/main/java/com/willfp/eco/core/price/ConfiguredPrice.java

@@ -0,0 +1,156 @@
+package com.willfp.eco.core.price;
+
+import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.math.MathContext;
+import com.willfp.eco.core.price.impl.PriceFree;
+import com.willfp.eco.core.serialization.ConfigDeserializer;
+import com.willfp.eco.util.NumberUtils;
+import com.willfp.eco.util.StringUtils;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Objects;
+
+/**
+ * A price that can be shown to a player.
+ */
+public final class ConfiguredPrice implements Price {
+    /**
+     * The deserializer.
+     */
+    private static final ConfigDeserializer<ConfiguredPrice> DESERIALIZER = new Deserializer();
+
+    /**
+     * Free.
+     */
+    private static final ConfiguredPrice FREE = new ConfiguredPrice(
+            new PriceFree(),
+            "Free"
+    );
+
+    /**
+     * The price.
+     */
+    private final Price price;
+
+    /**
+     * The format string.
+     */
+    private final String formatString;
+
+    /**
+     * Create a new Configured Price.
+     *
+     * @param price        The price.
+     * @param formatString The format string.
+     */
+    public ConfiguredPrice(@NotNull final Price price,
+                           @NotNull final String formatString) {
+        this.price = price;
+        this.formatString = formatString;
+    }
+
+    @Override
+    public boolean canAfford(@NotNull final Player player) {
+        return this.price.canAfford(player);
+    }
+
+    @Override
+    public void pay(@NotNull final Player player) {
+        this.price.pay(player);
+    }
+
+    @Override
+    public void giveTo(@NotNull final Player player) {
+        this.price.giveTo(player);
+    }
+
+    @Override
+    public double getValue(@NotNull final Player player) {
+        return this.price.getValue(player);
+    }
+
+    @Override
+    public double getMultiplier(@NotNull final Player player) {
+        return this.price.getMultiplier(player);
+    }
+
+    @Override
+    public void setMultiplier(@NotNull final Player player,
+                              final double multiplier) {
+        this.price.setMultiplier(player, multiplier);
+    }
+
+    /**
+     * Get the price that this delegates to.
+     *
+     * @return The price.
+     */
+    public Price getPrice() {
+        return price;
+    }
+
+    /**
+     * Get the display string for a player.
+     *
+     * @param player The player.
+     * @return The display string.
+     */
+    public String getDisplay(@NotNull final Player player) {
+        return StringUtils.format(
+                formatString.replace("%value%", NumberUtils.format(this.getPrice().getValue(player))),
+                player,
+                StringUtils.FormatOption.WITH_PLACEHOLDERS
+        );
+    }
+
+    /**
+     * Parse a configured price from config.
+     *
+     * @param config The config.
+     * @return The price, or null if it's invalid.
+     */
+    @Nullable
+    public static ConfiguredPrice create(@NotNull final Config config) {
+        return DESERIALIZER.deserialize(config);
+    }
+
+    /**
+     * Parse a configured price from config.
+     *
+     * @param config The config.
+     * @return The price, or free if invalid.
+     */
+    @NotNull
+    public static ConfiguredPrice createOrFree(@NotNull final Config config) {
+        return Objects.requireNonNullElse(create(config), FREE);
+    }
+
+    /**
+     * The deserializer for {@link ConfiguredPrice}.
+     */
+    private static final class Deserializer implements ConfigDeserializer<ConfiguredPrice> {
+        @Override
+        @Nullable
+        public ConfiguredPrice deserialize(@NotNull final Config config) {
+            if (!(
+                    config.has("value")
+                            && config.has("type")
+                            && config.has("display")
+            )) {
+                return null;
+            }
+
+            String formatString = config.getString("display");
+
+            Price price = Prices.create(
+                    config.getString("value"),
+                    config.getString("type"),
+                    MathContext.of(config)
+            );
+
+            return new ConfiguredPrice(price, formatString);
+        }
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/price/Price.java

@@ -0,0 +1,91 @@
+package com.willfp.eco.core.price;
+
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A price that a player should pay.
+ */
+public interface Price {
+    /**
+     * Get if the player can afford the price.
+     *
+     * @param player The player.
+     * @return If the player can afford.
+     */
+    boolean canAfford(@NotNull Player player);
+
+    /**
+     * Make the player pay the price.
+     * <p>
+     * Only run this if the player can afford the price.
+     *
+     * @param player The player.
+     */
+    void pay(@NotNull Player player);
+
+    /**
+     * Give the value of the price to the player.
+     * <p>
+     * You should override this method, it's only marked as default for
+     * backwards compatibility purposes.
+     *
+     * @param player The player.
+     */
+    default void giveTo(@NotNull Player player) {
+        // Override when needed.
+    }
+
+    /**
+     * If the price is backed by a value, get it here.
+     *
+     * @param player The player.
+     * @return The value.
+     */
+    default double getValue(@NotNull final Player player) {
+        return 0;
+    }
+
+    /**
+     * If the price is backed by a value, get it here.
+     *
+     * @return The value.
+     * @deprecated Use getValue(Player) instead.
+     */
+    @Deprecated(since = "6.45.0", forRemoval = true)
+    default double getValue() {
+        return 0;
+    }
+
+    /**
+     * If the price is backed by a value, set it here.
+     *
+     * @param value The value.
+     * @deprecated Values shouldn't be fixed.
+     */
+    @Deprecated(since = "6.45.0", forRemoval = true)
+    default void setValue(final double value) {
+        // Override when needed.
+    }
+
+    /**
+     * Get the price multiplier for a player.
+     *
+     * @param player The player.
+     * @return The value.
+     */
+    default double getMultiplier(@NotNull final Player player) {
+        return 1;
+    }
+
+    /**
+     * Set the price multiplier for a player.
+     *
+     * @param player     The        player.
+     * @param multiplier The multiplier.
+     */
+    default void setMultiplier(@NotNull final Player player,
+                               final double multiplier) {
+        // Override when needed.
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/price/PriceFactory.java

@@ -0,0 +1,46 @@
+package com.willfp.eco.core.price;
+
+import com.willfp.eco.core.math.MathContext;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+import java.util.function.Function;
+
+/**
+ * Create prices.
+ * <p>
+ * You must override one of the create methods.
+ */
+public interface PriceFactory {
+    /**
+     * Get the names (how the price looks in lookup strings).
+     * <p>
+     * For example, for XP Levels this would be 'l', 'xpl', 'levels', etc.
+     *
+     * @return The allowed names.
+     */
+    @NotNull List<String> getNames();
+
+    /**
+     * Create the price.
+     *
+     * @param value The value.
+     * @return The price.
+     */
+    default @NotNull Price create(final double value) {
+        return create(MathContext.EMPTY, (ctx) -> value);
+    }
+
+    /**
+     * Create the price.
+     *
+     * @param baseContext The base MathContext.
+     * @param function    The function to use. Should use {@link MathContext#copyWithPlayer(MathContext, Player)} on calls.
+     * @return The price.
+     */
+    default @NotNull Price create(@NotNull final MathContext baseContext,
+                                  @NotNull final Function<MathContext, Double> function) {
+        return create(function.apply(baseContext));
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/price/Prices.java

@@ -0,0 +1,103 @@
+package com.willfp.eco.core.price;
+
+import com.willfp.eco.core.items.Items;
+import com.willfp.eco.core.items.TestableItem;
+import com.willfp.eco.core.math.MathContext;
+import com.willfp.eco.core.price.impl.PriceEconomy;
+import com.willfp.eco.core.price.impl.PriceFree;
+import com.willfp.eco.core.price.impl.PriceItem;
+import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
+import com.willfp.eco.util.NumberUtils;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
+
+/**
+ * Class to manage prices.
+ */
+public final class Prices {
+    /**
+     * All factories.
+     */
+    private static final Map<String, PriceFactory> FACTORIES = new ConcurrentHashMap<>();
+
+    /**
+     * Register a new price factory.
+     *
+     * @param factory The factory.
+     */
+    public static void registerPriceFactory(@NotNull final PriceFactory factory) {
+        for (String name : factory.getNames()) {
+            FACTORIES.put(name.toLowerCase(), factory);
+        }
+    }
+
+    /**
+     * Create price from an expression (representing the value),
+     * and a price name.
+     * <p>
+     * Supports items as price names.
+     *
+     * @param expression The expression for the value.
+     * @param priceName  The price name.
+     * @return The price, or free if invalid.
+     */
+    @NotNull
+    public static Price create(@NotNull final String expression,
+                               @Nullable final String priceName) {
+        return create(expression, priceName, MathContext.EMPTY);
+    }
+
+    /**
+     * Create price from an expression (representing the value),
+     * and a price name. Uses a context to parse the expression.
+     * <p>
+     * Supports items as price names.
+     *
+     * @param expression The expression for the value.
+     * @param priceName  The price name.
+     * @param context    The math context to parse the expression.
+     * @return The price, or free if invalid.
+     */
+    @NotNull
+    public static Price create(@NotNull final String expression,
+                               @Nullable final String priceName,
+                               @NotNull final MathContext context) {
+        Function<MathContext, Double> function = (ctx) -> NumberUtils.evaluateExpression(
+                expression,
+                ctx
+        );
+
+        if (function.apply(context) <= 0) {
+            return new PriceFree();
+        }
+
+        // Default to economy
+        if (priceName == null) {
+            return new PriceEconomy(context, function);
+        }
+
+        // Find price factory
+        PriceFactory factory = FACTORIES.get(priceName);
+
+        // If no price factory, default to item price
+        if (factory == null) {
+            TestableItem item = Items.lookup(priceName);
+
+            if (item instanceof EmptyTestableItem) {
+                return new PriceFree();
+            }
+
+            return new PriceItem(context, function, item);
+        } else {
+            return factory.create(context, function);
+        }
+    }
+
+    private Prices() {
+        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/price/impl/PriceEconomy.java

@@ -0,0 +1,84 @@
+package com.willfp.eco.core.price.impl;
+
+import com.willfp.eco.core.integrations.economy.EconomyManager;
+import com.willfp.eco.core.math.MathContext;
+import com.willfp.eco.core.price.Price;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+import java.util.function.Function;
+
+/**
+ * Economy-based price (for Vault, Treasury, etc.)
+ */
+public final class PriceEconomy implements Price {
+    /**
+     * The value of the price.
+     */
+    private final Function<MathContext, Double> function;
+
+    /**
+     * The base math context.
+     */
+    private final MathContext baseContext;
+
+    /**
+     * The multipliers.
+     */
+    private final Map<UUID, Double> multipliers = new HashMap<>();
+
+    /**
+     * Create a new economy-based price.
+     *
+     * @param value The value.
+     */
+    public PriceEconomy(final double value) {
+        this(MathContext.EMPTY, ctx -> value);
+    }
+
+    /**
+     * Create a new economy-based price.
+     *
+     * @param baseContext The base context.
+     * @param function    The function.
+     */
+    public PriceEconomy(@NotNull final MathContext baseContext,
+                        @NotNull final Function<MathContext, Double> function) {
+        this.baseContext = baseContext;
+        this.function = function;
+    }
+
+    @Override
+    public boolean canAfford(@NotNull final Player player) {
+        return EconomyManager.getBalance(player) >= getValue(player);
+    }
+
+    @Override
+    public void pay(@NotNull final Player player) {
+        EconomyManager.removeMoney(player, getValue(player));
+    }
+
+    @Override
+    public void giveTo(@NotNull final Player player) {
+        EconomyManager.giveMoney(player, getValue(player));
+    }
+
+    @Override
+    public double getValue(@NotNull final Player player) {
+        return this.function.apply(MathContext.copyWithPlayer(baseContext, player)) * getMultiplier(player);
+    }
+
+    @Override
+    public double getMultiplier(@NotNull final Player player) {
+        return this.multipliers.getOrDefault(player.getUniqueId(), 1.0);
+    }
+
+    @Override
+    public void setMultiplier(@NotNull final Player player,
+                              final double multiplier) {
+        this.multipliers.put(player.getUniqueId(), multiplier);
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/price/impl/PriceFree.java

@@ -0,0 +1,27 @@
+package com.willfp.eco.core.price.impl;
+
+import com.willfp.eco.core.price.Price;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Free (default) price.
+ */
+public final class PriceFree implements Price {
+    /**
+     * Create a new free price.
+     */
+    public PriceFree() {
+
+    }
+
+    @Override
+    public boolean canAfford(@NotNull final Player player) {
+        return true;
+    }
+
+    @Override
+    public void pay(@NotNull final Player player) {
+        // Do nothing.
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/price/impl/PriceItem.java

@@ -0,0 +1,149 @@
+package com.willfp.eco.core.price.impl;
+
+import com.willfp.eco.core.drops.DropQueue;
+import com.willfp.eco.core.items.TestableItem;
+import com.willfp.eco.core.math.MathContext;
+import com.willfp.eco.core.price.Price;
+import org.bukkit.Material;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+import java.util.function.Function;
+
+/**
+ * Item-based price.
+ */
+public final class PriceItem implements Price {
+    /**
+     * The base MathContext.
+     */
+    private final MathContext baseContext;
+
+    /**
+     * The amount of items.
+     */
+    private final Function<MathContext, Double> function;
+
+    /**
+     * The item.
+     */
+    private final TestableItem item;
+
+    /**
+     * The multipliers.
+     */
+    private final Map<UUID, Double> multipliers = new HashMap<>();
+
+    /**
+     * Create a new item-based price.
+     *
+     * @param amount The amount.
+     * @param item   The item.
+     */
+    public PriceItem(final int amount,
+                     @NotNull final TestableItem item) {
+        this(MathContext.EMPTY, ctx -> (double) amount, item);
+    }
+
+    /**
+     * Create a new item-based price.
+     *
+     * @param baseContext The base MathContext.
+     * @param function    The function to get the amount of items to remove.
+     * @param item        The item.
+     */
+    public PriceItem(@NotNull final MathContext baseContext,
+                     @NotNull final Function<MathContext, Double> function,
+                     @NotNull final TestableItem item) {
+        this.baseContext = baseContext;
+        this.function = function;
+        this.item = item;
+    }
+
+    /**
+     * Get the item.
+     *
+     * @return The item.
+     */
+    public TestableItem getItem() {
+        return item;
+    }
+
+    @Override
+    public boolean canAfford(@NotNull final Player player) {
+        int toRemove = (int) getValue(player);
+        if (toRemove <= 0) {
+            return true;
+        }
+
+        int count = 0;
+
+        for (ItemStack itemStack : player.getInventory().getContents()) {
+            if (item.matches(itemStack)) {
+                count += itemStack.getAmount();
+            }
+        }
+
+        return count >= toRemove;
+    }
+
+    @Override
+    public void pay(@NotNull final Player player) {
+        int toRemove = (int) getValue(player);
+        int count = 0;
+
+        for (ItemStack itemStack : player.getInventory().getContents()) {
+            if (count >= toRemove) {
+                break;
+            }
+
+            if (item.matches(itemStack)) {
+                int itemAmount = itemStack.getAmount();
+
+                if (itemAmount > toRemove) {
+                    itemStack.setAmount(itemAmount - toRemove);
+                }
+
+                if (itemAmount <= toRemove) {
+                    itemStack.setAmount(0);
+                    itemStack.setType(Material.AIR);
+                }
+
+                count += itemAmount;
+            }
+        }
+    }
+
+    @Override
+    public void giveTo(@NotNull final Player player) {
+        ItemStack itemStack = item.getItem().clone();
+        itemStack.setAmount((int) getValue(player));
+
+        new DropQueue(player)
+                .addItem(itemStack)
+                .forceTelekinesis()
+                .push();
+    }
+
+    @Override
+    public double getValue(@NotNull final Player player) {
+        return Math.toIntExact(Math.round(
+                this.function.apply(MathContext.copyWithPlayer(baseContext, player)) * getMultiplier(player)
+        ));
+    }
+
+    @Override
+    public double getMultiplier(@NotNull final Player player) {
+        return this.multipliers.getOrDefault(player.getUniqueId(), 1.0);
+    }
+
+    @Override
+    public void setMultiplier(@NotNull final Player player,
+                              final double multiplier) {
+        this.multipliers.put(player.getUniqueId(), multiplier);
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/proxy/Cleaner.java

@@ -7,7 +7,10 @@ import org.jetbrains.annotations.NotNull;
  * A cleaner is an internal component to fix classloader errors.
  * <p>
  * Important to allow for PlugMan/ServerUtils support.
+ *
+ * @deprecated No reason for this to be in the API.
  */
+@Deprecated(since = "6.43.0", forRemoval = true)
 public interface Cleaner {
     /**
      * Clean up classes left over from plugin.

eco-api/src/main/java/com/willfp/eco/core/recipe/recipes/ShapedCraftingRecipe.java

@@ -2,7 +2,6 @@ package com.willfp.eco.core.recipe.recipes;
 
 import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.EcoPlugin;
-import com.willfp.eco.core.PluginDependent;
 import com.willfp.eco.core.items.TestableItem;
 import com.willfp.eco.core.recipe.Recipes;
 import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
@@ -25,7 +24,12 @@ import java.util.List;
 /**
  * Shaped 3x3 crafting recipe.
  */
-public final class ShapedCraftingRecipe extends PluginDependent<EcoPlugin> implements CraftingRecipe {
+public final class ShapedCraftingRecipe implements CraftingRecipe {
+    /**
+     * The plugin.
+     */
+    private final EcoPlugin plugin;
+
     /**
      * Recipe parts.
      */
@@ -56,8 +60,7 @@ public final class ShapedCraftingRecipe extends PluginDependent<EcoPlugin> imple
                                  @NotNull final List<TestableItem> parts,
                                  @NotNull final ItemStack output,
                                  @Nullable final String permission) {
-        super(plugin);
-
+        this.plugin = plugin;
         this.parts = parts;
         this.key = plugin.getNamespacedKeyFactory().create(key);
         this.displayedKey = plugin.getNamespacedKeyFactory().create(key + "_displayed");
@@ -96,7 +99,7 @@ public final class ShapedCraftingRecipe extends PluginDependent<EcoPlugin> imple
             shapedRecipe.setIngredient(character, parts.get(i).getItem().getType());
         }
 
-        if (Eco.getHandler().getEcoPlugin().getConfigYml().getBool("displayed-recipes")) {
+        if (Eco.get().getEcoPlugin().getConfigYml().getBool("displayed-recipes")) {
             ShapedRecipe displayedRecipe = new ShapedRecipe(this.getDisplayedKey(), this.getOutput());
             displayedRecipe.shape("012", "345", "678");
             for (int i = 0; i < 9; i++) {
@@ -124,7 +127,7 @@ public final class ShapedCraftingRecipe extends PluginDependent<EcoPlugin> imple
                         List<String> lore = meta.hasLore() ? meta.getLore() : new ArrayList<>();
                         assert lore != null;
                         lore.add("");
-                        String add = Eco.getHandler().getEcoPlugin().getLangYml().getFormattedString("multiple-in-craft");
+                        String add = Eco.get().getEcoPlugin().getLangYml().getFormattedString("multiple-in-craft");
                         add = add.replace("%amount%", String.valueOf(item.getAmount()));
                         lore.add(add);
                         meta.setLore(lore);
@@ -145,6 +148,15 @@ public final class ShapedCraftingRecipe extends PluginDependent<EcoPlugin> imple
         Bukkit.getServer().addRecipe(shapedRecipe);
     }
 
+    /**
+     * Get the plugin.
+     *
+     * @return The plugin.
+     */
+    public EcoPlugin getPlugin() {
+        return plugin;
+    }
+
     /**
      * Create a new recipe builder.
      *

eco-api/src/main/java/com/willfp/eco/core/recipe/recipes/ShapelessCraftingRecipe.java

@@ -3,7 +3,6 @@ package com.willfp.eco.core.recipe.recipes;
 import com.google.common.annotations.Beta;
 import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.EcoPlugin;
-import com.willfp.eco.core.PluginDependent;
 import com.willfp.eco.core.items.TestableItem;
 import com.willfp.eco.core.recipe.Recipes;
 import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
@@ -26,7 +25,12 @@ import java.util.Optional;
  * Shapeless crafting recipe.
  */
 @Beta
-public final class ShapelessCraftingRecipe extends PluginDependent<EcoPlugin> implements CraftingRecipe {
+public final class ShapelessCraftingRecipe implements CraftingRecipe {
+    /**
+     * The plugin.
+     */
+    private final EcoPlugin plugin;
+
     /**
      * Recipe parts.
      */
@@ -57,8 +61,7 @@ public final class ShapelessCraftingRecipe extends PluginDependent<EcoPlugin> im
                                     @NotNull final List<TestableItem> parts,
                                     @NotNull final ItemStack output,
                                     @Nullable final String permission) {
-        super(plugin);
-
+        this.plugin = plugin;
         this.parts = parts;
         this.key = plugin.getNamespacedKeyFactory().create(key);
         this.displayedKey = plugin.getNamespacedKeyFactory().create(key + "_displayed");
@@ -101,7 +104,7 @@ public final class ShapelessCraftingRecipe extends PluginDependent<EcoPlugin> im
             shapelessRecipe.addIngredient(part.getItem().getType());
         }
 
-        if (Eco.getHandler().getEcoPlugin().getConfigYml().getBool("displayed-recipes")) {
+        if (Eco.get().getEcoPlugin().getConfigYml().getBool("displayed-recipes")) {
             ShapelessRecipe displayedRecipe = new ShapelessRecipe(this.getDisplayedKey(), this.getOutput());
             for (TestableItem part : parts) {
                 List<TestableItem> items = new ArrayList<>();
@@ -122,7 +125,7 @@ public final class ShapelessCraftingRecipe extends PluginDependent<EcoPlugin> im
                         List<String> lore = meta.hasLore() ? meta.getLore() : new ArrayList<>();
                         assert lore != null;
                         lore.add("");
-                        String add = Eco.getHandler().getEcoPlugin().getLangYml().getFormattedString("multiple-in-craft");
+                        String add = Eco.get().getEcoPlugin().getLangYml().getFormattedString("multiple-in-craft");
                         add = add.replace("%amount%", String.valueOf(item.getAmount()));
                         lore.add(add);
                         meta.setLore(lore);
@@ -143,6 +146,15 @@ public final class ShapelessCraftingRecipe extends PluginDependent<EcoPlugin> im
         Bukkit.getServer().addRecipe(shapelessRecipe);
     }
 
+    /**
+     * Get the plugin.
+     *
+     * @return The plugin.
+     */
+    public EcoPlugin getPlugin() {
+        return plugin;
+    }
+
     /**
      * Create a new recipe builder.
      *

eco-api/src/main/java/com/willfp/eco/core/web/Paste.java

@@ -59,7 +59,7 @@ public class Paste {
      * @param callback The consumer to accept the response token.
      */
     public void getHastebinToken(@NotNull final Consumer<String> callback) {
-        Eco.getHandler().getEcoPlugin().getScheduler().runAsync(() -> {
+        Eco.get().getEcoPlugin().getScheduler().runAsync(() -> {
             try {
                 byte[] postData = URLEncoder.encode(contents, StandardCharsets.UTF_8).getBytes(StandardCharsets.UTF_8);
                 int postDataLength = postData.length;

eco-api/src/main/java/com/willfp/eco/core/web/UpdateChecker.java

@@ -1,7 +1,6 @@
 package com.willfp.eco.core.web;
 
 import com.willfp.eco.core.EcoPlugin;
-import com.willfp.eco.core.PluginDependent;
 import org.bukkit.util.Consumer;
 import org.jetbrains.annotations.NotNull;
 
@@ -13,14 +12,19 @@ import java.util.Scanner;
 /**
  * Class to check for updates of a plugin on spigot.
  */
-public class UpdateChecker extends PluginDependent<EcoPlugin> {
+public class UpdateChecker {
+    /**
+     * The plugin.
+     */
+    private final EcoPlugin plugin;
+
     /**
      * Create an update checker for the specified spigot resource id.
      *
      * @param plugin The plugin to check.
      */
     public UpdateChecker(@NotNull final EcoPlugin plugin) {
-        super(plugin);
+        this.plugin = plugin;
     }
 
     /**
@@ -44,4 +48,13 @@ public class UpdateChecker extends PluginDependent<EcoPlugin> {
             }
         });
     }
+
+    /**
+     * Get the plugin.
+     *
+     * @return The plugin.
+     */
+    public EcoPlugin getPlugin() {
+        return plugin;
+    }
 }

eco-api/src/main/java/com/willfp/eco/util/MenuUtils.java

@@ -1,24 +1,16 @@
 package com.willfp.eco.util;
 
+import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.gui.menu.Menu;
 import com.willfp.eco.core.tuples.Pair;
-import org.apache.commons.lang.Validate;
 import org.bukkit.entity.Player;
-import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.function.Function;
-
 /**
  * Utilities / API methods for menus.
  */
 public final class MenuUtils {
-    /**
-     * The menu supplier.
-     */
-    private static Function<Player, Menu> menuGetter = null;
-
     /**
      * Convert 0-53 slot to row and column pair.
      *
@@ -27,9 +19,7 @@ public final class MenuUtils {
      */
     @NotNull
     public static Pair<Integer, Integer> convertSlotToRowColumn(final int slot) {
-        int row = Math.floorDiv(slot, 9);
-        int column = slot - row * 9;
-        return new Pair<>(row + 1, column + 1);
+        return convertSlotToRowColumn(slot, 9);
     }
 
     /**
@@ -40,7 +30,36 @@ public final class MenuUtils {
      * @return The slot.
      */
     public static int rowColumnToSlot(final int row, final int column) {
-        return (column - 1) + ((row - 1) * 9);
+        return rowColumnToSlot(row, column, 9);
+    }
+
+    /**
+     * Convert 0-53 slot to row and column pair.
+     *
+     * @param slot    The slot.
+     * @param columns The columns.
+     * @return The pair of row and columns.
+     */
+    @NotNull
+    public static Pair<Integer, Integer> convertSlotToRowColumn(final int slot,
+                                                                final int columns) {
+        int row = Math.floorDiv(slot, columns);
+        int column = slot - row * columns;
+        return new Pair<>(row + 1, column + 1);
+    }
+
+    /**
+     * Convert row and column to 0-53 slot.
+     *
+     * @param row     The row.
+     * @param column  The column.
+     * @param columns The columns in the menu.
+     * @return The slot.
+     */
+    public static int rowColumnToSlot(final int row,
+                                      final int column,
+                                      final int columns) {
+        return (column - 1) + ((row - 1) * columns);
     }
 
     /**
@@ -51,19 +70,7 @@ public final class MenuUtils {
      */
     @Nullable
     public static Menu getOpenMenu(@NotNull final Player player) {
-        return menuGetter.apply(player);
-    }
-
-    /**
-     * Initialize the tps supplier function.
-     *
-     * @param function The function.
-     */
-    @ApiStatus.Internal
-    public static void initialize(@NotNull final Function<Player, Menu> function) {
-        Validate.isTrue(menuGetter == null, "Already initialized!");
-
-        menuGetter = function;
+        return Eco.get().getOpenMenu(player);
     }
 
     private MenuUtils() {

eco-api/src/main/java/com/willfp/eco/util/NamespacedKeyUtils.java

@@ -32,7 +32,7 @@ public final class NamespacedKeyUtils {
     @NotNull
     public static NamespacedKey create(@NotNull final String namespace,
                                        @NotNull final String key) {
-        return Eco.getHandler().createNamespacedKey(
+        return Eco.get().createNamespacedKey(
                 namespace,
                 key
         );

eco-api/src/main/java/com/willfp/eco/util/NumberUtils.java

@@ -1,19 +1,19 @@
 package com.willfp.eco.util;
 
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.integrations.placeholder.PlaceholderManager;
 import com.willfp.eco.core.placeholder.AdditionalPlayer;
 import com.willfp.eco.core.placeholder.InjectablePlaceholder;
+import com.willfp.eco.core.math.MathContext;
 import com.willfp.eco.core.placeholder.PlaceholderInjectable;
 import com.willfp.eco.core.placeholder.StaticPlaceholder;
-import org.apache.commons.lang.Validate;
 import org.bukkit.entity.Player;
-import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.text.DecimalFormat;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
@@ -28,11 +28,6 @@ public final class NumberUtils {
      */
     private static final double[] SIN_LOOKUP = new double[65536];
 
-    /**
-     * Crunch handler.
-     */
-    private static CrunchHandler crunch = null;
-
     /**
      * Set of roman numerals to look up.
      */
@@ -246,7 +241,7 @@ public final class NumberUtils {
      * @return The value of the expression, or zero if invalid.
      */
     public static double evaluateExpression(@NotNull final String expression) {
-        return evaluateExpression(expression, null);
+        return evaluateExpression(expression, MathContext.EMPTY);
     }
 
     /**
@@ -258,18 +253,7 @@ public final class NumberUtils {
      */
     public static double evaluateExpression(@NotNull final String expression,
                                             @Nullable final Player player) {
-        return evaluateExpression(expression, player, new PlaceholderInjectable() {
-            @Override
-            public void clearInjectedPlaceholders() {
-                // Nothing.
-            }
-
-            @Override
-            public @NotNull
-            List<InjectablePlaceholder> getPlaceholderInjections() {
-                return Collections.emptyList();
-            }
-        });
+        return evaluateExpression(expression, player, PlaceholderManager.EMPTY_INJECTABLE);
     }
 
     /**
@@ -329,38 +313,23 @@ public final class NumberUtils {
                                             @Nullable final Player player,
                                             @NotNull final PlaceholderInjectable context,
                                             @NotNull final Collection<AdditionalPlayer> additionalPlayers) {
-        return crunch.evaluate(expression, player, context, additionalPlayers);
+        return Eco.get().evaluate(expression, new MathContext(
+                context,
+                player,
+                additionalPlayers
+        ));
     }
 
     /**
-     * Init crunch handler.
+     * Evaluate an expression with respect to a player (for placeholders).
      *
-     * @param handler The handler.
+     * @param expression The expression.
+     * @param context    The math context.
+     * @return The value of the expression, or zero if invalid.
      */
-    @ApiStatus.Internal
-    public static void initCrunch(@NotNull final CrunchHandler handler) {
-        Validate.isTrue(crunch == null, "Already initialized!");
-        crunch = handler;
-    }
-
-    /**
-     * Bridge component for crunch.
-     */
-    @ApiStatus.Internal
-    public interface CrunchHandler {
-        /**
-         * Evaluate an expression.
-         *
-         * @param expression        The expression.
-         * @param player            The player.
-         * @param injectable        The injectable placeholders.
-         * @param additionalPlayers The additional players.
-         * @return The value of the expression, or zero if invalid.
-         */
-        double evaluate(@NotNull String expression,
-                        @Nullable Player player,
-                        @NotNull PlaceholderInjectable injectable,
-                        @NotNull Collection<AdditionalPlayer> additionalPlayers);
+    public static double evaluateExpression(@NotNull final String expression,
+                                            @NotNull final MathContext context) {
+        return Eco.get().evaluate(expression, context);
     }
 
     private NumberUtils() {

eco-api/src/main/java/com/willfp/eco/util/PlayerUtils.java

@@ -42,7 +42,7 @@ public final class PlayerUtils {
      */
     @NotNull
     public static Audience getAudience(@NotNull final Player player) {
-        BukkitAudiences adventure = Eco.getHandler().getAdventure();
+        BukkitAudiences adventure = Eco.get().getAdventure();
 
         if (Prerequisite.HAS_PAPER.isMet()) {
             if (player instanceof Audience) {
@@ -67,7 +67,7 @@ public final class PlayerUtils {
      */
     @NotNull
     public static Audience getAudience(@NotNull final CommandSender sender) {
-        BukkitAudiences adventure = Eco.getHandler().getAdventure();
+        BukkitAudiences adventure = Eco.get().getAdventure();
 
         if (Prerequisite.HAS_PAPER.isMet()) {
             if (sender instanceof Audience) {

eco-api/src/main/java/com/willfp/eco/util/ServerUtils.java

@@ -1,29 +1,18 @@
 package com.willfp.eco.util;
 
-import org.apache.commons.lang.Validate;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.function.Supplier;
+import com.willfp.eco.core.Eco;
 
 /**
  * Utilities / API methods for the server.
  */
 public final class ServerUtils {
-    /**
-     * The TPS supplier.
-     */
-    private static Supplier<Double> tpsSupplier = null;
-
     /**
      * Get the current server TPS.
      *
      * @return The TPS.
      */
     public static double getTps() {
-        Validate.notNull(tpsSupplier, "Not initialized!");
-
-        double tps = tpsSupplier.get();
+        double tps = Eco.get().getTPS();
 
         if (tps > 20) {
             return 20;
@@ -32,18 +21,6 @@ public final class ServerUtils {
         }
     }
 
-    /**
-     * Initialize the tps supplier function.
-     *
-     * @param function The function.
-     */
-    @ApiStatus.Internal
-    public static void initialize(@NotNull final Supplier<Double> function) {
-        Validate.isTrue(tpsSupplier == null, "Already initialized!");
-
-        tpsSupplier = function;
-    }
-
     private ServerUtils() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

eco-api/src/main/java/com/willfp/eco/util/SkullUtils.java

@@ -1,33 +1,14 @@
 package com.willfp.eco.util;
 
-import org.apache.commons.lang.Validate;
+import com.willfp.eco.core.Eco;
 import org.bukkit.inventory.meta.SkullMeta;
-import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.function.BiConsumer;
-import java.util.function.Function;
-
 /**
  * Utilities / API methods for player heads.
  */
 public final class SkullUtils {
-    /**
-     * If the meta set function has been set.
-     */
-    private static boolean initialized = false;
-
-    /**
-     * The meta set function.
-     */
-    private static BiConsumer<SkullMeta, String> metaSetConsumer = null;
-
-    /**
-     * The meta get function.
-     */
-    private static Function<SkullMeta, String> metaGetConsumer = null;
-
     /**
      * Set the texture of a skull from base64.
      *
@@ -36,10 +17,7 @@ public final class SkullUtils {
      */
     public static void setSkullTexture(@NotNull final SkullMeta meta,
                                        @NotNull final String base64) {
-        Validate.isTrue(initialized, "Must be initialized!");
-        Validate.notNull(metaSetConsumer, "Must be initialized!");
-
-        metaSetConsumer.accept(meta, base64);
+        Eco.get().setSkullTexture(meta, base64);
     }
 
     /**
@@ -50,26 +28,7 @@ public final class SkullUtils {
      */
     @Nullable
     public static String getSkullTexture(@NotNull final SkullMeta meta) {
-        Validate.isTrue(initialized, "Must be initialized!");
-        Validate.notNull(metaGetConsumer, "Must be initialized!");
-
-        return metaGetConsumer.apply(meta);
-    }
-
-    /**
-     * Initialize the skull texture function.
-     *
-     * @param function  The function.
-     * @param function2 Get function.
-     */
-    @ApiStatus.Internal
-    public static void initialize(@NotNull final BiConsumer<SkullMeta, String> function,
-                                  @NotNull final Function<SkullMeta, String> function2) {
-        Validate.isTrue(!initialized, "Already initialized!");
-
-        metaSetConsumer = function;
-        metaGetConsumer = function2;
-        initialized = true;
+        return Eco.get().getSkullTexture(meta);
     }
 
     private SkullUtils() {

eco-api/src/main/java/com/willfp/eco/util/StringUtils.java

@@ -339,7 +339,7 @@ public final class StringUtils {
     }
 
     private static String translateMiniMessage(@NotNull final String message) {
-        return Eco.getHandler().formatMiniMessage(message);
+        return Eco.get().formatMiniMessage(message);
     }
 
     private static String translateHexColorCodes(@NotNull final String message) {

eco-api/src/main/kotlin/com/willfp/eco/core/config/ConfigHelpers.kt

@@ -3,9 +3,12 @@
 package com.willfp.eco.core.config
 
 import com.willfp.eco.core.config.interfaces.Config
+import org.bukkit.configuration.ConfigurationSection
+import java.io.File
+import java.io.InputStream
 
 /** Helper class to create configs with a kotlin DSL. */
-class DSLConfig internal constructor(type: ConfigType) : TransientConfig(emptyMap(), type) {
+class DSLConfig internal constructor(type: ConfigType) : GenericConfig(type) {
     /**
      * Map a key to a value.
      *
@@ -34,3 +37,30 @@ class DSLConfig internal constructor(type: ConfigType) : TransientConfig(emptyMa
  */
 fun config(type: ConfigType = ConfigType.YAML, builder: DSLConfig.() -> Unit): Config =
     DSLConfig(type).apply(builder)
+
+/** @see Configs.empty */
+fun emptyConfig() = Configs.empty()
+
+/** @see Configs.empty */
+fun emptyConfig(type: ConfigType) = Configs.empty(type)
+
+/** @see Configs.fromBukkit */
+fun ConfigurationSection?.toConfig() = Configs.fromBukkit(this)
+
+/** @see Configs.fromStream */
+fun InputStream?.readConfig() = Configs.fromStream(this)
+
+/** @see Configs.fromFile */
+fun File?.readConfig() = Configs.fromFile(this)
+
+/** @see Configs.fromFile */
+fun File?.readConfig(type: ConfigType) = Configs.fromFile(this, type)
+
+/** @see Configs.fromMap */
+fun Map<String?, Any?>.toConfig() = Configs.fromMap(this)
+
+/** @see Configs.fromMap */
+fun Map<String?, Any?>.toConfig(type: ConfigType) = Configs.fromMap(this, type)
+
+/** @see Configs.fromString */
+fun readConfig(contents: String, type: ConfigType) = Configs.fromString(contents, type)

eco-api/src/main/kotlin/com/willfp/eco/core/gui/GUIHelpers.kt

@@ -4,34 +4,72 @@ package com.willfp.eco.core.gui
 
 import com.willfp.eco.core.gui.menu.Menu
 import com.willfp.eco.core.gui.menu.MenuBuilder
+import com.willfp.eco.core.gui.menu.MenuEvent
+import com.willfp.eco.core.gui.menu.MenuEventHandler
+import com.willfp.eco.core.gui.menu.MenuType
+import com.willfp.eco.core.gui.page.Page
+import com.willfp.eco.core.gui.page.PageBuilder
 import com.willfp.eco.core.gui.slot.Slot
 import com.willfp.eco.core.gui.slot.SlotBuilder
 import com.willfp.eco.core.items.TestableItem
 import org.bukkit.entity.Player
+import org.bukkit.event.inventory.ClickType
 import org.bukkit.event.inventory.InventoryClickEvent
 import org.bukkit.event.inventory.InventoryCloseEvent
 import org.bukkit.inventory.ItemStack
 
+/** Shorthand for the `event.whoClicked as Player` pattern used everywhere. */
+val InventoryClickEvent.player: Player
+    get() = this.whoClicked as Player
+
 /** @see SlotBuilder.onLeftClick */
-fun SlotBuilder.onLeftClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+fun SlotBuilder.onLeftClick(action: (event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
     this.onLeftClick { a, b, c -> action(a, b, c) }
 
+/** @see SlotBuilder.onLeftClick */
+fun SlotBuilder.onLeftClick(action: (Player, event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onLeftClick { a, b, c -> action(a.player, a, b, c) }
+
 /** @see SlotBuilder.onRightClick */
-fun SlotBuilder.onRightClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+fun SlotBuilder.onRightClick(action: (event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
     this.onRightClick { a, b, c -> action(a, b, c) }
 
+/** @see SlotBuilder.onRightClick */
+fun SlotBuilder.onRightClick(action: (Player, event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onRightClick { a, b, c -> action(a.player, a, b, c) }
+
 /** @see SlotBuilder.onShiftLeftClick */
-fun SlotBuilder.onShiftLeftClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+fun SlotBuilder.onShiftLeftClick(action: (event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
     this.onShiftLeftClick { a, b, c -> action(a, b, c) }
 
+/** @see SlotBuilder.onShiftLeftClick */
+fun SlotBuilder.onShiftLeftClick(action: (Player, event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onShiftLeftClick { a, b, c -> action(a.player, a, b, c) }
+
 /** @see SlotBuilder.onShiftRightClick */
-fun SlotBuilder.onShiftRightClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+fun SlotBuilder.onShiftRightClick(action: (event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
     this.onShiftRightClick { a, b, c -> action(a, b, c) }
 
 /** @see SlotBuilder.onShiftRightClick */
-fun SlotBuilder.onMiddleClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+fun SlotBuilder.onShiftRightClick(action: (Player, event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onShiftRightClick { a, b, c -> action(a.player, a, b, c) }
+
+/** @see SlotBuilder.onMiddleClick */
+fun SlotBuilder.onMiddleClick(action: (event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
     this.onMiddleClick { a, b, c -> action(a, b, c) }
 
+/** @see SlotBuilder.onMiddleClick */
+fun SlotBuilder.onMiddleClick(action: (Player, event: InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onMiddleClick { a, b, c -> action(a.player, a, b, c) }
+
+/** @see SlotBuilder.onClick */
+fun SlotBuilder.onClick(clickType: ClickType, action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onClick(clickType) { a, b, c -> action(a, b, c) }
+
+/** @see SlotBuilder.onClick */
+fun SlotBuilder.onClick(clickType: ClickType, action: (Player, InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onClick(clickType) { a, b, c -> action(a.player, a, b, c) }
+
 /** @see SlotBuilder.notCaptiveFor */
 fun SlotBuilder.notCaptiveFor(test: (Player) -> Boolean): SlotBuilder =
     this.notCaptiveFor { test(it) }
@@ -42,11 +80,11 @@ fun SlotBuilder.notCaptiveFor(test: (Player) -> Boolean): SlotBuilder =
  */
 @Deprecated("Use SlotUpdater instead")
 @Suppress("DEPRECATION")
-fun SlotBuilder.setModifier(action: (Player, Menu, ItemStack) -> Unit): SlotBuilder =
+fun SlotBuilder.setModifier(action: (Player, Menu, item: ItemStack) -> Unit): SlotBuilder =
     this.setUpdater { a, b, c -> c.apply { action(a, b, c) } }
 
 /** @see SlotBuilder.setUpdater */
-fun SlotBuilder.setUpdater(action: (Player, Menu, ItemStack) -> ItemStack): SlotBuilder =
+fun SlotBuilder.setUpdater(action: (Player, Menu, item: ItemStack) -> ItemStack): SlotBuilder =
     this.setUpdater { a, b, c -> action(a, b, c) }
 
 /** Kotlin builder for slots. */
@@ -85,6 +123,16 @@ fun slot(
     item: ItemStack
 ): Slot = Slot.builder(item).build()
 
+/** Kotlin builder for slots. */
+fun slot(
+    item: TestableItem,
+    init: SlotBuilder.() -> Unit
+): Slot {
+    val builder = Slot.builder(item)
+    init(builder)
+    return builder.build()
+}
+
 /** Kotlin builder for slots. */
 fun slot(
     item: TestableItem
@@ -106,7 +154,7 @@ fun slot(
 ): Slot = Slot.builder { a, b -> provider(a, b) }.build()
 
 /** @see MenuBuilder.onClose */
-fun MenuBuilder.onClose(action: (InventoryCloseEvent, Menu) -> Unit): MenuBuilder =
+fun MenuBuilder.onClose(action: (event: InventoryCloseEvent, Menu) -> Unit): MenuBuilder =
     this.onClose { a, b -> action(a, b) }
 
 /** @see MenuBuilder.onOpen */
@@ -114,13 +162,28 @@ fun MenuBuilder.onOpen(action: (Player, Menu) -> Unit): MenuBuilder =
     this.onOpen { a, b -> action(a, b) }
 
 /** @see MenuBuilder.modify */
-fun MenuBuilder.modify(modifier: (MenuBuilder) -> Unit): MenuBuilder =
+fun MenuBuilder.modify(modifier: (builder: MenuBuilder) -> Unit): MenuBuilder =
     this.modfiy { modifier(it) }
 
 /** @see MenuBuilder.onRender */
 fun MenuBuilder.onRender(action: (Player, Menu) -> Unit): MenuBuilder =
     this.onRender { a, b -> action(a, b) }
 
+/** @see MenuBuilder.addPage */
+fun MenuBuilder.addPage(page: Int, creation: PageBuilder.() -> Unit): MenuBuilder {
+    val builder = Menu.builder(this.rows)
+    creation(builder)
+    return this.addPage(Page(page, builder.build()))
+}
+
+/** @see MenuBuilder.onEvent */
+inline fun <reified T : MenuEvent> MenuBuilder.onEvent(crossinline handler: (Player, Menu, event: T) -> Unit): MenuBuilder {
+    return this.onEvent(object : MenuEventHandler<T>(T::class.java) {
+        override fun handle(player: Player, menu: Menu, event: T) =
+            handler(player, menu, event)
+    })
+}
+
 /** Kotlin builder for menus. */
 fun menu(
     rows: Int,
@@ -130,3 +193,12 @@ fun menu(
     init(builder)
     return builder.build()
 }
+
+/** Kotlin builder for menus. */
+fun dispenserMenu(
+    init: MenuBuilder.() -> Unit
+): Menu {
+    val builder = Menu.builder(MenuType.DISPENSER)
+    init(builder)
+    return builder.build()
+}

eco-api/src/main/kotlin/com/willfp/eco/core/integrations/economy/EconomyHelpers.kt

@@ -28,15 +28,15 @@ var OfflinePlayer.exactBalance: BigDecimal
     get() = EconomyManager.getBalance(this).toBigDecimal()
     set(value) {
         if (value <= BigDecimal.ZERO) {
-            EconomyManager.removeMoney(this, this.balance)
+            EconomyManager.removeMoney(this, this.exactBalance)
             return
         }
 
         val diff = this.exactBalance - value
 
         if (diff > BigDecimal.ZERO) {
-            EconomyManager.removeMoney(this, diff.toDouble())
+            EconomyManager.removeMoney(this, diff)
         } else if (diff < BigDecimal.ZERO) {
-            EconomyManager.giveMoney(this, -diff.toDouble())
+            EconomyManager.giveMoney(this, -diff)
         }
     }

eco-api/src/main/kotlin/com/willfp/eco/core/items/Items.kt

@@ -31,3 +31,11 @@ var ItemStack.baseNBT: PersistentDataContainer
 /** @see Items.setBaseNBT */
 fun ItemStack.clearNBT() =
     Items.setBaseNBT(this, null)
+
+/** @see Items.toSNBT */
+fun ItemStack.toSNBT() =
+    Items.toSNBT(this)
+
+/** @see Items.isEmpty */
+val ItemStack?.isEmpty: Boolean
+    get() = Items.isEmpty(this)

eco-api/src/main/kotlin/com/willfp/eco/core/lookup/Testable.kt

@@ -0,0 +1,7 @@
+@file:JvmName("TestableExtensions")
+
+package com.willfp.eco.core.lookup
+
+/** @see Testable.matches */
+fun <T> T?.matches(test: Testable<T>) =
+    test.matches(this)

eco-api/src/main/kotlin/com/willfp/eco/util/NamespacedKeyUtils.kt

@@ -18,4 +18,4 @@ fun namespacedKeyOf(namespace: String, key: String) =
 
 /** @see EcoPlugin.namespacedKeyFactory */
 fun namespacedKeyOf(plugin: EcoPlugin, key: String) =
-    plugin.namespacedKeyFactory.create(key)
+    plugin.createNamespacedKey(key)

eco-core/core-backend/build.gradle

@@ -10,4 +10,6 @@ dependencies {
     compileOnly 'me.clip:placeholderapi:2.10.10'
     compileOnly 'net.kyori:adventure-text-minimessage:4.10.0'
     compileOnly 'net.kyori:adventure-platform-bukkit:4.1.0'
+    compileOnly 'org.yaml:snakeyaml:1.33'
+    compileOnly 'com.moandjiezana.toml:toml4j:0.7.2'
 }