Fixed 1.19.3 build

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

README.md

@@ -39,7 +39,7 @@ and many more.
 # For developers
 
 ## Javadoc
-The 6.38.2 Javadoc can be found [here](https://javadoc.jitpack.io/com/willfp/eco/6.38.2/javadoc/)
+The 6.45.0 Javadoc can be found [here](https://javadoc.jitpack.io/com/willfp/eco/6.45.0/javadoc/)
 
 ## Plugin Information
 
@@ -68,7 +68,7 @@ dependencies {
 }
 ```
 
-Replace `Tag` with a release tag for eco, eg `6.27.2`.
+Replace `Tag` with a release tag for eco, eg `6.45.0`.
 
 Maven:
 
@@ -88,7 +88,7 @@ Maven:
 </dependency>
 ```
 
-Replace `Tag` with a release tag for eco, eg `6.27.2`.
+Replace `Tag` with a release tag for eco, eg `6.45.0`.
 
 ## Build locally:
 

build.gradle.kts

@@ -77,6 +77,8 @@ allprojects {
 
         // LibsDisguises
         maven("https://repo.md-5.net/content/groups/public/")
+
+        maven("https://repo.techscode.com/repository/maven-releases/")
     }
 
     dependencies {

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

@@ -1,5 +1,6 @@
 package com.willfp.eco.core;
 
+import com.willfp.eco.core.command.impl.PluginCommand;
 import com.willfp.eco.core.config.ConfigType;
 import com.willfp.eco.core.config.interfaces.Config;
 import com.willfp.eco.core.config.interfaces.LoadableConfig;
@@ -21,16 +22,15 @@ 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.integrations.placeholder.PlaceholderIntegration;
 import com.willfp.eco.core.items.TestableItem;
-import com.willfp.eco.core.placeholder.AdditionalPlayer;
-import com.willfp.eco.core.placeholder.PlaceholderInjectable;
+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.command.CommandMap;
 import org.bukkit.configuration.ConfigurationSection;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.Mob;
@@ -42,7 +42,6 @@ import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -74,7 +73,7 @@ public interface Eco {
     /**
      * Create an event manager.
      *
-     * @param plugin The plugin.
+     * @param plugin The plugin.F
      * @return The event manager.
      */
     @NotNull
@@ -138,10 +137,8 @@ public interface Eco {
      * Create a PAPI integration.
      *
      * @param plugin The plugin.
-     * @return The integration.
      */
-    @NotNull
-    PlaceholderIntegration createPAPIIntegration(@NotNull EcoPlugin plugin);
+    void createPAPIIntegration(@NotNull EcoPlugin plugin);
 
     /**
      * Create a proxy factory.
@@ -173,6 +170,7 @@ public interface Eco {
      * @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,
@@ -193,6 +191,7 @@ public interface Eco {
      * @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,
@@ -206,6 +205,7 @@ public interface Eco {
      * @param config The handle.
      * @return The config implementation.
      */
+    @NotNull
     Config wrapConfigurationSection(@NotNull ConfigurationSection config);
 
     /**
@@ -215,6 +215,7 @@ public interface Eco {
      * @param type   The config type.
      * @return The config implementation.
      */
+    @NotNull
     Config createConfig(@NotNull Map<String, Object> values,
                         @NotNull ConfigType type);
 
@@ -225,6 +226,7 @@ public interface Eco {
      * @param type     The type.
      * @return The config implementation.
      */
+    @NotNull
     Config createConfig(@NotNull String contents,
                         @NotNull ConfigType type);
 
@@ -335,23 +337,16 @@ public interface Eco {
      *
      * @return The keys.
      */
+    @NotNull
     Set<PersistentDataKey<?>> getRegisteredPersistentDataKeys();
 
-    /**
-     * Get persistent data key from namespaced key.
-     *
-     * @param namespacedKey The key.
-     * @return The key, or null if not found.
-     */
-    @Nullable
-    PersistentDataKey<?> getPersistentDataKeyFrom(@NotNull NamespacedKey namespacedKey);
-
     /**
      * Load a player profile.
      *
      * @param uuid The UUID.
      * @return The profile.
      */
+    @NotNull
     PlayerProfile loadPlayerProfile(@NotNull UUID uuid);
 
     /**
@@ -359,6 +354,7 @@ public interface Eco {
      *
      * @return The profile.
      */
+    @NotNull
     ServerProfile getServerProfile();
 
     /**
@@ -370,24 +366,6 @@ public interface Eco {
      */
     void unloadPlayerProfile(@NotNull UUID uuid);
 
-    /**
-     * Save keys for a player.
-     * <p>
-     * Can run async if using MySQL.
-     *
-     * @param uuid The uuid.
-     * @param keys The keys.
-     */
-    void savePersistentDataKeysFor(@NotNull UUID uuid,
-                                   @NotNull Set<PersistentDataKey<?>> keys);
-
-    /**
-     * Commit all changes to the file.
-     * <p>
-     * Does nothing if using MySQL.
-     */
-    void saveAllProfiles();
-
     /**
      * Create dummy entity - never spawned, exists purely in code.
      *
@@ -513,16 +491,12 @@ public interface Eco {
     /**
      * Evaluate an expression.
      *
-     * @param expression        The expression.
-     * @param player            The player.
-     * @param injectable        The injectable placeholders.
-     * @param additionalPlayers The additional players.
+     * @param expression The expression.
+     * @param context    The context.
      * @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);
+                    @NotNull MathContext context);
 
     /**
      * Get the menu a player currently has open.
@@ -533,6 +507,25 @@ public interface Eco {
     @Nullable
     Menu getOpenMenu(@NotNull Player player);
 
+    /**
+     * Sync commands.
+     */
+    void syncCommands();
+
+    /**
+     * Get the command map.
+     *
+     * @return The command map.
+     */
+    @NotNull CommandMap getCommandMap();
+
+    /**
+     * Unregister a command.
+     *
+     * @param command The command.
+     */
+    void unregisterCommand(@NotNull final PluginCommand command);
+
     /**
      * Get the instance of eco; the bridge between the api frontend
      * and the implementation backend.

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

@@ -13,7 +13,6 @@ 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;
@@ -153,6 +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>
@@ -375,8 +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.get().createPAPIIntegration(this));
+            Eco.get().createPAPIIntegration(this);
         }
 
         this.loadIntegrationLoaders().forEach(integrationLoader -> {
@@ -386,6 +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();
@@ -414,10 +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.
      */
@@ -429,6 +464,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         this.getScheduler().cancelAll();
 
         this.handleDisable();
+        this.onDisable.forEach(Runnable::run);
 
         if (this.isSupportingExtensions()) {
             this.getExtensionLoader().unloadExtensions();
@@ -438,6 +474,15 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         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);
+    }
+
     /**
      * Default code to be executed on plugin load.
      */
@@ -446,6 +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);
     }
 
     /**
@@ -478,6 +533,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         }
 
         this.handleAfterLoad();
+        this.afterLoad.forEach(Runnable::run);
 
         this.reload();
 
@@ -488,6 +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.
      */
@@ -499,12 +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.
      *
@@ -624,7 +699,15 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
      * @return lang.yml.
      */
     protected LangYml createLangYml() {
-        return new LangYml(this);
+        try {
+            return new LangYml(this);
+        } catch (NullPointerException e) {
+            this.getLogger().severe("Failed to load lang.yml!");
+            this.getLogger().severe("For the developer of this plugin: make sure you have a lang.yml");
+            e.printStackTrace();
+            Bukkit.getPluginManager().disablePlugin(this);
+            return null;
+        }
     }
 
     /**
@@ -635,7 +718,15 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
      * @return config.yml.
      */
     protected ConfigYml createConfigYml() {
-        return new ConfigYml(this);
+        try {
+            return new ConfigYml(this);
+        } catch (NullPointerException e) {
+            this.getLogger().severe("Failed to load config.yml!");
+            this.getLogger().severe("For the developer of this plugin: make sure you have a config.yml");
+            e.printStackTrace();
+            Bukkit.getPluginManager().disablePlugin(this);
+            return null;
+        }
     }
 
     /**

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 = new ArrayList<>(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 +42,60 @@ 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();
+
+        Eco.get().unregisterCommand(this);
+
+        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 +143,19 @@ 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/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/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/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/TransientConfig.java

@@ -20,7 +20,10 @@ 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.

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/display/Display.java

@@ -7,7 +7,6 @@ import org.bukkit.entity.Player;
 import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.persistence.PersistentDataType;
-import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 

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

@@ -63,11 +63,29 @@ public interface Menu {
      * @param player The player
      * @param menu   The menu.
      * @return The slot.
+     * @deprecated Menu shouldn't be a parameter.
      */
-    default Slot getSlot(int row,
-                         int column,
-                         @NotNull Player player,
-                         @NotNull Menu menu) {
+    @Deprecated(since = "6.46.0", forRemoval = true)
+    default Slot getSlot(final int row,
+                         final int column,
+                         @NotNull final Player player,
+                         @NotNull final Menu menu) {
+        return this.getSlot(row, column, player);
+    }
+
+    /**
+     * 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
+     * @return The slot.
+     */
+    default Slot getSlot(final int row,
+                         final int column,
+                         @NotNull final Player player) {
         return this.getSlot(row, column);
     }
 
@@ -110,15 +128,32 @@ public interface Menu {
     }
 
     /**
-     * Add state for a player.
+     * 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.
@@ -221,7 +256,7 @@ public interface Menu {
                                   @NotNull final NamespacedKey key,
                                   @NotNull final PersistentDataType<T, Z> type,
                                   @NotNull final Z value) {
-        this.addState(player, key.toString(), value);
+        this.setState(player, key.toString(), value);
     }
 
     /**

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

@@ -107,7 +107,7 @@ public interface MenuBuilder extends PageBuilder {
      * @return The builder.
      */
     default MenuBuilder addPage(@NotNull final Page page) {
-        return this.addComponent(MenuLayer.TOP, 1, 1, page);
+        return this.addComponent(MenuLayer.UPPER, 1, 1, page);
     }
 
     /**
@@ -139,7 +139,7 @@ public interface MenuBuilder extends PageBuilder {
      * @return The builder.
      */
     default MenuBuilder maxPages(@NotNull final Function<Player, Integer> pages) {
-        return onOpen((player, menu) -> menu.addState(player, Page.MAX_PAGE_KEY, pages.apply(player)));
+        return this.onRender((player, menu) -> menu.setState(player, Page.MAX_PAGE_KEY, pages.apply(player)));
     }
 
     /**
@@ -195,6 +195,16 @@ public interface MenuBuilder extends PageBuilder {
         return this;
     }
 
+    /**
+     * Add an action to run on build.
+     *
+     * @param action The action.
+     * @return The builder.
+     */
+    default MenuBuilder onBuild(@NotNull Consumer<Menu> action) {
+        return this;
+    }
+
     /**
      * Build the menu.
      *

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

@@ -0,0 +1,22 @@
+package com.willfp.eco.core.gui.menu.events;
+
+import com.willfp.eco.core.gui.menu.MenuEvent;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Represents a captive item change.
+ *
+ * @param row    The row.
+ * @param column The column.
+ * @param before The previous item in the slot.
+ * @param after  The new item in the slot.
+ */
+public record CaptiveItemChangeEvent(
+        int row,
+        int column,
+        @Nullable ItemStack before,
+        @Nullable ItemStack after
+) implements MenuEvent {
+
+}

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

@@ -9,8 +9,6 @@ import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.Objects;
-
 /**
  * A page is a component representing another menu.
  * This allows full component support in pagination.
@@ -85,7 +83,7 @@ public final class Page implements GUIComponent {
             delegate = Eco.get().blendMenuState(page, menu);
         }
 
-        return page.getSlot(row, column, player, delegate);
+        return page.getSlot(row, column, player);
     }
 
     @Override

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

@@ -48,7 +48,7 @@ public final class PageChanger implements GUIComponent {
                         return;
                     }
 
-                    menu.addState(player, Page.PAGE_KEY, newPage);
+                    menu.setState(player, Page.PAGE_KEY, newPage);
                     menu.callEvent(player, new PageChangeEvent(
                             newPage,
                             page
@@ -79,7 +79,7 @@ public final class PageChanger implements GUIComponent {
             return null;
         }
 
-        if (page >= maxPage - 1 && this.direction == Direction.FORWARDS) {
+        if (page >= maxPage && this.direction == Direction.FORWARDS) {
             return null;
         }
 

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

@@ -1,12 +1,14 @@
 package com.willfp.eco.core.gui.slot;
 
 import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.fast.FastItemStack;
 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.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
@@ -37,7 +39,25 @@ public class ConfigSlot extends CustomSlot {
     public ConfigSlot(@NotNull final Config config) {
         this.config = config;
 
-        SlotBuilder builder = Slot.builder(Items.lookup(config.getString("item")));
+        ItemStack item = Items.lookup(config.getString("item")).getItem();
+
+        SlotBuilder builder = Slot.builder((player, menu) -> {
+            if (!config.has("lore")) {
+                return item;
+            } else {
+                FastItemStack fast = FastItemStack.wrap(item.clone());
+                List<String> newLore = new ArrayList<>(fast.getLore());
+                newLore.addAll(
+                        StringUtils.formatList(
+                                config.getStrings("lore"),
+                                player,
+                                StringUtils.FormatOption.WITH_PLACEHOLDERS
+                        )
+                );
+                fast.setLore(newLore);
+                return fast.unwrap();
+            }
+        });
 
         for (ClickType clickType : ClickType.values()) {
             builder.onClick(

eco-api/src/main/java/com/willfp/eco/core/gui/slot/CustomSlot.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;
 
 /**
  * Base class for custom slot implementations.
@@ -31,7 +32,7 @@ public abstract class CustomSlot implements Slot {
     }
 
     @Override
-    public ItemStack getItemStack(@NotNull final Player player) {
+    public final @NotNull ItemStack getItemStack(@NotNull final Player player) {
         if (delegate == null) {
             throw new IllegalStateException("Custom Slot was not initialized!");
         }
@@ -40,8 +41,8 @@ public abstract class CustomSlot implements Slot {
     }
 
     @Override
-    public boolean isCaptive(@NotNull final Player player,
-                             @NotNull final Menu menu) {
+    public final boolean isCaptive(@NotNull final Player player,
+                                   @NotNull final Menu menu) {
         if (delegate == null) {
             throw new IllegalStateException("Custom Slot was not initialized!");
         }
@@ -50,7 +51,18 @@ public abstract class CustomSlot implements Slot {
     }
 
     @Override
-    public boolean isCaptiveFromEmpty() {
+    public final boolean isAllowedCaptive(@NotNull final Player player,
+                                          @NotNull final Menu menu,
+                                          @Nullable final ItemStack itemStack) {
+        if (delegate == null) {
+            throw new IllegalStateException("Custom Slot was not initialized!");
+        }
+
+        return delegate.isAllowedCaptive(player, menu, itemStack);
+    }
+
+    @Override
+    public final boolean isCaptiveFromEmpty() {
         if (delegate == null) {
             throw new IllegalStateException("Custom Slot was not initialized!");
         }
@@ -59,8 +71,8 @@ public abstract class CustomSlot implements Slot {
     }
 
     @Override
-    public final Slot getActionableSlot(@NotNull final Player player,
-                                        @NotNull final Menu menu) {
+    public final @NotNull Slot getActionableSlot(@NotNull final Player player,
+                                                 @NotNull final Menu menu) {
         return delegate;
     }
 

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

@@ -5,6 +5,7 @@ import org.bukkit.Material;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Base class for custom slot implementations.
@@ -29,19 +30,26 @@ public abstract class ReactiveSlot implements Slot {
                                  @NotNull final Menu menu);
 
     @Override
-    public ItemStack getItemStack(@NotNull final Player player) {
-        return new ItemStack(Material.STONE);
+    public @NotNull ItemStack getItemStack(@NotNull final Player player) {
+        return new ItemStack(Material.AIR);
     }
 
     @Override
-    public boolean isCaptive(@NotNull final Player player,
-                             @NotNull final Menu menu) {
+    public final 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) {
+    public final boolean isAllowedCaptive(@NotNull final Player player,
+                                          @NotNull final Menu menu,
+                                          @Nullable final ItemStack itemStack) {
+        return getSlot(player, menu).isAllowedCaptive(player, menu, itemStack);
+    }
+
+    @Override
+    public final @NotNull Slot getActionableSlot(@NotNull final Player player,
+                                                 @NotNull final Menu menu) {
         return getSlot(player, menu);
     }
 

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

@@ -9,6 +9,7 @@ import org.bukkit.Material;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.function.Function;
 
@@ -30,6 +31,7 @@ public interface Slot extends GUIComponent {
      * @param player The player.
      * @return The ItemStack.
      */
+    @NotNull
     ItemStack getItemStack(@NotNull Player player);
 
     /**
@@ -44,6 +46,20 @@ public interface Slot extends GUIComponent {
         return false;
     }
 
+    /**
+     * If the slot allows a certain item to be placed in it.
+     *
+     * @param player    The player.
+     * @param menu      The menu.
+     * @param itemStack The item; use null if the item is unknown.
+     * @return If captive.
+     */
+    default boolean isAllowedCaptive(@NotNull final Player player,
+                                     @NotNull final Menu menu,
+                                     @Nullable final ItemStack itemStack) {
+        return this.isCaptive(player, menu);
+    }
+
     /**
      * Get the actionable slot to be shown.
      * <p>
@@ -60,6 +76,7 @@ public interface Slot extends GUIComponent {
      * @param menu   The menu.
      * @return The slot.
      */
+    @NotNull
     default Slot getActionableSlot(@NotNull final Player player,
                                    @NotNull final Menu menu) {
         return this;
@@ -125,7 +142,9 @@ public interface Slot extends GUIComponent {
      *
      * @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.get().createSlotBuilder((player, menu) -> provider.apply(player));
     }

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

@@ -1,5 +1,6 @@
 package com.willfp.eco.core.gui.slot;
 
+import com.willfp.eco.core.gui.slot.functional.CaptiveFilter;
 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;
@@ -143,7 +144,17 @@ public interface SlotBuilder {
      * @param predicate The predicate. Returns true when the slot should not be captive.
      * @return The builder.
      */
-    SlotBuilder notCaptiveFor(@NotNull Predicate<Player> predicate);
+    SlotBuilder notCaptiveFor(@NotNull final Predicate<Player> predicate);
+
+    /**
+     * Set a whitelist for allowed captive items.
+     *
+     * @param filter The filter.
+     * @return The builder.
+     */
+    default SlotBuilder setCaptiveFilter(@NotNull final CaptiveFilter filter) {
+        return this;
+    }
 
     /**
      * Set the ItemStack updater.

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

@@ -0,0 +1,25 @@
+package com.willfp.eco.core.gui.slot.functional;
+
+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 test if a captive slot is allowed to contain an item given a player and a menu.
+ */
+@FunctionalInterface
+public interface CaptiveFilter {
+    /**
+     * Get if allowed.
+     *
+     * @param player    The player.
+     * @param menu      The menu.
+     * @param itemStack The item.
+     * @return If captive.
+     */
+    boolean isAllowed(@NotNull Player player,
+                      @NotNull Menu menu,
+                      @Nullable ItemStack itemStack);
+}

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.
      *

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

@@ -1,6 +1,8 @@
 package com.willfp.eco.core.integrations.shop;
 
 import com.willfp.eco.core.integrations.Integration;
+import com.willfp.eco.core.price.Price;
+import com.willfp.eco.core.price.impl.PriceFree;
 import org.bukkit.entity.Player;
 import org.bukkit.event.Listener;
 import org.bukkit.inventory.ItemStack;
@@ -29,12 +31,41 @@ public interface ShopIntegration extends Integration {
         return null;
     }
 
+    /**
+     * Get if an item is sellable for a player.
+     *
+     * @param itemStack The item.
+     * @param player    The player.
+     * @return If sellable.
+     */
+    default boolean isSellable(@NotNull final ItemStack itemStack,
+                               @NotNull final Player player) {
+        return false;
+    }
+
+    /**
+     * Get the value of one of an item for a player.
+     * <p>
+     * For example, if you pass in a stack, it will only return the value of <b>one</b> item, not the full stack.
+     *
+     * @param itemStack The item.
+     * @param player    The player.
+     * @return The price.
+     */
+    @NotNull
+    default Price getUnitValue(@NotNull final ItemStack itemStack,
+                               @NotNull final Player player) {
+        return new PriceFree();
+    }
+
     /**
      * Get the price of an item.
      *
      * @param itemStack The item.
      * @return The price.
+     * @deprecated Use getValue instead.
      */
+    @Deprecated(since = "6.47.0", forRemoval = true)
     default double getPrice(@NotNull final ItemStack itemStack) {
         // Do nothing unless overridden.
         return 0.0;
@@ -46,9 +77,11 @@ public interface ShopIntegration extends Integration {
      * @param itemStack The item.
      * @param player    The player.
      * @return The price.
+     * @deprecated Use getValue instead.
      */
+    @Deprecated(since = "6.47.0", forRemoval = true)
     default double getPrice(@NotNull final ItemStack itemStack,
                             @NotNull final Player player) {
-        return getPrice(itemStack);
+        return getUnitValue(itemStack, player).getValue(player);
     }
 }

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

@@ -1,10 +1,9 @@
 package com.willfp.eco.core.integrations.shop;
 
-import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.price.Price;
+import com.willfp.eco.core.price.impl.PriceFree;
 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;
 
@@ -39,12 +38,57 @@ public final class ShopManager {
         }
     }
 
+    /**
+     * Get if an item is sellable for a player.
+     *
+     * @param itemStack The item.
+     * @param player    The player.
+     * @return If sellable.
+     */
+    public static boolean isSellable(@Nullable final ItemStack itemStack,
+                                     @NotNull final Player player) {
+        if (itemStack == null) {
+            return false;
+        }
+
+        for (ShopIntegration integration : REGISTERED) {
+            return integration.isSellable(itemStack, player);
+        }
+
+        return false;
+    }
+
+    /**
+     * Get the value of one of an item for a player.
+     * <p>
+     * For example, if you pass in a stack, it will only return the value of <b>one</b> item, not the full stack.
+     *
+     * @param itemStack The item.
+     * @param player    The player.
+     * @return The price.
+     */
+    @NotNull
+    public static Price getUnitValue(@Nullable final ItemStack itemStack,
+                                     @NotNull final Player player) {
+        if (itemStack == null) {
+            return new PriceFree();
+        }
+
+        for (ShopIntegration integration : REGISTERED) {
+            return integration.getUnitValue(itemStack, player);
+        }
+
+        return new PriceFree();
+    }
+
     /**
      * Get the price of an item.
      *
      * @param itemStack The item.
      * @return The price.
+     * @deprecated Use getValue instead. This will always return 0 as prices depend on players.
      */
+    @Deprecated(since = "6.47.0", forRemoval = true)
     public static double getItemPrice(@Nullable final ItemStack itemStack) {
         return getItemPrice(itemStack, null);
     }
@@ -55,19 +99,17 @@ public final class ShopManager {
      * @param itemStack The item.
      * @param player    The player.
      * @return The price.
+     * @deprecated Use getValue instead. Null players / null items will always return 0.
      */
+    @Deprecated(since = "6.47.0", forRemoval = true)
     public static double getItemPrice(@Nullable final ItemStack itemStack,
                                       @Nullable final Player player) {
-        if (itemStack == null) {
+        if (itemStack == null || player == null) {
             return 0.0;
         }
 
         for (ShopIntegration shopIntegration : REGISTERED) {
-            if (player == null) {
-                return shopIntegration.getPrice(itemStack);
-            } else {
-                return shopIntegration.getPrice(itemStack, player);
-            }
+            return shopIntegration.getUnitValue(itemStack, player).getValue(player, itemStack.getAmount());
         }
 
         return 0.0;

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

@@ -1,5 +1,7 @@
 package com.willfp.eco.core.integrations.shop;
 
+import com.willfp.eco.core.price.Price;
+import com.willfp.eco.core.price.impl.PriceEconomy;
 import org.bukkit.entity.Player;
 import org.bukkit.event.HandlerList;
 import org.bukkit.event.player.PlayerEvent;
@@ -19,7 +21,12 @@ public class ShopSellEvent extends PlayerEvent {
     /**
      * The sell price.
      */
-    private double price;
+    private Price price;
+
+    /**
+     * The price multiplier.
+     */
+    private double multiplier;
 
     /**
      * The item to be sold.
@@ -33,31 +40,64 @@ public class ShopSellEvent extends PlayerEvent {
      * @param who   The player.
      * @param price The price.
      * @param item  The item.
+     * @deprecated Use the price system instead.
      */
+    @Deprecated(since = "6.47.0", forRemoval = true)
     public ShopSellEvent(@NotNull final Player who,
                          final double price,
                          @Nullable final ItemStack item) {
+        this(who, new PriceEconomy(price), item);
+    }
+
+    /**
+     * Create new shop sell event.
+     *
+     * @param who   The player.
+     * @param price The price.
+     * @param item  The item.
+     */
+    public ShopSellEvent(@NotNull final Player who,
+                         @NotNull final Price price,
+                         @Nullable final ItemStack item) {
+        this(who, price, item, 1.0);
+    }
+
+    /**
+     * Create new shop sell event.
+     *
+     * @param who        The player.
+     * @param price      The price.
+     * @param item       The item.
+     * @param multiplier The multiplier.
+     */
+    public ShopSellEvent(@NotNull final Player who,
+                         @NotNull final Price price,
+                         @Nullable final ItemStack item,
+                         final double multiplier) {
         super(who);
 
         this.price = price;
         this.item = item;
+
+        this.multiplier = multiplier;
     }
 
     /**
-     * Get the price.
+     * Get the value.
      *
-     * @return The price.
+     * @return The value.
      */
-    public double getPrice() {
+    @NotNull
+    public Price getValue() {
         return this.price;
     }
 
     /**
-     * Set the price.
+     * Set the value.
      *
-     * @param price The price.
+     * @param price The value.
      */
-    public void setPrice(final double price) {
+    public void setValue(@NotNull final Price price) {
         this.price = price;
     }
 
@@ -81,6 +121,46 @@ public class ShopSellEvent extends PlayerEvent {
         return item != null;
     }
 
+    /**
+     * Get the price multiplier.
+     *
+     * @return The multiplier.
+     */
+    public double getMultiplier() {
+        return multiplier;
+    }
+
+    /**
+     * Set the price multiplier.
+     *
+     * @param multiplier The multiplier.
+     */
+    public void setMultiplier(final double multiplier) {
+        this.multiplier = multiplier;
+    }
+
+    /**
+     * Get the price.
+     *
+     * @return The price.
+     * @deprecated Use the price system instead.
+     */
+    @Deprecated(since = "6.47.0", forRemoval = true)
+    public double getPrice() {
+        return this.getValue().getValue(player);
+    }
+
+    /**
+     * Set the price.
+     *
+     * @param price The price.
+     * @deprecated Use the price system instead.
+     */
+    @Deprecated(since = "6.47.0", forRemoval = true)
+    public void setPrice(final double price) {
+        this.setValue(new PriceEconomy(price));
+    }
+
     /**
      * Bukkit parity.
      *

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;
@@ -86,6 +87,11 @@ public final class Items {
      */
     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.
      *
@@ -216,7 +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();
             }
@@ -565,4 +571,25 @@ public final class Items {
     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/builder/AbstractItemStackBuilder.java

@@ -14,7 +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;
 
@@ -71,7 +70,7 @@ public abstract class AbstractItemStackBuilder<T extends ItemMeta, U extends Abs
 
     @Override
     public U setAmount(final int amount) {
-        Validate.isTrue(amount >= 1 && amount <= base.getMaxStackSize());
+        Validate.isTrue(amount >= 1);
         base.setAmount(amount);
         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/price/CombinedDisplayPrice.java

@@ -0,0 +1,156 @@
+package com.willfp.eco.core.price;
+
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A group of {@link ConfiguredPrice}s in order to show them
+ * to players in one go.
+ */
+public final class CombinedDisplayPrice {
+    /**
+     * Maps configured prices to multipliers.
+     */
+    private final Map<ConfiguredPrice, Double> prices;
+
+    /**
+     * The player to format for.
+     */
+    private final Player player;
+
+    /**
+     * Initialize a new combined price mapping formatters to multipliers.
+     *
+     * @param player The player.
+     * @param prices The prices.
+     */
+    private CombinedDisplayPrice(@NotNull final Player player,
+                                 @NotNull final Map<ConfiguredPrice, Double> prices) {
+        this.player = player;
+        this.prices = prices;
+    }
+
+    /**
+     * Get the display strings.
+     *
+     * @return The display strings.
+     */
+    @NotNull
+    public String[] getDisplayStrings() {
+        List<String> displayStrings = new ArrayList<>();
+
+        for (Map.Entry<ConfiguredPrice, Double> entry : prices.entrySet()) {
+            displayStrings.add(entry.getKey().getDisplay(player, entry.getValue()));
+        }
+
+        return displayStrings.toArray(new String[0]);
+    }
+
+    /**
+     * The builder.
+     */
+    public static class Builder {
+        /**
+         * All multiplied prices.
+         */
+        private final List<MultipliedPrice> prices = new ArrayList<>();
+
+        /**
+         * The player.
+         */
+        private final Player player;
+
+        /**
+         * Create a new builder.
+         *
+         * @param player The player.
+         */
+        Builder(@NotNull final Player player) {
+            this.player = player;
+        }
+
+        /**
+         * Add a new price with a certain multiplier.
+         *
+         * @param price      The price.
+         * @param multiplier The multiplier.
+         * @return The builder.
+         */
+        @NotNull
+        public Builder add(@NotNull final ConfiguredPrice price,
+                           final double multiplier) {
+            prices.add(new MultipliedPrice(price, multiplier));
+            return this;
+        }
+
+
+        /**
+         * Add a new price.
+         *
+         * @param price The price.
+         * @return The builder.
+         */
+        @NotNull
+        public Builder add(@NotNull final ConfiguredPrice price) {
+            return this.add(price, 1D);
+        }
+
+        /**
+         * Build into a {@link CombinedDisplayPrice}.
+         *
+         * @return The combined price.
+         */
+        @NotNull
+        public CombinedDisplayPrice build() {
+            Map<ConfiguredPrice, Double> unitPrices = new HashMap<>();
+
+            // Take first configured price at each ID as the format for all prices with that ID.
+            for (MultipliedPrice price : prices) {
+                // Find the base price.
+                ConfiguredPrice base = unitPrices.keySet()
+                        .stream()
+                        .filter(it -> it.getIdentifier().equals(price.price().getIdentifier()))
+                        .findFirst()
+                        .orElse(price.price());
+
+                // Find the multiplier for a value of 1, e.g. a price that's worth 20 will be 0.05.
+                double unitMultiplier = 1 / base.getValue(player);
+
+                double currentMultiplier = unitPrices.getOrDefault(base, 0D);
+                currentMultiplier += unitMultiplier * price.price().getValue(player, price.multiplier());
+                unitPrices.put(base, currentMultiplier);
+            }
+
+            return new CombinedDisplayPrice(player, unitPrices);
+        }
+
+        /**
+         * A price with a multiplier.
+         *
+         * @param price      The price.
+         * @param multiplier The multiplier.
+         */
+        private record MultipliedPrice(
+                @NotNull ConfiguredPrice price,
+                double multiplier
+        ) {
+
+        }
+    }
+
+    /**
+     * Create a new builder for a player.
+     *
+     * @param player The player.
+     * @return The builder.
+     */
+    @NotNull
+    public static Builder builder(@NotNull final Player player) {
+        return new Builder(player);
+    }
+}

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

@@ -0,0 +1,177 @@
+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.
+     */
+    public 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,
+                             final double multiplier) {
+        return this.price.canAfford(player, multiplier);
+    }
+
+    @Override
+    public void pay(@NotNull final Player player,
+                    final double multiplier) {
+        this.price.pay(player, multiplier);
+    }
+
+    @Override
+    public void giveTo(@NotNull final Player player,
+                       final double multiplier) {
+        this.price.giveTo(player, multiplier);
+    }
+
+    @Override
+    public double getValue(@NotNull final Player player,
+                           final double multiplier) {
+        return this.price.getValue(player, multiplier);
+    }
+
+    @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);
+    }
+
+    @Override
+    public String getIdentifier() {
+        return this.price.getIdentifier();
+    }
+
+    /**
+     * 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 this.getDisplay(player, 1.0);
+    }
+
+    /**
+     * Get the display string for a player.
+     *
+     * @param player     The player.
+     * @param multiplier The multiplier.
+     * @return The display string.
+     */
+    public String getDisplay(@NotNull final Player player,
+                             final double multiplier) {
+        return StringUtils.format(
+                formatString.replace("%value%", NumberUtils.format(this.getPrice().getValue(player, multiplier))),
+                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 +1,171 @@
+package com.willfp.eco.core.price;
+
+import org.apache.commons.lang.NotImplementedException;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A price that a player should pay.
+ * <p>
+ * There are important implementation details:
+ * <p>
+ * For backwards compatibility, all methods are default, however you must override the following:
+ * <ul>
+ *     <li><code>canAfford(Player, double)</code></li>
+ *     <li><code>pay(Player, double)</code></li>
+ *     <li><code>giveTo(Player, double)</code></li>
+ *     <li><code>getValue(Player, double)</code></li>
+ *     <li><code>getMultiplier(Player)</code></li>
+ *     <li><code>setMultiplier(Player, double)</code></li>
+ * </ul>
+ * Otherwise, your implementation will throw {@link NotImplementedException}.
+ * <p>
+ * Also, getValue() should always return the value with player multipliers applied.
+ */
+public interface Price {
+    /**
+     * Get if a player can afford to pay the price.
+     *
+     * @param player The player.
+     * @return If the player can afford.
+     */
+    default boolean canAfford(@NotNull final Player player) {
+        return this.canAfford(player, 1);
+    }
+
+    /**
+     * Get if a player can afford to pay x times the price.
+     *
+     * @param player     The player.
+     * @param multiplier The multiplier.
+     * @return If the player can afford.
+     */
+    default boolean canAfford(@NotNull final Player player,
+                              final double multiplier) {
+        throw new NotImplementedException("Override canAfford(Player, double) in your Price implementation!");
+    }
+
+    /**
+     * Make the player pay the price.
+     * <p>
+     * Check canAfford first.
+     *
+     * @param player The player.
+     */
+    default void pay(@NotNull final Player player) {
+        this.pay(player, 1);
+    }
+
+    /**
+     * Make the player pay the price x times.
+     * <p>
+     * Check canAfford first.
+     *
+     * @param player     The player.
+     * @param multiplier The multiplier.
+     */
+    default void pay(@NotNull final Player player,
+                     final double multiplier) {
+        throw new NotImplementedException("Override pay(Player, double) in your Price implementation!");
+    }
+
+    /**
+     * Give the price to the player.
+     *
+     * @param player The player.
+     */
+    default void giveTo(@NotNull final Player player) {
+        this.giveTo(player, 1);
+    }
+
+    /**
+     * Give the price to the player x times.
+     *
+     * @param player     The player.
+     * @param multiplier The multiplier.
+     */
+    default void giveTo(@NotNull final Player player,
+                        final double multiplier) {
+        throw new NotImplementedException("Override giveTo(Player, double) in your Price implementation!");
+    }
+
+    /**
+     * Get the numerical value that backs this price.
+     *
+     * @param player The player.
+     * @return The value.
+     */
+    default double getValue(@NotNull final Player player) {
+        return getValue(player, 1);
+    }
+
+    /**
+     * Get the numeral value that backs this price multiplied x times.
+     *
+     * @param player     The player.
+     * @param multiplier The multiplier.
+     * @return The value.
+     */
+    default double getValue(@NotNull final Player player,
+                            final double multiplier) {
+        throw new NotImplementedException("Override getValue(Player, double) in your Price implementation!");
+    }
+
+    /**
+     * Get the value multiplier for the player.
+     *
+     * @param player The player.
+     * @return The multiplier.
+     */
+    default double getMultiplier(@NotNull final Player player) {
+        return 1;
+    }
+
+    /**
+     * Set the value multiplier for the player.
+     *
+     * @param player     The player.
+     * @param multiplier The multiplier.
+     */
+    default void setMultiplier(@NotNull final Player player,
+                               final double multiplier) {
+        throw new NotImplementedException("Override setMultiplier(Player, double) in your Price implementation!");
+    }
+
+    /**
+     * Get the identifier of this price (as type/instance checks break with delegation,
+     * this is used for combining prices, etc.)
+     * <p>
+     * By default, this uses the class name, but it's good practice to override this.
+     * <p>
+     * It's also good practice to prefix your identifiers with some kind of namespace or
+     * internal ID, in order to prevent conflicts.
+     *
+     * @return The identifier.
+     */
+    default String getIdentifier() {
+        return this.getClass().getName();
+    }
+
+    /**
+     * 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. This method should never work.
+     */
+    @Deprecated(since = "6.45.0", forRemoval = true)
+    default void setValue(final double value) {
+        // 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 +1,93 @@
+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,
+                             final double multiplier) {
+        return EconomyManager.getBalance(player) >= getValue(player, multiplier);
+    }
+
+    @Override
+    public void pay(@NotNull final Player player,
+                    final double multiplier) {
+        EconomyManager.removeMoney(player, getValue(player, multiplier));
+    }
+
+    @Override
+    public void giveTo(@NotNull final Player player,
+                       final double multiplier) {
+        EconomyManager.giveMoney(player, getValue(player, multiplier));
+    }
+
+    @Override
+    public double getValue(@NotNull final Player player,
+                           final double multiplier) {
+        return this.function.apply(MathContext.copyWithPlayer(baseContext, player)) * getMultiplier(player) * multiplier;
+    }
+
+    @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);
+    }
+
+    @Override
+    public String getIdentifier() {
+        return "eco:economy";
+    }
+}

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

@@ -0,0 +1,57 @@
+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,
+                             final double multiplier) {
+        return true;
+    }
+
+    @Override
+    public void pay(@NotNull final Player player,
+                    final double multiplier) {
+        // Nothing.
+    }
+
+    @Override
+    public void giveTo(@NotNull final Player player,
+                       final double multiplier) {
+        // Nothing.
+    }
+
+    @Override
+    public double getMultiplier(@NotNull final Player player) {
+        return 1.0;
+    }
+
+    @Override
+    public void setMultiplier(@NotNull final Player player,
+                              final double multiplier) {
+        // Nothing.
+    }
+
+    @Override
+    public double getValue(@NotNull final Player player,
+                           final double multiplier) {
+        return 0;
+    }
+
+    @Override
+    public String getIdentifier() {
+        return "eco:free";
+    }
+}

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

@@ -0,0 +1,160 @@
+package com.willfp.eco.core.price.impl;
+
+import com.willfp.eco.core.drops.DropQueue;
+import com.willfp.eco.core.items.HashedItem;
+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,
+                             final double multiplier) {
+        int toRemove = (int) getValue(player, multiplier);
+        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,
+                    final double multiplier) {
+        int toRemove = (int) getValue(player, multiplier);
+        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,
+                       final double multiplier) {
+        ItemStack itemStack = item.getItem().clone();
+        itemStack.setAmount((int) getValue(player, multiplier));
+
+        new DropQueue(player)
+                .addItem(itemStack)
+                .forceTelekinesis()
+                .push();
+    }
+
+    @Override
+    public double getValue(@NotNull final Player player,
+                           final double multiplier) {
+        return Math.toIntExact(Math.round(
+                this.function.apply(MathContext.copyWithPlayer(baseContext, player))
+                        * getMultiplier(player) * multiplier
+        ));
+    }
+
+    @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);
+    }
+
+    @Override
+    public String getIdentifier() {
+        return "eco:item-" + HashedItem.of(this.item.getItem()).getHash();
+    }
+}

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

@@ -21,7 +21,8 @@ public final class ProxyConstants {
             "v1_17_R1",
             "v1_18_R1",
             "v1_18_R2",
-            "v1_19_R1"
+            "v1_19_R1",
+            "v1_19_R2"
     );
 
     private ProxyConstants() {

eco-api/src/main/java/com/willfp/eco/core/sound/PlayableSound.java

@@ -0,0 +1,101 @@
+package com.willfp.eco.core.sound;
+
+import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.serialization.ConfigDeserializer;
+import org.bukkit.Location;
+import org.bukkit.Sound;
+import org.bukkit.World;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Objects;
+
+/**
+ * A sound that can be played at a location.
+ *
+ * @param sound  The sound.
+ * @param pitch  The pitch.
+ * @param volume The volume.
+ */
+public record PlayableSound(@NotNull Sound sound,
+                            double pitch,
+                            double volume) {
+    /**
+     * The deserializer.
+     */
+    private static final ConfigDeserializer<PlayableSound> DESERIALIZER = new Deserializer();
+
+    /**
+     * Create a sound with a default volume.
+     *
+     * @param sound The sound.
+     * @param pitch The pitch.
+     */
+    public PlayableSound(@NotNull final Sound sound,
+                         final double pitch) {
+        this(sound, pitch, 1.0);
+    }
+
+    /**
+     * Play the sound to a player.
+     *
+     * @param player The player.
+     */
+    public void playTo(@NotNull final Player player) {
+        player.playSound(player.getLocation(), sound, (float) volume, (float) pitch);
+    }
+
+    /**
+     * Play the sound at a location.
+     *
+     * @param location The location.
+     */
+    public void playAt(@NotNull final Location location) {
+        World world = location.getWorld();
+
+        if (world == null) {
+            return;
+        }
+
+        world.playSound(location, sound, (float) volume, (float) pitch);
+    }
+
+    /**
+     * Parse a playable sound from config.
+     *
+     * @param config The config.
+     * @return The sound, or null if it's invalid.
+     */
+    @Nullable
+    public static PlayableSound create(@NotNull final Config config) {
+        return DESERIALIZER.deserialize(config);
+    }
+
+    /**
+     * The deserializer for {@link PlayableSound}.
+     */
+    private static final class Deserializer implements ConfigDeserializer<PlayableSound> {
+        @Override
+        public @Nullable PlayableSound deserialize(@NotNull final Config config) {
+            if (!config.has("sound")) {
+                return null;
+            }
+
+            try {
+                Sound sound = Sound.valueOf(config.getString("sound").toUpperCase());
+
+                double pitch = Objects.requireNonNullElse(config.getDouble("pitch"), 1.0);
+                double volume = Objects.requireNonNullElse(config.getDouble("volume"), 1.0);
+
+                return new PlayableSound(
+                        sound,
+                        pitch,
+                        volume
+                );
+            } catch (IllegalArgumentException e) {
+                return null;
+            }
+        }
+    }
+}

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

@@ -1,8 +1,10 @@
 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.bukkit.entity.Player;
@@ -12,7 +14,6 @@ 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;
@@ -240,7 +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);
     }
 
     /**
@@ -252,18 +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);
     }
 
     /**
@@ -323,7 +313,23 @@ public final class NumberUtils {
                                             @Nullable final Player player,
                                             @NotNull final PlaceholderInjectable context,
                                             @NotNull final Collection<AdditionalPlayer> additionalPlayers) {
-        return Eco.get().evaluate(expression, player, context, additionalPlayers);
+        return Eco.get().evaluate(expression, new MathContext(
+                context,
+                player,
+                additionalPlayers
+        ));
+    }
+
+    /**
+     * Evaluate an expression with respect to a player (for placeholders).
+     *
+     * @param expression The expression.
+     * @param context    The math context.
+     * @return The value of the expression, or zero if invalid.
+     */
+    public static double evaluateExpression(@NotNull final String expression,
+                                            @NotNull final MathContext context) {
+        return Eco.get().evaluate(expression, context);
     }
 
     private NumberUtils() {

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

@@ -4,9 +4,9 @@ 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.MenuType
 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
@@ -74,6 +74,10 @@ fun SlotBuilder.onClick(clickType: ClickType, action: (Player, InventoryClickEve
 fun SlotBuilder.notCaptiveFor(test: (Player) -> Boolean): SlotBuilder =
     this.notCaptiveFor { test(it) }
 
+/** @see SlotBuilder.setCaptiveFilter */
+fun SlotBuilder.setCaptiveFilter(test: (Player, Menu, ItemStack?) -> Boolean): SlotBuilder =
+    this.setCaptiveFilter { a, b, c -> test(a, b, c) }
+
 /**
  * @see SlotBuilder.setModifier
  * @deprecated Use SlotUpdater instead.
@@ -184,6 +188,10 @@ inline fun <reified T : MenuEvent> MenuBuilder.onEvent(crossinline handler: (Pla
     })
 }
 
+/** @see MenuBuilder.onBuild */
+fun MenuBuilder.onBuild(action: (Menu) -> Unit): MenuBuilder =
+    this.onBuild { action(it) }
+
 /** Kotlin builder for menus. */
 fun menu(
     rows: Int,

eco-api/src/main/kotlin/com/willfp/eco/core/integrations/shop/ShopHelpers.kt

@@ -2,13 +2,31 @@
 
 package com.willfp.eco.core.integrations.shop
 
+import com.willfp.eco.core.price.Price
 import org.bukkit.entity.Player
 import org.bukkit.inventory.ItemStack
 
-/** @see ShopManager.getItemPrice **/
+/** @see ShopManager.getItemPrice * */
+@Deprecated(
+    "Prices depend on players, this will always return 0.",
+    level = DeprecationLevel.ERROR,
+    replaceWith = ReplaceWith("this.getValue(player)")
+)
 val ItemStack.price: Double
-    get() = ShopManager.getItemPrice(this)
+    get() = 0.0
 
-/** @see ShopManager.getItemPrice **/
+/** @see ShopManager.getItemPrice * */
+@Deprecated(
+    "Use the price system instead, prices may not be currencies.",
+    ReplaceWith("this.getValue(player)"),
+)
 fun ItemStack.getPrice(player: Player): Double =
-    ShopManager.getItemPrice(this, player)
+    this.getUnitValue(player).getValue(player, this.amount.toDouble())
+
+/** @see ShopManager.getUnitValue */
+fun ItemStack.getUnitValue(player: Player): Price =
+    ShopManager.getUnitValue(this, player)
+
+/** @see ShopManager.isSellable */
+fun ItemStack?.isSellable(player: Player): Boolean =
+    ShopManager.isSellable(this, player)

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

@@ -0,0 +1,14 @@
+@file:JvmName("ItemBuilderExtensions")
+
+package com.willfp.eco.core.items.builder
+
+import com.willfp.eco.core.items.TestableItem
+import org.bukkit.inventory.ItemStack
+
+/** Modify an item with a builder. */
+fun TestableItem.modify(builder: ItemBuilder.() -> Unit): ItemStack =
+    this.item.modify(builder)
+
+/** Modify an item with a builder. */
+fun ItemStack.modify(builder: ItemBuilder.() -> Unit): ItemStack =
+    ItemStackBuilder(this).apply(builder).build()

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-core/core-backend/src/main/kotlin/com/willfp/eco/internal/EcoPropsParser.kt

@@ -2,8 +2,8 @@ package com.willfp.eco.internal
 
 import com.willfp.eco.core.EcoPlugin
 import com.willfp.eco.core.PluginProps
-import com.willfp.eco.core.config.TransientConfig
 import com.willfp.eco.core.config.interfaces.Config
+import com.willfp.eco.core.config.readConfig
 
 object EcoPropsParser : PluginProps.PropsParser<Config> {
     override fun parseFrom(config: Config): PluginProps {
@@ -28,7 +28,7 @@ object EcoPropsParser : PluginProps.PropsParser<Config> {
         }
 
         return PluginProps.parse(
-            TransientConfig(plugin.getResourceAsStream("/eco.yml")),
+            plugin.getResourceAsStream("/eco.yml").readConfig(),
             Config::class.java
         )
     }

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/config/EcoConfig.kt

@@ -108,7 +108,7 @@ open class EcoConfig(
     }
 
     override fun getSubsectionsOrNull(path: String): List<Config>? {
-        return (get(path) as? Iterable<Config>)
+        return getList<Config>(path)
             ?.map { it.apply { this.addInjectablePlaceholder(injections) } }
             ?.toList()
     }
@@ -122,7 +122,7 @@ open class EcoConfig(
     }
 
     override fun getIntsOrNull(path: String): List<Int>? {
-        return (get(path) as? Iterable<Number>)?.map { it.toInt() }
+        return getList<Number>(path)?.map { it.toInt() }
     }
 
     override fun getBoolOrNull(path: String): Boolean? {
@@ -130,7 +130,7 @@ open class EcoConfig(
     }
 
     override fun getBoolsOrNull(path: String): List<Boolean>? {
-        return (get(path) as? Iterable<Boolean>)?.toList()
+        return getList<Boolean>(path)?.toList()
     }
 
     override fun getStringOrNull(
@@ -154,7 +154,7 @@ open class EcoConfig(
         format: Boolean,
         option: StringUtils.FormatOption
     ): List<String>? {
-        val strings = (get(path) as? Iterable<*>)
+        val strings = getList<Any?>(path)
             ?.map { it?.toString() ?: "" }
             ?.toMutableList() ?: return null
         if (placeholderInjections.isNotEmpty() && format && option == StringUtils.FormatOption.WITH_PLACEHOLDERS) {
@@ -176,7 +176,7 @@ open class EcoConfig(
     }
 
     override fun getDoublesOrNull(path: String): List<Double>? {
-        return (get(path) as? Iterable<Number>)?.map { it.toDouble() }
+        return getList<Number>(path)?.map { it.toDouble() }
     }
 
     override fun addInjectablePlaceholder(placeholders: Iterable<InjectablePlaceholder>) {
@@ -215,4 +215,15 @@ open class EcoConfig(
     override fun toString(): String {
         return this.toPlaintext()
     }
+
+    private inline fun <reified T> getList(path: String): List<T>? {
+        val asIterable = get(path) as? Iterable<*> ?: return null
+        val asList = asIterable.toList()
+
+        if (asList.firstOrNull() !is T?) {
+            return emptyList()
+        }
+
+        return asList as List<T>
+    }
 }

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/extensions/EcoExtensionLoader.kt

@@ -3,7 +3,7 @@ package com.willfp.eco.internal.extensions
 import com.google.common.collect.ImmutableSet
 import com.willfp.eco.core.Eco
 import com.willfp.eco.core.EcoPlugin
-import com.willfp.eco.core.config.TransientConfig
+import com.willfp.eco.core.config.toConfig
 import com.willfp.eco.core.extensions.Extension
 import com.willfp.eco.core.extensions.ExtensionLoader
 import com.willfp.eco.core.extensions.ExtensionMetadata
@@ -48,7 +48,7 @@ class EcoExtensionLoader(
         val ymlIn = classLoader.getResourceAsStream("extension.yml")
             ?: throw MalformedExtensionException("No extension.yml found in " + extensionJar.name)
 
-        val extensionYml = TransientConfig(YamlConfiguration.loadConfiguration(InputStreamReader(ymlIn)))
+        val extensionYml = YamlConfiguration.loadConfiguration(InputStreamReader(ymlIn)).toConfig()
 
         val mainClass = extensionYml.getStringOrNull("main")
         var name = extensionYml.getStringOrNull("name")

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/MergedStateMenu.kt

@@ -11,8 +11,8 @@ class MergedStateMenu(
         return base.getState(player) + additional.getState(player)
     }
 
-    override fun addState(player: Player, key: String, value: Any?) {
-        base.addState(player, key, value)
+    override fun setState(player: Player, key: String, value: Any?) {
+        base.setState(player, key, value)
     }
 
     override fun clearState(player: Player) {

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/EcoMenu.kt

@@ -20,7 +20,7 @@ import org.bukkit.inventory.ItemStack
 class EcoMenu(
     private val rows: Int,
     private val columns: Int,
-    private val componentsAtPoints: Map<GUIPosition, List<OffsetComponent>>,
+    private val components: LayeredComponents,
     private val title: String,
     private val onClose: List<CloseHandler>,
     private val onRender: List<(Player, Menu) -> Unit>,
@@ -28,38 +28,19 @@ class EcoMenu(
     private val menuEventHandlers: List<MenuEventHandler<*>>,
     private val allowsChangingHeldItem: Boolean
 ) : Menu {
-    private fun getPossiblyReactiveSlot(row: Int, column: Int, player: Player?, menu: Menu?): Slot {
+    private fun getPossiblyReactiveSlot(row: Int, column: Int, player: Player?): Slot {
         if (row < 1 || row > this.rows || column < 1 || column > this.columns) {
             return emptyFillerSlot
         }
 
-        val guiPosition = GUIPosition(row, column)
-        val components = componentsAtPoints[guiPosition] ?: return emptyFillerSlot
-
-        for (component in components) {
-            val found = if (player != null && menu != null) component.component.getSlotAt(
-                component.rowOffset,
-                component.columnOffset,
-                player,
-                menu
-            ) else component.component.getSlotAt(
-                component.rowOffset,
-                component.columnOffset
-            )
-
-            if (found != null) {
-                return found
-            }
-        }
-
-        return emptyFillerSlot
+        return components.getSlotAt(row, column, player, this)
     }
 
     override fun getSlot(row: Int, column: Int): Slot =
-        getPossiblyReactiveSlot(row, column, null, null)
+        getPossiblyReactiveSlot(row, column, null)
 
-    override fun getSlot(row: Int, column: Int, player: Player, menu: Menu): Slot =
-        getPossiblyReactiveSlot(row, column, player, menu)
+    override fun getSlot(row: Int, column: Int, player: Player): Slot =
+        getPossiblyReactiveSlot(row, column, player)
 
     override fun open(player: Player): Inventory {
         val inventory = if (columns == 9) {
@@ -129,7 +110,7 @@ class EcoMenu(
         this.handle(player, this@EcoMenu, event as T)
     }
 
-    override fun addState(player: Player, key: String, value: Any?) {
+    override fun setState(player: Player, key: String, value: Any?) {
         val inventory = player.renderedInventory ?: return
         inventory.state[key] = value
     }

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/EcoMenuBuilder.kt

@@ -22,6 +22,7 @@ class EcoMenuBuilder(
     private val onOpen = mutableListOf<OpenHandler>()
     private val onRender = mutableListOf<(Player, Menu) -> Unit>()
     private val menuEventHandlers = mutableListOf<MenuEventHandler<*>>()
+    private val onBuild = mutableListOf<(Menu) -> Unit>()
     private var allowsChangingHeldItem = false
 
     override fun getRows() = rows
@@ -80,13 +81,18 @@ class EcoMenuBuilder(
         return this
     }
 
+    override fun onBuild(action: Consumer<Menu>): MenuBuilder {
+        onBuild += { action.accept(it) }
+        return this
+    }
+
     override fun allowChangingHeldItem(): MenuBuilder {
         allowsChangingHeldItem = true
         return this
     }
 
     override fun build(): Menu {
-        val layeredComponents = mutableMapOf<MenuLayer, MutableMap<GUIPosition, MutableList<OffsetComponent>>>()
+        val layeredComponents = LayeredComponents()
 
         // 5 nested for loops? Shut up. Silence. Quiet.
         for (layer in MenuLayer.values()) {
@@ -107,11 +113,14 @@ class EcoMenuBuilder(
 
                             val point = GUIPosition(row, column)
 
-                            layeredComponents.computeIfAbsent(layer) { mutableMapOf() }
-                                .computeIfAbsent(point) { mutableListOf() } += OffsetComponent(
-                                component,
-                                rowOffset,
-                                columnOffset
+                            layeredComponents.addOffsetComponent(
+                                layer,
+                                point,
+                                OffsetComponent(
+                                    component,
+                                    rowOffset,
+                                    columnOffset
+                                )
                             )
                         }
                     }
@@ -119,18 +128,10 @@ class EcoMenuBuilder(
             }
         }
 
-        val componentsAtPoints = mutableMapOf<GUIPosition, MutableList<OffsetComponent>>()
-
-        for (menuLayer in MenuLayer.values()) {
-            for ((anchor, offsetComponents) in layeredComponents[menuLayer] ?: emptyMap()) {
-                componentsAtPoints[anchor] = offsetComponents
-            }
-        }
-
-        return EcoMenu(
+        val menu = EcoMenu(
             rows,
             columns,
-            componentsAtPoints,
+            layeredComponents,
             title,
             onClose,
             onRender,
@@ -138,5 +139,9 @@ class EcoMenuBuilder(
             menuEventHandlers,
             allowsChangingHeldItem
         )
+
+        onBuild.forEach { it(menu) } // Run on build functions.
+
+        return menu
     }
 }

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/LayeredComponents.kt

@@ -0,0 +1,46 @@
+package com.willfp.eco.internal.gui.menu
+
+import com.willfp.eco.core.gui.menu.Menu
+import com.willfp.eco.core.gui.menu.MenuLayer
+import com.willfp.eco.core.gui.slot.Slot
+import org.bukkit.entity.Player
+
+class LayeredComponents {
+    private val layers = mutableMapOf<MenuLayer, Map<GUIPosition, List<OffsetComponent>>>()
+
+    fun getSlotAt(row: Int, column: Int, player: Player?, menu: Menu): Slot {
+        val guiPosition = GUIPosition(row, column)
+
+        for (layer in MenuLayer.values().reversed()) {
+            val componentsAtPoints = layers[layer] ?: continue
+
+            val components = componentsAtPoints[guiPosition] ?: continue
+
+            for (component in components) {
+                val found = if (player != null) component.component.getSlotAt(
+                    component.rowOffset,
+                    component.columnOffset,
+                    player,
+                    menu
+                ) else component.component.getSlotAt(
+                    component.rowOffset,
+                    component.columnOffset
+                )
+
+                if (found != null) {
+                    return found
+                }
+            }
+        }
+
+        return emptyFillerSlot
+    }
+
+    fun addOffsetComponent(layer: MenuLayer, position: GUIPosition, component: OffsetComponent) {
+        val inLayer = layers[layer]?.toMutableMap() ?: mutableMapOf()
+        val atPosition = inLayer[position]?.toMutableList() ?: mutableListOf()
+        atPosition.add(component)
+        inLayer[position] = atPosition
+        layers[layer] = inLayer
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/RenderedInventory.kt

@@ -1,8 +1,10 @@
 package com.willfp.eco.internal.gui.menu
 
+import com.willfp.eco.core.gui.menu.events.CaptiveItemChangeEvent
 import com.willfp.eco.core.items.isEmpty
 import com.willfp.eco.core.recipe.parts.EmptyTestableItem
 import com.willfp.eco.util.MenuUtils
+import com.willfp.eco.util.openMenu
 import org.bukkit.entity.Player
 import org.bukkit.inventory.Inventory
 import org.bukkit.inventory.ItemStack
@@ -31,14 +33,22 @@ class RenderedInventory(
     val state = mutableMapOf<String, Any?>()
 
     fun render() {
-        captiveItems.clear()
+        // This can happen when opening menus from other menus,
+        // fixing a bug where multiple paginated menus on top of
+        // each other caused bugs with page changer display.
+        if (this.menu != player.openMenu) {
+            MenuHandler.unregisterInventory(this.inventory)
+            return
+        }
+
+        val newCaptive = mutableMapOf<GUIPosition, ItemStack>()
 
         for (row in (1..menu.rows)) {
             for (column in (1..menu.columns)) {
                 val position = GUIPosition(row, column)
                 val bukkit = MenuUtils.rowColumnToSlot(row, column, menu.columns)
 
-                val slot = menu.getSlot(row, column, player, menu)
+                val slot = menu.getSlot(row, column, player)
                 val renderedItem = slot.getItemStack(player)
 
                 if (slot.isCaptive(player, menu)) {
@@ -46,11 +56,11 @@ class RenderedInventory(
 
                     if (slot.isCaptiveFromEmpty) {
                         if (!actualItem.isEmpty) {
-                            captiveItems[position] = actualItem
+                            newCaptive[position] = actualItem
                         }
                     } else {
                         if (actualItem != renderedItem && !EmptyTestableItem().matches(actualItem)) {
-                            captiveItems[position] = actualItem
+                            newCaptive[position] = actualItem
                         }
                     }
                 } else {
@@ -59,15 +69,51 @@ class RenderedInventory(
             }
         }
 
+        val previousCaptive = captiveItems.toMap()
+        captiveItems.clear()
+        captiveItems.putAll(newCaptive)
+
+        // Call captive item change event
+        for (position in previousCaptive.keys union newCaptive.keys) {
+            if (previousCaptive[position] != newCaptive[position]) {
+                menu.callEvent(
+                    player, CaptiveItemChangeEvent(
+                        position.row,
+                        position.column,
+                        previousCaptive[position],
+                        newCaptive[position]
+                    )
+                )
+            }
+        }
+
         menu.runOnRender(player)
+
+        // Run second render if captive items changed
+        if (captiveItems != previousCaptive) {
+            for (row in (1..menu.rows)) {
+                for (column in (1..menu.columns)) {
+                    val bukkit = MenuUtils.rowColumnToSlot(row, column, menu.columns)
+
+                    val slot = menu.getSlot(row, column, player)
+                    val renderedItem = slot.getItemStack(player)
+
+                    if (!slot.isCaptive(player, menu)) {
+                        inventory.setItem(bukkit, renderedItem)
+                    }
+                }
+            }
+        }
     }
 
     fun renderDefaultCaptiveItems() {
+        menu.runOnRender(player)
+
         for (row in (1..menu.rows)) {
             for (column in (1..menu.columns)) {
                 val bukkit = MenuUtils.rowColumnToSlot(row, column, menu.columns)
 
-                val slot = menu.getSlot(row, column, player, menu)
+                val slot = menu.getSlot(row, column, player)
 
                 if (slot.isCaptive(player, menu)) {
                     inventory.setItem(bukkit, slot.getItemStack(player))

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoCaptiveSlot.kt

@@ -1,20 +1,24 @@
 package com.willfp.eco.internal.gui.slot
 
 import com.willfp.eco.core.gui.menu.Menu
+import com.willfp.eco.core.gui.slot.functional.CaptiveFilter
 import com.willfp.eco.core.gui.slot.functional.SlotHandler
 import com.willfp.eco.core.gui.slot.functional.SlotProvider
 import com.willfp.eco.util.toSingletonList
+import org.bukkit.Material
 import org.bukkit.entity.Player
 import org.bukkit.event.inventory.ClickType
+import org.bukkit.inventory.ItemStack
 
 class EcoCaptiveSlot(
     provider: SlotProvider,
     private val captiveFromEmpty: Boolean,
-    private val notCaptiveFor: (Player) -> Boolean
+    private val notCaptiveFor: (Player) -> Boolean,
+    private val filter: CaptiveFilter
 ) : EcoSlot(
     provider,
     ClickType.values().associateWith {
-        captiveWithTest(notCaptiveFor).toSingletonList()
+        captiveWithTest(notCaptiveFor, filter).toSingletonList()
     },
     { _, _, prev -> prev }
 ) {
@@ -22,13 +26,25 @@ class EcoCaptiveSlot(
         return !notCaptiveFor(player)
     }
 
+    override fun isAllowedCaptive(player: Player, menu: Menu, itemStack: ItemStack?): Boolean {
+        return filter.isAllowed(player, menu, itemStack)
+    }
+
     override fun isCaptiveFromEmpty(): Boolean {
         return captiveFromEmpty
     }
 }
 
-private fun captiveWithTest(test: (Player) -> Boolean): SlotHandler {
-    return SlotHandler { event, _, _ ->
-        event.isCancelled = test(event.whoClicked as Player)
-    }
+private fun captiveWithTest(
+    notCaptiveFor: (Player) -> Boolean,
+    filter: CaptiveFilter
+): SlotHandler = SlotHandler { event, _, menu ->
+    val player = event.whoClicked as Player
+
+    val item = event.currentItem.nullIfAir() ?: event.cursor.nullIfAir()
+
+    event.isCancelled = !filter.isAllowed(player, menu, item) || notCaptiveFor(player)
 }
+
+private fun ItemStack?.nullIfAir(): ItemStack? =
+    if (this?.type == Material.AIR) null else this

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoSlot.kt

@@ -33,9 +33,5 @@ open class EcoSlot(
         return updater.update(player, menu, base) ?: return ItemStack(Material.AIR)
     }
 
-    override fun isCaptive(player: Player, menu: Menu): Boolean {
-        return false
-    }
-
     override fun getActionableSlot(player: Player, menu: Menu): EcoSlot = this
 }

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoSlotBuilder.kt

@@ -2,6 +2,7 @@ package com.willfp.eco.internal.gui.slot
 
 import com.willfp.eco.core.gui.slot.Slot
 import com.willfp.eco.core.gui.slot.SlotBuilder
+import com.willfp.eco.core.gui.slot.functional.CaptiveFilter
 import com.willfp.eco.core.gui.slot.functional.SlotHandler
 import com.willfp.eco.core.gui.slot.functional.SlotProvider
 import com.willfp.eco.core.gui.slot.functional.SlotUpdater
@@ -16,7 +17,9 @@ class EcoSlotBuilder(private val provider: SlotProvider) : SlotBuilder {
 
     private val handlers = mutableMapOf<ClickType, MutableList<SlotHandler>>()
 
-    private var notCaptiveFor: (Player) -> Boolean = { false }
+    private var captiveFilter =
+        CaptiveFilter { _, _, _ -> true }
+    private var notCaptiveFor: (Player) -> Boolean = { _ -> false}
 
     override fun onClick(type: ClickType, action: SlotHandler): SlotBuilder {
         handlers.computeIfAbsent(type) { mutableListOf() } += action
@@ -24,7 +27,12 @@ class EcoSlotBuilder(private val provider: SlotProvider) : SlotBuilder {
     }
 
     override fun notCaptiveFor(predicate: Predicate<Player>): SlotBuilder {
-        notCaptiveFor = { predicate.test(it) }
+        notCaptiveFor = { player -> predicate.test(player) }
+        return this
+    }
+
+    override fun setCaptiveFilter(filter: CaptiveFilter): SlotBuilder {
+        captiveFilter = filter
         return this
     }
 
@@ -44,7 +52,8 @@ class EcoSlotBuilder(private val provider: SlotProvider) : SlotBuilder {
             EcoCaptiveSlot(
                 provider,
                 captiveFromEmpty,
-                notCaptiveFor
+                notCaptiveFor,
+                captiveFilter
             )
         } else {
             EcoSlot(

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/integrations/PAPIExpansion.kt

@@ -1,13 +1,15 @@
 package com.willfp.eco.internal.integrations
 
 import com.willfp.eco.core.EcoPlugin
-import com.willfp.eco.core.integrations.placeholder.PlaceholderIntegration
 import com.willfp.eco.core.integrations.placeholder.PlaceholderManager
-import me.clip.placeholderapi.PlaceholderAPI
 import me.clip.placeholderapi.expansion.PlaceholderExpansion
 import org.bukkit.entity.Player
 
-class PlaceholderIntegrationPAPI(private val plugin: EcoPlugin) : PlaceholderExpansion(), PlaceholderIntegration {
+class PAPIExpansion(private val plugin: EcoPlugin) : PlaceholderExpansion() {
+    init {
+        register()
+    }
+
     override fun persist(): Boolean {
         return true
     }
@@ -34,29 +36,4 @@ class PlaceholderIntegrationPAPI(private val plugin: EcoPlugin) : PlaceholderExp
     ): String {
         return PlaceholderManager.getResult(player, identifier, plugin)
     }
-
-    override fun registerIntegration() {
-        register()
-    }
-
-    override fun getPluginName(): String {
-        return "PlaceholderAPI"
-    }
-
-    override fun translate(
-        text: String,
-        player: Player?
-    ): String {
-        return PlaceholderAPI.setPlaceholders(player, text)
-    }
-
-    override fun findPlaceholdersIn(text: String): MutableList<String> {
-        val placeholders = mutableListOf<String>()
-        val matcher = PlaceholderAPI.getPlaceholderPattern().matcher(text)
-        while (matcher.find()) {
-            placeholders.add(matcher.group())
-        }
-
-        return placeholders
-    }
-}
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/items/ArgParserCustomModelData.kt

@@ -27,6 +27,10 @@ object ArgParserCustomModelData : LookupArgParser {
         return Predicate {
             val testMeta = it.itemMeta ?: return@Predicate false
 
+            if (!testMeta.hasCustomModelData()) {
+                return@Predicate false
+            }
+
             testMeta.customModelData == modelData
         }
     }

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/particle/ParticleFactoryRGB.kt

@@ -0,0 +1,36 @@
+package com.willfp.eco.internal.particle
+
+import com.willfp.eco.core.particle.ParticleFactory
+import com.willfp.eco.core.particle.SpawnableParticle
+import org.bukkit.Color
+import org.bukkit.Location
+import org.bukkit.Particle
+
+object ParticleFactoryRGB : ParticleFactory {
+    override fun getNames() = listOf(
+        "color",
+        "rgb",
+        "hex"
+    )
+
+    override fun create(key: String): SpawnableParticle? {
+        val hex = key.toIntOrNull(16) ?: return null
+        val color = try {
+            Color.fromRGB(hex)
+        } catch (e: IllegalArgumentException) {
+            return null
+        }
+
+        return SpawnableParticleRGB(Particle.DustOptions(color, 1.0f))
+    }
+
+    private class SpawnableParticleRGB(
+        private val options: Particle.DustOptions
+    ) : SpawnableParticle {
+        override fun spawn(location: Location, amount: Int) {
+            val world = location.world ?: return
+
+            world.spawnParticle(Particle.REDSTONE, location, amount, 0.0, 0.0, 0.0, 0.0, options)
+        }
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/price/PriceFactoryEconomy.kt

@@ -0,0 +1,18 @@
+package com.willfp.eco.internal.price
+
+import com.willfp.eco.core.math.MathContext
+import com.willfp.eco.core.price.Price
+import com.willfp.eco.core.price.PriceFactory
+import com.willfp.eco.core.price.impl.PriceEconomy
+import java.util.function.Function
+
+object PriceFactoryEconomy : PriceFactory {
+    override fun getNames() = listOf(
+        "coins",
+        "$"
+    )
+
+    override fun create(baseContext: MathContext, function: Function<MathContext, Double>): Price {
+        return PriceEconomy(baseContext, function)
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/price/PriceFactoryXP.kt

@@ -0,0 +1,54 @@
+package com.willfp.eco.internal.price
+
+import com.willfp.eco.core.math.MathContext
+import com.willfp.eco.core.price.Price
+import com.willfp.eco.core.price.PriceFactory
+import org.bukkit.entity.Player
+import java.util.UUID
+import java.util.function.Function
+import kotlin.math.roundToInt
+
+object PriceFactoryXP : PriceFactory {
+    override fun getNames() = listOf(
+        "xp",
+        "exp",
+        "experience"
+    )
+
+    override fun create(baseContext: MathContext, function: Function<MathContext, Double>): Price {
+        return PriceXP(baseContext) { function.apply(it).roundToInt() }
+    }
+
+    private class PriceXP(
+        private val baseContext: MathContext,
+        private val xp: (MathContext) -> Int
+    ) : Price {
+        private val multipliers = mutableMapOf<UUID, Double>()
+
+        override fun canAfford(player: Player) = player.totalExperience >= getValue(player)
+
+        override fun pay(player: Player) {
+            player.totalExperience -= getValue(player).roundToInt()
+        }
+
+        override fun giveTo(player: Player) {
+            player.totalExperience += getValue(player).roundToInt()
+        }
+
+        override fun getValue(player: Player): Double {
+            return xp(MathContext.copyWithPlayer(baseContext, player)) * getMultiplier(player)
+        }
+
+        override fun getMultiplier(player: Player): Double {
+            return multipliers[player.uniqueId] ?: 1.0
+        }
+
+        override fun setMultiplier(player: Player, multiplier: Double) {
+            multipliers[player.uniqueId] = multiplier.roundToInt().toDouble()
+        }
+
+        override fun getIdentifier(): String {
+            return "eco:xp"
+        }
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/price/PriceFactoryXPLevels.kt

@@ -0,0 +1,55 @@
+package com.willfp.eco.internal.price
+
+import com.willfp.eco.core.math.MathContext
+import com.willfp.eco.core.price.Price
+import com.willfp.eco.core.price.PriceFactory
+import org.bukkit.entity.Player
+import java.util.UUID
+import java.util.function.Function
+import kotlin.math.roundToInt
+
+object PriceFactoryXPLevels : PriceFactory {
+    override fun getNames() = listOf(
+        "l",
+        "levels",
+        "xplevels",
+        "explevels",
+    )
+
+    override fun create(baseContext: MathContext, function: Function<MathContext, Double>): Price {
+        return PriceXPLevel(baseContext) { function.apply(it).roundToInt() }
+    }
+
+    private class PriceXPLevel(
+        private val baseContext: MathContext,
+        private val level: (MathContext) -> Int
+    ) : Price {
+        private val multipliers = mutableMapOf<UUID, Double>()
+
+        override fun canAfford(player: Player) = player.level >= getValue(player)
+
+        override fun pay(player: Player) {
+            player.level -= getValue(player).roundToInt()
+        }
+
+        override fun giveTo(player: Player) {
+            player.level += getValue(player).roundToInt()
+        }
+
+        override fun getValue(player: Player): Double {
+            return level(MathContext.copyWithPlayer(baseContext, player)) * getMultiplier(player)
+        }
+
+        override fun getMultiplier(player: Player): Double {
+            return multipliers[player.uniqueId] ?: 1.0
+        }
+
+        override fun setMultiplier(player: Player, multiplier: Double) {
+            multipliers[player.uniqueId] = multiplier.roundToInt().toDouble()
+        }
+
+        override fun getIdentifier(): String {
+            return "eco:xp-levels"
+        }
+    }
+}

eco-core/core-nms/nms-common/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/common/Skull.kt

@@ -29,7 +29,27 @@ var SkullMeta.texture: String?
             setProfile.isAccessible = true
         }
 
-        if (base64 == null) {
+        /* This length check below was lost in the conversion. For some reason the base64
+        * string is length 8 when this is called pretty frequently, causing an
+        * out of bounds exception.
+        *
+        * Could not pass event EntityPotionEffectEvent to Talismans v5.116.0
+        * java.lang.StringIndexOutOfBoundsException: begin -12, end 8, length 8
+        * at java.lang.String.checkBoundsBeginEnd(String.java:4604) ~[?:?]
+        * at java.lang.String.substring(String.java:2707) ~[?:?]
+        * at java.lang.String.substring(String.java:2680) ~[?:?]
+        * at com.willfp.eco.internal.spigot.proxy.v1_19_R1.common.SkullKt.setTexture(Skull.kt:36)
+        *
+        if (base64.length < 20) {
+            return
+        }
+        *
+        * ^ Update to this comment: a length 8 string ("textures") was being sent
+        * because the get() method wasn't working right. This has been fixed, but the
+        * check needs to remain implemented.
+        */
+
+        if (base64 == null || base64.length < 20) {
             setProfile.invoke(this, null)
         } else {
             val uuid = UUID(

eco-core/core-nms/nms-common/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/common/ai/entity/IllusionerBlindnessSpellGoalFactory.kt

@@ -1,21 +1,23 @@
 package com.willfp.eco.internal.spigot.proxy.common.ai.entity
 
-import com.willfp.eco.core.entities.ai.entity.EntityGoalLeapAtTarget
+import com.willfp.eco.core.entities.ai.entity.EntityGoalIllusionerBlindnessSpell
 import com.willfp.eco.internal.spigot.proxy.common.ai.EntityGoalFactory
-import com.willfp.eco.internal.spigot.proxy.common.ai.opengoals.IllusionerBlindnessSpellGoal
 import net.minecraft.world.entity.PathfinderMob
 import net.minecraft.world.entity.ai.goal.Goal
 import net.minecraft.world.entity.monster.Illusioner
 
-object IllusionerBlindnessSpellGoalFactory : EntityGoalFactory<EntityGoalLeapAtTarget> {
-    override fun create(apiGoal: EntityGoalLeapAtTarget, entity: PathfinderMob): Goal? {
+object IllusionerBlindnessSpellGoalFactory : EntityGoalFactory<EntityGoalIllusionerBlindnessSpell> {
+    override fun create(apiGoal: EntityGoalIllusionerBlindnessSpell, entity: PathfinderMob): Goal? {
         if (entity !is Illusioner) return null
 
-        return IllusionerBlindnessSpellGoal(
-            entity
-        )
+        // Have to use reflection for it to work
+        return Illusioner::class.java.declaredClasses[1]
+            .getDeclaredConstructor(Illusioner::class.java)
+            .apply { isAccessible = true }
+            .newInstance(entity) as Goal
     }
 
-    override fun isGoalOfType(goal: Goal) = goal is IllusionerBlindnessSpellGoal
-            || goal::class.java.name.contains("IllusionerBlindnessSpellGoal")
+    override fun isGoalOfType(goal: Goal): Boolean {
+        return Illusioner::class.java.declaredClasses[1].isInstance(goal)
+    }
 }

eco-core/core-nms/nms-common/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/common/ai/entity/IllusionerMirrorSpellGoalFactory.kt

@@ -1,21 +1,23 @@
 package com.willfp.eco.internal.spigot.proxy.common.ai.entity
 
-import com.willfp.eco.core.entities.ai.entity.EntityGoalLeapAtTarget
+import com.willfp.eco.core.entities.ai.entity.EntityGoalIllusionerMirrorSpell
 import com.willfp.eco.internal.spigot.proxy.common.ai.EntityGoalFactory
-import com.willfp.eco.internal.spigot.proxy.common.ai.opengoals.IllusionerMirrorSpellGoal
 import net.minecraft.world.entity.PathfinderMob
 import net.minecraft.world.entity.ai.goal.Goal
 import net.minecraft.world.entity.monster.Illusioner
 
-object IllusionerMirrorSpellGoalFactory : EntityGoalFactory<EntityGoalLeapAtTarget> {
-    override fun create(apiGoal: EntityGoalLeapAtTarget, entity: PathfinderMob): Goal? {
+object IllusionerMirrorSpellGoalFactory : EntityGoalFactory<EntityGoalIllusionerMirrorSpell> {
+    override fun create(apiGoal: EntityGoalIllusionerMirrorSpell, entity: PathfinderMob): Goal? {
         if (entity !is Illusioner) return null
 
-        return IllusionerMirrorSpellGoal(
-            entity
-        )
+        // Have to use reflection for it to work
+        return Illusioner::class.java.declaredClasses[0]
+            .getDeclaredConstructor(Illusioner::class.java)
+            .apply { isAccessible = true }
+            .newInstance(entity) as Goal
     }
 
-    override fun isGoalOfType(goal: Goal) = goal is IllusionerMirrorSpellGoal
-            || goal::class.java.name.contains("IllusionerMirrorSpellGoal")
+    override fun isGoalOfType(goal: Goal): Boolean {
+        return Illusioner::class.java.declaredClasses[0].isInstance(goal)
+    }
 }

eco-core/core-nms/nms-common/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/common/ai/opengoals/IllusionerBlindnessSpellGoal.kt

@@ -1,50 +0,0 @@
-package com.willfp.eco.internal.spigot.proxy.common.ai.opengoals
-
-import net.minecraft.sounds.SoundEvent
-import net.minecraft.sounds.SoundEvents
-import net.minecraft.world.Difficulty
-import net.minecraft.world.effect.MobEffectInstance
-import net.minecraft.world.effect.MobEffects
-import net.minecraft.world.entity.monster.Illusioner
-import net.minecraft.world.entity.monster.SpellcasterIllager
-import org.bukkit.event.entity.EntityPotionEffectEvent
-
-class IllusionerBlindnessSpellGoal(
-    private val illusioner: Illusioner
-) : OpenUseSpellGoal(illusioner) {
-    override val castingInterval = 180
-    override val castingTime = 20
-    override val spellPrepareSound: SoundEvent = SoundEvents.ILLUSIONER_PREPARE_BLINDNESS
-    override val spell: SpellcasterIllager.IllagerSpell = SpellcasterIllager.IllagerSpell.BLINDNESS
-
-    private var lastTargetId = 0
-
-    override fun canUse(): Boolean {
-        return if (super.canUse()) {
-            false
-        } else if (illusioner.target == null) {
-            false
-        } else if (illusioner.target!!.id == lastTargetId) {
-            false
-        } else {
-            illusioner.level.getCurrentDifficultyAt(illusioner.blockPosition()).isHarderThan(
-                Difficulty.NORMAL.ordinal.toFloat()
-            )
-        }
-    }
-
-    override fun start() {
-        super.start()
-        if (illusioner.target != null) {
-            lastTargetId = illusioner.target!!.id
-        }
-    }
-
-    override fun performSpellCasting() {
-        illusioner.target?.addEffect(
-            MobEffectInstance(MobEffects.BLINDNESS, 400),
-            illusioner,
-            EntityPotionEffectEvent.Cause.ATTACK
-        ) // CraftBukkit
-    }
-}

eco-core/core-nms/nms-common/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/common/ai/opengoals/IllusionerMirrorSpellGoal.kt

@@ -1,29 +0,0 @@
-package com.willfp.eco.internal.spigot.proxy.common.ai.opengoals
-
-import net.minecraft.sounds.SoundEvent
-import net.minecraft.sounds.SoundEvents
-import net.minecraft.world.effect.MobEffectInstance
-import net.minecraft.world.effect.MobEffects
-import net.minecraft.world.entity.monster.Illusioner
-import net.minecraft.world.entity.monster.SpellcasterIllager
-import org.bukkit.event.entity.EntityPotionEffectEvent
-
-class IllusionerMirrorSpellGoal(
-    private val illusioner: Illusioner
-) : OpenUseSpellGoal(illusioner) {
-    override val castingInterval = 340
-    override val castingTime = 20
-    override val spellPrepareSound: SoundEvent = SoundEvents.ILLUSIONER_PREPARE_MIRROR
-    override val spell: SpellcasterIllager.IllagerSpell = SpellcasterIllager.IllagerSpell.DISAPPEAR
-
-    override fun canUse(): Boolean {
-        return if (!super.canUse()) false else !illusioner.hasEffect(MobEffects.INVISIBILITY)
-    }
-
-    override fun performSpellCasting() {
-        illusioner.addEffect(
-            MobEffectInstance(MobEffects.INVISIBILITY, 1200),
-            EntityPotionEffectEvent.Cause.ILLUSION
-        )
-    }
-}

eco-core/core-nms/nms-common/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/common/ai/opengoals/Spellcaster.kt

@@ -1,79 +0,0 @@
-package com.willfp.eco.internal.spigot.proxy.common.ai.opengoals
-
-import net.minecraft.sounds.SoundEvent
-import net.minecraft.world.entity.EntityType
-import net.minecraft.world.entity.LivingEntity
-import net.minecraft.world.entity.ai.goal.Goal
-import net.minecraft.world.entity.monster.SpellcasterIllager
-
-@Suppress("UNCHECKED_CAST")
-class DelegatedSpellcaster(private val handle: SpellcasterIllager) : SpellcasterIllager(
-    handle.type as EntityType<out SpellcasterIllager>,
-    handle.level
-) {
-    var openSpellCastingTickCount
-        get() = this.spellCastingTickCount
-        set(value) {
-            this.spellCastingTickCount = value
-        }
-
-    val openCastingSoundEvent = this.castingSoundEvent
-
-    override fun applyRaidBuffs(wave: Int, unused: Boolean) {
-        handle.applyRaidBuffs(wave, unused)
-    }
-
-    override fun getCelebrateSound(): SoundEvent {
-        return handle.celebrateSound
-    }
-
-    override fun getCastingSoundEvent(): SoundEvent {
-        return this.openCastingSoundEvent
-    }
-}
-
-@Suppress("NULLABILITY_MISMATCH_BASED_ON_JAVA_ANNOTATIONS")
-abstract class OpenUseSpellGoal(
-    private val handle: SpellcasterIllager
-) : Goal() {
-    private var attackWarmupDelay = 0
-    private var nextAttackTickCount = 0
-
-    private val openHandle = DelegatedSpellcaster(handle)
-
-    override fun canUse(): Boolean {
-        val entityliving: LivingEntity = handle.target ?: return false
-        return if (entityliving.isAlive) if (handle.isCastingSpell) false else handle.tickCount >= nextAttackTickCount else false
-    }
-
-    override fun canContinueToUse(): Boolean {
-        val entityliving: LivingEntity = handle.target ?: return false
-        return entityliving.isAlive && attackWarmupDelay > 0
-    }
-
-    override fun start() {
-        attackWarmupDelay = castWarmupTime
-        openHandle.openSpellCastingTickCount = castingTime
-        nextAttackTickCount = handle.tickCount + castingInterval
-        val soundeffect = spellPrepareSound
-        if (soundeffect != null) {
-            handle.playSound(soundeffect, 1.0f, 1.0f)
-        }
-        handle.setIsCastingSpell(spell)
-    }
-
-    override fun tick() {
-        --attackWarmupDelay
-        if (attackWarmupDelay == 0) {
-            performSpellCasting()
-            handle.playSound(openHandle.openCastingSoundEvent, 1.0f, 1.0f)
-        }
-    }
-
-    protected abstract fun performSpellCasting()
-    protected abstract val castingTime: Int
-    protected abstract val castingInterval: Int
-    protected abstract val spellPrepareSound: SoundEvent?
-    protected abstract val spell: SpellcasterIllager.IllagerSpell?
-    protected open val castWarmupTime: Int = 60
-}

eco-core/core-nms/v1_17_R1/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_17_R1/BukkitCommands.kt

@@ -0,0 +1,35 @@
+package com.willfp.eco.internal.spigot.proxy.v1_17_R1
+
+import com.willfp.eco.core.command.impl.PluginCommand
+import com.willfp.eco.internal.spigot.proxy.BukkitCommandsProxy
+import org.bukkit.Bukkit
+import org.bukkit.command.Command
+import org.bukkit.command.SimpleCommandMap
+import org.bukkit.craftbukkit.v1_17_R1.CraftServer
+import java.lang.reflect.Field
+
+class BukkitCommands : BukkitCommandsProxy {
+    private val knownCommandsField: Field by lazy {
+        SimpleCommandMap::class.java.getDeclaredField("knownCommands")
+            .apply {
+                isAccessible = true
+            }
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    private val knownCommands: MutableMap<String, Command>
+        get() = knownCommandsField.get(getCommandMap()) as MutableMap<String, Command>
+
+    override fun getCommandMap(): SimpleCommandMap {
+        return (Bukkit.getServer() as CraftServer).commandMap
+    }
+
+    override fun syncCommands() {
+        (Bukkit.getServer() as CraftServer).syncCommands()
+    }
+
+    override fun unregisterCommand(command: PluginCommand) {
+        knownCommands.remove(command.name)
+        knownCommands.remove("${command.plugin.name.lowercase()}:${command.name}")
+    }
+}

eco-core/core-nms/v1_17_R1/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_17_R1/ExtendedPersistentDataContainerFactory.kt

@@ -3,16 +3,28 @@ package com.willfp.eco.internal.spigot.proxy.v1_17_R1
 import com.willfp.eco.core.data.ExtendedPersistentDataContainer
 import com.willfp.eco.internal.spigot.proxy.ExtendedPersistentDataContainerFactoryProxy
 import net.minecraft.nbt.Tag
+import org.bukkit.Material
+import org.bukkit.craftbukkit.v1_17_R1.inventory.CraftItemStack
 import org.bukkit.craftbukkit.v1_17_R1.persistence.CraftPersistentDataContainer
 import org.bukkit.craftbukkit.v1_17_R1.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.inventory.ItemStack
 import org.bukkit.persistence.PersistentDataContainer
 import org.bukkit.persistence.PersistentDataType
 
-class ExtendedPersistentDataContainerFactory: ExtendedPersistentDataContainerFactoryProxy {
+class ExtendedPersistentDataContainerFactory : ExtendedPersistentDataContainerFactoryProxy {
     @Suppress("UNCHECKED_CAST")
-    private val registry: CraftPersistentDataTypeRegistry =
-        CraftPersistentDataContainer::class.java.getDeclaredField("registry")
-            .apply { isAccessible = true }.get(null) as CraftPersistentDataTypeRegistry
+    private val registry: CraftPersistentDataTypeRegistry
+
+    init {
+        /*
+         Can't grab actual instance since it's in CraftMetaItem (which is package-private)
+         And getting it would mean more janky reflection
+         */
+        val item = CraftItemStack.asCraftCopy(ItemStack(Material.STONE))
+        val pdc = item.itemMeta!!.persistentDataContainer
+        this.registry = CraftPersistentDataContainer::class.java.getDeclaredField("registry")
+            .apply { isAccessible = true }.get(pdc) as CraftPersistentDataTypeRegistry
+    }
 
     override fun adapt(pdc: PersistentDataContainer): ExtendedPersistentDataContainer {
         return when (pdc) {
@@ -34,7 +46,8 @@ class ExtendedPersistentDataContainerFactory: ExtendedPersistentDataContainerFac
                 .apply { isAccessible = true }.get(handle) as MutableMap<String, Tag>
 
         override fun <T : Any, Z : Any> set(key: String, dataType: PersistentDataType<T, Z>, value: Z) {
-            customDataTags[key] = registry.wrap(dataType.primitiveType, dataType.toPrimitive(value, handle.adapterContext))
+            customDataTags[key] =
+                registry.wrap(dataType.primitiveType, dataType.toPrimitive(value, handle.adapterContext))
         }
 
         override fun <T : Any, Z : Any> has(key: String, dataType: PersistentDataType<T, Z>): Boolean {

eco-core/core-nms/v1_18_R1/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_18_R1/BukkitCommands.kt

@@ -0,0 +1,35 @@
+package com.willfp.eco.internal.spigot.proxy.v1_18_R1
+
+import com.willfp.eco.core.command.impl.PluginCommand
+import com.willfp.eco.internal.spigot.proxy.BukkitCommandsProxy
+import org.bukkit.Bukkit
+import org.bukkit.command.Command
+import org.bukkit.command.SimpleCommandMap
+import org.bukkit.craftbukkit.v1_18_R1.CraftServer
+import java.lang.reflect.Field
+
+class BukkitCommands : BukkitCommandsProxy {
+    private val knownCommandsField: Field by lazy {
+        SimpleCommandMap::class.java.getDeclaredField("knownCommands")
+            .apply {
+                isAccessible = true
+            }
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    private val knownCommands: MutableMap<String, Command>
+        get() = knownCommandsField.get(getCommandMap()) as MutableMap<String, Command>
+
+    override fun getCommandMap(): SimpleCommandMap {
+        return (Bukkit.getServer() as CraftServer).commandMap
+    }
+
+    override fun syncCommands() {
+        (Bukkit.getServer() as CraftServer).syncCommands()
+    }
+
+    override fun unregisterCommand(command: PluginCommand) {
+        knownCommands.remove(command.name)
+        knownCommands.remove("${command.plugin.name.lowercase()}:${command.name}")
+    }
+}

eco-core/core-nms/v1_18_R1/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_18_R1/ExtendedPersistentDataContainerFactory.kt

@@ -3,16 +3,28 @@ package com.willfp.eco.internal.spigot.proxy.v1_18_R1
 import com.willfp.eco.core.data.ExtendedPersistentDataContainer
 import com.willfp.eco.internal.spigot.proxy.ExtendedPersistentDataContainerFactoryProxy
 import net.minecraft.nbt.Tag
+import org.bukkit.Material
+import org.bukkit.craftbukkit.v1_18_R1.inventory.CraftItemStack
 import org.bukkit.craftbukkit.v1_18_R1.persistence.CraftPersistentDataContainer
 import org.bukkit.craftbukkit.v1_18_R1.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.inventory.ItemStack
 import org.bukkit.persistence.PersistentDataContainer
 import org.bukkit.persistence.PersistentDataType
 
 class ExtendedPersistentDataContainerFactory : ExtendedPersistentDataContainerFactoryProxy {
     @Suppress("UNCHECKED_CAST")
-    private val registry: CraftPersistentDataTypeRegistry =
-        CraftPersistentDataContainer::class.java.getDeclaredField("registry")
-            .apply { isAccessible = true }.get(null) as CraftPersistentDataTypeRegistry
+    private val registry: CraftPersistentDataTypeRegistry
+
+    init {
+        /*
+         Can't grab actual instance since it's in CraftMetaItem (which is package-private)
+         And getting it would mean more janky reflection
+         */
+        val item = CraftItemStack.asCraftCopy(ItemStack(Material.STONE))
+        val pdc = item.itemMeta!!.persistentDataContainer
+        this.registry = CraftPersistentDataContainer::class.java.getDeclaredField("registry")
+            .apply { isAccessible = true }.get(pdc) as CraftPersistentDataTypeRegistry
+    }
 
     override fun adapt(pdc: PersistentDataContainer): ExtendedPersistentDataContainer {
         return when (pdc) {

eco-core/core-nms/v1_18_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_18_R2/BukkitCommands.kt

@@ -0,0 +1,35 @@
+package com.willfp.eco.internal.spigot.proxy.v1_18_R2
+
+import com.willfp.eco.core.command.impl.PluginCommand
+import com.willfp.eco.internal.spigot.proxy.BukkitCommandsProxy
+import org.bukkit.Bukkit
+import org.bukkit.command.Command
+import org.bukkit.command.SimpleCommandMap
+import org.bukkit.craftbukkit.v1_18_R2.CraftServer
+import java.lang.reflect.Field
+
+class BukkitCommands : BukkitCommandsProxy {
+    private val knownCommandsField: Field by lazy {
+        SimpleCommandMap::class.java.getDeclaredField("knownCommands")
+            .apply {
+                isAccessible = true
+            }
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    private val knownCommands: MutableMap<String, Command>
+        get() = knownCommandsField.get(getCommandMap()) as MutableMap<String, Command>
+
+    override fun getCommandMap(): SimpleCommandMap {
+        return (Bukkit.getServer() as CraftServer).commandMap
+    }
+
+    override fun syncCommands() {
+        (Bukkit.getServer() as CraftServer).syncCommands()
+    }
+
+    override fun unregisterCommand(command: PluginCommand) {
+        knownCommands.remove(command.name)
+        knownCommands.remove("${command.plugin.name.lowercase()}:${command.name}")
+    }
+}

eco-core/core-nms/v1_18_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_18_R2/ExtendedPersistentDataContainerFactory.kt

@@ -3,16 +3,28 @@ package com.willfp.eco.internal.spigot.proxy.v1_18_R2
 import com.willfp.eco.core.data.ExtendedPersistentDataContainer
 import com.willfp.eco.internal.spigot.proxy.ExtendedPersistentDataContainerFactoryProxy
 import net.minecraft.nbt.Tag
+import org.bukkit.Material
+import org.bukkit.craftbukkit.v1_18_R2.inventory.CraftItemStack
 import org.bukkit.craftbukkit.v1_18_R2.persistence.CraftPersistentDataContainer
 import org.bukkit.craftbukkit.v1_18_R2.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.inventory.ItemStack
 import org.bukkit.persistence.PersistentDataContainer
 import org.bukkit.persistence.PersistentDataType
 
-class ExtendedPersistentDataContainerFactory: ExtendedPersistentDataContainerFactoryProxy {
+class ExtendedPersistentDataContainerFactory : ExtendedPersistentDataContainerFactoryProxy {
     @Suppress("UNCHECKED_CAST")
-    private val registry: CraftPersistentDataTypeRegistry =
-        CraftPersistentDataContainer::class.java.getDeclaredField("registry")
-            .apply { isAccessible = true }.get(null) as CraftPersistentDataTypeRegistry
+    private val registry: CraftPersistentDataTypeRegistry
+
+    init {
+        /*
+         Can't grab actual instance since it's in CraftMetaItem (which is package-private)
+         And getting it would mean more janky reflection
+         */
+        val item = CraftItemStack.asCraftCopy(ItemStack(Material.STONE))
+        val pdc = item.itemMeta!!.persistentDataContainer
+        this.registry = CraftPersistentDataContainer::class.java.getDeclaredField("registry")
+            .apply { isAccessible = true }.get(pdc) as CraftPersistentDataTypeRegistry
+    }
 
     override fun adapt(pdc: PersistentDataContainer): ExtendedPersistentDataContainer {
         return when (pdc) {
@@ -34,7 +46,8 @@ class ExtendedPersistentDataContainerFactory: ExtendedPersistentDataContainerFac
                 .apply { isAccessible = true }.get(handle) as MutableMap<String, Tag>
 
         override fun <T : Any, Z : Any> set(key: String, dataType: PersistentDataType<T, Z>, value: Z) {
-            customDataTags[key] = registry.wrap(dataType.primitiveType, dataType.toPrimitive(value, handle.adapterContext))
+            customDataTags[key] =
+                registry.wrap(dataType.primitiveType, dataType.toPrimitive(value, handle.adapterContext))
         }
 
         override fun <T : Any, Z : Any> has(key: String, dataType: PersistentDataType<T, Z>): Boolean {

eco-core/core-nms/v1_19_R1/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R1/BukkitCommands.kt

@@ -0,0 +1,35 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R1
+
+import com.willfp.eco.core.command.impl.PluginCommand
+import com.willfp.eco.internal.spigot.proxy.BukkitCommandsProxy
+import org.bukkit.Bukkit
+import org.bukkit.command.Command
+import org.bukkit.command.SimpleCommandMap
+import org.bukkit.craftbukkit.v1_19_R1.CraftServer
+import java.lang.reflect.Field
+
+class BukkitCommands : BukkitCommandsProxy {
+    private val knownCommandsField: Field by lazy {
+        SimpleCommandMap::class.java.getDeclaredField("knownCommands")
+            .apply {
+                isAccessible = true
+            }
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    private val knownCommands: MutableMap<String, Command>
+        get() = knownCommandsField.get(getCommandMap()) as MutableMap<String, Command>
+
+    override fun getCommandMap(): SimpleCommandMap {
+        return (Bukkit.getServer() as CraftServer).commandMap
+    }
+
+    override fun syncCommands() {
+        (Bukkit.getServer() as CraftServer).syncCommands()
+    }
+
+    override fun unregisterCommand(command: PluginCommand) {
+        knownCommands.remove(command.name)
+        knownCommands.remove("${command.plugin.name.lowercase()}:${command.name}")
+    }
+}

eco-core/core-nms/v1_19_R1/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R1/ExtendedPersistentDataContainerFactory.kt

@@ -3,21 +3,33 @@ package com.willfp.eco.internal.spigot.proxy.v1_19_R1
 import com.willfp.eco.core.data.ExtendedPersistentDataContainer
 import com.willfp.eco.internal.spigot.proxy.ExtendedPersistentDataContainerFactoryProxy
 import net.minecraft.nbt.Tag
+import org.bukkit.Material
+import org.bukkit.craftbukkit.v1_19_R1.inventory.CraftItemStack
 import org.bukkit.craftbukkit.v1_19_R1.persistence.CraftPersistentDataContainer
 import org.bukkit.craftbukkit.v1_19_R1.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.inventory.ItemStack
 import org.bukkit.persistence.PersistentDataContainer
 import org.bukkit.persistence.PersistentDataType
 
-class ExtendedPersistentDataContainerFactory: ExtendedPersistentDataContainerFactoryProxy {
+class ExtendedPersistentDataContainerFactory : ExtendedPersistentDataContainerFactoryProxy {
     @Suppress("UNCHECKED_CAST")
-    private val registry: CraftPersistentDataTypeRegistry =
-        CraftPersistentDataContainer::class.java.getDeclaredField("registry")
-            .apply { isAccessible = true }.get(null) as CraftPersistentDataTypeRegistry
+    private val registry: CraftPersistentDataTypeRegistry
+
+    init {
+        /*
+         Can't grab actual instance since it's in CraftMetaItem (which is package-private)
+         And getting it would mean more janky reflection
+         */
+        val item = CraftItemStack.asCraftCopy(ItemStack(Material.STONE))
+        val pdc = item.itemMeta!!.persistentDataContainer
+        this.registry = CraftPersistentDataContainer::class.java.getDeclaredField("registry")
+            .apply { isAccessible = true }.get(pdc) as CraftPersistentDataTypeRegistry
+    }
 
     override fun adapt(pdc: PersistentDataContainer): ExtendedPersistentDataContainer {
         return when (pdc) {
             is CraftPersistentDataContainer -> EcoPersistentDataContainer(pdc)
-            else -> throw IllegalArgumentException("Custom PDC instance is not supported!")
+            else -> throw IllegalArgumentException("Custom PDC instance ims not supported!")
         }
     }
 
@@ -34,7 +46,8 @@ class ExtendedPersistentDataContainerFactory: ExtendedPersistentDataContainerFac
                 .apply { isAccessible = true }.get(handle) as MutableMap<String, Tag>
 
         override fun <T : Any, Z : Any> set(key: String, dataType: PersistentDataType<T, Z>, value: Z) {
-            customDataTags[key] = registry.wrap(dataType.primitiveType, dataType.toPrimitive(value, handle.adapterContext))
+            customDataTags[key] =
+                registry.wrap(dataType.primitiveType, dataType.toPrimitive(value, handle.adapterContext))
         }
 
         override fun <T : Any, Z : Any> has(key: String, dataType: PersistentDataType<T, Z>): Boolean {

eco-core/core-nms/v1_19_R2/build.gradle.kts

@@ -0,0 +1,39 @@
+plugins {
+    id("io.papermc.paperweight.userdev") version "1.3.6"
+}
+
+group = "com.willfp"
+version = rootProject.version
+
+dependencies {
+    implementation(project(":eco-core:core-nms:nms-common"))
+    paperDevBundle("1.19.3-R0.1-SNAPSHOT")
+
+    implementation("net.kyori:adventure-text-minimessage:4.11.0") {
+        version {
+            strictly("4.11.0")
+        }
+        exclude(group = "net.kyori", module = "adventure-api")
+    }
+}
+
+tasks {
+    build {
+        dependsOn(reobfJar)
+    }
+
+    reobfJar {
+        mustRunAfter(shadowJar)
+    }
+
+    shadowJar {
+        relocate(
+            "com.willfp.eco.internal.spigot.proxy.common",
+            "com.willfp.eco.internal.spigot.proxy.v1_19_R2.common"
+        )
+        relocate(
+            "net.kyori.adventure.text.minimessage",
+            "com.willfp.eco.internal.spigot.proxy.v1_19_R2.minimessage"
+        )
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/AutoCraft.kt

@@ -0,0 +1,15 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.internal.spigot.proxy.AutoCraftProxy
+import net.minecraft.network.protocol.game.ClientboundPlaceGhostRecipePacket
+import net.minecraft.resources.ResourceLocation
+
+class AutoCraft : AutoCraftProxy {
+    override fun modifyPacket(packet: Any) {
+        val recipePacket = packet as ClientboundPlaceGhostRecipePacket
+        val fKey = recipePacket.javaClass.getDeclaredField("b")
+        fKey.isAccessible = true
+        val key = fKey[recipePacket] as ResourceLocation
+        fKey[recipePacket] = ResourceLocation(key.namespace, key.path + "_displayed")
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/BukkitCommands.kt

@@ -0,0 +1,35 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.core.command.impl.PluginCommand
+import com.willfp.eco.internal.spigot.proxy.BukkitCommandsProxy
+import org.bukkit.Bukkit
+import org.bukkit.command.Command
+import org.bukkit.command.SimpleCommandMap
+import org.bukkit.craftbukkit.v1_19_R2.CraftServer
+import java.lang.reflect.Field
+
+class BukkitCommands : BukkitCommandsProxy {
+    private val knownCommandsField: Field by lazy {
+        SimpleCommandMap::class.java.getDeclaredField("knownCommands")
+            .apply {
+                isAccessible = true
+            }
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    private val knownCommands: MutableMap<String, Command>
+        get() = knownCommandsField.get(getCommandMap()) as MutableMap<String, Command>
+
+    override fun getCommandMap(): SimpleCommandMap {
+        return (Bukkit.getServer() as CraftServer).commandMap
+    }
+
+    override fun syncCommands() {
+        (Bukkit.getServer() as CraftServer).syncCommands()
+    }
+
+    override fun unregisterCommand(command: PluginCommand) {
+        knownCommands.remove(command.name)
+        knownCommands.remove("${command.plugin.name.lowercase()}:${command.name}")
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/ChatComponent.kt

@@ -0,0 +1,93 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.internal.spigot.proxy.ChatComponentProxy
+import net.kyori.adventure.nbt.api.BinaryTagHolder
+import net.kyori.adventure.text.BuildableComponent
+import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.TranslatableComponent
+import net.kyori.adventure.text.event.HoverEvent
+import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer
+import net.minecraft.nbt.TagParser
+import org.bukkit.Material
+import org.bukkit.craftbukkit.v1_19_R2.inventory.CraftItemStack
+import org.bukkit.entity.Player
+import org.bukkit.inventory.ItemStack
+
+@Suppress("UNCHECKED_CAST")
+class ChatComponent : ChatComponentProxy {
+    private val gsonComponentSerializer = GsonComponentSerializer.gson()
+
+    override fun modifyComponent(obj: Any, player: Player): Any {
+        if (obj !is net.minecraft.network.chat.Component) {
+            return obj
+        }
+
+        val component = gsonComponentSerializer.deserialize(
+            net.minecraft.network.chat.Component.Serializer.toJson(
+                obj
+            )
+        ).asComponent() as BuildableComponent<*, *>
+
+        val newComponent = modifyBaseComponent(component, player)
+
+        return net.minecraft.network.chat.Component.Serializer.fromJson(
+            gsonComponentSerializer.serialize(newComponent.asComponent())
+        ) ?: obj
+    }
+
+    private fun modifyBaseComponent(baseComponent: Component, player: Player): Component {
+        var component = baseComponent
+
+        if (component is TranslatableComponent) {
+            val args = mutableListOf<Component>()
+            for (arg in component.args()) {
+                args.add(modifyBaseComponent(arg, player))
+            }
+            component = component.args(args)
+        }
+
+        val children = mutableListOf<Component>()
+        for (child in component.children()) {
+            children.add(modifyBaseComponent(child, player))
+        }
+        component = component.children(children)
+
+        val hoverEvent: HoverEvent<Any> = component.style().hoverEvent() as HoverEvent<Any>? ?: return component
+
+        val showItem = hoverEvent.value()
+
+        if (showItem !is HoverEvent.ShowItem) {
+            return component
+        }
+
+        val newShowItem = showItem.nbt(
+            BinaryTagHolder.binaryTagHolder(
+                CraftItemStack.asNMSCopy(
+                    Display.display(
+                        CraftItemStack.asBukkitCopy(
+                            CraftItemStack.asNMSCopy(
+                                ItemStack(
+                                    Material.matchMaterial(
+                                        showItem.item()
+                                            .toString()
+                                    ) ?: return component,
+                                    showItem.count()
+                                )
+                            ).apply {
+                                this.tag = TagParser.parseTag(
+                                    showItem.nbt()?.string() ?: return component
+                                ) ?: return component
+                            }
+                        ),
+                        player
+                    )
+                ).orCreateTag.toString()
+            )
+        )
+
+        val newHover = hoverEvent.value(newShowItem)
+        val style = component.style().hoverEvent(newHover)
+        return component.style(style)
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/CommonsInitializer.kt

@@ -0,0 +1,135 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.internal.spigot.proxy.CommonsInitializerProxy
+import com.willfp.eco.internal.spigot.proxy.common.CommonsProvider
+import net.minecraft.nbt.CompoundTag
+import net.minecraft.nbt.Tag
+import net.minecraft.resources.ResourceLocation
+import net.minecraft.world.entity.PathfinderMob
+import org.bukkit.Bukkit
+import org.bukkit.NamespacedKey
+import org.bukkit.craftbukkit.v1_19_R2.CraftServer
+import org.bukkit.craftbukkit.v1_19_R2.entity.CraftEntity
+import org.bukkit.craftbukkit.v1_19_R2.entity.CraftMob
+import org.bukkit.craftbukkit.v1_19_R2.inventory.CraftItemStack
+import org.bukkit.craftbukkit.v1_19_R2.persistence.CraftPersistentDataContainer
+import org.bukkit.craftbukkit.v1_19_R2.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.craftbukkit.v1_19_R2.util.CraftMagicNumbers
+import org.bukkit.craftbukkit.v1_19_R2.util.CraftNamespacedKey
+import org.bukkit.entity.LivingEntity
+import org.bukkit.entity.Mob
+import org.bukkit.inventory.ItemStack
+import org.bukkit.persistence.PersistentDataContainer
+import java.lang.reflect.Field
+
+class CommonsInitializer : CommonsInitializerProxy {
+    override fun init() {
+        CommonsProvider.setIfNeeded(CommonsProviderImpl)
+    }
+
+    object CommonsProviderImpl : CommonsProvider {
+        private val cisHandle: Field = CraftItemStack::class.java.getDeclaredField("handle").apply {
+            isAccessible = true
+        }
+
+        private val pdcRegsitry = Class.forName("org.bukkit.craftbukkit.v1_19_R2.inventory.CraftMetaItem")
+            .getDeclaredField("DATA_TYPE_REGISTRY")
+            .apply { isAccessible = true }
+            .get(null) as CraftPersistentDataTypeRegistry
+
+        override val nbtTagString = CraftMagicNumbers.NBT.TAG_STRING
+
+        override fun toPathfinderMob(mob: Mob): PathfinderMob? {
+            val craft = mob as? CraftMob ?: return null
+            return craft.handle as? PathfinderMob
+        }
+
+        override fun toResourceLocation(namespacedKey: NamespacedKey): ResourceLocation =
+            CraftNamespacedKey.toMinecraft(namespacedKey)
+
+        override fun asNMSStack(itemStack: ItemStack): net.minecraft.world.item.ItemStack {
+            return if (itemStack !is CraftItemStack) {
+                CraftItemStack.asNMSCopy(itemStack)
+            } else {
+                cisHandle[itemStack] as net.minecraft.world.item.ItemStack? ?: CraftItemStack.asNMSCopy(itemStack)
+            }
+        }
+
+        override fun asBukkitStack(itemStack: net.minecraft.world.item.ItemStack): ItemStack {
+            return CraftItemStack.asBukkitCopy(itemStack)
+        }
+
+        override fun mergeIfNeeded(itemStack: ItemStack, nmsStack: net.minecraft.world.item.ItemStack) {
+            if (itemStack !is CraftItemStack) {
+                itemStack.itemMeta = CraftItemStack.asCraftMirror(nmsStack).itemMeta
+            }
+        }
+
+        override fun toBukkitEntity(entity: net.minecraft.world.entity.LivingEntity): LivingEntity? =
+            CraftEntity.getEntity(Bukkit.getServer() as CraftServer, entity) as? LivingEntity
+
+        override fun makePdc(tag: CompoundTag, base: Boolean): PersistentDataContainer {
+            fun emptyPdc(): CraftPersistentDataContainer = CraftPersistentDataContainer(pdcRegsitry)
+
+            fun CompoundTag?.toPdc(): PersistentDataContainer {
+                val pdc = emptyPdc()
+                this ?: return pdc
+                val keys = this.allKeys
+                for (key in keys) {
+                    pdc.put(key, this[key])
+                }
+
+                return pdc
+            }
+
+            return if (base) {
+                tag.toPdc()
+            } else {
+                if (tag.contains("PublicBukkitValues")) {
+                    tag.getCompound("PublicBukkitValues").toPdc()
+                } else {
+                    emptyPdc()
+                }
+            }
+        }
+
+        override fun setPdc(
+            tag: CompoundTag,
+            pdc: PersistentDataContainer?,
+            item: net.minecraft.world.item.ItemStack?
+        ) {
+            fun CraftPersistentDataContainer.toTag(): CompoundTag {
+                val compound = CompoundTag()
+                val rawPublicMap: Map<String, Tag> = this.raw
+                for ((key, value) in rawPublicMap) {
+                    compound.put(key, value)
+                }
+
+                return compound
+            }
+
+            val container = when (pdc) {
+                is CraftPersistentDataContainer? -> pdc
+                else -> null
+            }
+
+            if (item != null) {
+                if (container != null && !container.isEmpty) {
+                    for (key in tag.allKeys.toSet()) {
+                        tag.remove(key)
+                    }
+
+                    tag.merge(container.toTag())
+                } else {
+                    item.setTag(null)
+                }
+            } else {
+                if (container != null && !container.isEmpty) {
+                    tag.put("PublicBukkitValues", container.toTag())
+                } else {
+                    tag.remove("PublicBukkitValues")
+                }
+            }
+        }
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/DummyEntityFactory.kt

@@ -0,0 +1,16 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.internal.entities.EcoDummyEntity
+import com.willfp.eco.internal.spigot.proxy.DummyEntityFactoryProxy
+import org.bukkit.Location
+import org.bukkit.craftbukkit.v1_19_R2.CraftWorld
+import org.bukkit.entity.Entity
+import org.bukkit.entity.EntityType
+
+class DummyEntityFactory : DummyEntityFactoryProxy {
+    override fun createDummyEntity(location: Location): Entity {
+        val world = location.world as CraftWorld
+        @Suppress("UsePropertyAccessSyntax")
+        return EcoDummyEntity(world.createEntity(location, EntityType.ZOMBIE.entityClass).getBukkitEntity())
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/EntityControllerFactory.kt

@@ -0,0 +1,12 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.core.entities.ai.EntityController
+import com.willfp.eco.internal.spigot.proxy.EntityControllerFactoryProxy
+import com.willfp.eco.internal.spigot.proxy.common.ai.EcoEntityController
+import org.bukkit.entity.Mob
+
+class EntityControllerFactory : EntityControllerFactoryProxy {
+    override fun <T : Mob> createEntityController(entity: T): EntityController<T> {
+        return EcoEntityController(entity)
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/ExtendedPersistentDataContainerFactory.kt

@@ -0,0 +1,83 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.core.data.ExtendedPersistentDataContainer
+import com.willfp.eco.internal.spigot.proxy.ExtendedPersistentDataContainerFactoryProxy
+import net.minecraft.nbt.Tag
+import org.bukkit.Material
+import org.bukkit.craftbukkit.v1_19_R2.inventory.CraftItemStack
+import org.bukkit.craftbukkit.v1_19_R2.persistence.CraftPersistentDataContainer
+import org.bukkit.craftbukkit.v1_19_R2.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.inventory.ItemStack
+import org.bukkit.persistence.PersistentDataContainer
+import org.bukkit.persistence.PersistentDataType
+
+class ExtendedPersistentDataContainerFactory : ExtendedPersistentDataContainerFactoryProxy {
+    @Suppress("UNCHECKED_CAST")
+    private val registry: CraftPersistentDataTypeRegistry
+
+    init {
+        /*
+         Can't grab actual instance since it's in CraftMetaItem (which is package-private)
+         And getting it would mean more janky reflection
+         */
+        val item = CraftItemStack.asCraftCopy(ItemStack(Material.STONE))
+        val pdc = item.itemMeta!!.persistentDataContainer
+        this.registry = CraftPersistentDataContainer::class.java.getDeclaredField("registry")
+            .apply { isAccessible = true }.get(pdc) as CraftPersistentDataTypeRegistry
+    }
+
+    override fun adapt(pdc: PersistentDataContainer): ExtendedPersistentDataContainer {
+        return when (pdc) {
+            is CraftPersistentDataContainer -> EcoPersistentDataContainer(pdc)
+            else -> throw IllegalArgumentException("Custom PDC instance ims not supported!")
+        }
+    }
+
+    override fun newPdc(): PersistentDataContainer {
+        return CraftPersistentDataContainer(registry)
+    }
+
+    inner class EcoPersistentDataContainer(
+        val handle: CraftPersistentDataContainer
+    ) : ExtendedPersistentDataContainer {
+        @Suppress("UNCHECKED_CAST")
+        private val customDataTags: MutableMap<String, Tag> =
+            CraftPersistentDataContainer::class.java.getDeclaredField("customDataTags")
+                .apply { isAccessible = true }.get(handle) as MutableMap<String, Tag>
+
+        override fun <T : Any, Z : Any> set(key: String, dataType: PersistentDataType<T, Z>, value: Z) {
+            customDataTags[key] =
+                registry.wrap(dataType.primitiveType, dataType.toPrimitive(value, handle.adapterContext))
+        }
+
+        override fun <T : Any, Z : Any> has(key: String, dataType: PersistentDataType<T, Z>): Boolean {
+            val value = customDataTags[key] ?: return false
+            return registry.isInstanceOf(dataType.primitiveType, value)
+        }
+
+        override fun <T : Any, Z : Any> get(key: String, dataType: PersistentDataType<T, Z>): Z? {
+            val value = customDataTags[key] ?: return null
+            return dataType.fromPrimitive(registry.extract(dataType.primitiveType, value), handle.adapterContext)
+        }
+
+        override fun <T : Any, Z : Any> getOrDefault(
+            key: String,
+            dataType: PersistentDataType<T, Z>,
+            defaultValue: Z
+        ): Z {
+            return get(key, dataType) ?: defaultValue
+        }
+
+        override fun remove(key: String) {
+            customDataTags.remove(key)
+        }
+
+        override fun getAllKeys(): MutableSet<String> {
+            return customDataTags.keys
+        }
+
+        override fun getBase(): PersistentDataContainer {
+            return handle
+        }
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/FastItemStackFactory.kt

@@ -0,0 +1,12 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.core.fast.FastItemStack
+import com.willfp.eco.internal.spigot.proxy.FastItemStackFactoryProxy
+import com.willfp.eco.internal.spigot.proxy.common.item.EcoFastItemStack
+import org.bukkit.inventory.ItemStack
+
+class FastItemStackFactory : FastItemStackFactoryProxy {
+    override fun create(itemStack: ItemStack): FastItemStack {
+        return EcoFastItemStack(itemStack)
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/MiniMessageTranslator.kt

@@ -0,0 +1,33 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.internal.spigot.proxy.MiniMessageTranslatorProxy
+import com.willfp.eco.util.toLegacy
+import net.kyori.adventure.text.minimessage.MiniMessage
+
+class MiniMessageTranslator : MiniMessageTranslatorProxy {
+    override fun format(message: String): String {
+        var mut = message
+
+        val startsWithPrefix = mut.startsWith(Display.PREFIX)
+        if (startsWithPrefix) {
+            mut = mut.substring(2)
+        }
+
+        mut = mut.replace('§', '&')
+
+        val miniMessage = runCatching {
+            MiniMessage.miniMessage().deserialize(
+                mut
+            ).toLegacy()
+        }.getOrNull() ?: mut
+
+        mut = if (startsWithPrefix) {
+            Display.PREFIX + miniMessage
+        } else {
+            miniMessage
+        }
+
+        return mut
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/SNBTConverter.kt

@@ -0,0 +1,52 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.core.items.TestableItem
+import com.willfp.eco.core.recipe.parts.EmptyTestableItem
+import com.willfp.eco.internal.spigot.proxy.SNBTConverterProxy
+import net.minecraft.nbt.CompoundTag
+import net.minecraft.nbt.SnbtPrinterTagVisitor
+import net.minecraft.nbt.TagParser
+import org.bukkit.craftbukkit.v1_19_R2.inventory.CraftItemStack
+import org.bukkit.inventory.ItemStack
+
+class SNBTConverter : SNBTConverterProxy {
+    override fun fromSNBT(snbt: String): ItemStack? {
+        val nbt = runCatching { TagParser.parseTag(snbt) }.getOrNull() ?: return null
+        val nms = net.minecraft.world.item.ItemStack.of(nbt)
+        return CraftItemStack.asBukkitCopy(nms)
+    }
+
+    override fun toSNBT(itemStack: ItemStack): String {
+        val nms = CraftItemStack.asNMSCopy(itemStack)
+        return SnbtPrinterTagVisitor().visit(nms.save(CompoundTag()))
+    }
+
+    override fun makeSNBTTestable(snbt: String): TestableItem {
+        val nbt = runCatching { TagParser.parseTag(snbt) }.getOrNull() ?: return EmptyTestableItem()
+        val nms = net.minecraft.world.item.ItemStack.of(nbt)
+        if (nms == net.minecraft.world.item.ItemStack.EMPTY) {
+            return EmptyTestableItem()
+        }
+
+        nbt.remove("Count")
+        return SNBTTestableItem(CraftItemStack.asBukkitCopy(nms), nbt)
+    }
+
+    class SNBTTestableItem(
+        private val item: ItemStack,
+        private val tag: CompoundTag
+    ) : TestableItem {
+        override fun matches(itemStack: ItemStack?): Boolean {
+            if (itemStack == null) {
+                return false
+            }
+
+            val nms = CraftItemStack.asNMSCopy(itemStack)
+            val nmsTag = nms.save(CompoundTag())
+            nmsTag.remove("Count")
+            return tag.copy().merge(nmsTag) == nmsTag
+        }
+
+        override fun getItem(): ItemStack = item
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/Skull.kt

@@ -0,0 +1,18 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.internal.spigot.proxy.SkullProxy
+import com.willfp.eco.internal.spigot.proxy.common.texture
+import org.bukkit.inventory.meta.SkullMeta
+
+class Skull : SkullProxy {
+    override fun setSkullTexture(
+        meta: SkullMeta,
+        base64: String
+    ) {
+        meta.texture = base64
+    }
+
+    override fun getSkullTexture(
+        meta: SkullMeta
+    ): String? = meta.texture
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/TPS.kt

@@ -0,0 +1,11 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.internal.spigot.proxy.TPSProxy
+import org.bukkit.Bukkit
+import org.bukkit.craftbukkit.v1_19_R2.CraftServer
+
+class TPS : TPSProxy {
+    override fun getTPS(): Double {
+        return (Bukkit.getServer() as CraftServer).handle.server.recentTps[0]
+    }
+}

eco-core/core-nms/v1_19_R2/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_19_R2/VillagerTrade.kt

@@ -0,0 +1,41 @@
+package com.willfp.eco.internal.spigot.proxy.v1_19_R2
+
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.internal.spigot.proxy.VillagerTradeProxy
+import net.minecraft.nbt.CompoundTag
+import net.minecraft.world.item.ItemStack
+import net.minecraft.world.item.trading.MerchantOffer
+import org.bukkit.craftbukkit.v1_19_R2.inventory.CraftItemStack
+import org.bukkit.craftbukkit.v1_19_R2.inventory.CraftMerchantRecipe
+import org.bukkit.entity.Player
+import org.bukkit.inventory.MerchantRecipe
+import java.lang.reflect.Field
+
+class VillagerTrade : VillagerTradeProxy {
+    private val handle: Field = CraftMerchantRecipe::class.java.getDeclaredField("handle")
+
+    override fun displayTrade(
+        recipe: MerchantRecipe,
+        player: Player
+    ): MerchantRecipe {
+        recipe as CraftMerchantRecipe
+
+        val nbt = getHandle(recipe).createTag()
+        for (tag in arrayOf("buy", "buyB", "sell")) {
+            val nms = ItemStack.of(nbt.getCompound(tag))
+            val displayed = Display.display(CraftItemStack.asBukkitCopy(nms), player)
+            val itemNBT = CraftItemStack.asNMSCopy(displayed).save(CompoundTag())
+            nbt.put(tag, itemNBT)
+        }
+
+        return CraftMerchantRecipe(MerchantOffer(nbt))
+    }
+
+    private fun getHandle(recipe: CraftMerchantRecipe): MerchantOffer {
+        return handle[recipe] as MerchantOffer
+    }
+
+    init {
+        handle.isAccessible = true
+    }
+}

eco-core/core-plugin/build.gradle

@@ -50,6 +50,7 @@ dependencies {
     compileOnly 'com.github.Gypopo:EconomyShopGUI-API:1.1.0'
     compileOnly 'com.github.N0RSKA:ScytherAPI:55a'
     compileOnly 'com.ticxo.modelengine:api:R3.0.1'
+    compileOnly 'me.TechsCode:UltraEconomyAPI:1.0.0'
 
     // MythicMobs
     compileOnly 'io.lumine:Mythic:5.0.1'

eco-core/core-plugin/src/main/kotlin/com/willfp/eco/internal/spigot/EcoImpl.kt

@@ -4,7 +4,7 @@ import com.willfp.eco.core.Eco
 import com.willfp.eco.core.EcoPlugin
 import com.willfp.eco.core.PluginLike
 import com.willfp.eco.core.PluginProps
-import com.willfp.eco.core.Prerequisite
+import com.willfp.eco.core.command.impl.PluginCommand
 import com.willfp.eco.core.config.ConfigType
 import com.willfp.eco.core.config.interfaces.Config
 import com.willfp.eco.core.data.keys.PersistentDataKey
@@ -12,8 +12,7 @@ import com.willfp.eco.core.gui.menu.Menu
 import com.willfp.eco.core.gui.menu.MenuType
 import com.willfp.eco.core.gui.slot.functional.SlotProvider
 import com.willfp.eco.core.items.Items
-import com.willfp.eco.core.placeholder.AdditionalPlayer
-import com.willfp.eco.core.placeholder.PlaceholderInjectable
+import com.willfp.eco.core.math.MathContext
 import com.willfp.eco.internal.EcoPropsParser
 import com.willfp.eco.internal.config.EcoConfigHandler
 import com.willfp.eco.internal.config.EcoConfigSection
@@ -34,13 +33,13 @@ import com.willfp.eco.internal.gui.MergedStateMenu
 import com.willfp.eco.internal.gui.menu.EcoMenuBuilder
 import com.willfp.eco.internal.gui.menu.renderedInventory
 import com.willfp.eco.internal.gui.slot.EcoSlotBuilder
-import com.willfp.eco.internal.integrations.PlaceholderIntegrationPAPI
+import com.willfp.eco.internal.integrations.PAPIExpansion
 import com.willfp.eco.internal.logging.EcoLogger
 import com.willfp.eco.internal.proxy.EcoProxyFactory
 import com.willfp.eco.internal.scheduling.EcoScheduler
 import com.willfp.eco.internal.spigot.data.DataYml
-import com.willfp.eco.internal.spigot.data.EcoProfileHandler
 import com.willfp.eco.internal.spigot.data.KeyRegistry
+import com.willfp.eco.internal.spigot.data.ProfileHandler
 import com.willfp.eco.internal.spigot.data.storage.HandlerType
 import com.willfp.eco.internal.spigot.integrations.bstats.MetricHandler
 import com.willfp.eco.internal.spigot.math.evaluateExpression
@@ -52,10 +51,12 @@ import com.willfp.eco.internal.spigot.proxy.FastItemStackFactoryProxy
 import com.willfp.eco.internal.spigot.proxy.MiniMessageTranslatorProxy
 import com.willfp.eco.internal.spigot.proxy.SNBTConverterProxy
 import com.willfp.eco.internal.spigot.proxy.SkullProxy
+import com.willfp.eco.internal.spigot.proxy.BukkitCommandsProxy
 import com.willfp.eco.internal.spigot.proxy.TPSProxy
-import net.kyori.adventure.platform.bukkit.BukkitAudiences
 import org.bukkit.Location
 import org.bukkit.NamespacedKey
+import org.bukkit.command.Command
+import org.bukkit.command.CommandMap
 import org.bukkit.configuration.ConfigurationSection
 import org.bukkit.entity.Entity
 import org.bukkit.entity.Mob
@@ -72,7 +73,7 @@ private val loadedEcoPlugins = mutableMapOf<String, EcoPlugin>()
 class EcoImpl : EcoSpigotPlugin(), Eco {
     override val dataYml = DataYml(this)
 
-    override val profileHandler = EcoProfileHandler(
+    override val profileHandler = ProfileHandler(
         HandlerType.valueOf(this.configYml.getString("data-handler").uppercase()),
         this
     )
@@ -81,10 +82,6 @@ class EcoImpl : EcoSpigotPlugin(), Eco {
         getProxy(CommonsInitializerProxy::class.java).init()
     }
 
-    private var adventure: BukkitAudiences? = if (!Prerequisite.HAS_PAPER.isMet) {
-        BukkitAudiences.create(this)
-    } else null
-
     @Suppress("RedundantNullableReturnType")
     private val keyFactory: InternalNamespacedKeyFactory? =
         if (this.configYml.getBool("use-safer-namespacedkey-creation"))
@@ -114,8 +111,9 @@ class EcoImpl : EcoSpigotPlugin(), Eco {
     override fun createLogger(plugin: EcoPlugin) =
         EcoLogger(plugin)
 
-    override fun createPAPIIntegration(plugin: EcoPlugin) =
-        PlaceholderIntegrationPAPI(plugin)
+    override fun createPAPIIntegration(plugin: EcoPlugin) {
+        PAPIExpansion(plugin)
+    }
 
     override fun getEcoPlugin(): EcoPlugin =
         this
@@ -174,9 +172,6 @@ class EcoImpl : EcoSpigotPlugin(), Eco {
     override fun createDropQueue(player: Player) = if (this.configYml.getBool("use-fast-collated-drops"))
         EcoFastCollatedDropQueue(player) else EcoDropQueue(player)
 
-    override fun getPersistentDataKeyFrom(namespacedKey: NamespacedKey) =
-        KeyRegistry.getKeyFrom(namespacedKey)
-
     override fun getRegisteredPersistentDataKeys() =
         KeyRegistry.getRegisteredKeys()
 
@@ -235,7 +230,7 @@ class EcoImpl : EcoSpigotPlugin(), Eco {
         MetricHandler.createMetrics(plugin)
 
     override fun getAdventure() =
-        adventure
+        bukkitAudiences
 
     override fun getServerProfile() =
         profileHandler.loadServerProfile()
@@ -243,12 +238,6 @@ class EcoImpl : EcoSpigotPlugin(), Eco {
     override fun loadPlayerProfile(uuid: UUID) =
         profileHandler.load(uuid)
 
-    override fun saveAllProfiles() =
-        profileHandler.save()
-
-    override fun savePersistentDataKeysFor(uuid: UUID, keys: Set<PersistentDataKey<*>>) =
-        profileHandler.saveKeysFor(uuid, keys)
-
     override fun unloadPlayerProfile(uuid: UUID) =
         profileHandler.unloadPlayer(uuid)
 
@@ -292,13 +281,18 @@ class EcoImpl : EcoSpigotPlugin(), Eco {
     override fun getTPS() =
         getProxy(TPSProxy::class.java).getTPS()
 
-    override fun evaluate(
-        expression: String,
-        player: Player?,
-        injectable: PlaceholderInjectable,
-        additionalPlayers: MutableCollection<AdditionalPlayer>
-    ) = evaluateExpression(expression, player, injectable, additionalPlayers)
+    override fun evaluate(expression: String, context: MathContext) =
+        evaluateExpression(expression, context)
 
     override fun getOpenMenu(player: Player) =
         player.renderedInventory?.menu
+
+    override fun syncCommands() =
+        this.getProxy(BukkitCommandsProxy::class.java).syncCommands()
+
+    override fun getCommandMap(): CommandMap =
+        this.getProxy(BukkitCommandsProxy::class.java).getCommandMap()
+
+    override fun unregisterCommand(command: PluginCommand) =
+        this.getProxy(BukkitCommandsProxy::class.java).unregisterCommand(command)
 }