Moved supported versions into ProxyConstants

This reverts commit 6361c0e8e9.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Auxilor Community Discord
+    url: https://discord.gg/ZcwpSsE/
+    about: Join the Auxilor discord to get help from support staff and the general community!
+  - name: The most common issues people have
+    url: https://github.com/Auxilor/eco/issues/78
+    about: Check the list of known common issues to see if your issue has already been solved

.github/ISSUE_TEMPLATE/report-a-bug.md

@@ -0,0 +1,31 @@
+---
+name: Report a Bug
+about: Report an issue with the plugin
+title: ''
+labels: bug
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior: 
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Server Information (please complete the following information):**
+- Version: (output of `/ver` command)
+- Version of plugin and eco (`/ver eco`, `/ver <plugin>`)
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/request-a-feature.md

@@ -0,0 +1,20 @@
+---
+name: Request a Feature
+about: Suggest an idea for this plugin
+title: ''
+labels: enhancement
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/workflows/checkstyle.yml

@@ -0,0 +1,15 @@
+name: Check PR Codestyle
+on: [ pull_request ]
+
+jobs:
+  checkstyle:
+    name: Checkstyle
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dbelyaev/action-checkstyle@v0.5.1
+        with:
+          github_token: ${{ secrets.github_token }}
+          reporter: github-pr-review
+          level: warning
+          checkstyle_config: ../../config/checkstyle/checkstyle.xml

.github/workflows/java-ci.yml

@@ -1,6 +1,6 @@
 name: Java CI
 
-on: [push]
+on: [ push, pull_request ]
 
 jobs:
   build:

.github/workflows/test-publish.yml

@@ -0,0 +1,42 @@
+name: Publish API (Dev)
+
+on: [ push, pull_request ]
+
+jobs:
+  publish-release:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout latest code
+        uses: actions/checkout@v2
+
+      - name: Set outputs
+        id: vars
+        run: echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v2
+        with:
+          distribution: 'temurin'
+          java-version: 17
+
+      - name: Setup build cache
+        uses: actions/cache@v2.1.6
+        with:
+          path: ~/.gradle/caches
+          key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle.kts') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+
+
+      - name: Publish artifact
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+        # The GITHUB_REF tag comes in the format 'refs/tags/xxx'.
+        # So if we split on '/' and take the 3rd value, we can get the release name.
+        run: |
+          NEW_VERSION=$(echo "${GITHUB_REF}" | cut -d "/" -f3)
+          echo "New version: ${{ steps.vars.outputs.sha_short }}"
+          echo "Github username: ${GITHUB_ACTOR}"
+          ./gradlew -Pversion=dev-${{ steps.vars.outputs.sha_short }} publish

CONTRIBUTING.md

@@ -1,24 +1,38 @@
 # How to contribute to eco
 
 ## Codestyle
+
 1. The eco checkstyle is in /config/checkstyle.xml
+
 - The pull request must not have any checkstyle issues.
 - Every method and field must have a javadoc attached.
 
 2. Use JetBrains annotations
+
 - Every parameter should be annotated with @NotNull or @Nullable
-- Use @NotNull over lombok @NonNull
 
 3. Imports
+
 - No group (*) imports.
 - No static imports.
 
+4. Kotlin
+
+- Kotlin should be the only language used in the backend, java should be the only language used in the frontend.
+- Kotlin API extensions should only be for creating extension functions and extra niceties that aren't possible in java.
+  Do not write API components in kotlin.
+- Kotlin code should never be called directly from the frontend Java API. Kotlin API extensions should always rely on
+  java, not the other way round.
+
 ## Dependency Injection
+
 - eco uses Dependency Injection
 - Any calls to Eco#getHandler#getEcoPlugin are code smells and should never be used unless **absolutely necessary**.
 - NamespacedKeys, FixedMetadataValues, Runnables, and Schedules should be managed using AbstractEcoPlugin through DI.
-- Any DI class should extend PluginDependent where possible. If the class extends another, then you **must** store the plugin instance in a private final variable called **plugin** with a private or protected getter.
+- Any DI class should extend PluginDependent where possible. If the class extends another, then you **must** store the
+  plugin instance in a private final variable called **plugin** with a private or protected getter.
 
 ## Other
+
 - All drops **must** be sent through a DropQueue - calls to World#dropItem will get your PR rejected.
 - eco is built with java 17.

README.md

@@ -29,7 +29,7 @@ and many more.
 
 # For server owners
 - Requires ProtocolLib to be installed: get the latest version [here](https://www.spigotmc.org/resources/protocollib.1997/)
-- Supports 1.16.5+
+- Supports 1.17+
 
 ## Downloads
 

build.gradle.kts

@@ -1,8 +1,19 @@
+buildscript {
+    repositories {
+        mavenCentral()
+    }
+
+    dependencies {
+        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:1.6.10")
+    }
+}
+
 plugins {
     id("java-library")
-    id("com.github.johnrengelman.shadow") version "7.1.0"
+    id("com.github.johnrengelman.shadow") version "7.1.2"
     id("maven-publish")
     id("java")
+    kotlin("jvm") version "1.6.10"
 }
 
 dependencies {
@@ -10,9 +21,8 @@ dependencies {
     implementation(project(":eco-core:core-plugin"))
     implementation(project(":eco-core:core-proxy"))
     implementation(project(":eco-core:core-backend"))
-    implementation(project(":eco-core:core-nms:v1_16_R3"))
     implementation(project(path = ":eco-core:core-nms:v1_17_R1", configuration = "reobf"))
-    implementation(project(":eco-core:core-nms:v1_18_R1"))
+    implementation(project(path = ":eco-core:core-nms:v1_18_R1", configuration = "reobf"))
 }
 
 allprojects {
@@ -20,6 +30,7 @@ allprojects {
     apply(plugin = "java-library")
     apply(plugin = "maven-publish")
     apply(plugin = "com.github.johnrengelman.shadow")
+    apply(plugin = "kotlin")
 
     repositories {
         mavenCentral()
@@ -61,19 +72,33 @@ allprojects {
 
         // IridiumSkyblock
         maven("https://nexus.iridiumdevelopment.net/repository/maven-releases/")
+
+        // MythicMobs
+        maven("https://mvn.lumine.io/repository/maven-public/")
+
+        // Crunch
+        maven("https://redempt.dev")
+
+        // LibsDisguises
+        maven("https://repo.md-5.net/content/groups/public/")
     }
 
     dependencies {
+        compileOnly(kotlin("stdlib", version = "1.6.10"))
         compileOnly("org.jetbrains:annotations:23.0.0")
 
         // Test
-        testImplementation("org.junit.jupiter:junit-jupiter-api:5.8.1")
+        testImplementation("org.junit.jupiter:junit-jupiter-api:5.8.2")
         testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:5.8.2")
         
         // Adventure
         compileOnly("net.kyori:adventure-api:4.9.3")
         compileOnly("net.kyori:adventure-text-serializer-gson:4.9.3")
         compileOnly("net.kyori:adventure-text-serializer-legacy:4.9.3")
+
+        // Other
+        compileOnly("com.google.guava:guava:31.0.1-jre")
+        compileOnly("com.github.ben-manes.caffeine:caffeine:3.0.5")
     }
 
     tasks.withType<JavaCompile> {
@@ -90,7 +115,19 @@ allprojects {
         exclude(group = "com.github.cryptomorin", module = "XSeries")
     }
 
+    configurations.testImplementation {
+        setExtendsFrom(listOf(configurations.compileOnly.get()))
+    }
+
     tasks {
+        compileKotlin {
+            kotlinOptions {
+                jvmTarget = "17"
+            }
+            targetCompatibility = "17"
+            sourceCompatibility = "17"
+        }
+
         shadowJar {
             relocate("org.bstats", "com.willfp.eco.shaded.bstats")
             relocate("net.kyori.adventure.text.minimessage", "com.willfp.eco.shaded.minimessage")

config/checkstyle/checkstyle.xml

@@ -32,10 +32,6 @@
 -->
 
 <module name="Checker">
-    <module name="SuppressionFilter">
-        <property name="file" value="config/checkstyle/suppression.xml"/>
-    </module>
-
     <!--
         If you set the basedir property below, then all reported file
         names will be relative to the specified directory. See

config/checkstyle/suppression.xml

@@ -1,24 +0,0 @@
-<?xml version="1.0"?>
-
-<!DOCTYPE suppressions PUBLIC
-        "-//Puppy Crawl//DTD Suppressions 1.1//EN"
-        "http://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
-
-<suppressions>
-    <!-- Internals don't need javadoc. -->
-    <suppress files="[\\/]internal[\\/]" checks="MissingJavadocMethod"/>
-    <suppress files="[\\/]internal[\\/]" checks="JavadocVariable"/>
-    <suppress files="[\\/]eco[\\/]spigot[\\/]" checks="MissingJavadocMethod"/>
-    <suppress files="[\\/]eco[\\/]spigot[\\/]" checks="JavadocVariable"/>
-    <suppress files="[\\/]eco[\\/]proxy[\\/]" checks="MissingJavadocMethod"/>
-    <suppress files="[\\/]eco[\\/]proxy[\\/]" checks="JavadocVariable"/>
-
-    <!-- Modified version of library -->
-    <suppress files="ArmorEquipEvent.java" checks="JavadocVariable"/>
-    <suppress files="ArmorEquipEvent.java" checks="MissingJavadocMethod"/>
-    <suppress files="ArmorEquipEvent.java" checks="JavadocStyle"/>
-    <suppress files="ArmorListener.java" checks="JavadocVariable"/>
-    <suppress files="ArmorListener.java" checks="MissingJavadocMethod"/>
-    <suppress files="ArmorType.java" checks="JavadocVariable"/>
-    <suppress files="ArmorType.java" checks="MissingJavadocMethod"/>
-</suppressions>

eco-api/build.gradle

@@ -1,10 +1,3 @@
-plugins {
-    id 'com.github.johnrengelman.shadow'
-}
-
-group 'com.willfp'
-version rootProject.version
-
 dependencies {
     // Adventure
     compileOnly 'net.kyori:adventure-platform-bukkit:4.0.0'
@@ -17,10 +10,8 @@ dependencies {
     compileOnly 'com.google.code.gson:gson:2.8.8'
 }
 
-java {
-    withJavadocJar()
-}
-
+group 'com.willfp'
+version rootProject.version
 
 build.dependsOn publishToMavenLocal
 

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

@@ -4,6 +4,12 @@ import org.apache.commons.lang.Validate;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
 /**
  * Holds the instance of the eco handler for bridging between the frontend
  * and backend.
@@ -52,6 +58,24 @@ public final class Eco {
         return handler;
     }
 
+    /**
+     * Eco Handler components are internals, so if a class is marked as a handler component,
+     * then it should be treated the same as if it was marked with {@link ApiStatus.Internal}.
+     * <p>
+     * If a class is marked with {@link HandlerComponent}, <strong>Do not reference it in
+     * your code!</strong> It can and will contain breaking changes between minor versions and
+     * even patches, and you will create compatibility issues by using them.
+     * <p>
+     * Handler components should also be marked with {@link ApiStatus.Internal} in order to
+     * cause compiler / IDE warnings.
+     */
+    @Documented
+    @Retention(RetentionPolicy.CLASS)
+    @Target({ElementType.TYPE})
+    public @interface HandlerComponent {
+
+    }
+
     private Eco() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

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

@@ -152,10 +152,14 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
     private final ProxyFactory proxyFactory;
 
     /**
-     * Create a new plugin without a specified color, proxy support, polymart, or bStats.
+     * Create a new plugin.
+     * <p>
+     * Will read from eco.yml (like plugin.yml) to fetch values that would otherwise be passed
+     * into the constructor. If no eco.yml is present, the plugin will load without extension
+     * support, without proxy support, with no update-checker or bStats, and with the color white.
      */
     protected EcoPlugin() {
-        this("&f");
+        this((PluginProps) null);
     }
 
     /**
@@ -236,6 +240,23 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
                         @NotNull final String proxyPackage,
                         @NotNull final String color,
                         final boolean supportingExtensions) {
+        this(
+                PluginProps.createSimple(
+                        resourceId,
+                        bStatsId,
+                        proxyPackage,
+                        color,
+                        supportingExtensions
+                )
+        );
+    }
+
+    /**
+     * Create a new plugin.
+     *
+     * @param pluginProps The props. If left null, it will read from eco.yml.
+     */
+    protected EcoPlugin(@Nullable final PluginProps pluginProps) {
         /*
         The handler must be initialized before any plugin's constructors
         are called, as the constructors call Eco#getHandler().
@@ -253,15 +274,15 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         a standalone handler class, but then there would be an interface
         left in the API that doesn't really help anything.
 
-        The other alternative would be do use reflection to get a 'createHandler'
-        method that only exists in EcoSpigotPlugin - but that feels really dirty
+        The other alternative would be to use reflection to get a 'createHandler'
+        method that only exists in EcoSpigotPlugin - but that feels filthy,
         and I'd rather only use reflection where necessary.
         */
 
         if (Eco.getHandler() == null && this instanceof Handler) {
             /*
             This code is only ever called by EcoSpigotPlugin (EcoHandler)
-            as it's the first plugin to load and it is a handler.
+            as it's the first plugin to load, and it is a handler.
 
             Any other plugins will never call this code as the handler
             will have already been initialized.
@@ -272,11 +293,16 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
 
         assert Eco.getHandler() != null;
 
-        this.resourceId = resourceId;
-        this.bStatsId = bStatsId;
-        this.proxyPackage = proxyPackage;
-        this.color = color;
-        this.supportingExtensions = supportingExtensions;
+        PluginProps generatedProps = Eco.getHandler().getProps(pluginProps, this.getClass());
+        generatedProps.validate();
+        PluginProps props = this.mutateProps(generatedProps);
+        props.validate();
+
+        this.resourceId = props.getResourceId();
+        this.bStatsId = props.getBStatsId();
+        this.proxyPackage = props.getProxyPackage();
+        this.color = props.getColor();
+        this.supportingExtensions = props.isSupportingExtensions();
 
         this.scheduler = Eco.getHandler().createScheduler(this);
         this.eventManager = Eco.getHandler().createEventManager(this);
@@ -296,8 +322,8 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
         /*
         The minimum eco version check was moved here because it's very common
         to add a lot of code in the constructor of plugins; meaning that the plugin
-        can throw errors without it being obvious to the user that the reason is
-        because they have an outdated version of eco installed.
+        can throw errors without it being obvious to the user that the reason is that
+        they have an outdated version of eco installed.
          */
 
         DefaultArtifactVersion runningVersion = new DefaultArtifactVersion(Eco.getHandler().getEcoPlugin().getDescription().getVersion());
@@ -327,11 +353,9 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
                 DefaultArtifactVersion mostRecentVersion = new DefaultArtifactVersion(version);
                 if (!(currentVersion.compareTo(mostRecentVersion) > 0 || currentVersion.equals(mostRecentVersion))) {
                     this.outdated = true;
-                    this.getScheduler().runTimer(() -> {
-                        this.getLogger().info("&c " + this.getName() + " is out of date! (Version " + this.getDescription().getVersion() + ")");
-                        this.getLogger().info("&cThe newest version is &f" + version);
-                        this.getLogger().info("&cDownload the new version!");
-                    }, 0, 864000);
+                    this.getLogger().warning("&c" + this.getName() + " is out of date! (Version " + this.getDescription().getVersion() + ")");
+                    this.getLogger().warning("&cThe newest version is &f" + version);
+                    this.getLogger().warning("&cDownload the new version!");
                 }
             });
         }
@@ -536,6 +560,21 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
 
     }
 
+    /**
+     * Mutate the plugin props.
+     * <p>
+     * Useful for eco-based plugin libraries to enforce certain properties, such as
+     * forcing extensions to be enabled.
+     * <p>
+     * Props are validated both before and after calling this method.
+     *
+     * @param props The props.
+     * @return The mutated props.
+     */
+    protected PluginProps mutateProps(@NotNull final PluginProps props) {
+        return props;
+    }
+
     /**
      * The plugin-specific integrations to be tested and loaded.
      *
@@ -637,7 +676,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
      * @return The proxy.
      */
     public final <T> T getProxy(@NotNull final Class<T> proxyClass) {
-        Validate.notNull(proxyFactory, "Plugin does not support proxy!");
+        Validate.notNull(proxyFactory, "Plugin does not support proxies!");
 
         return proxyFactory.getProxy(proxyClass);
     }

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

@@ -2,7 +2,7 @@ package com.willfp.eco.core;
 
 import com.willfp.eco.core.config.updating.ConfigHandler;
 import com.willfp.eco.core.config.wrapper.ConfigFactory;
-import com.willfp.eco.core.data.PlayerProfileHandler;
+import com.willfp.eco.core.data.ProfileHandler;
 import com.willfp.eco.core.data.keys.KeyRegistry;
 import com.willfp.eco.core.drops.DropQueueFactory;
 import com.willfp.eco.core.events.EventManager;
@@ -15,9 +15,11 @@ import com.willfp.eco.core.gui.GUIFactory;
 import com.willfp.eco.core.integrations.placeholder.PlaceholderIntegration;
 import com.willfp.eco.core.proxy.Cleaner;
 import com.willfp.eco.core.proxy.ProxyFactory;
-import com.willfp.eco.core.requirement.RequirementFactory;
 import com.willfp.eco.core.scheduling.Scheduler;
 import net.kyori.adventure.platform.bukkit.BukkitAudiences;
+import org.bukkit.Location;
+import org.bukkit.NamespacedKey;
+import org.bukkit.entity.Entity;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
@@ -30,6 +32,7 @@ import java.util.logging.Logger;
  * @see Eco#getHandler()
  */
 @ApiStatus.Internal
+@SuppressWarnings("removal")
 public interface Handler {
     /**
      * Create a scheduler.
@@ -201,14 +204,6 @@ public interface Handler {
      */
     void registerBStats(@NotNull EcoPlugin plugin);
 
-    /**
-     * Get the requirement factory.
-     *
-     * @return The factory.
-     */
-    @NotNull
-    RequirementFactory getRequirementFactory();
-
     /**
      * Get Adventure audiences.
      *
@@ -231,5 +226,40 @@ public interface Handler {
      * @return The handler.
      */
     @NotNull
-    PlayerProfileHandler getPlayerProfileHandler();
+    ProfileHandler getProfileHandler();
+
+    /**
+     * Create dummy entity - never spawned, exists purely in code.
+     *
+     * @param location The location.
+     * @return The entity.
+     */
+    @NotNull
+    Entity createDummyEntity(@NotNull Location location);
+
+    /**
+     * Create a {@link NamespacedKey} quickly
+     * <p>
+     * Bypasses the constructor, allowing for the creation of invalid keys,
+     * therefore this is considered unsafe and should only be called after
+     * the key has been confirmed to be valid.
+     *
+     * @param namespace The namespace.
+     * @param key       The key.
+     * @return The key.
+     */
+    @NotNull
+    NamespacedKey createNamespacedKey(@NotNull String namespace,
+                                      @NotNull String key);
+
+    /**
+     * Return or get props for a plugin.
+     *
+     * @param existing The existing constructor props.
+     * @param plugin   The plugin.
+     * @return The props.
+     */
+    @NotNull
+    PluginProps getProps(@Nullable PluginProps existing,
+                         @NotNull Class<? extends EcoPlugin> plugin);
 }

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

@@ -0,0 +1,275 @@
+package com.willfp.eco.core;
+
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Plugin props are the arguments related to the plugin that are required on start-up.
+ * <p>
+ * This class is complex in how it works intentionally. This is done so that fields can be
+ * added to the props without breaking API backwards compatibility. Thus, there is no public
+ * constructor and no way to instantiate props without creating a parser.
+ */
+public final class PluginProps {
+    /**
+     * All registered parsers.
+     */
+    private static final Map<Class<?>, PropsParser<?>> REGISTERED_PARSERS = new HashMap<>();
+
+    /**
+     * The polymart resource ID.
+     */
+    @Nullable
+    private Integer resourceId;
+
+    /**
+     * The bStats ID.
+     */
+    @Nullable
+    private Integer bStatsId;
+
+    /**
+     * The proxy package.
+     */
+    @Nullable
+    private String proxyPackage;
+
+    /**
+     * The color.
+     */
+    @Nullable
+    private String color;
+
+    /**
+     * If extensions are supported.
+     */
+    @Nullable
+    private Boolean supportingExtensions;
+
+    /**
+     * Create new blank props.
+     */
+    private PluginProps() {
+
+    }
+
+    /**
+     * Get resource ID.
+     *
+     * @return The resource ID.
+     */
+    public int getResourceId() {
+        assert resourceId != null;
+        return resourceId;
+    }
+
+    /**
+     * Set resource ID.
+     *
+     * @param resourceId The resource ID.
+     */
+    public void setResourceId(final int resourceId) {
+        this.resourceId = resourceId;
+    }
+
+    /**
+     * Get bStats ID.
+     *
+     * @return The bStats ID.
+     */
+    public int getBStatsId() {
+        assert bStatsId != null;
+        return bStatsId;
+    }
+
+    /**
+     * Set bStats ID.
+     *
+     * @param bStatsId The bStats ID.
+     */
+    public void setBStatsId(final int bStatsId) {
+        this.bStatsId = bStatsId;
+    }
+
+    /**
+     * Get the proxy package.
+     *
+     * @return The package.
+     */
+    @NotNull
+    public String getProxyPackage() {
+        assert proxyPackage != null;
+        return proxyPackage;
+    }
+
+    /**
+     * Set the proxy package.
+     *
+     * @param proxyPackage The proxy package.
+     */
+    public void setProxyPackage(@NotNull final String proxyPackage) {
+        this.proxyPackage = proxyPackage;
+    }
+
+    /**
+     * Get color.
+     *
+     * @return The color.
+     */
+    @NotNull
+    public String getColor() {
+        assert color != null;
+        return color;
+    }
+
+    /**
+     * Set the color.
+     *
+     * @param color The color.
+     */
+    public void setColor(@NotNull final String color) {
+        this.color = color;
+    }
+
+    /**
+     * Get if extensions are supported.
+     *
+     * @return If supported.
+     */
+    public boolean isSupportingExtensions() {
+        assert supportingExtensions != null;
+        return supportingExtensions;
+    }
+
+    /**
+     * Set if extensions are supported.
+     *
+     * @param supportingExtensions If supported.
+     */
+    public void setSupportingExtensions(final boolean supportingExtensions) {
+        this.supportingExtensions = supportingExtensions;
+    }
+
+    /**
+     * Ensure that all required props have been set.
+     */
+    public void validate() {
+        if (
+                supportingExtensions == null
+                        || proxyPackage == null
+                        || color == null
+                        || bStatsId == null
+                        || resourceId == null
+        ) {
+            throw new IllegalStateException("Missing required props!");
+        }
+    }
+
+    /**
+     * Parse props from source.
+     *
+     * @param source      The source.
+     * @param sourceClass The source class.
+     * @param <T>         The source type.
+     * @return The props.
+     */
+    public static <T> PluginProps parse(@NotNull final T source,
+                                        @NotNull final Class<? extends T> sourceClass) {
+        for (Map.Entry<Class<?>, PropsParser<?>> entry : REGISTERED_PARSERS.entrySet()) {
+            Class<?> clazz = entry.getKey();
+
+            if (clazz.equals(sourceClass)) {
+                @SuppressWarnings("unchecked")
+                PropsParser<T> parser = (PropsParser<T>) entry.getValue();
+                return parser.parseFrom(source);
+            }
+        }
+
+        throw new IllegalArgumentException("No parser exists for class " + sourceClass);
+    }
+
+    /**
+     * Register a parser for a type.
+     *
+     * @param clazz  The class.
+     * @param parser The parser.
+     * @param <T>    The source type.
+     */
+    public static <T> void registerParser(@NotNull final Class<T> clazz,
+                                          @NotNull final PropsParser<T> parser) {
+        REGISTERED_PARSERS.put(clazz, parser);
+    }
+
+    /**
+     * Get if there is a registered parser for a class.
+     *
+     * @param clazz The class.
+     * @return If there is a parser registered.
+     */
+    public static boolean hasParserFor(@NotNull final Class<?> clazz) {
+        for (Class<?> test : REGISTERED_PARSERS.keySet()) {
+            if (test.equals(clazz)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Create new props from known values.
+     *
+     * Marked as internal as this method will break whenever the properties themselves
+     * are updated (e.g. if a new property is added) - so to prevent any potential
+     * backwards-compatibility bugs, this method cannot be invoked outside eco itself.
+     *
+     * @param resourceId         The ID of the plugin on polymart.
+     * @param bStatsId           The ID of the plugin on bStats.
+     * @param proxyPackage       The package where proxies can be found.
+     * @param color              The primary color of the plugin.
+     * @param supportsExtensions If the plugin should attempt to look for extensions.
+     * @return The props.
+     */
+    @ApiStatus.Internal
+    static PluginProps createSimple(final int resourceId,
+                                    final int bStatsId,
+                                    @NotNull final String proxyPackage,
+                                    @NotNull final String color,
+                                    final boolean supportsExtensions) {
+        PluginProps props = new PluginProps();
+        props.setResourceId(resourceId);
+        props.setBStatsId(bStatsId);
+        props.setProxyPackage(proxyPackage);
+        props.setColor(color);
+        props.setSupportingExtensions(supportsExtensions);
+        return props;
+    }
+
+    /**
+     * Parse arguments into props for a plugin.
+     *
+     * @param <T> The type of source.
+     */
+    public interface PropsParser<T> {
+        /**
+         * Parse props from a given source.
+         *
+         * @param source The source.
+         * @return The props.
+         */
+        PluginProps parseFrom(@NotNull T source);
+
+        /**
+         * Get a new, blank props instance.
+         *
+         * @return Blank props.
+         */
+        default PluginProps getBlankProps() {
+            return new PluginProps();
+        }
+    }
+}

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

@@ -51,7 +51,10 @@ public class Prerequisite {
 
     /**
      * Requires the server to be running 1.17.
+     *
+     * @deprecated eco no longer supports versions before 1.17.
      */
+    @Deprecated(since = "6.25.2")
     public static final Prerequisite HAS_1_17 = new Prerequisite(
             () -> ProxyConstants.NMS_VERSION.contains("17") || HAS_1_18.isMet(),
             "Requires server to be running 1.17+"

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

@@ -1,5 +1,6 @@
 package com.willfp.eco.core.command;
 
+import com.willfp.eco.core.EcoPlugin;
 import org.bukkit.command.CommandSender;
 import org.jetbrains.annotations.NotNull;
 
@@ -66,6 +67,13 @@ public interface CommandBase {
         return new ArrayList<>();
     }
 
+    /**
+     * Get the plugin.
+     *
+     * @return The plugin.
+     */
+    EcoPlugin getPlugin();
+
     /**
      * Get the handler.
      *

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

@@ -1,7 +1,6 @@
 package com.willfp.eco.core.command.impl;
 
 import com.willfp.eco.core.EcoPlugin;
-import com.willfp.eco.core.PluginDependent;
 import com.willfp.eco.core.command.CommandBase;
 import com.willfp.eco.core.command.CommandHandler;
 import com.willfp.eco.core.command.TabCompleteHandler;
@@ -25,7 +24,12 @@ import java.util.stream.Collectors;
  * layer, hence why it's a package-private class.
  */
 @SuppressWarnings({"DeprecatedIsStillUsed"})
-abstract class HandledCommand extends PluginDependent<EcoPlugin> implements CommandBase {
+abstract class HandledCommand implements CommandBase {
+    /**
+     * The plugin.
+     */
+    private final EcoPlugin plugin;
+
     /**
      * The name of the command.
      */
@@ -78,7 +82,7 @@ abstract class HandledCommand extends PluginDependent<EcoPlugin> implements Comm
                    @NotNull final String name,
                    @NotNull final String permission,
                    final boolean playersOnly) {
-        super(plugin);
+        this.plugin = plugin;
         this.name = name;
         this.permission = permission;
         this.playersOnly = playersOnly;
@@ -98,6 +102,16 @@ abstract class HandledCommand extends PluginDependent<EcoPlugin> implements Comm
         return this;
     }
 
+    /**
+     * Get the plugin.
+     *
+     * @return The plugin.
+     */
+    @Override
+    public EcoPlugin getPlugin() {
+        return this.plugin;
+    }
+
     /**
      * Handle the command.
      *
@@ -124,6 +138,11 @@ abstract class HandledCommand extends PluginDependent<EcoPlugin> implements Comm
             }
         }
 
+        if (this.isPlayersOnly() && !(sender instanceof Player)) {
+            sender.sendMessage(this.getPlugin().getLangYml().getMessage("not-player"));
+            return;
+        }
+
         if (this.getHandler() != null) {
             this.getHandler().onExecute(sender, Arrays.asList(args));
         } else {
@@ -193,11 +212,6 @@ abstract class HandledCommand extends PluginDependent<EcoPlugin> implements Comm
     public static boolean canExecute(@NotNull final CommandSender sender,
                                      @NotNull final CommandBase command,
                                      @NotNull final EcoPlugin plugin) {
-        if (command.isPlayersOnly() && !(sender instanceof Player)) {
-            sender.sendMessage(plugin.getLangYml().getMessage("not-player"));
-            return false;
-        }
-
         if (!sender.hasPermission(command.getPermission()) && sender instanceof Player) {
             sender.sendMessage(plugin.getLangYml().getNoPermission());
             return false;

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

@@ -5,7 +5,10 @@ import com.willfp.eco.core.config.interfaces.Config;
 import com.willfp.eco.core.config.wrapper.ConfigWrapper;
 import org.bukkit.configuration.file.YamlConfiguration;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
+import java.io.InputStream;
+import java.io.InputStreamReader;
 import java.util.Map;
 
 /**
@@ -21,6 +24,15 @@ public class TransientConfig extends ConfigWrapper<Config> {
         super(Eco.getHandler().getConfigFactory().createConfig(config));
     }
 
+    /**
+     * @param stream The InputStream.
+     */
+    public TransientConfig(@Nullable final InputStream stream) {
+        super(stream != null ? Eco.getHandler().getConfigFactory().createConfig(YamlConfiguration.loadConfiguration(
+                new InputStreamReader(stream)
+        )) : new TransientConfig());
+    }
+
     /**
      * Create a new empty transient config.
      *

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

@@ -1,11 +1,16 @@
 package com.willfp.eco.core.config.interfaces;
 
 import com.willfp.eco.core.config.ConfigType;
+import com.willfp.eco.core.config.TransientConfig;
+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.ArrayList;
 import java.util.List;
+import java.util.Objects;
 
 /**
  * All configs implement this interface.
@@ -67,10 +72,12 @@ public interface Config extends Cloneable {
      * Get subsection from config.
      *
      * @param path The key to check.
-     * @return The subsection. Throws NPE if not found.
+     * @return The subsection. Returns an empty section if not found.
      */
     @NotNull
-    Config getSubsection(@NotNull String path);
+    default Config getSubsection(@NotNull String path) {
+        return Objects.requireNonNullElse(getSubsectionOrNull(path), new TransientConfig());
+    }
 
     /**
      * Get subsection from config.
@@ -87,7 +94,44 @@ public interface Config extends Cloneable {
      * @param path The key to fetch the value from.
      * @return The found value, or 0 if not found.
      */
-    int getInt(@NotNull String path);
+    default int getInt(@NotNull String path) {
+        return Objects.requireNonNullElse(getIntOrNull(path), 0);
+    }
+
+    /**
+     * Get an integer from config with a specified default (not found) value.
+     *
+     * @param path The key to fetch the value from.
+     * @param def  The value to default to if not found.
+     * @return The found value, or the default.
+     */
+    default int getInt(@NotNull String path,
+                       int def) {
+        return Objects.requireNonNullElse(getIntOrNull(path), def);
+    }
+
+    /**
+     * Get a decimal value via a mathematical expression.
+     *
+     * @param path The key to fetch the value from.
+     * @return The computed value, or 0 if not found or invalid.
+     */
+    default int getIntFromExpression(@NotNull String path) {
+        return getIntFromExpression(path, null);
+    }
+
+    /**
+     * Get a decimal value via a mathematical expression.
+     *
+     * @param path   The key to fetch the value from.
+     * @param player The player to evaluate placeholders with respect to.
+     * @return The computed value, or 0 if not found or invalid.
+     */
+    default int getIntFromExpression(@NotNull String path,
+                                     @Nullable Player player) {
+        return Double.valueOf(getDoubleFromExpression(path, player)).intValue();
+    }
+
 
     /**
      * Get an integer from config.
@@ -98,16 +142,6 @@ public interface Config extends Cloneable {
     @Nullable
     Integer getIntOrNull(@NotNull String path);
 
-    /**
-     * Get an integer from config with a specified default (not found) value.
-     *
-     * @param path The key to fetch the value from.
-     * @param def  The value to default to if not found.
-     * @return The found value, or the default.
-     */
-    int getInt(@NotNull String path,
-               int def);
-
     /**
      * Get a list of integers from config.
      *
@@ -115,7 +149,9 @@ public interface Config extends Cloneable {
      * @return The found value, or a blank {@link java.util.ArrayList} if not found.
      */
     @NotNull
-    List<Integer> getInts(@NotNull String path);
+    default List<Integer> getInts(@NotNull String path) {
+        return Objects.requireNonNullElse(getIntsOrNull(path), new ArrayList<>());
+    }
 
     /**
      * Get a list of integers from config.
@@ -132,7 +168,9 @@ public interface Config extends Cloneable {
      * @param path The key to fetch the value from.
      * @return The found value, or false if not found.
      */
-    boolean getBool(@NotNull String path);
+    default boolean getBool(@NotNull String path) {
+        return Objects.requireNonNullElse(getBoolOrNull(path), false);
+    }
 
     /**
      * Get a boolean from config.
@@ -150,7 +188,9 @@ public interface Config extends Cloneable {
      * @return The found value, or a blank {@link java.util.ArrayList} if not found.
      */
     @NotNull
-    List<Boolean> getBools(@NotNull String path);
+    default List<Boolean> getBools(@NotNull String path) {
+        return Objects.requireNonNullElse(getBoolsOrNull(path), new ArrayList<>());
+    }
 
     /**
      * Get a list of booleans from config.
@@ -169,7 +209,7 @@ public interface Config extends Cloneable {
      */
     @NotNull
     default String getFormattedString(@NotNull String path) {
-        return getString(path, true);
+        return getString(path, true, StringUtils.FormatOption.WITH_PLACEHOLDERS);
     }
 
     /**
@@ -188,25 +228,25 @@ public interface Config extends Cloneable {
     /**
      * Get a string from config.
      * <p>
-     * Formatted by default.
+     * Not formatted.
      *
      * @param path The key to fetch the value from.
      * @return The found value, or an empty string if not found.
      */
     @NotNull
     default String getString(@NotNull String path) {
-        return getString(path, true);
+        return getString(path, false, StringUtils.FormatOption.WITHOUT_PLACEHOLDERS);
     }
 
     /**
      * Get a string from config.
-     * <p>
-     * This will be deprecated when {@link Config#getString(String)} no longer formats by default.
      *
      * @param path   The key to fetch the value from.
      * @param format If the string should be formatted.
      * @return The found value, or an empty string if not found.
+     * @deprecated Since 6.18.0, {@link Config#getString(String)} is not formatted by default.
      */
+    @Deprecated(since = "6.18.0")
     default String getString(@NotNull String path,
                              boolean format) {
         return this.getString(path, format, StringUtils.FormatOption.WITH_PLACEHOLDERS);
@@ -236,9 +276,11 @@ public interface Config extends Cloneable {
      * @return The found value, or an empty string if not found.
      */
     @NotNull
-    String getString(@NotNull String path,
-                     boolean format,
-                     @NotNull StringUtils.FormatOption option);
+    default String getString(@NotNull String path,
+                             boolean format,
+                             @NotNull StringUtils.FormatOption option) {
+        return Objects.requireNonNullElse(getStringOrNull(path, format, option), "");
+    }
 
     /**
      * Get a formatted string from config.
@@ -248,7 +290,7 @@ public interface Config extends Cloneable {
      */
     @Nullable
     default String getFormattedStringOrNull(@NotNull String path) {
-        return getStringOrNull(path, true);
+        return getStringOrNull(path, true, StringUtils.FormatOption.WITH_PLACEHOLDERS);
     }
 
     /**
@@ -274,19 +316,19 @@ public interface Config extends Cloneable {
      */
     @Nullable
     default String getStringOrNull(@NotNull String path) {
-        return getStringOrNull(path, true);
+        return getStringOrNull(path, false, StringUtils.FormatOption.WITH_PLACEHOLDERS);
     }
 
     /**
      * Get a string from config.
-     * <p>
-     * This will be deprecated when {@link Config#getStringOrNull(String)} no longer formats by default.
      *
      * @param path   The key to fetch the value from.
      * @param format If the string should be formatted.
      * @return The found value, or null if not found.
+     * @deprecated Since 6.18.0, {@link Config#getString(String)} is not formatted by default.
      */
     @Nullable
+    @Deprecated(since = "6.18.0")
     default String getStringOrNull(@NotNull String path,
                                    boolean format) {
         return this.getStringOrNull(path, format, StringUtils.FormatOption.WITH_PLACEHOLDERS);
@@ -351,28 +393,26 @@ public interface Config extends Cloneable {
     /**
      * Get a list of strings from config.
      * <p>
-     * Formatted by default.
-     * <p>
-     * This will be changed in newer versions to <b>not</b> format by default.
+     * Not formatted.
      *
      * @param path The key to fetch the value from.
      * @return The found value, or a blank {@link java.util.ArrayList} if not found.
      */
     @NotNull
     default List<String> getStrings(@NotNull String path) {
-        return getStrings(path, true);
+        return getStrings(path, false, StringUtils.FormatOption.WITH_PLACEHOLDERS);
     }
 
     /**
      * Get a list of strings from config.
-     * <p>
-     * This will be deprecated when {@link Config#getStrings(String)} no longer formats by default.
      *
      * @param path   The key to fetch the value from.
      * @param format If the strings should be formatted.
      * @return The found value, or a blank {@link java.util.ArrayList} if not found.
+     * @deprecated Since 6.18.0, {@link Config#getString(String)} is not formatted by default.
      */
     @NotNull
+    @Deprecated(since = "6.18.0")
     default List<String> getStrings(@NotNull String path,
                                     boolean format) {
         return this.getStrings(path, format, StringUtils.FormatOption.WITH_PLACEHOLDERS);
@@ -390,7 +430,7 @@ public interface Config extends Cloneable {
     @Deprecated
     default List<String> getStrings(@NotNull String path,
                                     @NotNull StringUtils.FormatOption option) {
-        return getStrings(path, true, option);
+        return getStrings(path, false, option);
     }
 
     /**
@@ -402,14 +442,16 @@ public interface Config extends Cloneable {
      * @return The found value, or a blank {@link java.util.ArrayList} if not found.
      */
     @NotNull
-    List<String> getStrings(@NotNull String path,
-                            boolean format,
-                            @NotNull StringUtils.FormatOption option);
+    default List<String> getStrings(@NotNull String path,
+                                    boolean format,
+                                    @NotNull StringUtils.FormatOption option) {
+        return Objects.requireNonNullElse(getStringsOrNull(path, format, option), new ArrayList<>());
+    }
 
     /**
      * Get a list of strings from config.
      * <p>
-     * Formatted by default.
+     * Formatted.
      *
      * @param path The key to fetch the value from.
      * @return The found value, or null if not found.
@@ -422,7 +464,7 @@ public interface Config extends Cloneable {
     /**
      * Get a list of strings from config.
      * <p>
-     * Formatted by default.
+     * Formatted.
      *
      * @param path   The key to fetch the value from.
      * @param option The format option.
@@ -437,7 +479,7 @@ public interface Config extends Cloneable {
     /**
      * Get a list of strings from config.
      * <p>
-     * Formatted by default.
+     * Not formatted.
      * <p>
      * This will be changed in newer versions to <b>not</b> format by default.
      *
@@ -446,7 +488,7 @@ public interface Config extends Cloneable {
      */
     @Nullable
     default List<String> getStringsOrNull(@NotNull String path) {
-        return getStringsOrNull(path, true);
+        return getStringsOrNull(path, false, StringUtils.FormatOption.WITH_PLACEHOLDERS);
     }
 
     /**
@@ -455,8 +497,10 @@ public interface Config extends Cloneable {
      * @param path   The key to fetch the value from.
      * @param format If the strings should be formatted.
      * @return The found value, or null if not found.
+     * @deprecated Since 6.18.0, {@link Config#getString(String)} is not formatted by default.
      */
     @Nullable
+    @Deprecated(since = "6.18.0")
     default List<String> getStringsOrNull(@NotNull String path,
                                           boolean format) {
         return getStringsOrNull(path, format, StringUtils.FormatOption.WITH_PLACEHOLDERS);
@@ -474,7 +518,7 @@ public interface Config extends Cloneable {
     @Deprecated
     default List<String> getStringsOrNull(@NotNull String path,
                                           @NotNull StringUtils.FormatOption option) {
-        return getStringsOrNull(path, true, option);
+        return getStringsOrNull(path, false, option);
     }
 
     /**
@@ -496,7 +540,31 @@ public interface Config extends Cloneable {
      * @param path The key to fetch the value from.
      * @return The found value, or 0 if not found.
      */
-    double getDouble(@NotNull String path);
+    default double getDouble(@NotNull String path) {
+        return Objects.requireNonNullElse(getDoubleOrNull(path), 0.0);
+    }
+
+    /**
+     * Get a decimal value via a mathematical expression.
+     *
+     * @param path The key to fetch the value from.
+     * @return The computed value, or 0 if not found or invalid.
+     */
+    default double getDoubleFromExpression(@NotNull String path) {
+        return getDoubleFromExpression(path, null);
+    }
+
+    /**
+     * Get a decimal value via a mathematical expression.
+     *
+     * @param path   The key to fetch the value from.
+     * @param player The player to evaluate placeholders with respect to.
+     * @return The computed value, or 0 if not found or invalid.
+     */
+    default double getDoubleFromExpression(@NotNull String path,
+                                           @Nullable Player player) {
+        return NumberUtils.evaluateExpression(this.getString(path), player);
+    }
 
     /**
      * Get a decimal from config.
@@ -514,7 +582,9 @@ public interface Config extends Cloneable {
      * @return The found value, or a blank {@link java.util.ArrayList} if not found.
      */
     @NotNull
-    List<Double> getDoubles(@NotNull String path);
+    default List<Double> getDoubles(@NotNull String path) {
+        return Objects.requireNonNullElse(getDoublesOrNull(path), new ArrayList<>());
+    }
 
     /**
      * Get a list of decimals from config.
@@ -532,7 +602,9 @@ public interface Config extends Cloneable {
      * @return The found value, or a blank {@link java.util.ArrayList} if not found.
      */
     @NotNull
-    List<? extends Config> getSubsections(@NotNull String path);
+    default List<? extends Config> getSubsections(@NotNull String path) {
+        return Objects.requireNonNullElse(getSubsectionsOrNull(path), new ArrayList<>());
+    }
 
     /**
      * Get a list of subsections from config.

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

@@ -3,7 +3,9 @@ package com.willfp.eco.core.config.interfaces;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
 
 /**
  * JSON config.
@@ -22,7 +24,9 @@ public interface JSONConfig extends Config {
      * @return The found value, or a blank {@link java.util.ArrayList} if not found.
      */
     @NotNull
-    List<JSONConfig> getSubsections(@NotNull String path);
+    default List<JSONConfig> getSubsections(@NotNull String path) {
+        return Objects.requireNonNullElse(getSubsectionsOrNull(path), new ArrayList<>());
+    }
 
     /**
      * Get a list of subsections from config.

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

@@ -28,6 +28,9 @@ import java.lang.annotation.Target;
  * }
  * }</pre>
  * <p>
+ * If using kotlin, you have to annotate the method with {@code @JvmStatic}
+ * in order to prevent null pointer exceptions.
+ * <p>
  * Config update methods in all classes in a plugin jar will be called
  * on reload.
  * <p>

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

@@ -1,5 +1,6 @@
 package com.willfp.eco.core.config.wrapper;
 
+import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.PluginLike;
 import com.willfp.eco.core.config.ConfigType;
 import com.willfp.eco.core.config.interfaces.Config;
@@ -14,6 +15,7 @@ import java.util.Map;
  * Internal component to create backend config implementations.
  */
 @ApiStatus.Internal
+@Eco.HandlerComponent
 public interface ConfigFactory {
     /**
      * Updatable config.

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

@@ -70,70 +70,31 @@ public abstract class ConfigWrapper<T extends Config> implements Config {
         handle.set(path, object);
     }
 
-    @Override
-    public @NotNull Config getSubsection(@NotNull final String path) {
-        return handle.getSubsection(path);
-    }
-
     @Override
     public @Nullable Config getSubsectionOrNull(@NotNull final String path) {
         return handle.getSubsectionOrNull(path);
     }
 
-    @Override
-    public int getInt(@NotNull final String path) {
-        return handle.getInt(path);
-    }
-
     @Override
     public @Nullable Integer getIntOrNull(@NotNull final String path) {
         return handle.getIntOrNull(path);
     }
 
-    @Override
-    public int getInt(@NotNull final String path,
-                      final int def) {
-        return handle.getInt(path, def);
-    }
-
-    @Override
-    public @NotNull List<Integer> getInts(@NotNull final String path) {
-        return handle.getInts(path);
-    }
-
     @Override
     public @Nullable List<Integer> getIntsOrNull(@NotNull final String path) {
         return handle.getIntsOrNull(path);
     }
 
-    @Override
-    public boolean getBool(@NotNull final String path) {
-        return handle.getBool(path);
-    }
-
     @Override
     public @Nullable Boolean getBoolOrNull(@NotNull final String path) {
         return handle.getBoolOrNull(path);
     }
 
-    @Override
-    public @NotNull List<Boolean> getBools(@NotNull final String path) {
-        return handle.getBools(path);
-    }
-
     @Override
     public @Nullable List<Boolean> getBoolsOrNull(@NotNull final String path) {
         return handle.getBoolsOrNull(path);
     }
 
-
-    @Override
-    public @NotNull String getString(@NotNull final String path,
-                                     final boolean format,
-                                     @NotNull final StringUtils.FormatOption option) {
-        return handle.getString(path, format, option);
-    }
-
     @Override
     public @Nullable String getStringOrNull(@NotNull final String path,
                                             final boolean format,
@@ -141,13 +102,6 @@ public abstract class ConfigWrapper<T extends Config> implements Config {
         return handle.getStringOrNull(path, format, option);
     }
 
-    @Override
-    public @NotNull List<String> getStrings(@NotNull final String path,
-                                            final boolean format,
-                                            @NotNull final StringUtils.FormatOption option) {
-        return handle.getStrings(path, format, option);
-    }
-
     @Override
     public @Nullable List<String> getStringsOrNull(@NotNull final String path,
                                                    final boolean format,
@@ -155,31 +109,16 @@ public abstract class ConfigWrapper<T extends Config> implements Config {
         return handle.getStringsOrNull(path, format, option);
     }
 
-    @Override
-    public double getDouble(@NotNull final String path) {
-        return handle.getDouble(path);
-    }
-
     @Override
     public @Nullable Double getDoubleOrNull(@NotNull final String path) {
         return handle.getDoubleOrNull(path);
     }
 
-    @Override
-    public @NotNull List<Double> getDoubles(@NotNull final String path) {
-        return handle.getDoubles(path);
-    }
-
     @Override
     public @Nullable List<Double> getDoublesOrNull(@NotNull final String path) {
         return handle.getDoublesOrNull(path);
     }
 
-    @Override
-    public @NotNull List<? extends Config> getSubsections(@NotNull final String path) {
-        return handle.getSubsections(path);
-    }
-
     @Override
     public @Nullable List<? extends Config> getSubsectionsOrNull(@NotNull final String path) {
         return handle.getSubsectionsOrNull(path);

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

@@ -1,7 +1,6 @@
 package com.willfp.eco.core.data;
 
 import com.willfp.eco.core.Eco;
-import com.willfp.eco.core.data.keys.PersistentDataKey;
 import org.bukkit.OfflinePlayer;
 import org.jetbrains.annotations.NotNull;
 
@@ -12,26 +11,7 @@ import java.util.UUID;
  * <p>
  * Profiles save automatically, so there is no need to save after changes.
  */
-public interface PlayerProfile {
-    /**
-     * Write a key to a player's persistent data.
-     *
-     * @param key   The key.
-     * @param value The value.
-     * @param <T>   The type of the key.
-     */
-    <T> void write(@NotNull PersistentDataKey<T> key,
-                   @NotNull T value);
-
-    /**
-     * Read a key from a player's persistent data.
-     *
-     * @param key The key.
-     * @param <T> The type of the key.
-     * @return The value, or the default value if not found.
-     */
-    <T> @NotNull T read(@NotNull PersistentDataKey<T> key);
-
+public interface PlayerProfile extends Profile {
     /**
      * Load a player profile.
      *
@@ -51,6 +31,6 @@ public interface PlayerProfile {
      */
     @NotNull
     static PlayerProfile load(@NotNull final UUID uuid) {
-        return Eco.getHandler().getPlayerProfileHandler().load(uuid);
+        return Eco.getHandler().getProfileHandler().load(uuid);
     }
 }

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

@@ -0,0 +1,30 @@
+package com.willfp.eco.core.data;
+
+import com.willfp.eco.core.data.keys.PersistentDataKey;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Persistent data storage interface.
+ * <p>
+ * Profiles save automatically, so there is no need to save after changes.
+ */
+public interface Profile {
+    /**
+     * Write a key to persistent data.
+     *
+     * @param key   The key.
+     * @param value The value.
+     * @param <T>   The type of the key.
+     */
+    <T> void write(@NotNull PersistentDataKey<T> key,
+                   @NotNull T value);
+
+    /**
+     * Read a key from persistent data.
+     *
+     * @param key The key.
+     * @param <T> The type of the key.
+     * @return The value, or the default value if not found.
+     */
+    <T> @NotNull T read(@NotNull PersistentDataKey<T> key);
+}

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

@@ -1,15 +1,19 @@
 package com.willfp.eco.core.data;
 
+import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.data.keys.PersistentDataKey;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.Set;
 import java.util.UUID;
 
 /**
- * API to handle player profiles.
+ * API to handle profiles.
  */
-public interface PlayerProfileHandler {
+@ApiStatus.Internal
+@Eco.HandlerComponent
+public interface ProfileHandler {
     /**
      * Load a player profile.
      *
@@ -18,6 +22,13 @@ public interface PlayerProfileHandler {
      */
     PlayerProfile load(@NotNull UUID uuid);
 
+    /**
+     * Load the server profile.
+     *
+     * @return The profile.
+     */
+    ServerProfile loadServerProfile();
+
     /**
      * Unload a player profile from memory.
      * <p>
@@ -37,7 +48,7 @@ public interface PlayerProfileHandler {
      */
     @Deprecated
     default void savePlayer(@NotNull UUID uuid) {
-        this.saveKeysForPlayer(uuid, PersistentDataKey.values());
+        this.saveKeysFor(uuid, PersistentDataKey.values());
     }
 
     /**
@@ -48,8 +59,8 @@ public interface PlayerProfileHandler {
      * @param uuid The uuid.
      * @param keys The keys.
      */
-    void saveKeysForPlayer(@NotNull UUID uuid,
-                           @NotNull Set<PersistentDataKey<?>> keys);
+    void saveKeysFor(@NotNull UUID uuid,
+                     @NotNull Set<PersistentDataKey<?>> keys);
 
     /**
      * Save all player data.

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

@@ -0,0 +1,21 @@
+package com.willfp.eco.core.data;
+
+import com.willfp.eco.core.Eco;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Persistent data storage interface for servers.
+ * <p>
+ * Profiles save automatically, so there is no need to save after changes.
+ */
+public interface ServerProfile extends Profile {
+    /**
+     * Load the server profile.
+     *
+     * @return The profile.
+     */
+    @NotNull
+    static ServerProfile load() {
+        return Eco.getHandler().getProfileHandler().loadServerProfile();
+    }
+}

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

@@ -1,12 +1,18 @@
 package com.willfp.eco.core.data.keys;
 
+import com.willfp.eco.core.Eco;
+import org.bukkit.NamespacedKey;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.Set;
 
 /**
  * API to register persistent data keys.
  */
+@ApiStatus.Internal
+@Eco.HandlerComponent
 public interface KeyRegistry {
     /**
      * Register a persistent data key to be stored.
@@ -21,4 +27,37 @@ public interface KeyRegistry {
      * @return The keys.
      */
     Set<PersistentDataKey<?>> getRegisteredKeys();
+
+    /**
+     * Mark key as category.
+     *
+     * @param key      The key.
+     * @param category The category.
+     */
+    void markKeyAs(@NotNull PersistentDataKey<?> key,
+                   @NotNull KeyRegistry.KeyCategory category);
+
+    /**
+     * Get persistent data key from namespaced key.
+     *
+     * @param namespacedKey The key.
+     * @return The key, or null if not found.
+     */
+    @Nullable
+    PersistentDataKey<?> getKeyFrom(@NotNull NamespacedKey namespacedKey);
+
+    /**
+     * Locations for key categorization.
+     */
+    enum KeyCategory {
+        /**
+         * Player keys.
+         */
+        PLAYER,
+
+        /**
+         * Server keys.
+         */
+        SERVER
+    }
 }

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

@@ -3,7 +3,9 @@ package com.willfp.eco.core.data.keys;
 import com.willfp.eco.core.Eco;
 import org.bukkit.NamespacedKey;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
+import java.util.Objects;
 import java.util.Set;
 
 /**
@@ -11,7 +13,7 @@ import java.util.Set;
  *
  * @param <T> The type of the data.
  */
-public class PersistentDataKey<T> {
+public final class PersistentDataKey<T> {
     /**
      * The key of the persistent data value.
      */
@@ -25,7 +27,7 @@ public class PersistentDataKey<T> {
     /**
      * The persistent data key type.
      */
-    private final PersistentDataKeyType type;
+    private final PersistentDataKeyType<T> type;
 
     /**
      * Create a new Persistent Data Key.
@@ -35,7 +37,7 @@ public class PersistentDataKey<T> {
      * @param defaultValue The default value.
      */
     public PersistentDataKey(@NotNull final NamespacedKey key,
-                             @NotNull final PersistentDataKeyType type,
+                             @NotNull final PersistentDataKeyType<T> type,
                              @NotNull final T defaultValue) {
         this.key = key;
         this.defaultValue = defaultValue;
@@ -53,15 +55,6 @@ public class PersistentDataKey<T> {
                 + '}';
     }
 
-    /**
-     * Get all persistent data keys.
-     *
-     * @return The keys.
-     */
-    public static Set<PersistentDataKey<?>> values() {
-        return Eco.getHandler().getKeyRegistry().getRegisteredKeys();
-    }
-
     /**
      * Get the key.
      *
@@ -85,7 +78,58 @@ public class PersistentDataKey<T> {
      *
      * @return The key type.
      */
-    public PersistentDataKeyType getType() {
+    public PersistentDataKeyType<T> getType() {
         return this.type;
     }
+
+    /**
+     * Categorize key as a server key, will register new column to MySQL
+     * database immediately rather than waiting for auto-categorization.
+     * <p>
+     * This will improve performance.
+     *
+     * @return The key.
+     */
+    public PersistentDataKey<T> server() {
+        Eco.getHandler().getKeyRegistry().markKeyAs(this, KeyRegistry.KeyCategory.SERVER);
+        return this;
+    }
+
+    /**
+     * Categorize key as a player key, will register new column to MySQL
+     * database immediately rather than waiting for auto-categorization.
+     * <p>
+     * This will improve performance.
+     *
+     * @return The key.
+     */
+    public PersistentDataKey<T> player() {
+        Eco.getHandler().getKeyRegistry().markKeyAs(this, KeyRegistry.KeyCategory.PLAYER);
+        return this;
+    }
+
+    /**
+     * Get all persistent data keys.
+     *
+     * @return The keys.
+     */
+    public static Set<PersistentDataKey<?>> values() {
+        return Eco.getHandler().getKeyRegistry().getRegisteredKeys();
+    }
+
+    @Override
+    public boolean equals(@Nullable final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (!(o instanceof PersistentDataKey that)) {
+            return false;
+        }
+        return Objects.equals(this.getKey(), that.getKey());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.getKey());
+    }
 }

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

@@ -1,26 +1,108 @@
 package com.willfp.eco.core.data.keys;
 
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * All storable data key types.
+ *
+ * @param <T> The type.
  */
-public enum PersistentDataKeyType {
+public final class PersistentDataKeyType<T> {
+    /**
+     * The registered key types.
+     */
+    private static final List<PersistentDataKeyType<?>> VALUES = new ArrayList<>();
+
     /**
      * String.
      */
-    STRING,
+    public static final PersistentDataKeyType<String> STRING = new PersistentDataKeyType<>(String.class, "STRING");
 
     /**
      * Boolean.
      */
-    BOOLEAN,
+    public static final PersistentDataKeyType<Boolean> BOOLEAN = new PersistentDataKeyType<>(Boolean.class, "BOOLEAN");
 
     /**
-     * Integer.
+     * Int.
      */
-    INT,
+    public static final PersistentDataKeyType<Integer> INT = new PersistentDataKeyType<>(Integer.class, "INT");
 
     /**
      * Double.
      */
-    DOUBLE
+    public static final PersistentDataKeyType<Double> DOUBLE = new PersistentDataKeyType<>(Double.class, "DOUBLE");
+
+    /**
+     * The class of the type.
+     */
+    private final Class<T> typeClass;
+
+    /**
+     * The name of the key type.
+     */
+    private final String name;
+
+    /**
+     * Get the class of the type.
+     *
+     * @return The class.
+     */
+    public Class<T> getTypeClass() {
+        return typeClass;
+    }
+
+    /**
+     * Get the name of the key type.
+     *
+     * @return The name.
+     */
+    public String name() {
+        return name;
+    }
+
+    /**
+     * Create new PersistentDataKeyType.
+     *
+     * @param typeClass The type class.
+     * @param name      The name.
+     */
+    private PersistentDataKeyType(@NotNull final Class<T> typeClass,
+                                  @NotNull final String name) {
+        VALUES.add(this);
+
+        this.typeClass = typeClass;
+        this.name = name;
+    }
+
+    /**
+     * Get all registered {@link PersistentDataKeyType}s.
+     *
+     * @return The registered types.
+     */
+    @NotNull
+    public static PersistentDataKeyType<?>[] values() {
+        return VALUES.toArray(new PersistentDataKeyType[0]);
+    }
+
+    /**
+     * Get a key type from a name.
+     *
+     * @param name The name.
+     * @return The type, or null if not found.
+     */
+    @Nullable
+    public static PersistentDataKeyType<?> valueOf(@NotNull final String name) {
+        for (PersistentDataKeyType<?> type : VALUES) {
+            if (type.name.equalsIgnoreCase(name)) {
+                return type;
+            }
+        }
+
+        return null;
+    }
 }

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

@@ -1,13 +1,17 @@
 package com.willfp.eco.core.display;
 
+import com.willfp.eco.core.Eco;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 /**
  * Interface for display implementations.
  */
+@ApiStatus.Internal
+@Eco.HandlerComponent
 public interface DisplayHandler {
     /**
      * Register display module.

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

@@ -1,11 +1,15 @@
 package com.willfp.eco.core.drops;
 
+import com.willfp.eco.core.Eco;
 import org.bukkit.entity.Player;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
 /**
  * Internal component to create backend DropQueue implementations.
  */
+@ApiStatus.Internal
+@Eco.HandlerComponent
 public interface DropQueueFactory {
     /**
      * Create a DropQueue.

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

@@ -1,7 +1,9 @@
 package com.willfp.eco.core.drops;
 
+import com.willfp.eco.core.Eco;
 import org.bukkit.Location;
 import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.Collection;
@@ -9,6 +11,8 @@ import java.util.Collection;
 /**
  * Internal interface for backend DropQueue implementations.
  */
+@ApiStatus.Internal
+@Eco.HandlerComponent
 public interface InternalDropQueue {
     /**
      * Add item to queue.

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

@@ -0,0 +1,84 @@
+package com.willfp.eco.core.entities;
+
+import org.apache.commons.lang.Validate;
+import org.bukkit.Location;
+import org.bukkit.NamespacedKey;
+import org.bukkit.entity.Entity;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+/**
+ * A custom entity has 3 components.
+ *
+ * <ul>
+ *     <li>The key to identify it</li>
+ *     <li>The test to check if any entity is this custom entity</li>
+ *     <li>The supplier to spawn the custom {@link org.bukkit.entity.Entity}</li>
+ * </ul>
+ */
+public class CustomEntity implements TestableEntity {
+    /**
+     * The key.
+     */
+    private final NamespacedKey key;
+
+    /**
+     * The test for Entities to pass.
+     */
+    private final Predicate<@NotNull Entity> test;
+
+    /**
+     * The provider to spawn the entity.
+     */
+    private final Function<Location, Entity> provider;
+
+    /**
+     * Create a new custom entity.
+     *
+     * @param key      The entity key.
+     * @param test     The test.
+     * @param provider The provider to spawn the entity.
+     */
+    public CustomEntity(@NotNull final NamespacedKey key,
+                        @NotNull final Predicate<@NotNull Entity> test,
+                        @NotNull final Function<Location, Entity> provider) {
+        this.key = key;
+        this.test = test;
+        this.provider = provider;
+    }
+
+    @Override
+    public boolean matches(@Nullable final Entity entity) {
+        if (entity == null) {
+            return false;
+        }
+
+        return test.test(entity);
+    }
+
+    @Override
+    public Entity spawn(@NotNull final Location location) {
+        Validate.notNull(location.getWorld());
+
+        return provider.apply(location);
+    }
+
+    /**
+     * Register the entity.
+     */
+    public void register() {
+        Entities.registerCustomEntity(this.getKey(), this);
+    }
+
+    /**
+     * Get the key.
+     *
+     * @return The key.
+     */
+    public NamespacedKey getKey() {
+        return this.key;
+    }
+}

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

@@ -0,0 +1,10 @@
+package com.willfp.eco.core.entities;
+
+import org.bukkit.entity.Entity;
+
+/**
+ * Interface for Dummy Entities in order to filter them using instanceof.
+ */
+public interface DummyEntity extends Entity {
+
+}

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

@@ -0,0 +1,232 @@
+package com.willfp.eco.core.entities;
+
+import com.willfp.eco.core.entities.args.EntityArgParseResult;
+import com.willfp.eco.core.entities.args.EntityArgParser;
+import com.willfp.eco.core.entities.impl.EmptyTestableEntity;
+import com.willfp.eco.core.entities.impl.ModifiedTestableEntity;
+import com.willfp.eco.core.entities.impl.SimpleTestableEntity;
+import com.willfp.eco.util.NamespacedKeyUtils;
+import org.bukkit.Location;
+import org.bukkit.NamespacedKey;
+import org.bukkit.entity.Entity;
+import org.bukkit.entity.EntityType;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
+
+/**
+ * Class to manage all custom and vanilla entities.
+ */
+public final class Entities {
+    /**
+     * All entities.
+     */
+    private static final Map<NamespacedKey, TestableEntity> REGISTRY = new ConcurrentHashMap<>();
+
+    /**
+     * All entity parsers.
+     */
+    private static final List<EntityArgParser> ARG_PARSERS = new ArrayList<>();
+
+    /**
+     * The lookup handler.
+     */
+    private static final EntitiesLookupHandler ENTITIES_LOOKUP_HANDLER = new EntitiesLookupHandler(Entities::doParse);
+
+    /**
+     * Register a new custom item.
+     *
+     * @param key  The key of the item.
+     * @param item The item.
+     */
+    public static void registerCustomEntity(@NotNull final NamespacedKey key,
+                                            @NotNull final TestableEntity item) {
+        REGISTRY.put(key, item);
+    }
+
+    /**
+     * Register a new arg parser.
+     *
+     * @param parser The parser.
+     */
+    public static void registerArgParser(@NotNull final EntityArgParser parser) {
+        ARG_PARSERS.add(parser);
+    }
+
+    /**
+     * Remove an entity.
+     *
+     * @param key The key of the entity.
+     */
+    public static void removeCustomEntity(@NotNull final NamespacedKey key) {
+        REGISTRY.remove(key);
+    }
+
+    /**
+     * This is the backbone of the entire eco entity system.
+     * <p>
+     * You can look up a TestableEntity for any type or custom entity,
+     * and it will return it with any modifiers passed as parameters.
+     * <p>
+     * If you want to get an Entity instance from this, then just call
+     * {@link TestableEntity#spawn(Location)}.
+     * <p>
+     * The advantages of the testable entity system are that there is the inbuilt
+     * {@link TestableEntity#matches(Entity)} - this allows to check if any entity
+     * is that testable entity; which may sound negligible, but actually it allows for
+     * much more power and flexibility. For example, you can have an entity with an
+     * extra metadata tag, extra lore lines, different display name - and it
+     * will still work as long as the test passes.
+     *
+     * @param key The lookup string.
+     * @return The testable entity, or an empty testable entity if not found.
+     */
+    @NotNull
+    public static TestableEntity lookup(@NotNull final String key) {
+        return ENTITIES_LOOKUP_HANDLER.parseKey(key);
+    }
+
+    @NotNull
+    private static TestableEntity doParse(@NotNull final String[] args) {
+        if (args.length == 0) {
+            return new EmptyTestableEntity();
+        }
+
+        TestableEntity entity;
+
+        String[] split = args[0].toLowerCase().split(":");
+
+        if (split.length == 1) {
+            EntityType type;
+            try {
+                type = EntityType.valueOf(args[0].toUpperCase());
+            } catch (IllegalArgumentException e) {
+                return new EmptyTestableEntity();
+            }
+            entity = new SimpleTestableEntity(type);
+        } else {
+            String namespace = split[0];
+            String keyID = split[1];
+            NamespacedKey namespacedKey = NamespacedKeyUtils.create(namespace, keyID);
+
+            TestableEntity part = REGISTRY.get(namespacedKey);
+
+            if (part == null) {
+                return new EmptyTestableEntity();
+            }
+
+            entity = part;
+        }
+
+        String[] modifierArgs = Arrays.copyOfRange(args, 1, args.length);
+
+        List<EntityArgParseResult> parseResults = new ArrayList<>();
+
+        for (EntityArgParser argParser : ARG_PARSERS) {
+            EntityArgParseResult result = argParser.parseArguments(modifierArgs);
+            if (result != null) {
+                parseResults.add(result);
+            }
+        }
+
+        Function<Location, Entity> spawner = entity::spawn;
+
+        if (!parseResults.isEmpty()) {
+            entity = new ModifiedTestableEntity(
+                    entity,
+                    test -> {
+                        for (EntityArgParseResult parseResult : parseResults) {
+                            if (!parseResult.test().test(test)) {
+                                return false;
+                            }
+                        }
+
+                        return true;
+                    },
+                    location -> {
+                        Entity spawned = spawner.apply(location);
+
+                        for (EntityArgParseResult parseResult : parseResults) {
+                            parseResult.modifier().accept(spawned);
+                        }
+
+                        return spawned;
+                    }
+            );
+        }
+
+        return entity;
+    }
+
+    /**
+     * Get a Testable Entity from an ItemStack.
+     * <p>
+     * Will search for registered entity first. If there are no matches in the registry,
+     * then it will return a {@link com.willfp.eco.core.entities.impl.SimpleTestableEntity} matching the entity type.
+     * <p>
+     * If the entity is not custom and has unknown type, this will return null.
+     *
+     * @param entity The Entity.
+     * @return The found Testable Entity.
+     */
+    @Nullable
+    public static TestableEntity getEntity(@Nullable final Entity entity) {
+        if (entity == null) {
+            return null;
+        }
+
+        TestableEntity customEntity = getEntity(entity);
+
+        if (customEntity != null) {
+            return customEntity;
+        }
+
+        for (TestableEntity known : REGISTRY.values()) {
+            if (known.matches(entity)) {
+                return known;
+            }
+        }
+
+        if (entity.getType() == EntityType.UNKNOWN) {
+            return null;
+        }
+
+        return new SimpleTestableEntity(entity.getType());
+    }
+
+    /**
+     * Get if entity is a custom entity.
+     *
+     * @param entity The entity to check.
+     * @return If is custom.
+     */
+    public static boolean isCustomEntity(@NotNull final Entity entity) {
+        for (TestableEntity testable : REGISTRY.values()) {
+            if (testable.matches(entity)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Get all registered custom items.
+     *
+     * @return A set of all items.
+     */
+    public static Set<TestableEntity> getCustomEntities() {
+        return new HashSet<>(REGISTRY.values());
+    }
+
+    private Entities() {
+        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    }
+}

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

@@ -0,0 +1,48 @@
+package com.willfp.eco.core.entities;
+
+import com.willfp.eco.core.entities.impl.EmptyTestableEntity;
+import com.willfp.eco.core.entities.impl.GroupedTestableEntities;
+import com.willfp.eco.core.lookup.LookupHandler;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+import java.util.function.Function;
+
+/**
+ * Handle item lookup strings.
+ */
+public class EntitiesLookupHandler implements LookupHandler<TestableEntity> {
+    /**
+     * The parser.
+     */
+    private final Function<String[], @NotNull TestableEntity> parser;
+
+    /**
+     * Create new lookup handler.
+     *
+     * @param parser The parser.
+     */
+    public EntitiesLookupHandler(@NotNull final Function<String[], @NotNull TestableEntity> parser) {
+        this.parser = parser;
+    }
+
+    @Override
+    public @NotNull TestableEntity parse(@NotNull final String[] args) {
+        return parser.apply(args);
+    }
+
+    @Override
+    public boolean validate(@NotNull final TestableEntity object) {
+        return !(object instanceof EmptyTestableEntity);
+    }
+
+    @Override
+    public @NotNull TestableEntity getFailsafe() {
+        return new EmptyTestableEntity();
+    }
+
+    @Override
+    public @NotNull TestableEntity join(@NotNull final Collection<TestableEntity> options) {
+        return new GroupedTestableEntities(options);
+    }
+}

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

@@ -0,0 +1,29 @@
+package com.willfp.eco.core.entities;
+
+import com.willfp.eco.core.lookup.Testable;
+import org.bukkit.Location;
+import org.bukkit.entity.Entity;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * An item with a test to see if any item is that item.
+ */
+public interface TestableEntity extends Testable<Entity> {
+    /**
+     * If an Entity matches the test.
+     *
+     * @param entity The entity to test.
+     * @return If the entity matches.
+     */
+    @Override
+    boolean matches(@Nullable Entity entity);
+
+    /**
+     * Spawn the entity.
+     *
+     * @param location The location.
+     * @return The entity.
+     */
+    Entity spawn(@NotNull Location location);
+}

eco-api/src/main/java/com/willfp/eco/core/entities/args/EntityArgParseResult.java

@@ -0,0 +1,33 @@
+package com.willfp.eco.core.entities.args;
+
+import org.bukkit.entity.Entity;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+
+/**
+ * @param test     The test for the entity.
+ * @param modifier The modifier to apply to the entity.
+ * @see EntityArgParser
+ */
+public record EntityArgParseResult(@NotNull Predicate<Entity> test,
+                                   @NotNull Consumer<Entity> modifier) {
+    /**
+     * Kotlin destructuring support.
+     *
+     * @return The test.
+     */
+    public Predicate<Entity> component1() {
+        return test;
+    }
+
+    /**
+     * Kotlin destructuring support.
+     *
+     * @return The modifier.
+     */
+    public Consumer<Entity> component2() {
+        return modifier;
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/entities/args/EntityArgParser.java

@@ -0,0 +1,20 @@
+package com.willfp.eco.core.entities.args;
+
+import com.willfp.eco.core.entities.TestableEntity;
+import org.bukkit.Location;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * An argument parser should generate the predicate as well
+ * as modify the Entity for {@link TestableEntity#spawn(Location)}.
+ */
+public interface EntityArgParser {
+    /**
+     * Parse the arguments.
+     *
+     * @param args The arguments.
+     * @return The predicate test to apply to the modified entity.
+     */
+    @Nullable EntityArgParseResult parseArguments(@NotNull String[] args);
+}

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

@@ -0,0 +1,33 @@
+package com.willfp.eco.core.entities.impl;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.entities.TestableEntity;
+import org.apache.commons.lang.Validate;
+import org.bukkit.Location;
+import org.bukkit.entity.Entity;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Empty entity.
+ */
+public class EmptyTestableEntity implements TestableEntity {
+    /**
+     * Create a new empty testable entity.
+     */
+    public EmptyTestableEntity() {
+
+    }
+
+    @Override
+    public boolean matches(@Nullable final Entity entity) {
+        return false;
+    }
+
+    @Override
+    public Entity spawn(@NotNull final Location location) {
+        Validate.notNull(location.getWorld());
+
+        return Eco.getHandler().createDummyEntity(location);
+    }
+}

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

@@ -0,0 +1,68 @@
+package com.willfp.eco.core.entities.impl;
+
+import com.willfp.eco.core.entities.TestableEntity;
+import com.willfp.eco.util.NumberUtils;
+import org.apache.commons.lang.Validate;
+import org.bukkit.Location;
+import org.bukkit.entity.Entity;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+/**
+ * A group of testable entities.
+ *
+ * @see com.willfp.eco.core.entities.CustomEntity
+ */
+public class GroupedTestableEntities implements TestableEntity {
+    /**
+     * The children.
+     */
+    private final Collection<TestableEntity> children;
+
+    /**
+     * Create a new group of testable entities.
+     *
+     * @param children The children.
+     */
+    public GroupedTestableEntities(@NotNull final Collection<TestableEntity> children) {
+        Validate.isTrue(!children.isEmpty(), "Group must have at least one child!");
+
+        this.children = children;
+    }
+
+    /**
+     * If the item matches any children.
+     *
+     * @param entity The entity to test.
+     * @return If the entity matches the test of any children.
+     */
+    @Override
+    public boolean matches(@Nullable final Entity entity) {
+        for (TestableEntity child : children) {
+            if (child.matches(entity)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    @Override
+    public Entity spawn(@NotNull final Location location) {
+        return new ArrayList<>(children)
+                .get(NumberUtils.randInt(0, children.size() - 1))
+                .spawn(location);
+    }
+
+    /**
+     * Get the children.
+     *
+     * @return The children.
+     */
+    public Collection<TestableEntity> getChildren() {
+        return new ArrayList<>(children);
+    }
+}

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

@@ -0,0 +1,69 @@
+package com.willfp.eco.core.entities.impl;
+
+import com.willfp.eco.core.entities.TestableEntity;
+import org.apache.commons.lang.Validate;
+import org.bukkit.Location;
+import org.bukkit.entity.Entity;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+/**
+ * Existing testable entity with an extra filter.
+ *
+ * @see com.willfp.eco.core.entities.CustomEntity
+ */
+public class ModifiedTestableEntity implements TestableEntity {
+    /**
+     * The item.
+     */
+    private final TestableEntity handle;
+
+    /**
+     * The amount.
+     */
+    private final Predicate<Entity> test;
+
+    /**
+     * The provider to spawn the entity.
+     */
+    private final Function<Location, Entity> provider;
+
+    /**
+     * Create a new modified testable entity.
+     *
+     * @param entity   The base entity.
+     * @param test     The test.
+     * @param provider The provider to spawn the entity.
+     */
+    public ModifiedTestableEntity(@NotNull final TestableEntity entity,
+                                  @NotNull final Predicate<@NotNull Entity> test,
+                                  @NotNull final Function<Location, Entity> provider) {
+        this.handle = entity;
+        this.test = test;
+        this.provider = provider;
+    }
+
+    @Override
+    public boolean matches(@Nullable final Entity entity) {
+        return entity != null && handle.matches(entity) && test.test(entity);
+    }
+
+    @Override
+    public Entity spawn(@NotNull final Location location) {
+        Validate.notNull(location.getWorld());
+
+        return provider.apply(location);
+    }
+
+    /**
+     * Get the handle.
+     *
+     * @return The handle.
+     */
+    public TestableEntity getHandle() {
+        return this.handle;
+    }
+}

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

@@ -0,0 +1,53 @@
+package com.willfp.eco.core.entities.impl;
+
+import com.willfp.eco.core.entities.TestableEntity;
+import org.apache.commons.lang.Validate;
+import org.bukkit.Location;
+import org.bukkit.entity.Entity;
+import org.bukkit.entity.EntityType;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Default vanilla entities.
+ */
+public class SimpleTestableEntity implements TestableEntity {
+    /**
+     * The entity type.
+     */
+    private final EntityType type;
+
+    /**
+     * Create a new simple testable entity.
+     *
+     * @param type The entity type.
+     */
+    public SimpleTestableEntity(@NotNull final EntityType type) {
+        this.type = type;
+
+        Validate.notNull(type.getEntityClass(), "Entity cannot be of unknown type!");
+    }
+
+    @Override
+    public boolean matches(@Nullable final Entity entity) {
+        return entity != null && entity.getType() == type;
+    }
+
+    @Override
+    public Entity spawn(@NotNull final Location location) {
+        Validate.notNull(location.getWorld());
+
+        assert type.getEntityClass() != null;
+
+        return location.getWorld().spawn(location, type.getEntityClass());
+    }
+
+    /**
+     * Get the type.
+     *
+     * @return The type.
+     */
+    public EntityType getType() {
+        return this.type;
+    }
+}

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

@@ -22,8 +22,30 @@ public interface FastItemStack {
      *
      * @param checkStored If stored NBT should also be checked.
      * @return A map of all enchantments.
+     * @deprecated Poorly named method. Use getEnchants instead.
      */
-    Map<Enchantment, Integer> getEnchantmentsOnItem(boolean checkStored);
+    @Deprecated(since = "6.24.0")
+    default Map<Enchantment, Integer> getEnchantmentsOnItem(boolean checkStored) {
+        return getEnchants(checkStored);
+    }
+
+    /**
+     * Get all enchantments on an item.
+     * Does not account for stored enchants.
+     *
+     * @return A map of all enchantments.
+     */
+    default Map<Enchantment, Integer> getEnchants() {
+        return getEnchants(false);
+    }
+
+    /**
+     * Get all enchantments on an item.
+     *
+     * @param checkStored If stored enchantments should be accounted for.
+     * @return A map of all enchantments.
+     */
+    Map<Enchantment, Integer> getEnchants(boolean checkStored);
 
     /**
      * Get the level of an enchantment on an item.

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

@@ -1,15 +1,19 @@
 package com.willfp.eco.core.gui;
 
+import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.gui.menu.MenuBuilder;
 import com.willfp.eco.core.gui.slot.SlotBuilder;
 import com.willfp.eco.core.gui.slot.functional.SlotProvider;
 import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
 /**
  * Internal component used by {@link com.willfp.eco.core.gui.menu.Menu#builder(int)}
  * and {@link com.willfp.eco.core.gui.slot.Slot#builder(ItemStack)}.
  */
+@ApiStatus.Internal
+@Eco.HandlerComponent
 public interface GUIFactory {
     /**
      * Create slot builder.

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

@@ -1,6 +1,8 @@
 package com.willfp.eco.core.gui.slot;
 
 import com.willfp.eco.core.items.builder.ItemStackBuilder;
+import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
+import com.willfp.eco.core.recipe.parts.MaterialTestableItem;
 import com.willfp.eco.util.ListUtils;
 import org.bukkit.Material;
 import org.bukkit.inventory.ItemStack;
@@ -38,7 +40,7 @@ public class FillerMask {
      */
     public FillerMask(@NotNull final Material material,
                       @NotNull final String... pattern) {
-        this(new MaskMaterials(material), pattern);
+        this(new MaskItems(new MaterialTestableItem(material)), pattern);
     }
 
     /**
@@ -46,17 +48,33 @@ public class FillerMask {
      *
      * @param materials The mask materials.
      * @param pattern   The pattern.
+     * @deprecated Use {@link MaskItems} instead.
      */
+    @Deprecated(since = "6.24.0")
     public FillerMask(@NotNull final MaskMaterials materials,
                       @NotNull final String... pattern) {
-        if (Arrays.stream(materials.materials()).anyMatch(material -> material == Material.AIR)) {
-            throw new IllegalArgumentException("Materials cannot be air!");
+        this(
+                materials.toMaskItems(),
+                pattern
+        );
+    }
+
+    /**
+     * Create a new filler mask.
+     *
+     * @param items   The mask items.
+     * @param pattern The pattern.
+     */
+    public FillerMask(@NotNull final MaskItems items,
+                      @NotNull final String... pattern) {
+        if (Arrays.stream(items.items()).anyMatch(item -> item instanceof EmptyTestableItem)) {
+            throw new IllegalArgumentException("Items cannot be empty!");
         }
 
         mask = ListUtils.create2DList(6, 9);
 
-        for (int i = 0; i < materials.materials().length; i++) {
-            ItemStack itemStack = new ItemStackBuilder(materials.materials()[i])
+        for (int i = 0; i < items.items().length; i++) {
+            ItemStack itemStack = new ItemStackBuilder(items.items()[i])
                     .setDisplayName("&r")
                     .build();
 

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

@@ -0,0 +1,45 @@
+package com.willfp.eco.core.gui.slot;
+
+import com.willfp.eco.core.items.Items;
+import com.willfp.eco.core.items.TestableItem;
+import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
+import com.willfp.eco.core.recipe.parts.MaterialTestableItem;
+import org.bukkit.Material;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Mask materials store a set of items which can be accessed by
+ * a filler mask.
+ *
+ * @param items The items.
+ */
+public record MaskItems(@NotNull TestableItem... items) {
+    /**
+     * Create MaskItems from a list of item names.
+     *
+     * @param names The names.
+     * @return The mask items.
+     */
+    public static MaskItems fromItemNames(@NotNull final Iterable<String> names) {
+        List<TestableItem> items = new ArrayList<>();
+
+        for (String name : names) {
+            TestableItem item = Items.lookup(name);
+
+            if (item instanceof EmptyTestableItem) {
+                continue;
+            }
+
+            items.add(item);
+        }
+
+        if (items.isEmpty()) {
+            return new MaskItems(new MaterialTestableItem(Material.BLACK_STAINED_GLASS_PANE));
+        }
+
+        return new MaskItems(items.toArray(new TestableItem[0]));
+    }
+}

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

@@ -1,5 +1,6 @@
 package com.willfp.eco.core.gui.slot;
 
+import com.willfp.eco.core.items.Items;
 import org.bukkit.Material;
 import org.jetbrains.annotations.NotNull;
 
@@ -8,7 +9,16 @@ import org.jetbrains.annotations.NotNull;
  * a filler mask.
  *
  * @param materials The materials.
+ * @deprecated Use {@link MaskItems} instead.
  */
+@Deprecated(since = "6.24.0")
 public record MaskMaterials(@NotNull Material... materials) {
-
+    /**
+     * Convert MaskMaterials to MaskItems.
+     *
+     * @return The MaskItems.
+     */
+    public MaskItems toMaskItems() {
+        return new MaskItems(Items.fromMaterials(this.materials()));
+    }
 }

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

@@ -2,6 +2,7 @@ package com.willfp.eco.core.gui.slot;
 
 import com.willfp.eco.core.gui.slot.functional.SlotHandler;
 import com.willfp.eco.core.gui.slot.functional.SlotModifier;
+import com.willfp.eco.core.gui.slot.functional.SlotUpdater;
 import org.bukkit.event.inventory.InventoryClickEvent;
 import org.jetbrains.annotations.NotNull;
 
@@ -106,8 +107,23 @@ public interface SlotBuilder {
      *
      * @param modifier The modifier.
      * @return The builder.
+     * @deprecated Use {@link SlotBuilder#setUpdater(SlotUpdater)} instead.
      */
-    SlotBuilder setModifier(@NotNull SlotModifier modifier);
+    @Deprecated
+    default SlotBuilder setModifier(@NotNull SlotModifier modifier) {
+        return setUpdater((player, menu, previous) -> {
+            modifier.modify(player, menu, previous);
+            return previous;
+        });
+    }
+
+    /**
+     * Set the ItemStack updater.
+     *
+     * @param updater The updater.
+     * @return The builder.
+     */
+    SlotBuilder setUpdater(@NotNull SlotUpdater updater);
 
     /**
      * Set slot to be a captive slot.

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

@@ -7,8 +7,11 @@ import org.jetbrains.annotations.NotNull;
 
 /**
  * Interface to run on slot modify.
+ *
+ * @deprecated Use {@link SlotUpdater} instead.
  */
 @FunctionalInterface
+@Deprecated
 public interface SlotModifier {
     /**
      * Performs this operation on the given arguments.

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

@@ -0,0 +1,24 @@
+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;
+
+/**
+ * Interface to run on slot update.
+ */
+@FunctionalInterface
+public interface SlotUpdater {
+    /**
+     * Performs this operation on the given arguments.
+     *
+     * @param player   The player.
+     * @param menu     The menu.
+     * @param previous The previous ItemStack.
+     * @return The new ItemStack.
+     */
+    ItemStack update(@NotNull Player player,
+                     @NotNull Menu menu,
+                     @NotNull ItemStack previous);
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/antigrief/AntigriefManager.java

@@ -44,7 +44,8 @@ public final class AntigriefManager {
      * @param location The location.
      * @return If player can pick up item.
      */
-    public static boolean canPickupItem(@NotNull final Player player, @NotNull final Location location) {
+    public static boolean canPickupItem(@NotNull final Player player,
+                                        @NotNull final Location location) {
         return REGISTERED.stream().allMatch(antigriefWrapper -> antigriefWrapper.canPickupItem(player, location));
     }
 

eco-api/src/main/java/com/willfp/eco/core/integrations/customentities/CustomEntitiesManager.java

@@ -0,0 +1,40 @@
+package com.willfp.eco.core.integrations.customentities;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Class to handle custom entity integrations.
+ */
+public final class CustomEntitiesManager {
+    /**
+     * A set of all registered integrations.
+     */
+    private static final Set<CustomEntitiesWrapper> REGISTERED = new HashSet<>();
+
+    /**
+     * Register a new integration.
+     *
+     * @param integration The integration to register.
+     */
+    public static void register(@NotNull final CustomEntitiesWrapper integration) {
+        REGISTERED.add(integration);
+    }
+
+    /**
+     * Register all the custom entities for a specific plugin into eco.
+     *
+     * @see com.willfp.eco.core.entities.Entities
+     */
+    public static void registerAllEntities() {
+        for (CustomEntitiesWrapper wrapper : REGISTERED) {
+            wrapper.registerAllEntities();
+        }
+    }
+
+    private CustomEntitiesManager() {
+        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/customentities/CustomEntitiesWrapper.java

@@ -0,0 +1,15 @@
+package com.willfp.eco.core.integrations.customentities;
+
+import com.willfp.eco.core.integrations.Integration;
+
+/**
+ * Wrapper class for custom item integrations.
+ */
+public interface CustomEntitiesWrapper extends Integration {
+    /**
+     * Register all the custom entities for a specific plugin into eco.
+     *
+     * @see com.willfp.eco.core.entities.Entities
+     */
+    void registerAllEntities();
+}

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

@@ -1,10 +1,12 @@
 package com.willfp.eco.core.integrations.placeholder;
 
+import com.willfp.eco.core.EcoPlugin;
 import org.apache.commons.lang.Validate;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Objects;
 import java.util.function.Function;
 
 /**
@@ -28,12 +30,20 @@ public class PlaceholderEntry {
      */
     private final boolean requiresPlayer;
 
+    /**
+     * The plugin for the placeholder.
+     */
+    @Nullable
+    private final EcoPlugin plugin;
+
     /**
      * Create a placeholder entry that doesn't require a player.
      *
      * @param identifier The identifier of the placeholder.
      * @param function   A lambda to get the result of the placeholder given a player.
+     * @deprecated Specify a plugin.
      */
+    @Deprecated
     public PlaceholderEntry(@NotNull final String identifier,
                             @NotNull final Function<Player, String> function) {
         this(identifier, function, false);
@@ -45,10 +55,41 @@ public class PlaceholderEntry {
      * @param identifier     The identifier of the placeholder.
      * @param function       A lambda to get the result of the placeholder.
      * @param requiresPlayer If the placeholder requires a player.
+     * @deprecated Specify a plugin.
      */
+    @Deprecated
     public PlaceholderEntry(@NotNull final String identifier,
                             @NotNull final Function<Player, String> function,
                             final boolean requiresPlayer) {
+        this(null, identifier, function, requiresPlayer);
+    }
+
+    /**
+     * Create a placeholder entry that doesn't require a player.
+     *
+     * @param plugin     The plugin for the placeholder.
+     * @param identifier The identifier of the placeholder.
+     * @param function   A lambda to get the result of the placeholder given a player.
+     */
+    public PlaceholderEntry(@Nullable final EcoPlugin plugin,
+                            @NotNull final String identifier,
+                            @NotNull final Function<Player, String> function) {
+        this(plugin, identifier, function, false);
+    }
+
+    /**
+     * Create a placeholder entry that may require a player.
+     *
+     * @param plugin         The plugin for the placeholder.
+     * @param identifier     The identifier of the placeholder.
+     * @param function       A lambda to get the result of the placeholder.
+     * @param requiresPlayer If the placeholder requires a player.
+     */
+    public PlaceholderEntry(@Nullable final EcoPlugin plugin,
+                            @NotNull final String identifier,
+                            @NotNull final Function<Player, String> function,
+                            final boolean requiresPlayer) {
+        this.plugin = plugin;
         this.identifier = identifier;
         this.function = function;
         this.requiresPlayer = requiresPlayer;
@@ -85,10 +126,37 @@ public class PlaceholderEntry {
         return identifier;
     }
 
+    /**
+     * Get the plugin.
+     *
+     * @return The plugin.
+     */
+    @Nullable
+    public EcoPlugin getPlugin() {
+        return plugin;
+    }
+
     /**
      * Register the placeholder.
      */
     public void register() {
         PlaceholderManager.registerPlaceholder(this);
     }
+
+    @Override
+    public boolean equals(@Nullable final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (!(o instanceof PlaceholderEntry entry)) {
+            return false;
+        }
+        return Objects.equals(this.getIdentifier(), entry.getIdentifier())
+                && Objects.equals(this.getPlugin(), entry.getPlugin());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.getIdentifier(), this.getPlugin());
+    }
 }

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

@@ -5,6 +5,9 @@ import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * Wrapper class for placeholder integrations.
  */
@@ -24,4 +27,14 @@ public interface PlaceholderIntegration extends Integration {
      */
     String translate(@NotNull String text,
                      @Nullable Player player);
+
+    /**
+     * Find all placeholders in a given text.
+     *
+     * @param text The text.
+     * @return The placeholders.
+     */
+    default List<String> findPlaceholdersIn(@NotNull String text) {
+        return new ArrayList<>();
+    }
 }

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

@@ -1,13 +1,20 @@
 package com.willfp.eco.core.integrations.placeholder;
 
+import com.github.benmanes.caffeine.cache.Caffeine;
+import com.github.benmanes.caffeine.cache.LoadingCache;
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.EcoPlugin;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Class to handle placeholder integrations.
@@ -16,17 +23,24 @@ public final class PlaceholderManager {
     /**
      * All registered placeholders.
      */
-    private static final Map<String, PlaceholderEntry> REGISTERED_PLACEHOLDERS = new HashMap<>();
+    private static final Map<EcoPlugin, Map<String, PlaceholderEntry>> REGISTERED_PLACEHOLDERS = new HashMap<>();
 
     /**
      * All registered placeholder integrations.
      */
     private static final Set<PlaceholderIntegration> REGISTERED_INTEGRATIONS = new HashSet<>();
 
+    /**
+     * Placeholder Cache.
+     */
+    private static final LoadingCache<EntryWithPlayer, String> PLACEHOLDER_CACHE = Caffeine.newBuilder()
+            .expireAfterWrite(50, TimeUnit.MILLISECONDS)
+            .build(key -> key.entry.getResult(key.player));
+
     /**
      * Register a new placeholder integration.
      *
-     * @param integration The {@link PlaceholderIntegration} to register.
+     * @param integration The {@link com.willfp.eco.core.integrations.placeholder.PlaceholderIntegration} to register.
      */
     public static void addIntegration(@NotNull final PlaceholderIntegration integration) {
         integration.registerIntegration();
@@ -36,11 +50,14 @@ public final class PlaceholderManager {
     /**
      * Register a placeholder.
      *
-     * @param expansion The {@link PlaceholderEntry} to register.
+     * @param expansion The {@link com.willfp.eco.core.integrations.placeholder.PlaceholderEntry} to register.
      */
     public static void registerPlaceholder(@NotNull final PlaceholderEntry expansion) {
-        REGISTERED_PLACEHOLDERS.remove(expansion.getIdentifier());
-        REGISTERED_PLACEHOLDERS.put(expansion.getIdentifier(), expansion);
+        EcoPlugin plugin = expansion.getPlugin() == null ? Eco.getHandler().getEcoPlugin() : expansion.getPlugin();
+        Map<String, PlaceholderEntry> pluginPlaceholders = REGISTERED_PLACEHOLDERS
+                .getOrDefault(plugin, new HashMap<>());
+        pluginPlaceholders.put(expansion.getIdentifier(), expansion);
+        REGISTERED_PLACEHOLDERS.put(plugin, pluginPlaceholders);
     }
 
     /**
@@ -49,10 +66,36 @@ public final class PlaceholderManager {
      * @param player     The player to get the result from.
      * @param identifier The placeholder identifier.
      * @return The value of the placeholder.
+     * @deprecated Specify a plugin to get the result from.
      */
+    @Deprecated
     public static String getResult(@Nullable final Player player,
                                    @NotNull final String identifier) {
-        PlaceholderEntry entry = REGISTERED_PLACEHOLDERS.get(identifier.toLowerCase());
+        return getResult(player, identifier, null);
+    }
+
+    /**
+     * Get the result of a placeholder with respect to a player.
+     *
+     * @param player     The player to get the result from.
+     * @param identifier The placeholder identifier.
+     * @param plugin     The plugin for the placeholder.
+     * @return The value of the placeholder.
+     */
+    public static String getResult(@Nullable final Player player,
+                                   @NotNull final String identifier,
+                                   @Nullable final EcoPlugin plugin) {
+        EcoPlugin owner = plugin == null ? Eco.getHandler().getEcoPlugin() : plugin;
+        PlaceholderEntry entry = REGISTERED_PLACEHOLDERS.getOrDefault(owner, new HashMap<>()).get(identifier.toLowerCase());
+
+        if (entry == null && plugin != null) {
+            PlaceholderEntry alternate = REGISTERED_PLACEHOLDERS.getOrDefault(Eco.getHandler().getEcoPlugin(), new HashMap<>())
+                    .get(identifier.toLowerCase());
+            if (alternate != null) {
+                entry = alternate;
+            }
+        }
+
         if (entry == null) {
             return "";
         }
@@ -61,7 +104,7 @@ public final class PlaceholderManager {
             return "";
         }
 
-        return entry.getResult(player);
+        return PLACEHOLDER_CACHE.get(new EntryWithPlayer(entry, player));
     }
 
     /**
@@ -80,6 +123,26 @@ public final class PlaceholderManager {
         return processed;
     }
 
+    /**
+     * Find all placeholders in a given text.
+     *
+     * @param text The text.
+     * @return The placeholders.
+     */
+    public static List<String> findPlaceholdersIn(@NotNull final String text) {
+        List<String> found = new ArrayList<>();
+        for (PlaceholderIntegration integration : REGISTERED_INTEGRATIONS) {
+            found.addAll(integration.findPlaceholdersIn(text));
+        }
+
+        return found;
+    }
+
+    private static record EntryWithPlayer(@NotNull PlaceholderEntry entry,
+                                          @Nullable Player player) {
+
+    }
+
     private PlaceholderManager() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

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

@@ -66,7 +66,7 @@ public class CustomItem implements TestableItem {
 
     @Override
     public ItemStack getItem() {
-        return item;
+        return item.clone();
     }
 
     /**

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

@@ -0,0 +1,103 @@
+package com.willfp.eco.core.items;
+
+import com.willfp.eco.core.fast.FastItemStack;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * An item and its {@link com.willfp.eco.core.fast.FastItemStack} hash.
+ */
+public final class HashedItem {
+    /**
+     * The item.
+     */
+    private final ItemStack item;
+
+    /**
+     * The hash.
+     */
+    private final int hash;
+
+    /**
+     * Create new hashed item.
+     *
+     * @param item The item.
+     * @param hash The hash.
+     */
+    private HashedItem(@NotNull final ItemStack item,
+                       final int hash) {
+        this.item = item;
+        this.hash = hash;
+    }
+
+    /**
+     * Get the item.
+     *
+     * @return The ItemStack.
+     */
+    public ItemStack getItem() {
+        return this.item;
+    }
+
+    /**
+     * Get the hash.
+     *
+     * @return The hash.
+     */
+    public int getHash() {
+        return this.hash;
+    }
+
+    /**
+     * Kotlin destructuring support.
+     *
+     * @return The ItemStack.
+     */
+    public ItemStack component1() {
+        return this.getItem();
+    }
+
+    /**
+     * Kotlin destructuring support.
+     *
+     * @return The hash.
+     */
+    public int component2() {
+        return this.getHash();
+    }
+
+    @Override
+    public int hashCode() {
+        return this.hash;
+    }
+
+    @Override
+    public boolean equals(@Nullable final Object other) {
+        if (!(other instanceof HashedItem o)) {
+            return false;
+        }
+
+        return o.hash == this.hash;
+    }
+
+    /**
+     * Hashed item from an item.
+     *
+     * @param item The item.
+     * @return The hashed item.
+     */
+    public static HashedItem of(@NotNull final ItemStack item) {
+        return new HashedItem(item, FastItemStack.wrap(item).hashCode());
+    }
+
+    /**
+     * Hashed item from a fast item stack.
+     *
+     * @param item The item.
+     * @return The hashed item.
+     */
+    public static HashedItem of(@NotNull final FastItemStack item) {
+        return new HashedItem(item.unwrap(), item.hashCode());
+    }
+}

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

@@ -1,5 +1,7 @@
 package com.willfp.eco.core.items;
 
+import com.github.benmanes.caffeine.cache.Caffeine;
+import com.github.benmanes.caffeine.cache.LoadingCache;
 import com.willfp.eco.core.items.args.LookupArgParser;
 import com.willfp.eco.core.items.provider.ItemProvider;
 import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
@@ -17,10 +19,13 @@ import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -33,6 +38,25 @@ public final class Items {
      */
     private static final Map<NamespacedKey, TestableItem> REGISTRY = new ConcurrentHashMap<>();
 
+    /**
+     * Cached custom item lookups, using {@link HashedItem}.
+     */
+    private static final LoadingCache<HashedItem, Optional<TestableItem>> CACHE = Caffeine.newBuilder()
+            .expireAfterAccess(5, TimeUnit.MINUTES)
+            .build(
+                    key -> {
+                        TestableItem match = null;
+                        for (TestableItem item : REGISTRY.values()) {
+                            if (item.matches(key.getItem())) {
+                                match = item;
+                                break;
+                            }
+                        }
+
+                        return Optional.ofNullable(match);
+                    }
+            );
+
     /**
      * All item providers.
      */
@@ -43,6 +67,11 @@ public final class Items {
      */
     private static final List<LookupArgParser> ARG_PARSERS = new ArrayList<>();
 
+    /**
+     * The handler.
+     */
+    private static final ItemsLookupHandler ITEMS_LOOKUP_HANDLER = new ItemsLookupHandler(Items::doParse);
+
     /**
      * Register a new custom item.
      *
@@ -106,19 +135,11 @@ public final class Items {
      */
     @NotNull
     public static TestableItem lookup(@NotNull final String key) {
-        if (key.contains("?")) {
-            String[] options = key.split("\\?");
-            for (String option : options) {
-                TestableItem lookup = lookup(option);
-                if (!(lookup instanceof EmptyTestableItem)) {
-                    return lookup;
-                }
-            }
+        return ITEMS_LOOKUP_HANDLER.parseKey(key);
+    }
 
-            return new EmptyTestableItem();
-        }
-
-        String[] args = key.split(" ");
+    @NotNull
+    private static TestableItem doParse(@NotNull final String[] args) {
         if (args.length == 0) {
             return new EmptyTestableItem();
         }
@@ -192,7 +213,7 @@ public final class Items {
             }
         }
 
-        // Marked as redundant but i am covering all bases here
+        // Marked as redundant but I am covering all bases here
         if (item == null || item instanceof EmptyTestableItem) {
             return new EmptyTestableItem();
         }
@@ -274,12 +295,7 @@ public final class Items {
      * @return If is recipe.
      */
     public static boolean isCustomItem(@NotNull final ItemStack itemStack) {
-        for (TestableItem item : REGISTRY.values()) {
-            if (item.matches(itemStack)) {
-                return true;
-            }
-        }
-        return false;
+        return getCustomItem(itemStack) != null;
     }
 
     /**
@@ -290,12 +306,7 @@ public final class Items {
      */
     @Nullable
     public static CustomItem getCustomItem(@NotNull final ItemStack itemStack) {
-        for (TestableItem item : REGISTRY.values()) {
-            if (item.matches(itemStack)) {
-                return getOrWrap(item);
-            }
-        }
-        return null;
+        return CACHE.get(HashedItem.of(itemStack)).map(Items::getOrWrap).orElse(null);
     }
 
     /**
@@ -329,6 +340,35 @@ public final class Items {
         }
     }
 
+    /**
+     * Convert an array of materials to an array of testable items.
+     *
+     * @param materials The materials.
+     * @return An array of functionally identical testable items.
+     */
+    @NotNull
+    public static TestableItem[] fromMaterials(@NotNull final Material... materials) {
+        return Arrays.stream(materials)
+                .map(MaterialTestableItem::new)
+                .toArray(MaterialTestableItem[]::new);
+    }
+
+    /**
+     * Convert a collection of materials into a collection of testable items.
+     *
+     * @param materials The materials.
+     * @return A collection of functionally identical testable items.
+     */
+    @NotNull
+    public static Collection<TestableItem> fromMaterials(@NotNull final Iterable<Material> materials) {
+        List<TestableItem> items = new ArrayList<>();
+        for (Material material : materials) {
+            items.add(new MaterialTestableItem(material));
+        }
+
+        return items;
+    }
+
     private Items() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

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

@@ -0,0 +1,48 @@
+package com.willfp.eco.core.items;
+
+import com.willfp.eco.core.lookup.LookupHandler;
+import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
+import com.willfp.eco.core.recipe.parts.GroupedTestableItems;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+import java.util.function.Function;
+
+/**
+ * Handle item lookup strings.
+ */
+public class ItemsLookupHandler implements LookupHandler<TestableItem> {
+    /**
+     * The parser.
+     */
+    private final Function<String[], @NotNull TestableItem> parser;
+
+    /**
+     * Create new lookup handler.
+     *
+     * @param parser The parser.
+     */
+    public ItemsLookupHandler(@NotNull final Function<String[], @NotNull TestableItem> parser) {
+        this.parser = parser;
+    }
+
+    @Override
+    public @NotNull TestableItem parse(@NotNull final String[] args) {
+        return parser.apply(args);
+    }
+
+    @Override
+    public boolean validate(@NotNull final TestableItem object) {
+        return !(object instanceof EmptyTestableItem);
+    }
+
+    @Override
+    public @NotNull TestableItem getFailsafe() {
+        return new EmptyTestableItem();
+    }
+
+    @Override
+    public @NotNull TestableItem join(@NotNull final Collection<TestableItem> options) {
+        return new GroupedTestableItems(options);
+    }
+}

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

@@ -1,18 +1,20 @@
 package com.willfp.eco.core.items;
 
+import com.willfp.eco.core.lookup.Testable;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.Nullable;
 
 /**
  * An item with a test to see if any item is that item.
  */
-public interface TestableItem {
+public interface TestableItem extends Testable<ItemStack> {
     /**
      * If an ItemStack matches the recipe part.
      *
      * @param itemStack The item to test.
      * @return If the item matches.
      */
+    @Override
     boolean matches(@Nullable ItemStack itemStack);
 
     /**

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

@@ -1,30 +0,0 @@
-package com.willfp.eco.core.items.args;
-
-import org.bukkit.Bukkit;
-import org.bukkit.inventory.ItemStack;
-import org.bukkit.inventory.meta.ItemMeta;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.function.Predicate;
-
-/**
- * Parse leather armor colors.
- *
- * @deprecated Moved to internals.
- */
-@Deprecated(since = "6.16.0", forRemoval = true)
-public class ColorArgParser implements LookupArgParser {
-    /**
-     * Instantiate arg parser.
-     */
-    public ColorArgParser() {
-        Bukkit.getLogger().severe("Instantiation of class marked for removal! (" + this.getClass().getName() + "), this will throw an error in a future release!");
-    }
-
-    @Override
-    public @Nullable Predicate<ItemStack> parseArguments(@NotNull final String[] args,
-                                                         @NotNull final ItemMeta meta) {
-        return null;
-    }
-}

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

@@ -1,30 +0,0 @@
-package com.willfp.eco.core.items.args;
-
-import org.bukkit.Bukkit;
-import org.bukkit.inventory.ItemStack;
-import org.bukkit.inventory.meta.ItemMeta;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.function.Predicate;
-
-/**
- * Parse custom model data.
- *
- * @deprecated Moved to internals.
- */
-@Deprecated(since = "6.16.0", forRemoval = true)
-public class CustomModelDataArgParser implements LookupArgParser {
-    /**
-     * Instantiate arg parser.
-     */
-    public CustomModelDataArgParser() {
-        Bukkit.getLogger().severe("Instantiation of class marked for removal! (" + this.getClass().getName() + "), this will throw an error in a future release!");
-    }
-
-    @Override
-    public @Nullable Predicate<ItemStack> parseArguments(@NotNull final String[] args,
-                                                         @NotNull final ItemMeta meta) {
-        return null;
-    }
-}

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

@@ -1,30 +0,0 @@
-package com.willfp.eco.core.items.args;
-
-import org.bukkit.Bukkit;
-import org.bukkit.inventory.ItemStack;
-import org.bukkit.inventory.meta.ItemMeta;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.function.Predicate;
-
-/**
- * Parses enchantment arguments.
- *
- * @deprecated Moved to internals.
- */
-@Deprecated(since = "6.16.0", forRemoval = true)
-public class EnchantmentArgParser implements LookupArgParser {
-    /**
-     * Instantiate arg parser.
-     */
-    public EnchantmentArgParser() {
-        Bukkit.getLogger().severe("Instantiation of class marked for removal! (" + this.getClass().getName() + "), this will throw an error in a future release!");
-    }
-
-    @Override
-    public @Nullable Predicate<ItemStack> parseArguments(@NotNull final String[] args,
-                                                         @NotNull final ItemMeta meta) {
-        return null;
-    }
-}

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

@@ -1,30 +0,0 @@
-package com.willfp.eco.core.items.args;
-
-import org.bukkit.Bukkit;
-import org.bukkit.inventory.ItemStack;
-import org.bukkit.inventory.meta.ItemMeta;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.function.Predicate;
-
-/**
- * Parse skull textures.
- *
- * @deprecated Moved to internals.
- */
-@Deprecated(since = "6.16.0", forRemoval = true)
-public class TextureArgParser implements LookupArgParser {
-    /**
-     * Instantiate arg parser.
-     */
-    public TextureArgParser() {
-        Bukkit.getLogger().severe("Instantiation of class marked for removal! (" + this.getClass().getName() + "), this will throw an error in a future release!");
-    }
-
-    @Override
-    public @Nullable Predicate<ItemStack> parseArguments(@NotNull final String[] args,
-                                                         @NotNull final ItemMeta meta) {
-        return null;
-    }
-}

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

@@ -39,7 +39,7 @@ public class EnchantedBookBuilder extends AbstractItemStackBuilder<EnchantmentSt
      * @return The builder.
      */
     public EnchantedBookBuilder addStoredEnchantment(@NotNull final Supplier<Enchantment> enchantment,
-                                                     final Supplier<Integer> level) {
+                                                     @NotNull final Supplier<Integer> level) {
         return this.addStoredEnchantment(enchantment.get(), level.get());
     }
 }

eco-api/src/main/java/com/willfp/eco/core/lookup/LookupHandler.java

@@ -0,0 +1,76 @@
+package com.willfp.eco.core.lookup;
+
+import com.willfp.eco.util.StringUtils;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+
+/**
+ * Handle lookups, used in {@link com.willfp.eco.core.entities.Entities} and {@link com.willfp.eco.core.items.Items}.
+ *
+ * @param <T> The type of testable object, eg {@link com.willfp.eco.core.items.TestableItem}.
+ */
+public interface LookupHandler<T extends Testable<?>> {
+    /**
+     * Parse lookup string completely.
+     * <p>
+     * You shouldn't override this method unless you're doing something
+     * technically interesting or weird. This is the entry point for all
+     * lookup parsers, {@link this#parse(String[])} is to specify implementation-specific
+     * parsing.
+     *
+     * @param key The key.
+     * @return The object.
+     */
+    default T parseKey(@NotNull String key) {
+        for (SegmentParser parser : SegmentParser.values()) {
+            T generated = parser.parse(key, this);
+
+            if (generated != null) {
+                return generated;
+            }
+        }
+
+        String[] args = StringUtils.parseTokens(key);
+
+        return this.parse(args);
+    }
+
+    /**
+     * Parse arguments to an object.
+     *
+     * @param args The arguments.
+     * @return The object.
+     */
+    @NotNull
+    T parse(@NotNull String[] args);
+
+    /**
+     * Validate an object.
+     *
+     * @param object The object.
+     * @return If validated.
+     */
+    boolean validate(@NotNull T object);
+
+    /**
+     * Get the failsafe object.
+     * <p>
+     * A failsafe object should never pass {@link this#validate(Testable)}, as this will
+     * cause issues with segment parsers. See {@link com.willfp.eco.core.items.ItemsLookupHandler} and
+     * {@link com.willfp.eco.core.recipe.parts.EmptyTestableItem} for examples.
+     *
+     * @return The failsafe.
+     */
+    @NotNull
+    T getFailsafe();
+
+    /**
+     * Join several options together.
+     *
+     * @param options The options.
+     * @return The joined object.
+     */
+    @NotNull
+    T join(@NotNull Collection<T> options);
+}

eco-api/src/main/java/com/willfp/eco/core/lookup/SegmentParser.java

@@ -0,0 +1,83 @@
+package com.willfp.eco.core.lookup;
+
+import com.willfp.eco.util.StringUtils;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+/**
+ * Parse a key into segments.
+ */
+public abstract class SegmentParser {
+    /**
+     * All segment parsers.
+     */
+    private static final List<SegmentParser> REGISTERED = new ArrayList<>();
+
+    /**
+     * The pattern to split keys on.
+     */
+    private final String pattern;
+
+    /**
+     * Create new lookup segment parser.
+     *
+     * @param pattern The pattern.
+     */
+    protected SegmentParser(@NotNull final String pattern) {
+        this.pattern = pattern;
+    }
+
+    /**
+     * Register the parser.
+     *
+     * @return The parser.
+     */
+    public SegmentParser register() {
+        REGISTERED.add(this);
+        return this;
+    }
+
+    /**
+     * Try parse segments from key.
+     *
+     * @param key     The key.
+     * @param handler The handler.
+     * @param <T>     The object type.
+     * @return Null if no segments were found, or the object generated from the segments.
+     */
+    @Nullable
+    public <T extends Testable<?>> T parse(@NotNull final String key,
+                                           @NotNull final LookupHandler<T> handler) {
+        if (!key.contains(" " + pattern + " ")) {
+            return null;
+        }
+
+        String[] segments = StringUtils.splitAround(key, pattern);
+
+        return handleSegments(segments, handler);
+    }
+
+    /**
+     * Handle segments from key.
+     *
+     * @param segments The key segments.
+     * @param handler  The handler.
+     * @param <T>      The object type.
+     * @return The returned object.
+     */
+    protected abstract <T extends Testable<?>> T handleSegments(@NotNull String[] segments,
+                                                                @NotNull LookupHandler<T> handler);
+
+    /**
+     * Get all segment parsers.
+     *
+     * @return All parsers.
+     */
+    public static Collection<SegmentParser> values() {
+        return new ArrayList<>(REGISTERED);
+    }
+}

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

@@ -0,0 +1,18 @@
+package com.willfp.eco.core.lookup;
+
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Interface for testing if any object matches another object.
+ *
+ * @param <T> The type of object.
+ */
+public interface Testable<T> {
+    /**
+     * If object matches the test.
+     *
+     * @param other The other object.
+     * @return If matches.
+     */
+    boolean matches(@Nullable T other);
+}

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

@@ -2,6 +2,9 @@ package com.willfp.eco.core.proxy;
 
 import org.bukkit.Bukkit;
 
+import java.util.Arrays;
+import java.util.List;
+
 /**
  * Proxy / NMS constants.
  */
@@ -11,6 +14,14 @@ public final class ProxyConstants {
      */
     public static final String NMS_VERSION = Bukkit.getServer().getClass().getPackage().getName().split("\\.")[3];
 
+    /**
+     * All supported NMS versions.
+     */
+    public static final List<String> SUPPORTED_VERSIONS = Arrays.asList(
+            "v1_17_R1",
+            "v1_18_R1"
+    );
+
     private ProxyConstants() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

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

@@ -5,12 +5,25 @@ import org.jetbrains.annotations.NotNull;
 /**
  * Generic error with proxy loading.
  */
-public class ProxyError extends RuntimeException {
+public class ProxyError extends Error {
     /**
      * Thrown if there is an error getting a proxy.
      *
      * @param message The message to send.
+     * @param cause   The cause.
      */
+    public ProxyError(@NotNull final String message,
+                      @NotNull final Throwable cause) {
+        super(message, cause);
+    }
+
+    /**
+     * Thrown if there is an error getting a proxy.
+     *
+     * @param message The message to send.
+     * @deprecated Proxy Errors should include a cause.
+     */
+    @Deprecated
     public ProxyError(@NotNull final String message) {
         super(message);
     }

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

@@ -0,0 +1,15 @@
+package com.willfp.eco.core.proxy.exceptions;
+
+import com.willfp.eco.core.proxy.ProxyConstants;
+
+/**
+ * Server running an unsupported version.
+ */
+public class UnsupportedVersionError extends Error {
+    /**
+     * Thrown if the server is running an unsupported version.
+     */
+    public UnsupportedVersionError() {
+        super("You're running an unsupported server version: " + ProxyConstants.NMS_VERSION);
+    }
+}

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

@@ -1,17 +1,30 @@
 package com.willfp.eco.core.proxy.exceptions;
 
+import com.willfp.eco.core.proxy.ProxyConstants;
 import org.jetbrains.annotations.NotNull;
 
 /**
  * Error if the server is running an unsupported version.
+ *
+ * @deprecated Poorly named, exception when it's actually an error, contains doubly nested errors.
  */
+@Deprecated(since = "6.24.0", forRemoval = true)
 public class UnsupportedVersionException extends ProxyError {
     /**
      * Thrown if the server is running an unsupported NMS version.
      *
      * @param message The message to send.
+     * @deprecated Use the default constructor.
      */
+    @Deprecated(since = "6.24.0")
     public UnsupportedVersionException(@NotNull final String message) {
         super(message);
     }
+
+    /**
+     * Thrown if the server is running an unsupported NMS version.
+     */
+    public UnsupportedVersionException() {
+        super("You're running an unsupported server version: " + ProxyConstants.NMS_VERSION, new IllegalStateException());
+    }
 }

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

@@ -6,6 +6,8 @@ import com.willfp.eco.core.EcoPlugin;
 import com.willfp.eco.core.items.Items;
 import com.willfp.eco.core.recipe.recipes.CraftingRecipe;
 import com.willfp.eco.core.recipe.recipes.ShapedCraftingRecipe;
+import com.willfp.eco.util.NamespacedKeyUtils;
+import org.bukkit.Bukkit;
 import org.bukkit.NamespacedKey;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
@@ -16,7 +18,6 @@ import java.util.List;
 /**
  * Utility class to manage and register crafting recipes.
  */
-@SuppressWarnings("deprecation")
 public final class Recipes {
     /**
      * Registry of all recipes.
@@ -58,7 +59,10 @@ public final class Recipes {
         }
 
         if (key.getKey().contains("_displayed")) {
-            NamespacedKey otherKey = new NamespacedKey(key.getNamespace(), key.getKey().replace("_displayed", ""));
+            NamespacedKey otherKey = NamespacedKeyUtils.create(
+                    key.getNamespace(),
+                    key.getKey().replace("_displayed", "")
+            );
 
             return RECIPES.get(otherKey);
         }
@@ -92,6 +96,7 @@ public final class Recipes {
      * @param permission    The permission.
      * @return The recipe.
      */
+    @Nullable
     public static CraftingRecipe createAndRegisterRecipe(@NotNull final EcoPlugin plugin,
                                                          @NotNull final String key,
                                                          @NotNull final ItemStack output,
@@ -105,6 +110,12 @@ public final class Recipes {
             builder.setRecipePart(i, Items.lookup(recipeStrings.get(i)));
         }
 
+        if (builder.isAir()) {
+            Bukkit.getLogger().warning("RECIPE ERROR! " + plugin.getName() + ":" + key + " consists only");
+            Bukkit.getLogger().warning("of air or invalid items! Please change that or disable this recipe.");
+            return null;
+        }
+
         ShapedCraftingRecipe recipe = builder.build();
         recipe.register();
 

eco-api/src/main/java/com/willfp/eco/core/recipe/parts/GroupedTestableItems.java

@@ -0,0 +1,68 @@
+package com.willfp.eco.core.recipe.parts;
+
+import com.willfp.eco.core.items.TestableItem;
+import org.apache.commons.lang.Validate;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+/**
+ * A group of testable items.
+ *
+ * @see com.willfp.eco.core.items.CustomItem
+ */
+public class GroupedTestableItems implements TestableItem {
+    /**
+     * The children.
+     */
+    private final Collection<TestableItem> children;
+
+    /**
+     * Create a new group of testable items.
+     *
+     * @param children The children.
+     */
+    public GroupedTestableItems(@NotNull final Collection<TestableItem> children) {
+        Validate.isTrue(!children.isEmpty(), "Group must have at least one child!");
+
+        this.children = children;
+    }
+
+    /**
+     * If the item matches any children.
+     *
+     * @param itemStack The item to test.
+     * @return If the item matches the test of any children..
+     */
+    @Override
+    public boolean matches(@Nullable final ItemStack itemStack) {
+        for (TestableItem child : children) {
+            if (child.matches(itemStack)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    @Override
+    public ItemStack getItem() {
+        for (TestableItem child : children) {
+            return child.getItem();
+        }
+
+        throw new IllegalStateException("Empty group of children!");
+    }
+
+    /**
+     * Get the children.
+     *
+     * @return The children.
+     */
+    public Collection<TestableItem> getChildren() {
+        return new ArrayList<>(children);
+    }
+}

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

@@ -111,7 +111,7 @@ public final class ShapedCraftingRecipe extends PluginDependent<EcoPlugin> imple
                 List<String> lore = meta.hasLore() ? meta.getLore() : new ArrayList<>();
                 assert lore != null;
                 lore.add("");
-                String add = Eco.getHandler().getEcoPlugin().getLangYml().getString("multiple-in-craft");
+                String add = Eco.getHandler().getEcoPlugin().getLangYml().getFormattedString("multiple-in-craft");
                 add = add.replace("%amount%", String.valueOf(item.getAmount()));
                 lore.add(add);
                 meta.setLore(lore);
@@ -287,6 +287,20 @@ public final class ShapedCraftingRecipe extends PluginDependent<EcoPlugin> imple
             return this;
         }
 
+        /**
+         * Check if recipe parts are all air.
+         *
+         * @return If recipe parts are all air.
+         */
+        public boolean isAir() {
+            for (TestableItem recipePart : this.recipeParts) {
+                if (recipePart != null && !(recipePart instanceof EmptyTestableItem)) {
+                    return false;
+                }
+            }
+            return true;
+        }
+
         /**
          * Build the recipe.
          *

eco-api/src/main/java/com/willfp/eco/core/requirement/Requirement.java

@@ -1,13 +1,19 @@
 package com.willfp.eco.core.requirement;
 
+import com.willfp.eco.core.Eco;
 import org.bukkit.entity.Player;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.List;
 
 /**
  * A requirement is a defined goal that a player must meet.
+ *
+ * @deprecated No typing, weak definitions, and not an API component. Shouldn't be in eco.
  */
+@ApiStatus.ScheduledForRemoval(inVersion = "6.27.0")
+@Deprecated(since = "6.24.0", forRemoval = true)
 public abstract class Requirement {
     /**
      * Create a new requirement.
@@ -25,4 +31,9 @@ public abstract class Requirement {
      */
     public abstract boolean doesPlayerMeet(@NotNull Player player,
                                            @NotNull List<String> args);
+
+    static {
+        Eco.getHandler().getEcoPlugin().getLogger().severe("Loading for-removal Requirements system! This will throw an error once 6.27.0 is released."
+                + "Make sure you're running the latest version of all your plugins!");
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/requirement/RequirementFactory.java

@@ -1,17 +0,0 @@
-package com.willfp.eco.core.requirement;
-
-import org.jetbrains.annotations.NotNull;
-
-/**
- * Interface for internal requirement factory implementations.
- */
-public interface RequirementFactory {
-    /**
-     * Create a requirement.
-     *
-     * @param name The name.
-     * @return The requirement returned for the name.
-     * Will return a requirement that is always true if not found.
-     */
-    Requirement create(@NotNull String name);
-}

eco-api/src/main/java/com/willfp/eco/core/requirement/Requirements.java

@@ -1,31 +1,40 @@
 package com.willfp.eco.core.requirement;
 
 import com.willfp.eco.core.Eco;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.List;
+
 /**
  * Contains methods and fields pertaining to requirements.
+ *
+ * @deprecated See {@link Requirement}.
  */
+@ApiStatus.ScheduledForRemoval(inVersion = "6.27.0")
+@Deprecated(since = "6.24.0", forRemoval = true)
+@SuppressWarnings("removal")
 public final class Requirements {
     /**
      * Requires a player to have a permission.
      */
-    public static final Requirement HAS_PERMISSION = Eco.getHandler().getRequirementFactory().create("has-permission");
+    public static final Requirement HAS_PERMISSION = new com.willfp.eco.core.requirement.impl.RequirementHasPermission();
 
     /**
      * Placeholder equals value.
      */
-    public static final Requirement PLACEHOLDER_EQUALS = Eco.getHandler().getRequirementFactory().create("placeholder-equals");
+    public static final Requirement PLACEHOLDER_EQUALS = new com.willfp.eco.core.requirement.impl.RequirementPlaceholderEquals();
 
     /**
      * Numeric placeholder greater than value.
      */
-    public static final Requirement PLACEHOLDER_GREATER_THAN = Eco.getHandler().getRequirementFactory().create("placeholder-greater-than");
+    public static final Requirement PLACEHOLDER_GREATER_THAN = new com.willfp.eco.core.requirement.impl.RequirementPlaceholderGreaterThan();
 
     /**
      * Numeric placeholder less than value.
      */
-    public static final Requirement PLACEHOLDER_LESS_THAN = Eco.getHandler().getRequirementFactory().create("placeholder-less-than");
+    public static final Requirement PLACEHOLDER_LESS_THAN = new com.willfp.eco.core.requirement.impl.RequirementPlaceholderLessThan();
 
     /**
      * Get Requirements matching ID.
@@ -34,10 +43,27 @@ public final class Requirements {
      * @return The matching Requirements.
      */
     public static Requirement getByID(@NotNull final String name) {
-        return Eco.getHandler().getRequirementFactory().create(name);
+        return switch (name.toLowerCase()) {
+            case "has-permission" -> HAS_PERMISSION;
+            case "placeholder-equals" -> PLACEHOLDER_EQUALS;
+            case "placeholder-greater-than" -> PLACEHOLDER_GREATER_THAN;
+            case "placeholder-less-than" -> PLACEHOLDER_LESS_THAN;
+            default -> new Requirement() {
+                @Override
+                public boolean doesPlayerMeet(@NotNull final Player player,
+                                              @NotNull final List<String> args) {
+                    return true;
+                }
+            };
+        };
     }
 
     private Requirements() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }
+
+    static {
+        Eco.getHandler().getEcoPlugin().getLogger().severe("Loading for-removal Requirements system! This will throw an error once 6.27.0 is released."
+                + "Make sure you're running the latest version of all your plugins!");
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/requirement/impl/RequirementHasPermission.java

@@ -0,0 +1,34 @@
+package com.willfp.eco.core.requirement.impl;
+
+import com.willfp.eco.core.Eco;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * Moved to API in 6.26.0 after being marked for removal. This class should never be referenced, it
+ * was moved back to the API in order to remove backend components related to Requirements.
+ *
+ * @deprecated No typing, weak definitions, and not an API component. Shouldn't be in eco.
+ */
+@SuppressWarnings("removal")
+@ApiStatus.ScheduledForRemoval(inVersion = "6.27.0")
+@Deprecated(since = "6.26.0", forRemoval = true)
+public class RequirementHasPermission extends com.willfp.eco.core.requirement.Requirement {
+    @Override
+    public boolean doesPlayerMeet(@NotNull final Player player,
+                                  @NotNull final List<String> args) {
+        if (args.isEmpty()) {
+            return false;
+        }
+
+        return player.hasPermission(args.get(0));
+    }
+
+    static {
+        Eco.getHandler().getEcoPlugin().getLogger().severe("Loading for-removal Requirements system! This will throw an error once 6.27.0 is released."
+                + "Make sure you're running the latest version of all your plugins!");
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/requirement/impl/RequirementPlaceholderEquals.java

@@ -0,0 +1,35 @@
+package com.willfp.eco.core.requirement.impl;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.integrations.placeholder.PlaceholderManager;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * Moved to API in 6.26.0 after being marked for removal. This class should never be referenced, it
+ * was moved back to the API in order to remove backend components related to Requirements.
+ *
+ * @deprecated No typing, weak definitions, and not an API component. Shouldn't be in eco.
+ */
+@SuppressWarnings("removal")
+@ApiStatus.ScheduledForRemoval(inVersion = "6.27.0")
+@Deprecated(since = "6.26.0", forRemoval = true)
+public class RequirementPlaceholderEquals extends com.willfp.eco.core.requirement.Requirement {
+    @Override
+    public boolean doesPlayerMeet(@NotNull final Player player,
+                                  @NotNull final List<String> args) {
+        if (args.size() < 2) {
+            return false;
+        }
+
+        return PlaceholderManager.translatePlaceholders(args.get(0), player).equalsIgnoreCase(args.get(1));
+    }
+
+    static {
+        Eco.getHandler().getEcoPlugin().getLogger().severe("Loading for-removal Requirements system! This will throw an error once 6.27.0 is released."
+                + "Make sure you're running the latest version of all your plugins!");
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/requirement/impl/RequirementPlaceholderGreaterThan.java

@@ -0,0 +1,49 @@
+package com.willfp.eco.core.requirement.impl;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.integrations.placeholder.PlaceholderManager;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * Moved to API in 6.26.0 after being marked for removal. This class should never be referenced, it
+ * was moved back to the API in order to remove backend components related to Requirements.
+ *
+ * @deprecated No typing, weak definitions, and not an API component. Shouldn't be in eco.
+ */
+@SuppressWarnings("removal")
+@ApiStatus.ScheduledForRemoval(inVersion = "6.27.0")
+@Deprecated(since = "6.26.0", forRemoval = true)
+public class RequirementPlaceholderGreaterThan extends com.willfp.eco.core.requirement.Requirement {
+    @Override
+    public boolean doesPlayerMeet(@NotNull final Player player,
+                                  @NotNull final List<String> args) {
+        if (args.size() < 2) {
+            return false;
+        }
+
+        double actual;
+        try {
+            actual = Double.parseDouble(PlaceholderManager.translatePlaceholders(args.get(0), player));
+        } catch (NumberFormatException e) {
+            return false;
+        }
+
+        double expected;
+        try {
+            expected = Double.parseDouble(args.get(1));
+        } catch (NumberFormatException e) {
+            return false;
+        }
+
+        return actual >= expected;
+    }
+
+    static {
+        Eco.getHandler().getEcoPlugin().getLogger().severe("Loading for-removal Requirements system! This will throw an error once 6.27.0 is released."
+                + "Make sure you're running the latest version of all your plugins!");
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/requirement/impl/RequirementPlaceholderLessThan.java

@@ -0,0 +1,49 @@
+package com.willfp.eco.core.requirement.impl;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.integrations.placeholder.PlaceholderManager;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * Moved to API in 6.26.0 after being marked for removal. This class should never be referenced, it
+ * was moved back to the API in order to remove backend components related to Requirements.
+ *
+ * @deprecated No typing, weak definitions, and not an API component. Shouldn't be in eco.
+ */
+@SuppressWarnings("removal")
+@ApiStatus.ScheduledForRemoval(inVersion = "6.27.0")
+@Deprecated(since = "6.26.0", forRemoval = true)
+public class RequirementPlaceholderLessThan extends com.willfp.eco.core.requirement.Requirement {
+    @Override
+    public boolean doesPlayerMeet(@NotNull final Player player,
+                                  @NotNull final List<String> args) {
+        if (args.size() < 2) {
+            return false;
+        }
+
+        double actual;
+        try {
+            actual = Double.parseDouble(PlaceholderManager.translatePlaceholders(args.get(0), player));
+        } catch (NumberFormatException e) {
+            return false;
+        }
+
+        double expected;
+        try {
+            expected = Double.parseDouble(args.get(1));
+        } catch (NumberFormatException e) {
+            return false;
+        }
+
+        return actual < expected;
+    }
+
+    static {
+        Eco.getHandler().getEcoPlugin().getLogger().severe("Loading for-removal Requirements system! This will throw an error once 6.27.0 is released."
+                + "Make sure you're running the latest version of all your plugins!");
+    }
+}

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

@@ -92,7 +92,7 @@ public class Paste {
             conn.setRequestMethod("GET");
             try (var reader = new BufferedReader(
                     new InputStreamReader(conn.getInputStream()))) {
-                for (String line; (line = reader.readLine()) != null; ) {
+                for (String line; (line = reader.readLine()) != null;) {
                     result.append(line);
                 }
             }

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

@@ -26,11 +26,26 @@ public final class DurabilityUtils {
      * @param item   The item to damage.
      * @param damage The amount of damage to deal.
      * @param slot   The slot in the inventory of the item.
+     * @deprecated The slot is not required.
      */
+    @Deprecated(since = "6.24.0")
     public static void damageItem(@NotNull final Player player,
                                   @NotNull final ItemStack item,
                                   final int damage,
                                   final int slot) {
+        damageItem(player, item, damage);
+    }
+
+    /**
+     * Damage an item in a player's inventory.
+     *
+     * @param player The player.
+     * @param item   The item to damage.
+     * @param damage The amount of damage to deal.
+     */
+    public static void damageItem(@NotNull final Player player,
+                                  @NotNull final ItemStack item,
+                                  final int damage) {
         if (item.getItemMeta() == null) {
             return;
         }
@@ -61,7 +76,7 @@ public final class DurabilityUtils {
                 item.setItemMeta((ItemMeta) meta);
                 PlayerItemBreakEvent event = new PlayerItemBreakEvent(player, item);
                 Bukkit.getPluginManager().callEvent(event);
-                player.getInventory().clear(slot);
+                item.setType(Material.AIR);
                 player.playSound(player.getLocation(), Sound.ENTITY_ITEM_BREAK, SoundCategory.BLOCKS, 1, 1);
             } else {
                 item.setItemMeta((ItemMeta) meta);
@@ -69,6 +84,44 @@ public final class DurabilityUtils {
         }
     }
 
+    /**
+     * Damage an item.
+     *
+     * @param item   The item to damage.
+     * @param damage The amount of damage to deal.
+     */
+    public static void damageItem(@NotNull final ItemStack item,
+                                  final int damage) {
+        if (item.getItemMeta() == null) {
+            return;
+        }
+
+        if (item.getItemMeta().isUnbreakable()) {
+            return;
+        }
+
+        if (!(item.getItemMeta() instanceof Damageable)) {
+            return;
+        }
+
+        // Special edge case
+        if (item.getType() == Material.CARVED_PUMPKIN || item.getType() == Material.PLAYER_HEAD) {
+            return;
+        }
+
+
+        Damageable meta = (Damageable) item.getItemMeta();
+        meta.setDamage(meta.getDamage() + damage);
+
+        if (meta.getDamage() >= item.getType().getMaxDurability()) {
+            meta.setDamage(item.getType().getMaxDurability());
+            item.setItemMeta((ItemMeta) meta);
+            item.setType(Material.AIR);
+        } else {
+            item.setItemMeta((ItemMeta) meta);
+        }
+    }
+
     /**
      * Damage an item in a player's inventory without breaking it.
      *

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

@@ -91,6 +91,24 @@ public final class ListUtils {
         return index >= 0 && index < list.size() ? list.get(index) : null;
     }
 
+    /**
+     * Get if an iterable of strings contains a certain element regardless of case.
+     *
+     * @param list    The list.
+     * @param element The element.
+     * @return If contained.
+     */
+    public static boolean containsIgnoreCase(@NotNull final Iterable<String> list,
+                                             @NotNull final String element) {
+        for (String s : list) {
+            if (s.equalsIgnoreCase(element)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     private ListUtils() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

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

@@ -1,7 +1,9 @@
 package com.willfp.eco.util;
 
+import com.willfp.eco.core.Eco;
 import org.bukkit.NamespacedKey;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.Objects;
 
@@ -17,7 +19,7 @@ public final class NamespacedKeyUtils {
      */
     @NotNull
     public static NamespacedKey createEcoKey(@NotNull final String string) {
-        return Objects.requireNonNull(NamespacedKey.fromString("eco:" + string));
+        return NamespacedKeyUtils.create("eco", string);
     }
 
     /**
@@ -30,7 +32,45 @@ public final class NamespacedKeyUtils {
     @NotNull
     public static NamespacedKey create(@NotNull final String namespace,
                                        @NotNull final String key) {
-        return Objects.requireNonNull(NamespacedKey.fromString(namespace + ":" + key));
+        return Eco.getHandler().createNamespacedKey(
+                namespace,
+                key
+        );
+    }
+
+    /**
+     * Create a NamespacedKey from a string.
+     * <p>
+     * Preferred over {@link NamespacedKey#fromString(String)} for performance reasons.
+     *
+     * @param string The string.
+     * @return The key.
+     */
+    @NotNull
+    public static NamespacedKey fromString(@NotNull final String string) {
+        return Objects.requireNonNull(NamespacedKeyUtils.fromStringOrNull(string));
+    }
+
+    /**
+     * Create a NamespacedKey from a string.
+     * <p>
+     * Preferred over {@link NamespacedKey#fromString(String)} for performance reasons.
+     *
+     * @param string The string.
+     * @return The key, or null if not a key.
+     */
+    @Nullable
+    public static NamespacedKey fromStringOrNull(@NotNull final String string) {
+        int index = string.indexOf(":");
+
+        if (index < 0) {
+            return null;
+        }
+
+        return NamespacedKeyUtils.create(
+                string.substring(0, index),
+                string.substring(index + 1)
+        );
     }
 
     private NamespacedKeyUtils() {

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

@@ -1,11 +1,16 @@
 package com.willfp.eco.util;
 
+import org.apache.commons.lang.Validate;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.text.DecimalFormat;
 import java.util.Map;
 import java.util.TreeMap;
 import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.BiFunction;
 
 /**
  * Utilities / API methods for numbers.
@@ -16,6 +21,11 @@ public final class NumberUtils {
      */
     private static final double[] SIN_LOOKUP = new double[65536];
 
+    /**
+     * Crunch handler.
+     */
+    private static BiFunction<String, Player, Double> crunch = null;
+
     /**
      * Set of roman numerals to look up.
      */
@@ -83,7 +93,9 @@ public final class NumberUtils {
      * @param toChange The value to test.
      * @param limit    The maximum.
      * @return The new value.
+     * @deprecated Pointless method.
      */
+    @Deprecated(since = "6.19.0")
     public static int equalIfOver(final int toChange,
                                   final int limit) {
         return Math.min(toChange, limit);
@@ -95,7 +107,9 @@ public final class NumberUtils {
      * @param toChange The value to test.
      * @param limit    The maximum.
      * @return The new value.
+     * @deprecated Pointless method.
      */
+    @Deprecated(since = "6.19.0")
     public static double equalIfOver(final double toChange,
                                      final double limit) {
         return Math.min(toChange, limit);
@@ -185,11 +199,23 @@ public final class NumberUtils {
     /**
      * Get Log base 2 of a number.
      *
-     * @param toLog The number.
+     * @param a The number.
      * @return The result.
      */
-    public static int log2(final int toLog) {
-        return (int) (Math.log(toLog) / Math.log(2));
+    public static int log2(final int a) {
+        return (int) logBase(a, 2);
+    }
+
+    /**
+     * Log with a base.
+     *
+     * @param a    The number.
+     * @param base The base.
+     * @return The logarithm.
+     */
+    public static double logBase(final double a,
+                                 final double base) {
+        return Math.log(a) / Math.log(base);
     }
 
     /**
@@ -206,6 +232,39 @@ public final class NumberUtils {
         return formatted.endsWith("00") ? String.valueOf((int) toFormat) : formatted;
     }
 
+    /**
+     * Evaluate an expression.
+     *
+     * @param expression The expression.
+     * @return The value of the expression, or zero if invalid.
+     */
+    public static double evaluateExpression(@NotNull final String expression) {
+        return evaluateExpression(expression, null);
+    }
+
+    /**
+     * Evaluate an expression with respect to a player (for placeholders).
+     *
+     * @param expression The expression.
+     * @param player     The player.
+     * @return The value of the expression, or zero if invalid.
+     */
+    public static double evaluateExpression(@NotNull final String expression,
+                                            @Nullable final Player player) {
+        return crunch.apply(expression, player);
+    }
+
+    /**
+     * Init crunch handler.
+     *
+     * @param handler The handler.
+     */
+    @ApiStatus.Internal
+    public static void initCrunch(@NotNull final BiFunction<String, Player, Double> handler) {
+        Validate.isTrue(crunch == null, "Already initialized!");
+        crunch = handler;
+    }
+
     private NumberUtils() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

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

@@ -5,6 +5,7 @@ import com.willfp.eco.core.Prerequisite;
 import com.willfp.eco.core.data.PlayerProfile;
 import com.willfp.eco.core.data.keys.PersistentDataKey;
 import com.willfp.eco.core.data.keys.PersistentDataKeyType;
+import com.willfp.eco.core.integrations.anticheat.AnticheatManager;
 import net.kyori.adventure.audience.Audience;
 import net.kyori.adventure.platform.bukkit.BukkitAudiences;
 import org.bukkit.OfflinePlayer;
@@ -12,6 +13,8 @@ import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.function.Consumer;
+
 /**
  * Utilities / API methods for players.
  */
@@ -107,6 +110,38 @@ public final class PlayerUtils {
         profile.write(PLAYER_NAME_KEY, player.getDisplayName());
     }
 
+    /**
+     * Run something with the player exempted.
+     *
+     * @param player The player.
+     * @param action The action.
+     */
+    public static void runExempted(@NotNull final Player player,
+                                   @NotNull final Consumer<Player> action) {
+        try {
+            AnticheatManager.exemptPlayer(player);
+            action.accept(player);
+        } finally {
+            AnticheatManager.unexemptPlayer(player);
+        }
+    }
+
+    /**
+     * Run something with the player exempted.
+     *
+     * @param player The player.
+     * @param action The action.
+     */
+    public static void runExempted(@NotNull final Player player,
+                                   @NotNull final Runnable action) {
+        try {
+            AnticheatManager.exemptPlayer(player);
+            action.run();
+        } finally {
+            AnticheatManager.unexemptPlayer(player);
+        }
+    }
+
     private PlayerUtils() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

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

@@ -1,7 +1,10 @@
 package com.willfp.eco.util;
 
+import com.github.benmanes.caffeine.cache.Caffeine;
+import com.github.benmanes.caffeine.cache.LoadingCache;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.gson.JsonSyntaxException;
 import com.willfp.eco.core.Prerequisite;
 import com.willfp.eco.core.integrations.placeholder.PlaceholderManager;
 import net.kyori.adventure.text.Component;
@@ -19,6 +22,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.TimeUnit;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
@@ -58,6 +62,49 @@ public final class StringUtils {
             .hexColors()
             .build();
 
+    /**
+     * GSON serializer.
+     */
+    private static final GsonComponentSerializer GSON_COMPONENT_SERIALIZER = GsonComponentSerializer.builder()
+            .emitLegacyHoverEvent()
+            .build();
+
+    /**
+     * String format cache.
+     */
+    private static final LoadingCache<String, String> STRING_FORMAT_CACHE = Caffeine.newBuilder()
+            .expireAfterAccess(10, TimeUnit.SECONDS)
+            .build(StringUtils::processFormatting);
+
+    /**
+     * Json -> Legacy Cache.
+     */
+    private static final LoadingCache<String, String> JSON_TO_LEGACY = Caffeine.newBuilder()
+            .expireAfterAccess(10, TimeUnit.SECONDS)
+            .build(
+                    json -> {
+                        try {
+                            Component component = GSON_COMPONENT_SERIALIZER.deserialize(json);
+                            return LEGACY_COMPONENT_SERIALIZER.serialize(component);
+                        } catch (JsonSyntaxException e) {
+                            return json;
+                        }
+                    }
+            );
+
+    /**
+     * Legacy -> Json Cache.
+     */
+    private static final LoadingCache<String, String> LEGACY_TO_JSON = Caffeine.newBuilder()
+            .expireAfterAccess(10, TimeUnit.SECONDS)
+            .build(
+                    legacy -> GSON_COMPONENT_SERIALIZER.serialize(
+                            Component.empty().decoration(TextDecoration.ITALIC, false).append(
+                                    LEGACY_COMPONENT_SERIALIZER.deserialize(legacy)
+                            )
+                    )
+            );
+
     /**
      * Color map.
      */
@@ -74,6 +121,14 @@ public final class StringUtils {
             .put("§k", ChatColor.MAGIC)
             .build();
 
+    /**
+     * Regex map for splitting values.
+     */
+    private static final LoadingCache<String, Pattern> SPACE_AROUND_CHARACTER = Caffeine.newBuilder()
+            .build(
+                    character -> Pattern.compile("( " + Pattern.quote(character) + " )")
+            );
+
     /**
      * Format a list of strings.
      * <p>
@@ -264,6 +319,11 @@ public final class StringUtils {
         if (option == FormatOption.WITH_PLACEHOLDERS) {
             processedMessage = PlaceholderManager.translatePlaceholders(processedMessage, player);
         }
+        return STRING_FORMAT_CACHE.get(processedMessage);
+    }
+
+    private static String processFormatting(@NotNull final String message) {
+        String processedMessage = message;
         processedMessage = ChatColor.translateAlternateColorCodes('&', processedMessage);
         processedMessage = translateGradients(processedMessage);
         processedMessage = translateHexColorCodes(processedMessage);
@@ -367,9 +427,23 @@ public final class StringUtils {
      *
      * @param object The object to convert to string.
      * @return The object stringified.
+     * @deprecated Poorly named method. Use {@link StringUtils#toNiceString(Object)} instead.
      */
     @NotNull
+    @Deprecated(since = "6.26.0", forRemoval = true)
     public static String internalToString(@Nullable final Object object) {
+        return toNiceString(object);
+    }
+
+    /**
+     * Internal implementation of {@link String#valueOf}.
+     * Formats collections and doubles better.
+     *
+     * @param object The object to convert to string.
+     * @return The object stringified.
+     */
+    @NotNull
+    public static String toNiceString(@Nullable final Object object) {
         if (object == null) {
             return "null";
         }
@@ -381,7 +455,7 @@ public final class StringUtils {
         } else if (object instanceof Double) {
             return NumberUtils.format((Double) object);
         } else if (object instanceof Collection<?> c) {
-            return c.stream().map(StringUtils::internalToString).collect(Collectors.joining(", "));
+            return c.stream().map(StringUtils::toNiceString).collect(Collectors.joining(", "));
         } else {
             return String.valueOf(object);
         }
@@ -415,11 +489,8 @@ public final class StringUtils {
         if (legacy == null) {
             processed = "";
         }
-        return GsonComponentSerializer.gson().serialize(
-                Component.empty().decoration(TextDecoration.ITALIC, false).append(
-                        LEGACY_COMPONENT_SERIALIZER.deserialize(processed)
-                )
-        );
+
+        return LEGACY_TO_JSON.get(processed);
     }
 
     /**
@@ -429,10 +500,12 @@ public final class StringUtils {
      * @return The legacy string.
      */
     @NotNull
-    public static String jsonToLegacy(@NotNull final String json) {
-        return LEGACY_COMPONENT_SERIALIZER.serialize(
-                GsonComponentSerializer.gson().deserialize(json)
-        );
+    public static String jsonToLegacy(@Nullable final String json) {
+        if (json == null || json.isEmpty()) {
+            return "";
+        }
+
+        return JSON_TO_LEGACY.get(json);
     }
 
     /**
@@ -462,6 +535,69 @@ public final class StringUtils {
         return LEGACY_COMPONENT_SERIALIZER.serialize(component);
     }
 
+    /**
+     * Parse string into tokens.
+     * <p>
+     * Handles quoted strings for names.
+     *
+     * @param lookup The lookup string.
+     * @return An array of tokens to be processed.
+     * @author Shawn (https://stackoverflow.com/questions/70606170/split-a-list-on-spaces-and-group-quoted-characters/70606653#70606653)
+     */
+    @NotNull
+    public static String[] parseTokens(@NotNull final String lookup) {
+        char[] chars = lookup.toCharArray();
+        List<String> tokens = new ArrayList<>();
+        StringBuilder tokenBuilder = new StringBuilder();
+        for (int i = 0; i < chars.length; i++) {
+            if (chars[i] == ' ') {
+                /*
+                Take the current value of the argument builder, append it to the
+                list of found tokens, and then clear it for the next argument.
+                 */
+                tokens.add(tokenBuilder.toString());
+                tokenBuilder.setLength(0);
+            } else if (chars[i] == '"') {
+                /*
+                Work until the next unescaped quote to handle quotes with
+                spaces in them - assumes the input string is well-formatted
+                 */
+                for (i++; chars[i] != '"'; i++) {
+                    /*
+                    If the found quote is escaped, ignore it in the parsing
+                     */
+                    if (chars[i] == '\\') {
+                        i++;
+                    }
+                    tokenBuilder.append(chars[i]);
+                }
+            } else {
+                /*
+                If it's a regular character, just append it to the current argument.
+                 */
+                tokenBuilder.append(chars[i]);
+            }
+        }
+        tokens.add(tokenBuilder.toString()); // Adds the last argument to the tokens.
+        return tokens.toArray(new String[0]);
+    }
+
+    /**
+     * Split input string around separator surrounded by spaces.
+     * <p>
+     * e.g. {@code splitAround("hello ? how are you", "?")} will split, but
+     * {@code splitAround("hello? how are you", "?")} will not.
+     *
+     * @param input     Input string.
+     * @param separator Separator.
+     * @return The split string.
+     */
+    @NotNull
+    public static String[] splitAround(@NotNull final String input,
+                                       @NotNull final String separator) {
+        return SPACE_AROUND_CHARACTER.get(separator).split(input);
+    }
+
     /**
      * Options for formatting.
      */

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

@@ -2,7 +2,6 @@ package com.willfp.eco.util;
 
 import com.google.common.collect.BiMap;
 import com.google.common.collect.HashBiMap;
-import com.willfp.eco.core.Prerequisite;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
 import org.bukkit.Material;
@@ -69,8 +68,10 @@ public final class TeamUtils {
      *
      * @param material The material to find the team from.
      * @return The team.
+     * @deprecated Stupid method.
      */
     @NotNull
+    @Deprecated(since = "6.24.0")
     public static Team getMaterialColorTeam(@NotNull final Material material) {
         return fromChatColor(MATERIAL_COLORS.getOrDefault(material, ChatColor.WHITE));
     }
@@ -89,17 +90,15 @@ public final class TeamUtils {
         MATERIAL_COLORS.put(Material.EMERALD_ORE, ChatColor.GREEN);
         MATERIAL_COLORS.put(Material.ANCIENT_DEBRIS, ChatColor.DARK_RED);
 
-        if (Prerequisite.HAS_1_17.isMet()) {
-            MATERIAL_COLORS.put(Material.COPPER_ORE, ChatColor.GOLD);
-            MATERIAL_COLORS.put(Material.DEEPSLATE_COPPER_ORE, ChatColor.GOLD);
-            MATERIAL_COLORS.put(Material.DEEPSLATE_COAL_ORE, ChatColor.BLACK);
-            MATERIAL_COLORS.put(Material.DEEPSLATE_IRON_ORE, ChatColor.GRAY);
-            MATERIAL_COLORS.put(Material.DEEPSLATE_GOLD_ORE, ChatColor.YELLOW);
-            MATERIAL_COLORS.put(Material.DEEPSLATE_LAPIS_ORE, ChatColor.BLUE);
-            MATERIAL_COLORS.put(Material.DEEPSLATE_REDSTONE_ORE, ChatColor.RED);
-            MATERIAL_COLORS.put(Material.DEEPSLATE_DIAMOND_ORE, ChatColor.AQUA);
-            MATERIAL_COLORS.put(Material.DEEPSLATE_EMERALD_ORE, ChatColor.GREEN);
-        }
+        MATERIAL_COLORS.put(Material.COPPER_ORE, ChatColor.GOLD);
+        MATERIAL_COLORS.put(Material.DEEPSLATE_COPPER_ORE, ChatColor.GOLD);
+        MATERIAL_COLORS.put(Material.DEEPSLATE_COAL_ORE, ChatColor.BLACK);
+        MATERIAL_COLORS.put(Material.DEEPSLATE_IRON_ORE, ChatColor.GRAY);
+        MATERIAL_COLORS.put(Material.DEEPSLATE_GOLD_ORE, ChatColor.YELLOW);
+        MATERIAL_COLORS.put(Material.DEEPSLATE_LAPIS_ORE, ChatColor.BLUE);
+        MATERIAL_COLORS.put(Material.DEEPSLATE_REDSTONE_ORE, ChatColor.RED);
+        MATERIAL_COLORS.put(Material.DEEPSLATE_DIAMOND_ORE, ChatColor.AQUA);
+        MATERIAL_COLORS.put(Material.DEEPSLATE_EMERALD_ORE, ChatColor.GREEN);
     }
 
     private TeamUtils() {

eco-api/src/main/kotlin/com/willfp/eco/core/commands/CommandHelpers.kt

@@ -0,0 +1,142 @@
+@file:JvmName("CommandHelperExtensions")
+
+package com.willfp.eco.core.commands
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.core.command.CommandBase
+import com.willfp.eco.core.command.impl.PluginCommand
+import com.willfp.eco.core.command.impl.Subcommand
+import org.bukkit.command.CommandSender
+
+/**
+ * Helper class for creating commands with builders.
+ *
+ * @param plugin The plugin.
+ * @param name The command name.
+ * @param permission The permission.
+ * @param playersOnly If only players should run the command.
+ * @param executor The command executor.
+ * @param tabCompleter The tab completer.
+ */
+class BuiltPluginCommand internal constructor(
+    plugin: EcoPlugin,
+    name: String,
+    permission: String,
+    playersOnly: Boolean = false,
+    var executor: (CommandSender, List<String>) -> Unit,
+    var tabCompleter: (CommandSender, List<String>) -> List<String>,
+) : PluginCommand(plugin, name, permission, playersOnly) {
+    override fun onExecute(sender: CommandSender, args: List<String>) =
+        executor(sender, args)
+
+    override fun tabComplete(sender: CommandSender, args: List<String>): List<String> =
+        tabCompleter(sender, args)
+}
+
+
+/**
+ * Helper class for creating commands with builders.
+ *
+ * @param plugin The plugin.
+ * @param name The command name.
+ * @param permission The permission.
+ * @param playersOnly If only players should run the command.
+ * @param executor The command executor.
+ * @param tabCompleter The tab completer.
+ */
+class BuiltSubcommand internal constructor(
+    plugin: EcoPlugin,
+    name: String,
+    permission: String,
+    playersOnly: Boolean = false,
+    var executor: (CommandSender, List<String>) -> Unit,
+    var tabCompleter: (CommandSender, List<String>) -> List<String>,
+) : Subcommand(plugin, name, permission, playersOnly) {
+    internal constructor(
+        parent: CommandBase,
+        name: String,
+        executor: (CommandSender, List<String>) -> Unit,
+        tabCompleter: (CommandSender, List<String>) -> List<String>,
+    ) : this(parent.plugin, name, parent.permission, parent.isPlayersOnly, executor, tabCompleter)
+
+    override fun onExecute(sender: CommandSender, args: List<String>) =
+        executor(sender, args)
+
+    override fun tabComplete(sender: CommandSender, args: List<String>): List<String> =
+        tabCompleter(sender, args)
+}
+
+/**
+ * Kotlin builder for commands.
+ *
+ * @param plugin The plugin.
+ * @param name The command name.
+ * @param permission The permission.
+ * @param playersOnly If only players should execute the command.
+ * @param init The builder.
+ */
+fun command(
+    plugin: EcoPlugin,
+    name: String,
+    permission: String,
+    playersOnly: Boolean = false,
+    init: BuiltPluginCommand.() -> Unit
+): PluginCommand {
+    val command = BuiltPluginCommand(
+        plugin,
+        name,
+        permission,
+        playersOnly,
+        { _, _ -> },
+        { _, _ -> emptyList() }
+    )
+    init(command)
+    return command
+}
+
+/**
+ * Kotlin builder for commands.
+ *
+ * @param name The command name.
+ * @param permission The permission.
+ * @param playersOnly If only players should execute the command.
+ * @param init The builder.
+ */
+fun CommandBase.addSubcommand(
+    name: String,
+    permission: String,
+    playersOnly: Boolean = false,
+    init: BuiltSubcommand.() -> Unit
+): Subcommand {
+    val command = BuiltSubcommand(
+        this.plugin,
+        name,
+        permission,
+        playersOnly,
+        { _, _ -> },
+        { _, _ -> emptyList() }
+    )
+    init(command)
+    return command
+}
+
+/**
+ * Kotlin builder for commands.
+ * Inherits plugin, permission, players only.
+ *
+ * @param name The command name.
+ * @param init The builder.
+ */
+fun CommandBase.addSubcommand(
+    name: String,
+    init: BuiltSubcommand.() -> Unit
+): Subcommand {
+    val command = BuiltSubcommand(
+        this,
+        name,
+        { _, _ -> },
+        { _, _ -> emptyList() }
+    )
+    init(command)
+    return command
+}

eco-api/src/main/kotlin/com/willfp/eco/core/data/Profiles.kt

@@ -0,0 +1,18 @@
+@file:JvmName("ProfileExtensions")
+
+package com.willfp.eco.core.data
+
+import org.bukkit.OfflinePlayer
+import org.bukkit.Server
+
+/**
+ * @see PlayerProfile.load
+ */
+val OfflinePlayer.profile: PlayerProfile
+    get() = PlayerProfile.load(this)
+
+/**
+ * @see ServerProfile.load
+ */
+val Server.profile: ServerProfile
+    get() = ServerProfile.load()

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

@@ -0,0 +1,11 @@
+@file:JvmName("FastItemStackExtensions")
+
+package com.willfp.eco.core.fast
+
+import org.bukkit.inventory.ItemStack
+
+/**
+ * @see FastItemStack.wrap
+ */
+fun ItemStack.fast(): FastItemStack =
+    FastItemStack.wrap(this)

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

@@ -0,0 +1,105 @@
+@file:JvmName("GUIHelperExtensions")
+
+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.slot.Slot
+import com.willfp.eco.core.gui.slot.SlotBuilder
+import org.bukkit.entity.Player
+import org.bukkit.event.inventory.InventoryClickEvent
+import org.bukkit.event.inventory.InventoryCloseEvent
+import org.bukkit.inventory.ItemStack
+
+/**
+ * @see SlotBuilder.onLeftClick
+ */
+fun SlotBuilder.onLeftClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onLeftClick { a, b, c -> action(a, b, c) }
+
+/**
+ * @see SlotBuilder.onRightClick
+ */
+fun SlotBuilder.onRightClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onRightClick { a, b, c -> action(a, b, c) }
+
+/**
+ * @see SlotBuilder.onShiftLeftClick
+ */
+fun SlotBuilder.onShiftLeftClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onShiftLeftClick { a, b, c -> action(a, b, c) }
+
+/**
+ * @see SlotBuilder.onShiftRightClick
+ */
+fun SlotBuilder.onShiftRightClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onShiftRightClick { a, b, c -> action(a, b, c) }
+
+/**
+ * @see SlotBuilder.onShiftRightClick
+ */
+fun SlotBuilder.onMiddleClick(action: (InventoryClickEvent, Slot, Menu) -> Unit): SlotBuilder =
+    this.onMiddleClick { a, b, c -> action(a, b, c) }
+
+/**
+ * @see SlotBuilder.setModifier
+ * @deprecated Use SlotUpdater instead.
+ */
+@Deprecated("Use SlotUpdater instead")
+@Suppress("DEPRECATION")
+fun SlotBuilder.setModifier(action: (Player, Menu, ItemStack) -> Unit): SlotBuilder =
+    this.setUpdater { a, b, c -> c.apply { action(a, b, c) } }
+
+/**
+ * @see SlotBuilder.setUpdater
+ */
+fun SlotBuilder.setUpdater(action: (Player, Menu, ItemStack) -> ItemStack): SlotBuilder =
+    this.setUpdater { a, b, c -> action(a, b, c) }
+
+/**
+ * Kotlin builder for slots.
+ */
+fun slot(
+    item: ItemStack,
+    init: SlotBuilder.() -> Unit
+): Slot {
+    val builder = Slot.builder(item)
+    init(builder)
+    return builder.build()
+}
+
+/**
+ * Kotlin builder for slots.
+ */
+fun slot(
+    provider: (Player, Menu) -> ItemStack,
+    init: SlotBuilder.() -> Unit
+): Slot {
+    val builder = Slot.builder { a, b -> provider(a, b) }
+    init(builder)
+    return builder.build()
+}
+
+/**
+ * @see MenuBuilder.onClose
+ */
+fun MenuBuilder.onClose(action: (InventoryCloseEvent, Menu) -> Unit): MenuBuilder =
+    this.onClose { a, b -> action(a, b) }
+
+/**
+ * @see MenuBuilder.modify
+ */
+fun MenuBuilder.modify(modifier: (MenuBuilder) -> Unit): MenuBuilder =
+    this.modfiy { modifier(it) }
+
+/**
+ * Kotlin builder for menus.
+ */
+fun menu(
+    rows: Int,
+    init: MenuBuilder.() -> Unit
+): Menu {
+    val builder = Menu.builder(rows)
+    init(builder)
+    return builder.build()
+}

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

@@ -0,0 +1,12 @@
+@file:JvmName("ArrowUtilsExtensions")
+
+package com.willfp.eco.util
+
+import org.bukkit.entity.Arrow
+import org.bukkit.inventory.ItemStack
+
+/**
+ * @see ArrowUtils.getBow
+ */
+val Arrow.bow: ItemStack?
+    get() = ArrowUtils.getBow(this)