Fixed plugin.yml

# Conflicts:
#	eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/data/storage/MySQLDataHandler.kt

.github/dependabot.yml

@@ -0,0 +1,11 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://help.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  - package-ecosystem: "gradle" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "daily"

.github/workflows/publish-release.yml

@@ -0,0 +1,38 @@
+name: Publish release
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  publish-release:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout latest code
+        uses: actions/checkout@v2
+
+      - name: Set up JDK 16
+        uses: actions/setup-java@v2
+        with:
+          distribution: 'adopt'
+          java-version: 16
+
+      - 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: ${NEW_VERSION}"
+          echo "Github username: ${GITHUB_ACTOR}"
+          ./gradlew -Pversion=${NEW_VERSION} publish

.gitignore

@@ -14,7 +14,8 @@ bin/
 # Gradle
 .gradle
 **/build/
-!src/**/build/
+**/out/
+!eco-api/src/**/build/
 .gradletasknamecache
 !gradle-wrapper.jar
 gradle-app.setting

CONTRIBUTING.md

@@ -6,7 +6,7 @@
 - Every method and field must have a javadoc attached.
 
 2. Use lombok wherever possible.
-- @Getter, @Setter, @ToString, @EqualsAndHashCode, @UtilityClass are the most important.
+- @Getter, @Setter, @UtilityClass only.
 
 3. Use JetBrains annotations
 - Every parameter should be annotated with @NotNull or @Nullable
@@ -24,4 +24,4 @@
 
 ## Other
 - All drops **must** be sent through a DropQueue - calls to World#dropItem will get your PR rejected.
-- eco is built with java 8. Usage of J9+ will get your PR rejected.
+- eco is built with java 16.

README.md

@@ -1 +1,168 @@
-## eco - Library for spigot plugin development.
+<h1 align="center">
+  <br>
+  <img src="https://i.imgur.com/kU3ejCt.png" alt="eco logo" width="256">
+  <br>
+</h1>
+
+<h4 align="center">eco - Simplify spigot development.</h4>
+
+### Plugin Information
+- Requires ProtocolLib to be installed: get the latest version [here](https://www.spigotmc.org/resources/protocollib.1997/)
+- Supports 1.16.5+
+
+### bStats
+<img src="https://bstats.org/signatures/bukkit/eco.svg" width="512">
+
+# Information for development
+
+## Javadoc
+The 6.8.0 Javadoc can be found [here](https://javadoc.jitpack.io/com/willfp/eco/6.8.0/javadoc/)
+
+## Plugin Information
+
+eco is a standalone plugin, so you will need to install it on any servers that have plugins which depend on it,
+and specify it as a dependency in your plugin.yml:
+
+```yaml
+depend:
+  - eco
+```
+
+eco is available from any of these places:
+
+- [GitHub](https://github.com/Auxilor/eco/releases)
+- [Polymart](https://polymart.org/resource/eco.773)
+- [Build it locally](https://github.com/Auxilor/eco#build-locally).
+
+## Get from JitPack:
+
+Gradle:
+
+```groovy
+repositories {
+        maven { url 'https://jitpack.io' }
+}
+
+```
+
+```groovy
+dependencies {
+        compileOnly 'com.willfp:eco:Tag'
+}
+```
+
+Replace `Tag` with a release tag for eco, eg `6.0.0`.
+
+Maven:
+
+```xml
+<repository>
+        <id>jitpack.io</id>
+        <url>https://jitpack.io</url>
+</repository>
+```
+
+```xml
+<dependency>
+        <groupId>com.willfp</groupId>
+        <artifactId>eco</artifactId>
+        <version>Tag</version>
+        <scope>provided</scope>
+</dependency>
+```
+
+Replace `Tag` with a release tag for eco, eg `6.8.0`.
+
+## Build locally:
+
+Run the following commands in your terminal of choice.
+
+If you're on windows, you will need to have git bash installed.
+```
+git clone https://github.com/Auxilor/eco
+cd eco
+./gradlew build
+```
+
+# Features
+
+Here's a list of some (not all) of the features of eco:
+
+- Command system with subcommands
+- Reworked config system
+- JSON Config Support
+- Client-Side item display
+- World drop system
+- Event manager
+    - PlayerJumpEvent
+    - ArmorEquipEvent
+    - EntityDeathByEntityEvent
+    - NaturalExpGainEvent
+- Plugin extensions (com.willfp.eco.internal.Plugins for plugins)
+- GUI System
+- Integration system for external plugins
+    - Anticheat support
+        - AAC
+        - Matrix
+        - NCP
+        - Spartan
+        - Vulcan
+    - Antigrief/Combat support
+        - CombatLogX (V10 + V11)
+        - FactionsUUID
+        - GriefPrevention
+        - Kingdoms
+        - Lands
+        - Towny
+        - WorldGuard
+    - mcMMO support
+    - Custom Items support
+        - Oraxen
+    - PlaceholderAPI support
+- NMS Proxy / Wrapper system built in
+- Custom Items system
+- Crafting Recipe handler
+- Tuples
+- Support uploading to / downloading from hastebin
+- Packet System (via ProtocolLib)
+- Dependency Injection systems
+- Prerequisite system
+- API additions (via utility classes)
+    - Get bow from arrow
+    - Break a block as a player
+    - Get a vein of blocks
+    - Create 2D lists
+    - Create NamespacedKeys safely
+    - Random number, distribution, roman numerals
+    - Set skull texture
+    - Format all strings
+        - Hex Support
+        - Gradient Support
+        - Placeholder Support
+    - Get a scoreboard team from any color
+    - Telekinesis (Drops straight to inventory) system
+    - More vector options
+- Update checker
+- bStats integration
+- Reworked systems for:
+    - NamespacedKey
+    - MetadataValue
+    - Runnables / Scheduling
+
+... and a lot more!
+
+## License
+
+*Click here to read [the entire license](https://github.com/Auxilor/eco/blob/master/LICENSE.md).*
+
+<h1 align="center">
+  <br>
+    <a href="https://gamersupps.gg/discount/Auxilor?afmc=Auxilor" target="_blank">
+      <img src="https://i.imgur.com/uFDpBAC.png" alt="supps banner">
+    </a>
+    <a href="https://dedimc.promo/Auxilor" target="_blank">
+      <img src="https://i.imgur.com/zdDLhFA.png" alt="dedimc banner">
+    </a>
+  <br>
+</h1>
+

build.gradle

@@ -1,102 +1,133 @@
 plugins {
     id 'java-library'
-    id 'com.github.johnrengelman.shadow' version '5.2.0'
+    id 'com.github.johnrengelman.shadow' version '7.0.0'
     id 'maven-publish'
     id 'java'
 }
 
 dependencies {
-    implementation 'org.apache.maven:maven-artifact:3.0.3'
-    implementation 'org.bstats:bstats-bukkit:1.7'
-    compileOnly 'org.spigotmc:spigot-api:1.16.4-R0.1-SNAPSHOT'
-    compileOnly 'me.clip:placeholderapi:2.10.9'
-    compileOnly 'com.comphenix.protocol:ProtocolLib:4.6.0-SNAPSHOT'
-    compileOnly 'com.sk89q.worldguard:worldguard-bukkit:7.0.4-SNAPSHOT'
-    compileOnly 'com.github.TechFortress:GriefPrevention:16.14.0'
-    compileOnly 'com.massivecraft:Factions:1.6.9.5-U0.5.10'
-    compileOnly 'com.github.cryptomorin:kingdoms:1.10.3.1'
-    compileOnly 'com.github.TownyAdvanced:Towny:0.96.2.0'
-    compileOnly 'com.github.angeschossen:LandsAPI:4.7.3'
-    compileOnly 'fr.neatmonster:nocheatplus:3.16.1-SNAPSHOT'
-    compileOnly 'com.github.jiangdashao:matrix-api-repo:317d4635fd'
-    compileOnly 'org.jetbrains:annotations:19.0.0'
-    compileOnly fileTree(dir: '/lib', include: ['*.jar'])
-
-    // Lombok
-    compileOnly 'org.projectlombok:lombok:1.18.16'
-    annotationProcessor 'org.projectlombok:lombok:1.18.16'
-    testCompileOnly 'org.projectlombok:lombok:1.18.16'
-    testAnnotationProcessor 'org.projectlombok:lombok:1.18.16'
+    implementation project(":eco-api")
+    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: 'mapped')
 }
 
+allprojects {
+    apply plugin: 'java'
+    apply plugin: 'java-library'
+    apply plugin: 'maven-publish'
+    apply plugin: 'com.github.johnrengelman.shadow'
 
-repositories {
-    mavenCentral()
-    jcenter()
-    mavenLocal()
-    maven { url 'https://jitpack.io' }
+    repositories {
+        mavenCentral()
+        mavenLocal()
+        maven { url 'https://jitpack.io' }
 
-    // NMS (for jitpack compilation)
-    maven { url 'https://repo.codemc.org/repository/nms/' }
+        // SuperiorSkyblock2
+        maven { url 'https://repo.bg-software.com/repository/api/' }
 
-    // bStats
-    maven { url 'https://repo.codemc.org/repository/maven-public' }
+        // NMS (for jitpack compilation)
+        maven { url 'https://repo.codemc.org/repository/nms/' }
 
-    // Spigot API
-    maven { url 'https://hub.spigotmc.org/nexus/content/repositories/snapshots/' }
+        // bStats, mcMMO, BentoBox
+        maven { url 'https://repo.codemc.org/repository/maven-public/' }
 
-    // PlaceholderAPI
-    maven { url 'https://repo.extendedclip.com/content/repositories/placeholderapi/' }
+        // Spigot API, Bungee API
+        maven { url 'https://hub.spigotmc.org/nexus/content/repositories/snapshots/' }
 
-    // ProtocolLib
-    maven { url 'https://repo.dmulloy2.net/nexus/repository/public/' }
+        // PlaceholderAPI
+        maven { url 'https://repo.extendedclip.com/content/repositories/placeholderapi/' }
 
-    // WorldGuard
-    maven { url 'https://maven.enginehub.org/repo/' }
+        // ProtocolLib
+        maven { url 'https://repo.dmulloy2.net/nexus/repository/public/' }
 
-    // FactionsUUID
-    maven { url 'https://ci.ender.zone/plugin/repository/everything/' }
+        // WorldGuard
+        maven { url 'https://maven.enginehub.org/repo/' }
 
-    // NoCheatPlus
-    maven { url 'https://repo.md-5.net/content/repositories/snapshots/' }
-}
+        // FactionsUUID
+        maven { url 'https://ci.ender.zone/plugin/repository/everything/' }
 
-tasks.withType(JavaCompile) {
-    options.deprecation = true
-    options.encoding = 'UTF-8'
-}
+        // NoCheatPlus
+        maven { url 'https://repo.md-5.net/content/repositories/snapshots/' }
 
-configurations.all {
-    exclude group: "org.codehaus.plexus", module: "plexus-utils"
-    exclude group: "com.mojang", module: "brigadier"
-    exclude group: "org.kitteh", module: "paste-gg-api"
-    exclude group: "org.spongepowered", module: "configurate-hocon"
-    exclude group: "com.darkblade12", module: "particleeffect"
-}
+        // CombatLogX
+        maven { url 'https://nexus.sirblobman.xyz/repository/public/' }
 
-shadowJar {
-    relocate('org.bstats.bukkit', 'com.willfp.eco.util.shaded.bstats')
-    relocate('org.apache.maven', 'com.willfp.eco.util.shaded.maven')
-}
+        // IridiumSkyblock
+        maven { url 'https://nexus.iridiumdevelopment.net/repository/maven-releases/' }
 
-publishing {
-    publications {
-        shadow(MavenPublication) {
-            from components.java
-            artifact shadowJar
+        // Velocity
+        maven { url 'https://repo.velocitypowered.com/snapshots/' }
+    }
+
+    dependencies {
+        compileOnly 'org.jetbrains:annotations:19.0.0'
+
+        // Lombok
+        compileOnly 'org.projectlombok:lombok:1.18.22'
+        annotationProcessor 'org.projectlombok:lombok:1.18.20'
+        testCompileOnly 'org.projectlombok:lombok:1.18.20'
+        testAnnotationProcessor 'org.projectlombok:lombok:1.18.20'
+
+        // Test
+        testImplementation 'org.junit.jupiter:junit-jupiter-api:5.3.1'
+        testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
+    }
+
+    tasks.withType(JavaCompile) {
+        options.deprecation = true
+        options.encoding = 'UTF-8'
+    }
+
+    configurations.all {
+        exclude group: "org.codehaus.plexus", module: "plexus-utils"
+        exclude group: "com.mojang", module: "brigadier"
+        exclude group: "org.kitteh", module: "paste-gg-api"
+        exclude group: "org.kitteh", module: "pastegg"
+        exclude group: "org.spongepowered", module: "configurate-hocon"
+        exclude group: "com.darkblade12", module: "particleeffect"
+        exclude group: "com.github.cryptomorin", module: "XSeries"
+    }
+
+    shadowJar {
+        relocate('org.bstats', 'com.willfp.eco.shaded.bstats')
+        relocate('net.kyori.adventure.text.minimessage', 'com.willfp.eco.shaded.minimessage')
+    }
+
+    jar {
+        onlyIf { !sourceSets.main.allSource.files.isEmpty() }
+    }
+
+    compileJava {
+        onlyIf { !sourceSets.main.allSource.files.isEmpty() }
+    }
+
+    java {
+        sourceCompatibility = JavaVersion.VERSION_16
+        targetCompatibility = JavaVersion.VERSION_16
+        withSourcesJar()
+    }
+
+    test {
+        useJUnitPlatform()
+
+        // Always run tests, even when nothing changed.
+        dependsOn cleanTest
+
+        // Show test results.
+        testLogging {
+            events "passed", "skipped", "failed"
         }
     }
+
+    compileJava.options.encoding = 'UTF-8'
+    compileJava.dependsOn clean
+
+    build.dependsOn shadowJar
 }
 
-compileJava.options.encoding = 'UTF-8'
-compileJava.dependsOn clean
-
-publishToMavenLocal.dependsOn shadowJar
-
-build.dependsOn shadowJar
-build.dependsOn publishToMavenLocal
-
 group = 'com.willfp'
 archivesBaseName = project.name
-version = '1.0.1'
-java.sourceCompatibility = JavaVersion.VERSION_1_8
+version = findProperty("version")

config/checkstyle/checkstyle.xml

@@ -45,7 +45,7 @@
     -->
     <property name="severity" value="error"/>
 
-    <property name="fileExtensions" value="java, properties, xml"/>
+    <property name="fileExtensions" value="java, properties, xml, kt"/>
 
     <!-- Excludes all 'module-info.java' files              -->
     <!-- See https://checkstyle.org/config_filefilters.html -->
@@ -66,6 +66,7 @@
     <module name="FileLength"/>
     <module name="LineLength">
         <property name="fileExtensions" value="java"/>
+        <property name="fileExtensions" value="kt"/>
         <property name="max" value="200"/>
     </module>
 
@@ -115,7 +116,6 @@
         <!-- Checks for imports                              -->
         <!-- See https://checkstyle.org/config_imports.html -->
         <module name="AvoidStarImport"/>
-        <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
         <module name="RedundantImport"/>
         <module name="UnusedImports">
             <property name="processJavadoc" value="true"/>

config/checkstyle/suppression.xml

@@ -5,6 +5,14 @@
         "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"/>

eco-api/build.gradle

@@ -0,0 +1,48 @@
+plugins {
+    id 'com.github.johnrengelman.shadow'
+}
+
+group 'com.willfp'
+version rootProject.version
+
+dependencies {
+    // Adventure
+    compileOnly 'net.kyori:adventure-platform-bukkit:4.0.0'
+    compileOnly 'net.kyori:adventure-text-minimessage:4.1.0-SNAPSHOT'
+    compileOnly 'net.kyori:adventure-api:4.9.2'
+    compileOnly 'net.kyori:adventure-text-serializer-gson:4.9.2'
+    compileOnly 'net.kyori:adventure-text-serializer-legacy:4.9.2'
+
+    // Other
+    compileOnly 'org.spigotmc:spigot-api:1.17.1-R0.1-SNAPSHOT'
+    compileOnly 'org.apache.maven:maven-artifact:3.8.1'
+    compileOnly 'com.comphenix.protocol:ProtocolLib:4.7.1-SNAPSHOT'
+    compileOnly 'com.google.code.gson:gson:2.8.8'
+}
+
+java {
+    withJavadocJar()
+}
+
+
+build.dependsOn publishToMavenLocal
+
+publishing {
+    publications {
+        shadow(MavenPublication) {
+            from components.java
+            artifactId 'eco'
+        }
+    }
+
+    repositories {
+        maven {
+            name = "GitHubPackages"
+            url = uri("https://maven.pkg.github.com/Auxilor/eco")
+            credentials {
+                username = System.getenv("GITHUB_ACTOR")
+                password = System.getenv("GITHUB_TOKEN")
+            }
+        }
+    }
+}

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

@@ -1,4 +1,4 @@
-package com.willfp.eco.util.protocollib;
+package com.willfp.eco.core;
 
 import com.comphenix.protocol.PacketType;
 import com.comphenix.protocol.ProtocolLibrary;
@@ -6,12 +6,15 @@ import com.comphenix.protocol.events.ListenerPriority;
 import com.comphenix.protocol.events.PacketAdapter;
 import com.comphenix.protocol.events.PacketContainer;
 import com.comphenix.protocol.events.PacketEvent;
-import com.willfp.eco.util.plugin.AbstractEcoPlugin;
 import lombok.Getter;
+import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.Collections;
 
+/**
+ * Wrapper class for ProtocolLib packets.
+ */
 public abstract class AbstractPacketAdapter extends PacketAdapter {
     /**
      * The packet type to listen for.
@@ -34,7 +37,7 @@ public abstract class AbstractPacketAdapter extends PacketAdapter {
      * @param priority The priority at which the adapter should be ran on packet send/receive.
      * @param postLoad If the packet adapter should be registered after the server has loaded.
      */
-    protected AbstractPacketAdapter(@NotNull final AbstractEcoPlugin plugin,
+    protected AbstractPacketAdapter(@NotNull final EcoPlugin plugin,
                                     @NotNull final PacketType type,
                                     @NotNull final ListenerPriority priority,
                                     final boolean postLoad) {
@@ -50,7 +53,7 @@ public abstract class AbstractPacketAdapter extends PacketAdapter {
      * @param type     The {@link PacketType} to listen for.
      * @param postLoad If the packet adapter should be registered after the server has loaded.
      */
-    protected AbstractPacketAdapter(@NotNull final AbstractEcoPlugin plugin,
+    protected AbstractPacketAdapter(@NotNull final EcoPlugin plugin,
                                     @NotNull final PacketType type,
                                     final boolean postLoad) {
         this(plugin, type, ListenerPriority.NORMAL, postLoad);
@@ -60,8 +63,12 @@ public abstract class AbstractPacketAdapter extends PacketAdapter {
      * The code that should be executed once the packet has been received.
      *
      * @param packet The packet.
+     * @param player The player.
+     * @param event  The event.
      */
-    public void onReceive(@NotNull final PacketContainer packet) {
+    public void onReceive(@NotNull final PacketContainer packet,
+                          @NotNull final Player player,
+                          @NotNull final PacketEvent event) {
         // Empty rather than abstract as implementations don't need both
     }
 
@@ -69,8 +76,12 @@ public abstract class AbstractPacketAdapter extends PacketAdapter {
      * THe code that should be executed once the packet has been sent.
      *
      * @param packet The packet.
+     * @param player The player.
+     * @param event  The event.
      */
-    public void onSend(@NotNull final PacketContainer packet) {
+    public void onSend(@NotNull final PacketContainer packet,
+                       @NotNull final Player player,
+                       @NotNull final PacketEvent event) {
         // Empty rather than abstract as implementations don't need both
     }
 
@@ -89,7 +100,7 @@ public abstract class AbstractPacketAdapter extends PacketAdapter {
             return;
         }
 
-        onReceive(event.getPacket());
+        onReceive(event.getPacket(), event.getPlayer(), event);
     }
 
     /**
@@ -107,7 +118,12 @@ public abstract class AbstractPacketAdapter extends PacketAdapter {
             return;
         }
 
-        onSend(event.getPacket());
+        onSend(event.getPacket(), event.getPlayer(), event);
+    }
+
+    @Override
+    public final EcoPlugin getPlugin() {
+        return (EcoPlugin) super.getPlugin();
     }
 
     /**

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

@@ -0,0 +1,52 @@
+package com.willfp.eco.core;
+
+import lombok.experimental.UtilityClass;
+import org.apache.commons.lang.Validate;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Base class to hold the handler.
+ *
+ * @see Handler
+ */
+@UtilityClass
+public class Eco {
+    /**
+     * Instance of eco handler.
+     */
+    @ApiStatus.Internal
+    private Handler handler;
+
+    /**
+     * Set the handler.
+     * @param handler The handler.
+     */
+    @ApiStatus.Internal
+    public void setHandler(@NotNull final Handler handler) {
+        Validate.isTrue(Eco.handler == null, "Already initialized!");
+
+        Eco.handler = handler;
+    }
+
+    /**
+     * Get the instance of the eco handler.
+     * <p>
+     * The handler is, in essence, a way to interface between the eco-api
+     * frontend module, and the eco-backend implementations.
+     * <p>
+     * There shouldn't really be any reason to ever use the handler
+     * in your own plugins, and you are likely to break things. All parts of
+     * the handler are abstracted into logically named parts of the API.
+     * <p>
+     * In versions of eco before 6.12.0, the handler was considered part of
+     * the eco API, however it has since been moved into an internal component
+     * that shouldn't be used in your plugins.
+     *
+     * @return The handler.
+     */
+    @ApiStatus.Internal
+    public Handler getHandler() {
+        return handler;
+    }
+}

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

@@ -0,0 +1,727 @@
+package com.willfp.eco.core;
+
+import com.willfp.eco.core.command.impl.PluginCommand;
+import com.willfp.eco.core.config.base.ConfigYml;
+import com.willfp.eco.core.config.base.LangYml;
+import com.willfp.eco.core.config.updating.ConfigHandler;
+import com.willfp.eco.core.display.Display;
+import com.willfp.eco.core.display.DisplayModule;
+import com.willfp.eco.core.events.EventManager;
+import com.willfp.eco.core.extensions.ExtensionLoader;
+import com.willfp.eco.core.factory.MetadataValueFactory;
+import com.willfp.eco.core.factory.NamespacedKeyFactory;
+import com.willfp.eco.core.factory.RunnableFactory;
+import com.willfp.eco.core.integrations.IntegrationLoader;
+import com.willfp.eco.core.integrations.placeholder.PlaceholderManager;
+import com.willfp.eco.core.proxy.AbstractProxy;
+import com.willfp.eco.core.proxy.ProxyFactory;
+import com.willfp.eco.core.scheduling.Scheduler;
+import com.willfp.eco.core.web.UpdateChecker;
+import lombok.Getter;
+import org.apache.commons.lang.Validate;
+import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
+import org.bukkit.Bukkit;
+import org.bukkit.configuration.file.FileConfiguration;
+import org.bukkit.event.Listener;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.plugin.java.JavaPlugin;
+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.Set;
+import java.util.logging.Logger;
+import java.util.stream.Collectors;
+
+/**
+ * EcoPlugin is the base plugin class for eco-based plugins.
+ * <p>
+ * It functions as a replacement for {@link JavaPlugin}.
+ * <p>
+ * EcoPlugin is a lot more powerful than {@link JavaPlugin} and
+ * contains many methods to reduce boilerplate code and reduce
+ * plugin complexity.
+ * <p>
+ * It is recommended to view the source code for this class to
+ * gain a better understanding of how it works.
+ * <p>
+ * <b>IMPORTANT: When reloading a plugin, all runnables / tasks will
+ * be cancelled.</b>
+ */
+@SuppressWarnings("unused")
+public abstract class EcoPlugin extends JavaPlugin implements PluginLike {
+    /**
+     * The polymart resource ID of the plugin.
+     */
+    @Getter
+    private final int resourceId;
+
+    /**
+     * The bStats resource ID of the plugin.
+     */
+    @Getter
+    private final int bStatsId;
+
+    /**
+     * The package where proxy implementations are.
+     */
+    @Getter
+    private final String proxyPackage;
+
+    /**
+     * The color of the plugin, used in messages.
+     */
+    @Getter
+    private final String color;
+
+    /**
+     * Loaded integrations.
+     */
+    @Getter
+    private final Set<String> loadedIntegrations = new HashSet<>();
+
+    /**
+     * The internal plugin scheduler.
+     */
+    @Getter
+    private final Scheduler scheduler;
+
+    /**
+     * The internal plugin Event Manager.
+     */
+    @Getter
+    private final EventManager eventManager;
+
+    /**
+     * Config.yml.
+     */
+    @Getter
+    private final ConfigYml configYml;
+
+    /**
+     * Lang.yml.
+     */
+    @Getter
+    private final LangYml langYml;
+
+    /**
+     * The internal factory to produce {@link org.bukkit.NamespacedKey}s.
+     */
+    @Getter
+    private final NamespacedKeyFactory namespacedKeyFactory;
+
+    /**
+     * The internal factory to produce {@link org.bukkit.metadata.FixedMetadataValue}s.
+     */
+    @Getter
+    private final MetadataValueFactory metadataValueFactory;
+
+    /**
+     * The internal factory to produce {@link com.willfp.eco.core.scheduling.RunnableTask}s.
+     */
+    @Getter
+    private final RunnableFactory runnableFactory;
+
+    /**
+     * The loader for all plugin extensions.
+     *
+     * @see com.willfp.eco.core.extensions.Extension
+     */
+    @Getter
+    private final ExtensionLoader extensionLoader;
+
+    /**
+     * The handler class for updatable classes.
+     */
+    @Getter
+    private final ConfigHandler configHandler;
+
+    /**
+     * The display module for the plugin.
+     */
+    @Getter
+    private DisplayModule displayModule;
+
+    /**
+     * The logger for the plugin.
+     */
+    private final Logger logger;
+
+    /**
+     * If the server is running an outdated version of the plugin.
+     */
+    @Getter
+    private boolean outdated = false;
+
+    /**
+     * If the plugin supports extensions.
+     */
+    @Getter
+    private final boolean supportingExtensions;
+
+    /**
+     * The proxy factory.
+     */
+    @Getter
+    private final ProxyFactory proxyFactory;
+
+    /**
+     * Create a new plugin without a specified color, proxy support, polymart, or bStats.
+     */
+    protected EcoPlugin() {
+        this("&f");
+    }
+
+    /**
+     * Create a new plugin without proxy support, polymart, or bStats.
+     *
+     * @param color The color.
+     */
+    protected EcoPlugin(@NotNull final String color) {
+        this("", color);
+    }
+
+
+    /**
+     * Create a new plugin unlinked to polymart and bStats.
+     *
+     * @param proxyPackage The package where proxy implementations are stored.
+     * @param color        The color of the plugin (used in messages, using standard formatting)
+     */
+    protected EcoPlugin(@NotNull final String proxyPackage,
+                        @NotNull final String color) {
+        this(0, 0, proxyPackage, color);
+    }
+
+    /**
+     * Create a new plugin without proxy or extension support.
+     *
+     * @param resourceId The polymart resource ID for the plugin.
+     * @param bStatsId   The bStats resource ID for the plugin.
+     * @param color      The color of the plugin (used in messages, using standard formatting)
+     */
+    protected EcoPlugin(final int resourceId,
+                        final int bStatsId,
+                        @NotNull final String color) {
+        this(resourceId, bStatsId, "", color);
+    }
+
+    /**
+     * Create a new plugin without proxy support.
+     *
+     * @param resourceId           The polymart resource ID for the plugin.
+     * @param bStatsId             The bStats resource ID for the plugin.
+     * @param color                The color of the plugin (used in messages, using standard formatting)
+     * @param supportingExtensions If the plugin supports extensions.
+     */
+    protected EcoPlugin(final int resourceId,
+                        final int bStatsId,
+                        @NotNull final String color,
+                        final boolean supportingExtensions) {
+        this(resourceId, bStatsId, "", color, supportingExtensions);
+    }
+
+    /**
+     * Create a new plugin without extension support.
+     *
+     * @param resourceId   The polymart resource ID for the plugin.
+     * @param bStatsId     The bStats resource ID for the plugin.
+     * @param proxyPackage The package where proxy implementations are stored.
+     * @param color        The color of the plugin (used in messages, using standard formatting)
+     */
+    protected EcoPlugin(final int resourceId,
+                        final int bStatsId,
+                        @NotNull final String proxyPackage,
+                        @NotNull final String color) {
+        this(resourceId, bStatsId, proxyPackage, color, false);
+    }
+
+    /**
+     * Create a new plugin.
+     *
+     * @param resourceId           The polymart resource ID for the plugin.
+     * @param bStatsId             The bStats resource ID for the plugin.
+     * @param proxyPackage         The package where proxy implementations are stored.
+     * @param color                The color of the plugin (used in messages, using standard formatting)
+     * @param supportingExtensions If the plugin supports extensions.
+     */
+    protected EcoPlugin(final int resourceId,
+                        final int bStatsId,
+                        @NotNull final String proxyPackage,
+                        @NotNull final String color,
+                        final boolean supportingExtensions) {
+        /*
+        The handler must be initialized before any plugin's constructors
+        are called, as the constructors call Eco#getHandler().
+
+        To fix this, EcoSpigotPlugin an abstract class and the 'actual'
+        plugin class is EcoHandler - that way I can create the handler
+        before any plugins are loaded while still having a separation between
+        the plugin class and the handler class (for code clarity).
+
+        I don't really like the fact that the handler class *is* the
+        spigot plugin, but it is what it is.
+
+        There is probably a better way of doing it - maybe with
+        some sort of HandlerCreator interface in order to still have
+        a standalone handler class, but then there would be an interface
+        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
+        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.
+
+            Any other plugins will never call this code as the handler
+            will have already been initialized.
+             */
+
+            Eco.setHandler((Handler) this);
+        }
+
+        assert Eco.getHandler() != null;
+
+        this.resourceId = resourceId;
+        this.bStatsId = bStatsId;
+        this.proxyPackage = proxyPackage;
+        this.color = color;
+        this.supportingExtensions = supportingExtensions;
+
+        this.scheduler = Eco.getHandler().createScheduler(this);
+        this.eventManager = Eco.getHandler().createEventManager(this);
+        this.namespacedKeyFactory = Eco.getHandler().createNamespacedKeyFactory(this);
+        this.metadataValueFactory = Eco.getHandler().createMetadataValueFactory(this);
+        this.runnableFactory = Eco.getHandler().createRunnableFactory(this);
+        this.extensionLoader = Eco.getHandler().createExtensionLoader(this);
+        this.configHandler = Eco.getHandler().createConfigHandler(this);
+        this.logger = Eco.getHandler().createLogger(this);
+        this.proxyFactory = this.proxyPackage.equalsIgnoreCase("") ? null : Eco.getHandler().createProxyFactory(this);
+
+        this.langYml = this.createLangYml();
+        this.configYml = this.createConfigYml();
+
+        Eco.getHandler().addNewPlugin(this);
+
+        /*
+        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.
+         */
+
+        DefaultArtifactVersion runningVersion = new DefaultArtifactVersion(Eco.getHandler().getEcoPlugin().getDescription().getVersion());
+        DefaultArtifactVersion requiredVersion = new DefaultArtifactVersion(this.getMinimumEcoVersion());
+        if (!(runningVersion.compareTo(requiredVersion) > 0 || runningVersion.equals(requiredVersion))) {
+            this.getLogger().severe("You are running an outdated version of eco!");
+            this.getLogger().severe("You must be on at least" + this.getMinimumEcoVersion());
+            this.getLogger().severe("Download the newest version here:");
+            this.getLogger().severe("https://polymart.org/download/773/recent/JSpprMspkuyecf5y1wQ2Jn8OoLQSQ_IW");
+            Bukkit.getPluginManager().disablePlugin(this);
+        }
+    }
+
+    /**
+     * Default code to be executed on plugin enable.
+     */
+    @Override
+    public final void onEnable() {
+        super.onEnable();
+
+        this.getLogger().info("");
+        this.getLogger().info("Loading " + this.getColor() + this.getName());
+
+        if (this.getResourceId() != 0) {
+            new UpdateChecker(this).getVersion(version -> {
+                DefaultArtifactVersion currentVersion = new DefaultArtifactVersion(this.getDescription().getVersion());
+                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);
+                }
+            });
+        }
+
+        if (this.getBStatsId() != 0) {
+            Eco.getHandler().registerBStats(this);
+        }
+
+        Set<String> enabledPlugins = Arrays.stream(Bukkit.getPluginManager().getPlugins())
+                .map(Plugin::getName)
+                .map(String::toLowerCase)
+                .collect(Collectors.toSet());
+
+        if (enabledPlugins.contains("PlaceholderAPI".toLowerCase())) {
+            this.loadedIntegrations.add("PlaceholderAPI");
+            PlaceholderManager.addIntegration(Eco.getHandler().createPAPIIntegration(this));
+        }
+
+        this.loadIntegrationLoaders().forEach((integrationLoader -> {
+            if (enabledPlugins.contains(integrationLoader.getPluginName().toLowerCase())) {
+                this.loadedIntegrations.add(integrationLoader.getPluginName());
+                integrationLoader.load();
+            }
+        }));
+
+        this.getLogger().info("Loaded integrations: " + String.join(", ", this.getLoadedIntegrations()));
+
+        Prerequisite.update();
+
+        this.loadPacketAdapters().forEach(abstractPacketAdapter -> {
+            if (!abstractPacketAdapter.isPostLoad()) {
+                abstractPacketAdapter.register();
+            }
+        });
+
+        this.loadListeners().forEach(listener -> this.getEventManager().registerListener(listener));
+
+        this.loadPluginCommands().forEach(PluginCommand::register);
+
+        this.getScheduler().runLater(this::afterLoad, 1);
+
+        if (this.isSupportingExtensions()) {
+            this.getExtensionLoader().loadExtensions();
+
+            if (this.getExtensionLoader().getLoadedExtensions().isEmpty()) {
+                this.getLogger().info("&cNo extensions found");
+            } else {
+                this.getLogger().info("Extensions Loaded:");
+                this.getExtensionLoader().getLoadedExtensions().forEach(extension -> this.getLogger().info("- " + extension.getName() + " v" + extension.getVersion()));
+            }
+        }
+
+        this.handleEnable();
+
+        this.getLogger().info("");
+    }
+
+    /**
+     * Default code to be executed on plugin disable.
+     */
+    @Override
+    public final void onDisable() {
+        super.onDisable();
+
+        this.getEventManager().unregisterAllListeners();
+        this.getScheduler().cancelAll();
+
+        this.handleDisable();
+
+        if (this.isSupportingExtensions()) {
+            this.getExtensionLoader().unloadExtensions();
+        }
+
+        this.getLogger().info("Cleaning up...");
+        Eco.getHandler().getCleaner().clean(this);
+    }
+
+    /**
+     * Default code to be executed on plugin load.
+     */
+    @Override
+    public final void onLoad() {
+        super.onLoad();
+
+        this.handleLoad();
+    }
+
+    /**
+     * Default code to be executed after the server is up.
+     */
+    public final void afterLoad() {
+        this.displayModule = createDisplayModule();
+
+        if (this.getDisplayModule() != null) {
+            Display.registerDisplayModule(this.getDisplayModule());
+        }
+
+        this.loadPacketAdapters().forEach(abstractPacketAdapter -> {
+            if (abstractPacketAdapter.isPostLoad()) {
+                abstractPacketAdapter.register();
+            }
+        });
+
+        if (!Prerequisite.HAS_PAPER.isMet()) {
+            this.getLogger().severe("");
+            this.getLogger().severe("----------------------------");
+            this.getLogger().severe("");
+            this.getLogger().severe("You don't seem to be running paper!");
+            this.getLogger().severe("Paper is strongly recommended for all servers,");
+            this.getLogger().severe("and some things may not function properly without it");
+            this.getLogger().severe("Download Paper from &fhttps://papermc.io");
+            this.getLogger().severe("");
+            this.getLogger().severe("----------------------------");
+            this.getLogger().severe("");
+        }
+
+        this.handleAfterLoad();
+
+        this.reload();
+
+        this.getLogger().info("Loaded " + this.color + this.getName());
+    }
+
+    /**
+     * Reload the plugin.
+     */
+    public final void reload() {
+        this.getConfigHandler().updateConfigs();
+
+        this.getConfigHandler().callUpdate();
+        this.getConfigHandler().callUpdate(); // Call twice to fix issues
+        this.getScheduler().cancelAll();
+
+        this.handleReload();
+    }
+
+    /**
+     * Reload the plugin and return the time taken to reload.
+     *
+     * @return The time.
+     */
+    public final long reloadWithTime() {
+        long startTime = System.currentTimeMillis();
+
+        this.reload();
+
+        return System.currentTimeMillis() - startTime;
+    }
+
+    /**
+     * The plugin-specific code to be executed on enable.
+     * <p>
+     * Override when needed.
+     */
+    protected void handleEnable() {
+
+    }
+
+    /**
+     * The plugin-specific code to be executed on disable.
+     * <p>
+     * Override when needed.
+     */
+    protected void handleDisable() {
+
+    }
+
+    /**
+     * The plugin-specific code to be executed on load.
+     * <p>
+     * This is executed before enabling.
+     * <p>
+     * Override when needed.
+     */
+    protected void handleLoad() {
+
+    }
+
+    /**
+     * The plugin-specific code to be executed on reload.
+     * <p>
+     * Override when needed.
+     */
+    protected void handleReload() {
+
+    }
+
+    /**
+     * The plugin-specific code to be executed after the server is up.
+     * <p>
+     * Override when needed.
+     */
+    protected void handleAfterLoad() {
+
+    }
+
+    /**
+     * The plugin-specific integrations to be tested and loaded.
+     *
+     * @return A list of integrations.
+     */
+    protected List<IntegrationLoader> loadIntegrationLoaders() {
+        return new ArrayList<>();
+    }
+
+    /**
+     * The commands to be registered.
+     *
+     * @return A list of commands.
+     */
+    protected List<PluginCommand> loadPluginCommands() {
+        return new ArrayList<>();
+    }
+
+    /**
+     * ProtocolLib packet adapters to be registered.
+     * <p>
+     * If the plugin does not require ProtocolLib this can be left empty.
+     *
+     * @return A list of packet adapters.
+     */
+    protected List<AbstractPacketAdapter> loadPacketAdapters() {
+        return new ArrayList<>();
+    }
+
+    /**
+     * All listeners to be registered.
+     *
+     * @return A list of all listeners.
+     */
+    protected abstract List<Listener> loadListeners();
+
+    /**
+     * Useful for custom LangYml implementations.
+     * <p>
+     * Override if needed.
+     *
+     * @return lang.yml.
+     */
+    protected LangYml createLangYml() {
+        return new LangYml(this);
+    }
+
+    /**
+     * Useful for custom ConfigYml implementations.
+     * <p>
+     * Override if needed.
+     *
+     * @return config.yml.
+     */
+    protected ConfigYml createConfigYml() {
+        return new ConfigYml(this);
+    }
+
+    /**
+     * Create the display module for the plugin.
+     *
+     * @return The display module, or null.
+     */
+    @Nullable
+    protected DisplayModule createDisplayModule() {
+        Validate.isTrue(
+                this.getDisplayModule() == null,
+                "Display module exists!"
+        );
+
+        return null;
+    }
+
+    /**
+     * Get the minimum version of eco to use the plugin.
+     *
+     * @return The version.
+     */
+    public String getMinimumEcoVersion() {
+        return "6.0.0";
+    }
+
+    /**
+     * Get the plugin's logger.
+     *
+     * @return The logger.
+     */
+    @NotNull
+    @Override
+    public Logger getLogger() {
+        return logger;
+    }
+
+    /**
+     * Get a proxy.
+     *
+     * @param proxyClass The proxy class.
+     * @param <T>        The proxy type.
+     * @return The proxy.
+     */
+    public final <T extends AbstractProxy> T getProxy(@NotNull final Class<T> proxyClass) {
+        Validate.notNull(proxyFactory, "Plugin does not support proxy!");
+
+        return proxyFactory.getProxy(proxyClass);
+    }
+
+    /**
+     * Get unwrapped config.
+     * Does not use eco config system, don't use.
+     *
+     * @return The bukkit config.
+     * @deprecated Use getConfigYml() instead.
+     */
+    @NotNull
+    @Override
+    @Deprecated
+    public final FileConfiguration getConfig() {
+        this.getLogger().warning("Call to default config method in eco plugin!");
+
+        return this.getConfigYml().getBukkitHandle();
+    }
+
+    /**
+     * Does not use eco config system, don't use.
+     *
+     * @deprecated Use eco config system.
+     */
+    @Override
+    @Deprecated
+    public final void saveConfig() {
+        this.getLogger().warning("Call to default config method in eco plugin!");
+
+        super.saveConfig();
+    }
+
+    /**
+     * Does not use eco config system, don't use.
+     *
+     * @deprecated Use eco config system.
+     */
+    @Override
+    @Deprecated
+    public final void saveDefaultConfig() {
+        this.getLogger().warning("Call to default config method in eco plugin!");
+
+        super.saveDefaultConfig();
+    }
+
+    /**
+     * Does not use eco config system, don't use.
+     *
+     * @deprecated Use eco config system.
+     */
+    @Override
+    @Deprecated
+    public final void reloadConfig() {
+        this.getLogger().warning("Call to default config method in eco plugin!");
+
+        super.reloadConfig();
+    }
+
+    /**
+     * Get an EcoPlugin by name.
+     *
+     * @param pluginName The name.
+     * @return The plugin.
+     */
+    public static EcoPlugin getPlugin(@NotNull final String pluginName) {
+        return Eco.getHandler().getPluginByName(pluginName);
+    }
+
+    /**
+     * Get all EcoPlugin names.
+     *
+     * @return The set of names.
+     */
+    public static Set<String> getPluginNames() {
+        return new HashSet<>(Eco.getHandler().getLoadedPlugins());
+    }
+}

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

@@ -0,0 +1,234 @@
+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.keys.KeyRegistry;
+import com.willfp.eco.core.data.PlayerProfileHandler;
+import com.willfp.eco.core.drops.DropQueueFactory;
+import com.willfp.eco.core.events.EventManager;
+import com.willfp.eco.core.extensions.ExtensionLoader;
+import com.willfp.eco.core.factory.MetadataValueFactory;
+import com.willfp.eco.core.factory.NamespacedKeyFactory;
+import com.willfp.eco.core.factory.RunnableFactory;
+import com.willfp.eco.core.fast.FastItemStack;
+import com.willfp.eco.core.gui.GUIFactory;
+import com.willfp.eco.core.integrations.placeholder.PlaceholderIntegration;
+import com.willfp.eco.core.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.inventory.ItemStack;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+import java.util.logging.Logger;
+
+/**
+ * @see Eco#getHandler()
+ */
+@ApiStatus.Internal
+public interface Handler {
+    /**
+     * Create a scheduler.
+     *
+     * @param plugin The plugin.
+     * @return The scheduler.
+     */
+    @NotNull
+    Scheduler createScheduler(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create an event manager.
+     *
+     * @param plugin The plugin.
+     * @return The event manager.
+     */
+    @NotNull
+    EventManager createEventManager(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a NamespacedKey factory.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    NamespacedKeyFactory createNamespacedKeyFactory(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a MetadataValue factory.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    MetadataValueFactory createMetadataValueFactory(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a Runnable factory.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    RunnableFactory createRunnableFactory(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create an ExtensionLoader.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    ExtensionLoader createExtensionLoader(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a config handler.
+     *
+     * @param plugin The plugin.
+     * @return The handler.
+     */
+    @NotNull
+    ConfigHandler createConfigHandler(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a logger.
+     *
+     * @param plugin The plugin.
+     * @return The logger.
+     */
+    @NotNull
+    Logger createLogger(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a PAPI integration.
+     *
+     * @param plugin The plugin.
+     * @return The integration.
+     */
+    @NotNull
+    PlaceholderIntegration createPAPIIntegration(@NotNull EcoPlugin plugin);
+
+    /**
+     * Create a proxy factory.
+     *
+     * @param plugin The plugin.
+     * @return The factory.
+     */
+    @NotNull
+    ProxyFactory createProxyFactory(@NotNull EcoPlugin plugin);
+
+    /**
+     * Get eco Spigot plugin.
+     *
+     * @return The plugin.
+     */
+    @NotNull
+    EcoPlugin getEcoPlugin();
+
+    /**
+     * Get config factory.
+     *
+     * @return The factory.
+     */
+    @NotNull
+    ConfigFactory getConfigFactory();
+
+    /**
+     * Get drop queue factory.
+     *
+     * @return The factory.
+     */
+    @NotNull
+    DropQueueFactory getDropQueueFactory();
+
+    /**
+     * Get GUI factory.
+     *
+     * @return The factory.
+     */
+    @NotNull
+    GUIFactory getGUIFactory();
+
+    /**
+     * Get cleaner.
+     *
+     * @return The cleaner.
+     */
+    @NotNull
+    Cleaner getCleaner();
+
+    /**
+     * Add new plugin.
+     *
+     * @param plugin The plugin.
+     */
+    void addNewPlugin(@NotNull EcoPlugin plugin);
+
+    /**
+     * Get plugin by name.
+     *
+     * @param name The name.
+     * @return The plugin.
+     */
+    @Nullable
+    EcoPlugin getPluginByName(@NotNull String name);
+
+    /**
+     * Get all loaded eco plugins.
+     *
+     * @return A list of plugin names in lowercase.
+     */
+    @NotNull
+    List<String> getLoadedPlugins();
+
+    /**
+     * Create a FastItemStack.
+     *
+     * @param itemStack The base ItemStack.
+     * @return The FastItemStack.
+     */
+    @NotNull
+    FastItemStack createFastItemStack(@NotNull ItemStack itemStack);
+
+    /**
+     * Register bStats metrics.
+     *
+     * @param plugin The plugin.
+     */
+    void registerBStats(@NotNull EcoPlugin plugin);
+
+    /**
+     * Get the requirement factory.
+     *
+     * @return The factory.
+     */
+    @NotNull
+    RequirementFactory getRequirementFactory();
+
+    /**
+     * Get Adventure audiences.
+     *
+     * @return The audiences.
+     */
+    @Nullable
+    BukkitAudiences getAdventure();
+
+    /**
+     * Get the key registry.
+     *
+     * @return The registry.
+     */
+    @NotNull
+    KeyRegistry getKeyRegistry();
+
+    /**
+     * Get the PlayerProfile handler.
+     *
+     * @return The handler.
+     */
+    PlayerProfileHandler getPlayerProfileHandler();
+}

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

@@ -0,0 +1,28 @@
+package com.willfp.eco.core;
+
+import lombok.AccessLevel;
+import lombok.Getter;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Quick DI class to manage passing eco plugins.
+ *
+ * @param <T> The eco plugin type.
+ */
+public abstract class PluginDependent<T extends EcoPlugin> {
+    /**
+     * The {@link EcoPlugin} that is stored.
+     */
+    @Getter(AccessLevel.PROTECTED)
+    @NotNull
+    private final T plugin;
+
+    /**
+     * Pass an {@link EcoPlugin} in order to interface with it.
+     *
+     * @param plugin The plugin to manage.
+     */
+    protected PluginDependent(@NotNull final T plugin) {
+        this.plugin = plugin;
+    }
+}

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

@@ -0,0 +1,29 @@
+package com.willfp.eco.core;
+
+import com.willfp.eco.core.config.updating.ConfigHandler;
+
+import java.io.File;
+
+/**
+ * Represents any class that acts like a plugin, for example {@link EcoPlugin}
+ * or {@link com.willfp.eco.core.extensions.Extension}. This exists to create
+ * things such as extension base configs rather than needing to pass an instance
+ * of the owning plugin.
+ */
+public interface PluginLike {
+    /**
+     * Get the data folder of the object.
+     * <p>
+     * Returns the plugin data folder for a plugin, or the extension's parent plugin's folder
+     *
+     * @return The data folder.
+     */
+    File getDataFolder();
+
+    /**
+     * Get the handler class for updatable classes.
+     *
+     * @return The config handler.
+     */
+    ConfigHandler getConfigHandler();
+}

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

@@ -1,8 +1,9 @@
-package com.willfp.eco.util.optional;
+package com.willfp.eco.core;
 
+import com.willfp.eco.core.integrations.economy.EconomyManager;
+import com.willfp.eco.core.proxy.ProxyConstants;
 import com.willfp.eco.util.ClassUtils;
 import lombok.Getter;
-import org.bukkit.Bukkit;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
@@ -10,20 +11,18 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.function.Supplier;
 
+/**
+ * A prerequisite is a requirement for something.
+ * <p>
+ * For example, you can require the server to have paper or be a specific version,
+ * or have some other dependency.
+ */
 public class Prerequisite {
     /**
      * All existing prerequisites are registered on creation.
      */
     private static final List<Prerequisite> VALUES = new ArrayList<>();
 
-    /**
-     * Requires the server to be running minecraft version 1.16 or higher.
-     */
-    public static final Prerequisite MINIMUM_1_16 = new Prerequisite(
-            () -> !Bukkit.getServer().getClass().getPackage().getName().split("\\.")[3].contains("15"),
-            "Requires minimum server version of 1.16"
-    );
-
     /**
      * Requires the server to be running an implementation of paper.
      */
@@ -32,6 +31,41 @@ public class Prerequisite {
             "Requires server to be running paper (or a fork)"
     );
 
+    /**
+     * Requires the server to have vault installed.
+     *
+     * @deprecated Use {@link EconomyManager#hasRegistrations()} instead.
+     */
+    @Deprecated
+    public static final Prerequisite HAS_VAULT = new Prerequisite(
+            () -> ClassUtils.exists("net.milkbowl.vault.economy.Economy"),
+            "Requires server to have vault"
+    );
+
+    /**
+     * Requires the server to be running 1.17.
+     */
+    public static final Prerequisite HAS_1_17 = new Prerequisite(
+            () -> ProxyConstants.NMS_VERSION.contains("17"),
+            "Requires server to be running 1.17+"
+    );
+
+    /**
+     * Requires the server to be running an implementation of BungeeCord.
+     */
+    public static final Prerequisite HAS_BUNGEECORD = new Prerequisite(
+            () -> ClassUtils.exists("net.md_5.bungee.api.event.ServerConnectedEvent"),
+            "Requires server to be running BungeeCord (or a fork)"
+    );
+
+    /**
+     * Requires the server to be running an implementation of Velocity.
+     */
+    public static final Prerequisite HAS_VELOCITY = new Prerequisite(
+            () -> ClassUtils.exists("com.velocitypowered.api.event.player.ServerConnectedEvent"),
+            "Requires server to be running Velocity (or a fork)"
+    );
+
     /**
      * If the necessary prerequisite condition has been met.
      */

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

@@ -0,0 +1,65 @@
+package com.willfp.eco.core.command;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Interface for all command implementations.
+ */
+public interface CommandBase {
+    /**
+     * Get command name.
+     *
+     * @return The name.
+     */
+    String getName();
+
+    /**
+     * Get command permission.
+     *
+     * @return The permission.
+     */
+    String getPermission();
+
+    /**
+     * If only players can execute the command.
+     *
+     * @return If true.
+     */
+    boolean isPlayersOnly();
+
+    /**
+     * Add a subcommand to the command.
+     *
+     * @param command The subcommand.
+     * @return The parent command.
+     */
+    CommandBase addSubcommand(@NotNull CommandBase command);
+
+    /**
+     * Get the handler.
+     *
+     * @return The handler.
+     */
+    CommandHandler getHandler();
+
+    /**
+     * Set the handler.
+     *
+     * @param handler The handler.
+     */
+    void setHandler(@NotNull CommandHandler handler);
+
+    /**
+     * Get the tab completer.
+     *
+     * @return The tab completer.
+     */
+    TabCompleteHandler getTabCompleter();
+
+    /**
+     * Set the tab completer.
+     *
+     * @param handler The handler.
+     */
+    void setTabCompleter(@NotNull TabCompleteHandler handler);
+}

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

@@ -0,0 +1,25 @@
+package com.willfp.eco.core.command;
+
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * A command handler handles the actual code for a command.
+ * <p>
+ * The replacement for {@link org.bukkit.command.CommandExecutor#onCommand(CommandSender, Command, String, String[])}
+ * @see CommandBase
+ */
+@FunctionalInterface
+public interface CommandHandler {
+    /**
+     * The code to be called on execution.
+     *
+     * @param sender The sender.
+     * @param args   The arguments.
+     */
+    void onExecute(@NotNull CommandSender sender,
+                   @NotNull List<String> args);
+}

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

@@ -0,0 +1,26 @@
+package com.willfp.eco.core.command;
+
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * A Tab Complete handler handles the actual tab-completion code.
+ * <p>
+ * The replacement for {@link org.bukkit.command.TabCompleter#onTabComplete(CommandSender, Command, String, String[])}
+ * @see CommandBase
+ */
+@FunctionalInterface
+public interface TabCompleteHandler {
+    /**
+     * Handle Tab Completion.
+     *
+     * @param sender The sender.
+     * @param args   The arguments.
+     * @return The tab completion results.
+     */
+    List<String> tabComplete(@NotNull CommandSender sender,
+                             @NotNull List<String> args);
+}

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

@@ -0,0 +1,205 @@
+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;
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.Setter;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+import org.bukkit.util.StringUtil;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * Abstract class for commands that can be handled.
+ * <p>
+ * Handled commands have a method to pass in raw input from bukkit commands
+ * in order to execute the command-specific code. It's essentially an internal
+ * layer, hence why it's a package-private class.
+ */
+abstract class HandledCommand extends PluginDependent<EcoPlugin> implements CommandBase {
+    /**
+     * The name of the command.
+     */
+    @Getter
+    private final String name;
+
+    /**
+     * The permission required to execute the command.
+     * <p>
+     * Written out as a string for flexibility with subclasses.
+     */
+    @Getter
+    private final String permission;
+
+    /**
+     * Should the command only be allowed to be executed by players?
+     * <p>
+     * In other worlds, only allowed to be executed by console.
+     */
+    @Getter
+    private final boolean playersOnly;
+
+    /**
+     * The actual code to be executed in the command.
+     */
+    @Getter
+    @Setter
+    private CommandHandler handler = (sender, args) -> { };
+
+    /**
+     * The tab completion code to be executed in the command.
+     */
+    @Getter
+    @Setter
+    private TabCompleteHandler tabCompleter = (sender, args) -> new ArrayList<>();
+
+    /**
+     * All subcommands for the command.
+     */
+    @Getter(AccessLevel.PROTECTED)
+    private final List<CommandBase> subcommands;
+
+    /**
+     * Create a new command.
+     * <p>
+     * The name cannot be the same as an existing command as this will conflict.
+     *
+     * @param plugin      Instance of a plugin.
+     * @param name        The name used in execution.
+     * @param permission  The permission required to execute the command.
+     * @param playersOnly If only players should be able to execute this command.
+     */
+    HandledCommand(@NotNull final EcoPlugin plugin,
+                   @NotNull final String name,
+                   @NotNull final String permission,
+                   final boolean playersOnly) {
+        super(plugin);
+        this.name = name;
+        this.permission = permission;
+        this.playersOnly = playersOnly;
+        this.subcommands = new ArrayList<>();
+    }
+
+    /**
+     * Add a subcommand to the command.
+     *
+     * @param subcommand The subcommand.
+     * @return The parent command.
+     */
+    @Override
+    public final CommandBase addSubcommand(@NotNull final CommandBase subcommand) {
+        subcommands.add(subcommand);
+
+        return this;
+    }
+
+    /**
+     * Handle the command.
+     *
+     * @param sender The sender.
+     * @param args   The arguments.
+     */
+    protected final void handle(@NotNull final CommandSender sender,
+                                @NotNull final String[] args) {
+        if (!canExecute(sender, this, this.getPlugin())) {
+            return;
+        }
+
+        if (args.length > 0) {
+            for (CommandBase subcommand : this.getSubcommands()) {
+                if (subcommand.getName().equalsIgnoreCase(args[0])) {
+                    if (!canExecute(sender, subcommand, this.getPlugin())) {
+                        return;
+                    }
+
+                    ((HandledCommand) subcommand).handle(sender, Arrays.copyOfRange(args, 1, args.length));
+
+                    return;
+                }
+            }
+        }
+
+        this.getHandler().onExecute(sender, Arrays.asList(args));
+    }
+
+    /**
+     * Handle the tab completion.
+     *
+     * @param sender The sender.
+     * @param args   The arguments.
+     * @return The tab completion results.
+     */
+    protected final List<String> handleTabCompletion(@NotNull final CommandSender sender,
+                                                     @NotNull final String[] args) {
+
+        if (!sender.hasPermission(this.getPermission())) {
+            return null;
+        }
+
+        if (args.length == 1) {
+            List<String> completions = new ArrayList<>();
+
+            StringUtil.copyPartialMatches(
+                    args[0],
+                    this.getSubcommands().stream().map(CommandBase::getName).collect(Collectors.toList()),
+                    completions
+            );
+
+            Collections.sort(completions);
+
+            if (!completions.isEmpty()) {
+                return completions;
+            }
+        }
+
+        if (args.length >= 2) {
+            HandledCommand command = null;
+
+            for (CommandBase subcommand : this.getSubcommands()) {
+                if (args[0].equalsIgnoreCase(subcommand.getName())) {
+                    command = (HandledCommand) subcommand;
+                }
+            }
+
+            if (command != null) {
+                return command.handleTabCompletion(sender, Arrays.copyOfRange(args, 1, args.length));
+            }
+        }
+
+        return this.getTabCompleter().tabComplete(sender, Arrays.asList(args));
+    }
+
+    /**
+     * If a sender can execute the command.
+     *
+     * @param sender  The sender.
+     * @param command The command.
+     * @param plugin  The plugin.
+     * @return If the sender can execute.
+     */
+    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;
+        }
+
+        return true;
+    }
+}

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

@@ -0,0 +1,94 @@
+package com.willfp.eco.core.command.impl;
+
+import com.willfp.eco.core.EcoPlugin;
+import org.bukkit.Bukkit;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandExecutor;
+import org.bukkit.command.CommandSender;
+import org.bukkit.command.TabCompleter;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+
+/**
+ * PluginCommands are the class to be used instead of CommandExecutor.
+ * <p>
+ * The command will not be registered until register() is called.
+ * <p>
+ * The name cannot be the same as an existing command as this will conflict.
+ */
+public abstract class PluginCommand extends HandledCommand implements CommandExecutor, TabCompleter {
+    /**
+     * Create a new command.
+     *
+     * @param plugin      The plugin.
+     * @param name        The name used in execution.
+     * @param permission  The permission required to execute the command.
+     * @param playersOnly If only players should be able to execute this command.
+     */
+    protected PluginCommand(@NotNull final EcoPlugin plugin,
+                            @NotNull final String name,
+                            @NotNull final String permission,
+                            final boolean playersOnly) {
+        super(plugin, name, permission, playersOnly);
+    }
+
+    /**
+     * Registers the command with the server,
+     * <p>
+     * Requires the command name to exist, defined in plugin.yml.
+     */
+    public final void register() {
+        org.bukkit.command.PluginCommand command = Bukkit.getPluginCommand(this.getName());
+        assert command != null;
+        command.setExecutor(this);
+        command.setTabCompleter(this);
+    }
+
+    /**
+     * Internal implementation used to clean up boilerplate.
+     * Used for parity with {@link CommandExecutor#onCommand(CommandSender, Command, String, String[])}.
+     *
+     * @param sender  The executor of the command.
+     * @param command The bukkit command.
+     * @param label   The name of the executed command.
+     * @param args    The arguments of the command (anything after the physical command name)
+     * @return If the command was processed by the linked {@link EcoPlugin}
+     */
+    @Override
+    public final boolean onCommand(@NotNull final CommandSender sender,
+                                   @NotNull final Command command,
+                                   @NotNull final String label,
+                                   @NotNull final String[] args) {
+        if (!command.getName().equalsIgnoreCase(this.getName())) {
+            return false;
+        }
+
+        this.handle(sender, args);
+
+        return true;
+    }
+
+    /**
+     * Internal implementation used to clean up boilerplate.
+     * Used for parity with {@link TabCompleter#onTabComplete(CommandSender, Command, String, String[])}.
+     *
+     * @param sender  The executor of the command.
+     * @param command The bukkit command.
+     * @param label   The name of the executed command.
+     * @param args    The arguments of the command (anything after the physical command name).
+     * @return The list of tab-completions.
+     */
+    @Override
+    public @Nullable List<String> onTabComplete(@NotNull final CommandSender sender,
+                                                @NotNull final Command command,
+                                                @NotNull final String label,
+                                                @NotNull final String[] args) {
+        if (!command.getName().equalsIgnoreCase(this.getName())) {
+            return null;
+        }
+
+        return this.handleTabCompletion(sender, args);
+    }
+}

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

@@ -0,0 +1,38 @@
+package com.willfp.eco.core.command.impl;
+
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.command.CommandBase;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Subcommands can be added to PluginCommands or to other Subcommands.
+ */
+public abstract class Subcommand extends HandledCommand {
+    /**
+     * Create subcommand.
+     *
+     * @param plugin      The plugin.
+     * @param name        The subcommand name.
+     * @param permission  The subcommand permission.
+     * @param playersOnly If the subcommand only works on players.
+     */
+    protected Subcommand(@NotNull final EcoPlugin plugin,
+                         @NotNull final String name,
+                         @NotNull final String permission,
+                         final boolean playersOnly) {
+        super(plugin, name, permission, playersOnly);
+    }
+
+    /**
+     * Create subcommand.
+     *
+     * @param plugin The plugin.
+     * @param name   The name of the subcommand.
+     * @param parent The parent command.
+     */
+    protected Subcommand(@NotNull final EcoPlugin plugin,
+                         @NotNull final String name,
+                         @NotNull final CommandBase parent) {
+        super(plugin, name, parent.getPermission(), parent.isPlayersOnly());
+    }
+}

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

@@ -0,0 +1,19 @@
+package com.willfp.eco.core.config.base;
+
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.config.yaml.YamlBaseConfig;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Default plugin config.yml.
+ */
+public class ConfigYml extends YamlBaseConfig {
+    /**
+     * Config.yml.
+     *
+     * @param plugin The plugin.
+     */
+    public ConfigYml(@NotNull final EcoPlugin plugin) {
+        super("config", true, plugin);
+    }
+}

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

@@ -0,0 +1,60 @@
+package com.willfp.eco.core.config.base;
+
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.config.yaml.YamlBaseConfig;
+import com.willfp.eco.util.StringUtils;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Default plugin lang.yml.
+ */
+public class LangYml extends YamlBaseConfig {
+    /**
+     * Lang.yml.
+     *
+     * @param plugin The plugin.
+     */
+    public LangYml(@NotNull final EcoPlugin plugin) {
+        super("lang", false, plugin);
+    }
+
+    /**
+     * Get the prefix for messages in chat.
+     *
+     * @return The prefix.
+     */
+    public String getPrefix() {
+        return this.getString("messages.prefix");
+    }
+
+    /**
+     * Get the no permission message.
+     *
+     * @return The message.
+     */
+    public String getNoPermission() {
+        return getPrefix() + this.getString("messages.no-permission");
+    }
+
+    /**
+     * Get a chat message.
+     *
+     * @param message The key of the message.
+     * @return The message with a prefix appended.
+     */
+    public String getMessage(@NotNull final String message) {
+        return getMessage(message, StringUtils.FormatOption.WITH_PLACEHOLDERS);
+    }
+
+    /**
+     * Get a chat message.
+     *
+     * @param message The key of the message.
+     * @param option  The format options.
+     * @return The message with a prefix appended.
+     */
+    public String getMessage(@NotNull final String message,
+                             @NotNull final StringUtils.FormatOption option) {
+        return getPrefix() + this.getString("messages." + message, option);
+    }
+}

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

@@ -0,0 +1,405 @@
+package com.willfp.eco.core.config.interfaces;
+
+import com.willfp.eco.util.StringUtils;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+
+/**
+ * All canfigs implement this interface.
+ * <p>
+ * Contains all methods that must exist in yaml and json configurations.
+ */
+public interface Config extends Cloneable {
+    /**
+     * Clears cache.
+     */
+    void clearCache();
+
+    /**
+     * Convert the config into readable text.
+     *
+     * @return The plaintext.
+     */
+    String toPlaintext();
+
+    /**
+     * Get if the config contains a key.
+     *
+     * @param path The key to check.
+     * @return If contained.
+     */
+    boolean has(@NotNull String path);
+
+    /**
+     * Get config keys.
+     *
+     * @param deep If keys from subsections should be fetched too.
+     * @return A list of keys.
+     */
+    @NotNull
+    List<String> getKeys(boolean deep);
+
+    /**
+     * Get an object from config.
+     * Default implementations call {@link org.bukkit.configuration.file.YamlConfiguration#get(String)}.
+     *
+     * @param path The path.
+     * @return The object.
+     */
+    @Nullable
+    Object get(@NotNull String path);
+
+    /**
+     * Set an object in config.
+     * Default implementations call {@link org.bukkit.configuration.file.YamlConfiguration#set(String, Object)}
+     *
+     * @param path   The path.
+     * @param object The object.
+     */
+    void set(@NotNull String path,
+             @Nullable Object object);
+
+    /**
+     * Get subsection from config.
+     *
+     * @param path The key to check.
+     * @return The subsection. Throws NPE if not found.
+     */
+    @NotNull
+    Config getSubsection(@NotNull String path);
+
+    /**
+     * Get subsection from config.
+     *
+     * @param path The key to check.
+     * @return The subsection, or null if not found.
+     */
+    @Nullable
+    Config getSubsectionOrNull(@NotNull String path);
+
+    /**
+     * Get an integer from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or 0 if not found.
+     */
+    int getInt(@NotNull String path);
+
+    /**
+     * Get an integer from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or null if not found.
+     */
+    @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.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or a blank {@link java.util.ArrayList} if not found.
+     */
+    @NotNull
+    List<Integer> getInts(@NotNull String path);
+
+    /**
+     * Get a list of integers from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    List<Integer> getIntsOrNull(@NotNull String path);
+
+    /**
+     * Get a boolean from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or false if not found.
+     */
+    boolean getBool(@NotNull String path);
+
+    /**
+     * Get a boolean from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    Boolean getBoolOrNull(@NotNull String path);
+
+    /**
+     * Get a list of booleans from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or a blank {@link java.util.ArrayList} if not found.
+     */
+    @NotNull
+    List<Boolean> getBools(@NotNull String path);
+
+    /**
+     * Get a list of booleans from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    List<Boolean> getBoolsOrNull(@NotNull String path);
+
+    /**
+     * Get a string from config.
+     *
+     * @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);
+    }
+
+    /**
+     * Get a string from config.
+     *
+     * @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.
+     */
+    @NotNull
+    default String getString(@NotNull String path,
+                             boolean format) {
+        return this.getString(path, format, StringUtils.FormatOption.WITH_PLACEHOLDERS);
+    }
+
+    /**
+     * Get a string from config.
+     *
+     * @param path   The key to fetch the value from.
+     * @param option The format option.
+     * @return The found value, or an empty string if not found.
+     */
+    @NotNull
+    default String getString(@NotNull String path,
+                             @NotNull final StringUtils.FormatOption option) {
+        return this.getString(path, true, option);
+    }
+
+    /**
+     * Get a string from config.
+     *
+     * @param path   The key to fetch the value from.
+     * @param format If the string should be formatted.
+     * @param option The format option.
+     * @return The found value, or an empty string if not found.
+     */
+    @NotNull
+    String getString(@NotNull String path,
+                     boolean format,
+                     @NotNull StringUtils.FormatOption option);
+
+    /**
+     * Get a string from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    default String getStringOrNull(@NotNull String path) {
+        return getStringOrNull(path, true);
+    }
+
+    /**
+     * Get a string from config.
+     *
+     * @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.
+     */
+    @Nullable
+    default String getStringOrNull(@NotNull String path,
+                                   boolean format) {
+        return this.getStringOrNull(path, format, StringUtils.FormatOption.WITH_PLACEHOLDERS);
+    }
+
+    /**
+     * Get a string from config.
+     *
+     * @param path   The key to fetch the value from.
+     * @param option The format option.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    default String getStringOrNull(@NotNull String path,
+                                   @NotNull StringUtils.FormatOption option) {
+        return this.getStringOrNull(path, true, option);
+    }
+
+    /**
+     * Get a string from config.
+     *
+     * @param path   The key to fetch the value from.
+     * @param format If the string should be formatted.
+     * @param option The format option.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    String getStringOrNull(@NotNull String path,
+                           boolean format,
+                           @NotNull StringUtils.FormatOption option);
+
+    /**
+     * Get a list of strings from config.
+     * <p>
+     * Formatted by default.
+     *
+     * @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);
+    }
+
+    /**
+     * Get a list of strings from config.
+     *
+     * @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.
+     */
+    @NotNull
+    default List<String> getStrings(@NotNull String path,
+                                    boolean format) {
+        return this.getStrings(path, format, StringUtils.FormatOption.WITH_PLACEHOLDERS);
+    }
+
+    /**
+     * Get a list of strings from config.
+     *
+     * @param path   The key to fetch the value from.
+     * @param option The format option.
+     * @return The found value, or a blank {@link java.util.ArrayList} if not found.
+     */
+    @Nullable
+    default List<String> getStrings(@NotNull String path,
+                                    @NotNull StringUtils.FormatOption option) {
+        return getStrings(path, true, option);
+    }
+
+    /**
+     * Get a list of strings from config.
+     *
+     * @param path   The key to fetch the value from.
+     * @param format If the strings should be formatted.
+     * @param option The option.
+     * @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);
+
+    /**
+     * Get a list of strings from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    default List<String> getStringsOrNull(@NotNull String path) {
+        return getStringsOrNull(path, true);
+    }
+
+    /**
+     * Get a list of strings from config.
+     *
+     * @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.
+     */
+    @Nullable
+    default List<String> getStringsOrNull(@NotNull String path,
+                                          boolean format) {
+        return getStringsOrNull(path, format, StringUtils.FormatOption.WITH_PLACEHOLDERS);
+    }
+
+    /**
+     * Get a list of strings from config.
+     *
+     * @param path   The key to fetch the value from.
+     * @param option The format option.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    default List<String> getStringsOrNull(@NotNull String path,
+                                          @NotNull StringUtils.FormatOption option) {
+        return getStringsOrNull(path, true, option);
+    }
+
+    /**
+     * Get a list of strings from config.
+     *
+     * @param path   The key to fetch the value from.
+     * @param format If the strings should be formatted.
+     * @param option The format option.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    List<String> getStringsOrNull(@NotNull String path,
+                                  boolean format,
+                                  @NotNull StringUtils.FormatOption option);
+
+    /**
+     * Get a decimal from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or 0 if not found.
+     */
+    double getDouble(@NotNull String path);
+
+    /**
+     * Get a decimal from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    Double getDoubleOrNull(@NotNull String path);
+
+    /**
+     * Get a list of decimals from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or a blank {@link java.util.ArrayList} if not found.
+     */
+    @NotNull
+    List<Double> getDoubles(@NotNull String path);
+
+    /**
+     * Get a list of decimals from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    List<Double> getDoublesOrNull(@NotNull String path);
+
+    /**
+     * Clone the config.
+     *
+     * @return The clone.
+     */
+    Config clone();
+}

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

@@ -0,0 +1,55 @@
+package com.willfp.eco.core.config.interfaces;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+
+/**
+ * JSON configs have extra methods compared to yaml configs.
+ * <p>
+ * If you need to use them, then use JSONConfig instead.
+ */
+public interface JSONConfig extends Config {
+    /**
+     * Get a list of subsections from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or a blank {@link java.util.ArrayList} if not found.
+     */
+    @NotNull
+    List<JSONConfig> getSubsections(@NotNull String path);
+
+    /**
+     * Get a list of subsections from config.
+     *
+     * @param path The key to fetch the value from.
+     * @return The found value, or null if not found.
+     */
+    @Nullable
+    List<JSONConfig> getSubsectionsOrNull(@NotNull String path);
+
+
+    /**
+     * Get subsection from config.
+     *
+     * @param path The key to check.
+     * @return The subsection. Throws NPE if not found.
+     */
+    @Override
+    @NotNull
+    JSONConfig getSubsection(@NotNull String path);
+
+    /**
+     * Get subsection from config.
+     *
+     * @param path The key to check.
+     * @return The subsection, or null if not found.
+     */
+    @Override
+    @Nullable
+    JSONConfig getSubsectionOrNull(@NotNull String path);
+
+    @Override
+    JSONConfig clone();
+}

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

@@ -0,0 +1,42 @@
+package com.willfp.eco.core.config.interfaces;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * Interface for configs that physically exist as files in plugins.
+ */
+public interface LoadableConfig {
+    /**
+     * Create the file.
+     */
+    void createFile();
+
+    /**
+     * Get resource path as relative to base directory.
+     *
+     * @return The resource path.
+     */
+    String getResourcePath();
+
+    /**
+     * Save the config.
+     *
+     * @throws IOException If error in saving.
+     */
+    void save() throws IOException;
+
+    /**
+     * Get the config file.
+     *
+     * @return The file.
+     */
+    File getConfigFile();
+
+    /**
+     * Get the config name (including extension).
+     *
+     * @return The name.
+     */
+    String getName();
+}

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

@@ -0,0 +1,17 @@
+package com.willfp.eco.core.config.interfaces;
+
+import org.bukkit.configuration.file.YamlConfiguration;
+
+/**
+ * Interface for configs that wrap an {@link YamlConfiguration}.
+ *
+ * @see com.willfp.eco.core.config.yaml.wrapper.YamlConfigWrapper
+ */
+public interface WrappedYamlConfiguration {
+    /**
+     * Get the ConfigurationSection handle.
+     *
+     * @return The handle.
+     */
+    YamlConfiguration getBukkitHandle();
+}

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

@@ -0,0 +1,78 @@
+package com.willfp.eco.core.config.json;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.PluginLike;
+import com.willfp.eco.core.config.json.wrapper.LoadableJSONConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Config implementation for configs present in the plugin's base directory (eg config.json).
+ * <p>
+ * Automatically updates.
+ */
+public abstract class JSONBaseConfig extends LoadableJSONConfigWrapper {
+    /**
+     * @param configName      The name of the config
+     * @param removeUnused    Whether keys not present in the default config should be removed on update.
+     * @param plugin          The plugin.
+     * @param updateBlacklist Substring of keys to not add/remove keys for.
+     */
+    protected JSONBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final PluginLike plugin,
+                             @NotNull final String... updateBlacklist) {
+        super(
+                Eco.getHandler().getConfigFactory().createUpdatableJSONConfig(
+                        configName,
+                        plugin,
+                        "",
+                        plugin.getClass(),
+                        removeUnused, updateBlacklist
+                )
+        );
+    }
+
+    /**
+     * @param configName   The name of the config
+     * @param removeUnused Whether keys not present in the default config should be removed on update.
+     * @param plugin       The plugin.
+     */
+    protected JSONBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final PluginLike plugin) {
+        super(
+                Eco.getHandler().getConfigFactory().createUpdatableJSONConfig(
+                        configName,
+                        plugin,
+                        "",
+                        plugin.getClass(),
+                        removeUnused
+                )
+        );
+    }
+
+    /**
+     * @param configName      The name of the config
+     * @param removeUnused    Whether keys not present in the default config should be removed on update.
+     * @param plugin          The plugin.
+     * @param updateBlacklist Substring of keys to not add/remove keys for.
+     */
+    protected JSONBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final EcoPlugin plugin,
+                             @NotNull final String... updateBlacklist) {
+        this(configName, removeUnused, (PluginLike) plugin, updateBlacklist);
+    }
+
+    /**
+     * @param configName   The name of the config
+     * @param removeUnused Whether keys not present in the default config should be removed on update.
+     * @param plugin       The plugin.
+     */
+    protected JSONBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final EcoPlugin plugin) {
+        this(configName, removeUnused, (PluginLike) plugin);
+    }
+}

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

@@ -0,0 +1,60 @@
+package com.willfp.eco.core.config.json;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.PluginLike;
+import com.willfp.eco.core.config.json.wrapper.LoadableJSONConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Config implementation for configs present in one of two places:
+ * <ul>
+ *     <li>Plugin base directory (eg config.yml, lang.yml)</li>
+ *     <li>Other extension's configs</li>
+ * </ul>
+ * <p>
+ * Automatically updates.
+ */
+public abstract class JSONExtendableConfig extends LoadableJSONConfigWrapper {
+    /**
+     * @param configName       The name of the config
+     * @param removeUnused     Whether keys not present in the default config should be removed on update.
+     * @param plugin           The plugin.
+     * @param updateBlacklist  Substring of keys to not add/remove keys for.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     */
+    protected JSONExtendableConfig(@NotNull final String configName,
+                                   final boolean removeUnused,
+                                   @NotNull final PluginLike plugin,
+                                   @NotNull final Class<?> source,
+                                   @NotNull final String subDirectoryPath,
+                                   @NotNull final String... updateBlacklist) {
+        super(
+                Eco.getHandler().getConfigFactory().createUpdatableJSONConfig(
+                        configName,
+                        plugin,
+                        subDirectoryPath,
+                        source,
+                        removeUnused,
+                        updateBlacklist
+                )
+        );
+    }
+    /**
+     * @param configName       The name of the config
+     * @param removeUnused     Whether keys not present in the default config should be removed on update.
+     * @param plugin           The plugin.
+     * @param updateBlacklist  Substring of keys to not add/remove keys for.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     */
+    protected JSONExtendableConfig(@NotNull final String configName,
+                                   final boolean removeUnused,
+                                   @NotNull final EcoPlugin plugin,
+                                   @NotNull final Class<?> source,
+                                   @NotNull final String subDirectoryPath,
+                                   @NotNull final String... updateBlacklist) {
+        this(configName, removeUnused, (PluginLike) plugin, source, subDirectoryPath, updateBlacklist);
+    }
+}

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

@@ -0,0 +1,38 @@
+package com.willfp.eco.core.config.json;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.PluginLike;
+import com.willfp.eco.core.config.json.wrapper.LoadableJSONConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Non-updatable JSON config that exists within a plugin jar.
+ */
+public abstract class JSONStaticBaseConfig extends LoadableJSONConfigWrapper {
+    /**
+     * Config implementation for configs present in the plugin's base directory (eg config.json, lang.json).
+     * <p>
+     * Does not automatically update.
+     *
+     * @param configName The name of the config
+     * @param plugin     The plugin.
+     */
+    protected JSONStaticBaseConfig(@NotNull final String configName,
+                                   @NotNull final PluginLike plugin) {
+        super(Eco.getHandler().getConfigFactory().createLoadableJSONConfig(configName, plugin, "", plugin.getClass()));
+    }
+
+    /**
+     * Config implementation for configs present in the plugin's base directory (eg config.json, lang.json).
+     * <p>
+     * Does not automatically update.
+     *
+     * @param configName The name of the config
+     * @param plugin     The plugin.
+     */
+    protected JSONStaticBaseConfig(@NotNull final String configName,
+                                   @NotNull final EcoPlugin plugin) {
+        this(configName, (PluginLike) plugin);
+    }
+}

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

@@ -0,0 +1,23 @@
+package com.willfp.eco.core.config.json;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.config.json.wrapper.JSONConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Map;
+
+/**
+ * Raw JSON config with a map of values at its core.
+ */
+public class JSONTransientConfig extends JSONConfigWrapper {
+    /**
+     * Config implementation for passing maps.
+     * <p>
+     * Does not automatically update.
+     *
+     * @param values The map of values.
+     */
+    public JSONTransientConfig(@NotNull final Map<String, Object> values) {
+        super(Eco.getHandler().getConfigFactory().createJSONConfig(values));
+    }
+}

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

@@ -0,0 +1,48 @@
+package com.willfp.eco.core.config.json.wrapper;
+
+import com.willfp.eco.core.config.interfaces.JSONConfig;
+import com.willfp.eco.core.config.wrapper.ConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+
+/**
+ * Wrapper to handle the backend JSON config implementations.
+ */
+public abstract class JSONConfigWrapper extends ConfigWrapper<JSONConfig> implements JSONConfig {
+    /**
+     * Create a config wrapper.
+     *
+     * @param handle The handle.
+     */
+    protected JSONConfigWrapper(@NotNull final JSONConfig handle) {
+        super(handle);
+    }
+
+
+    @Override
+    public @NotNull List<JSONConfig> getSubsections(@NotNull final String path) {
+        return this.getHandle().getSubsections(path);
+    }
+
+    @Override
+    public @Nullable List<JSONConfig> getSubsectionsOrNull(@NotNull final String path) {
+        return this.getHandle().getSubsectionsOrNull(path);
+    }
+
+    @Override
+    public @NotNull JSONConfig getSubsection(@NotNull final String path) {
+        return this.getHandle().getSubsection(path);
+    }
+
+    @Override
+    public @Nullable JSONConfig getSubsectionOrNull(@NotNull final String path) {
+        return this.getHandle().getSubsectionOrNull(path);
+    }
+
+    @Override
+    public JSONConfig clone() {
+        return this.getHandle().clone();
+    }
+}

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

@@ -0,0 +1,51 @@
+package com.willfp.eco.core.config.json.wrapper;
+
+import com.willfp.eco.core.config.interfaces.JSONConfig;
+import com.willfp.eco.core.config.interfaces.LoadableConfig;
+import org.apache.commons.lang.Validate;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * Wrapper to handle the backend loadable JSON config implementations.
+ */
+public abstract class LoadableJSONConfigWrapper extends JSONConfigWrapper implements LoadableConfig {
+    /**
+     * Create a config wrapper.
+     *
+     * @param handle The handle.
+     */
+    protected LoadableJSONConfigWrapper(@NotNull final JSONConfig handle) {
+        super(handle);
+
+        Validate.isTrue(handle instanceof LoadableConfig, "Wrapped config must be loadable!");
+    }
+
+
+    @Override
+    public void createFile() {
+        ((LoadableConfig) this.getHandle()).createFile();
+    }
+
+    @Override
+    public String getResourcePath() {
+        return ((LoadableConfig) this.getHandle()).getResourcePath();
+    }
+
+    @Override
+    public void save() throws IOException {
+        ((LoadableConfig) this.getHandle()).save();
+    }
+
+    @Override
+    public File getConfigFile() {
+        return ((LoadableConfig) this.getHandle()).getConfigFile();
+    }
+
+    @Override
+    public String getName() {
+        return ((LoadableConfig) this.getHandle()).getName();
+    }
+}

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

@@ -0,0 +1,33 @@
+package com.willfp.eco.core.config.updating;
+
+import com.willfp.eco.core.config.interfaces.LoadableConfig;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Every {@link com.willfp.eco.core.PluginLike} has a config handler.
+ * <p>
+ * Handles updating and saving configs.
+ */
+public interface ConfigHandler {
+    /**
+     * Invoke all update methods.
+     */
+    void callUpdate();
+
+    /**
+     * Save all configs.
+     */
+    void saveAllConfigs();
+
+    /**
+     * Update all updatable configs.
+     */
+    void updateConfigs();
+
+    /**
+     * Add new config to be saved.
+     *
+     * @param config The config.
+     */
+    void addConfig(@NotNull LoadableConfig config);
+}

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

@@ -0,0 +1,39 @@
+package com.willfp.eco.core.config.updating;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to put on update methods.
+ * <p>
+ * All update methods must be public and static,
+ * and can accept an EcoPlugin as a parameter.
+ * <p>
+ * As such, there are only 2 valid update methods:
+ * <p>
+ * The first:
+ * <pre>{@code
+ * @ConfigUpdater
+ * public static void update() {
+ *     // Update code
+ * }
+ * }</pre>
+ * <p>
+ * The second:
+ * <pre>{@code
+ * public static void update(EcoPlugin plugin) {}
+ *     // Update code
+ * }</pre>
+ * <p>
+ * Config update methods in all classes in a plugin jar will be called
+ * on reload.
+ * <p>
+ * By having a plugin as a parameter, you shouldn't really need getInstance()
+ * calls in your code.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface ConfigUpdater {
+}

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

@@ -0,0 +1,94 @@
+package com.willfp.eco.core.config.wrapper;
+
+import com.willfp.eco.core.PluginLike;
+import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.config.interfaces.JSONConfig;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Map;
+
+/**
+ * Internal component to create backend config implementations.
+ */
+public interface ConfigFactory {
+    /**
+     * Updatable config.
+     *
+     * @param configName       The name of the config
+     * @param plugin           The plugin.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     * @param removeUnused     Whether keys not present in the default config should be removed on update.
+     * @param updateBlacklist  Substring of keys to not add/remove keys for.
+     * @return The config implementation.
+     */
+    Config createUpdatableYamlConfig(@NotNull String configName,
+                                     @NotNull PluginLike plugin,
+                                     @NotNull String subDirectoryPath,
+                                     @NotNull Class<?> source,
+                                     boolean removeUnused,
+                                     @NotNull String... updateBlacklist);
+
+    /**
+     * Updatable config.
+     *
+     * @param configName       The name of the config
+     * @param plugin           The plugin.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     * @param removeUnused     Whether keys not present in the default config should be removed on update.
+     * @param updateBlacklist  Substring of keys to not add/remove keys for.
+     * @return The config implementation.
+     */
+    JSONConfig createUpdatableJSONConfig(@NotNull String configName,
+                                         @NotNull PluginLike plugin,
+                                         @NotNull String subDirectoryPath,
+                                         @NotNull Class<?> source,
+                                         boolean removeUnused,
+                                         @NotNull String... updateBlacklist);
+
+    /**
+     * JSON loadable config.
+     *
+     * @param configName       The name of the config
+     * @param plugin           The plugin.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     * @return The config implementation.
+     */
+    JSONConfig createLoadableJSONConfig(@NotNull String configName,
+                                        @NotNull PluginLike plugin,
+                                        @NotNull String subDirectoryPath,
+                                        @NotNull Class<?> source);
+
+    /**
+     * Yaml loadable config.
+     *
+     * @param configName       The name of the config
+     * @param plugin           The plugin.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     * @return The config implementation.
+     */
+    Config createLoadableYamlConfig(@NotNull String configName,
+                                    @NotNull PluginLike plugin,
+                                    @NotNull String subDirectoryPath,
+                                    @NotNull Class<?> source);
+
+    /**
+     * Yaml config.
+     *
+     * @param config The handle.
+     * @return The config implementation.
+     */
+    Config createYamlConfig(@NotNull YamlConfiguration config);
+
+    /**
+     * JSON config.
+     *
+     * @param values The values.
+     * @return The config implementation.
+     */
+    JSONConfig createJSONConfig(@NotNull Map<String, Object> values);
+}

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

@@ -0,0 +1,182 @@
+package com.willfp.eco.core.config.wrapper;
+
+import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.util.StringUtils;
+import lombok.Getter;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+
+/**
+ * Configs from eco have an internal implementation,
+ * which is the handle.
+ * <p>
+ * This class handles them.
+ *
+ * @param <T> The type of the handle.
+ */
+public abstract class ConfigWrapper<T extends Config> implements Config {
+    /**
+     * Configs from eco have an internal implementation,
+     * which is the handle.
+     * <p>
+     * The handle should only ever be used if you want to
+     * do something <i>interesting</i> config-wise with some
+     * internals.
+     * <p>
+     * In general use, though, the handle isn't necessary.
+     */
+    @Getter
+    private final T handle;
+
+    /**
+     * Create a config wrapper.
+     *
+     * @param handle The config that is being wrapped.
+     */
+    protected ConfigWrapper(@NotNull final T handle) {
+        this.handle = handle;
+    }
+
+    @Override
+    public void clearCache() {
+        handle.clearCache();
+    }
+
+    @Override
+    public String toPlaintext() {
+        return handle.toPlaintext();
+    }
+
+    @Override
+    public boolean has(@NotNull final String path) {
+        return handle.has(path);
+    }
+
+    @Override
+    public @NotNull List<String> getKeys(final boolean deep) {
+        return handle.getKeys(deep);
+    }
+
+    @Override
+    public @Nullable Object get(@NotNull final String path) {
+        return handle.get(path);
+    }
+
+    @Override
+    public void set(@NotNull final String path,
+                    @Nullable final Object object) {
+        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,
+                                            @NotNull final StringUtils.FormatOption option) {
+        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,
+                                                   @NotNull final StringUtils.FormatOption option) {
+        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 Config clone() {
+        return handle.clone();
+    }
+}

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

@@ -0,0 +1,78 @@
+package com.willfp.eco.core.config.yaml;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.PluginLike;
+import com.willfp.eco.core.config.yaml.wrapper.LoadableYamlConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Config implementation for configs present in the plugin's base directory (eg config.yml, lang.yml).
+ * <p>
+ * Automatically updates.
+ */
+public abstract class YamlBaseConfig extends LoadableYamlConfigWrapper {
+    /**
+     * @param configName      The name of the config
+     * @param removeUnused    Whether keys not present in the default config should be removed on update.
+     * @param plugin          The plugin.
+     * @param updateBlacklist Substring of keys to not add/remove keys for.
+     */
+    protected YamlBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final PluginLike plugin,
+                             @NotNull final String... updateBlacklist) {
+        super(
+                Eco.getHandler().getConfigFactory().createUpdatableYamlConfig(
+                        configName,
+                        plugin,
+                        "",
+                        plugin.getClass(),
+                        removeUnused, updateBlacklist
+                )
+        );
+    }
+
+    /**
+     * @param configName   The name of the config
+     * @param removeUnused Whether keys not present in the default config should be removed on update.
+     * @param plugin       The plugin.
+     */
+    protected YamlBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final PluginLike plugin) {
+        super(
+                Eco.getHandler().getConfigFactory().createUpdatableYamlConfig(
+                        configName,
+                        plugin,
+                        "",
+                        plugin.getClass(),
+                        removeUnused
+                )
+        );
+    }
+
+    /**
+     * @param configName      The name of the config
+     * @param removeUnused    Whether keys not present in the default config should be removed on update.
+     * @param plugin          The plugin.
+     * @param updateBlacklist Substring of keys to not add/remove keys for.
+     */
+    protected YamlBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final EcoPlugin plugin,
+                             @NotNull final String... updateBlacklist) {
+        this(configName, removeUnused, (PluginLike) plugin, updateBlacklist);
+    }
+
+    /**
+     * @param configName   The name of the config
+     * @param removeUnused Whether keys not present in the default config should be removed on update.
+     * @param plugin       The plugin.
+     */
+    protected YamlBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final EcoPlugin plugin) {
+        this(configName, removeUnused, (PluginLike) plugin);
+    }
+}

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

@@ -0,0 +1,60 @@
+package com.willfp.eco.core.config.yaml;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.PluginLike;
+import com.willfp.eco.core.config.yaml.wrapper.LoadableYamlConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Config implementation for configs present in one of two places:
+ * <ul>
+ *     <li>Plugin base directory (eg config.yml, lang.yml)</li>
+ *     <li>Other extension's configs</li>
+ * </ul>
+ * <p>
+ * Automatically updates.
+ */
+public abstract class YamlExtendableConfig extends LoadableYamlConfigWrapper {
+    /**
+     * @param configName       The name of the config
+     * @param removeUnused     Whether keys not present in the default config should be removed on update.
+     * @param plugin           The plugin.
+     * @param updateBlacklist  Substring of keys to not add/remove keys for.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     */
+    protected YamlExtendableConfig(@NotNull final String configName,
+                                   final boolean removeUnused,
+                                   @NotNull final PluginLike plugin,
+                                   @NotNull final Class<?> source,
+                                   @NotNull final String subDirectoryPath,
+                                   @NotNull final String... updateBlacklist) {
+        super(
+                Eco.getHandler().getConfigFactory().createUpdatableYamlConfig(
+                        configName,
+                        plugin,
+                        subDirectoryPath,
+                        source,
+                        removeUnused,
+                        updateBlacklist
+                )
+        );
+    }
+    /**
+     * @param configName       The name of the config
+     * @param removeUnused     Whether keys not present in the default config should be removed on update.
+     * @param plugin           The plugin.
+     * @param updateBlacklist  Substring of keys to not add/remove keys for.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     */
+    protected YamlExtendableConfig(@NotNull final String configName,
+                                   final boolean removeUnused,
+                                   @NotNull final EcoPlugin plugin,
+                                   @NotNull final Class<?> source,
+                                   @NotNull final String subDirectoryPath,
+                                   @NotNull final String... updateBlacklist) {
+        this(configName, removeUnused, (PluginLike) plugin, source, subDirectoryPath, updateBlacklist);
+    }
+}

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

@@ -0,0 +1,38 @@
+package com.willfp.eco.core.config.yaml;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.PluginLike;
+import com.willfp.eco.core.config.yaml.wrapper.LoadableYamlConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Non-updatable yaml config that exists within a plugin jar.
+ */
+public abstract class YamlStaticBaseConfig extends LoadableYamlConfigWrapper {
+    /**
+     * Config implementation for configs present in the plugin's base directory (eg config.yml, lang.yml).
+     * <p>
+     * Does not automatically update.
+     *
+     * @param configName The name of the config
+     * @param plugin     The plugin.
+     */
+    protected YamlStaticBaseConfig(@NotNull final String configName,
+                                   @NotNull final PluginLike plugin) {
+        super(Eco.getHandler().getConfigFactory().createLoadableYamlConfig(configName, plugin, "", plugin.getClass()));
+    }
+
+    /**
+     * Config implementation for configs present in the plugin's base directory (eg config.yml, lang.yml).
+     * <p>
+     * Does not automatically update.
+     *
+     * @param configName The name of the config
+     * @param plugin     The plugin.
+     */
+    protected YamlStaticBaseConfig(@NotNull final String configName,
+                                   @NotNull final EcoPlugin plugin) {
+        this(configName, (PluginLike) plugin);
+    }
+}

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

@@ -0,0 +1,29 @@
+package com.willfp.eco.core.config.yaml;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.config.yaml.wrapper.YamlConfigWrapper;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.StringReader;
+
+/**
+ * Config implementation for passing YamlConfigurations.
+ * <p>
+ * Does not automatically update.
+ */
+public class YamlTransientConfig extends YamlConfigWrapper {
+    /**
+     * @param config     The YamlConfiguration handle.
+     */
+    public YamlTransientConfig(@NotNull final YamlConfiguration config) {
+        super(Eco.getHandler().getConfigFactory().createYamlConfig(config));
+    }
+
+    /**
+     * @param contents     The contents of the config.
+     */
+    public YamlTransientConfig(@NotNull final String contents) {
+        super(Eco.getHandler().getConfigFactory().createYamlConfig(YamlConfiguration.loadConfiguration(new StringReader(contents))));
+    }
+}

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

@@ -0,0 +1,51 @@
+package com.willfp.eco.core.config.yaml.wrapper;
+
+import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.config.interfaces.LoadableConfig;
+import org.apache.commons.lang.Validate;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * Wrapper to handle the backend loadable yaml config implementations.
+ */
+public abstract class LoadableYamlConfigWrapper extends YamlConfigWrapper implements LoadableConfig {
+    /**
+     * Create a config wrapper.
+     *
+     * @param handle The handle.
+     */
+    protected LoadableYamlConfigWrapper(@NotNull final Config handle) {
+        super(handle);
+
+        Validate.isTrue(handle instanceof LoadableConfig, "Wrapped config must be loadable!");
+    }
+
+
+    @Override
+    public void createFile() {
+        ((LoadableConfig) this.getHandle()).createFile();
+    }
+
+    @Override
+    public String getResourcePath() {
+        return ((LoadableConfig) this.getHandle()).getResourcePath();
+    }
+
+    @Override
+    public void save() throws IOException {
+        ((LoadableConfig) this.getHandle()).save();
+    }
+
+    @Override
+    public File getConfigFile() {
+        return ((LoadableConfig) this.getHandle()).getConfigFile();
+    }
+
+    @Override
+    public String getName() {
+        return ((LoadableConfig) this.getHandle()).getName();
+    }
+}

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

@@ -0,0 +1,27 @@
+package com.willfp.eco.core.config.yaml.wrapper;
+
+import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.config.interfaces.WrappedYamlConfiguration;
+import com.willfp.eco.core.config.wrapper.ConfigWrapper;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Wrapper to handle the backend yaml config implementations.
+ */
+public abstract class YamlConfigWrapper extends ConfigWrapper<Config> implements WrappedYamlConfiguration {
+    /**
+     * Create a config wrapper.
+     *
+     * @param handle The handle.
+     */
+    protected YamlConfigWrapper(@NotNull final Config handle) {
+        super(handle);
+    }
+
+
+    @Override
+    public YamlConfiguration getBukkitHandle() {
+        return ((WrappedYamlConfiguration) this.getHandle()).getBukkitHandle();
+    }
+}

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

@@ -0,0 +1,56 @@
+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;
+
+import java.util.UUID;
+
+/**
+ * Persistent data storage interface for players.
+ * <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);
+
+    /**
+     * Load a player profile.
+     *
+     * @param player The player.
+     * @return The profile.
+     */
+    @NotNull
+    static PlayerProfile load(@NotNull final OfflinePlayer player) {
+        return load(player.getUniqueId());
+    }
+
+    /**
+     * Load a player profile.
+     *
+     * @param uuid The player's UUID.
+     * @return The profile.
+     */
+    @NotNull
+    static PlayerProfile load(@NotNull final UUID uuid) {
+        return Eco.getHandler().getPlayerProfileHandler().load(uuid);
+    }
+}

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

@@ -0,0 +1,41 @@
+package com.willfp.eco.core.data;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.UUID;
+
+/**
+ * API to handle player profiles.
+ */
+public interface PlayerProfileHandler {
+    /**
+     * Load a player profile.
+     *
+     * @param uuid The UUID.
+     * @return The profile.
+     */
+    PlayerProfile load(@NotNull UUID uuid);
+
+    /**
+     * Save a player profile.
+     *
+     * @param uuid The uuid.
+     */
+    void savePlayer(@NotNull UUID uuid);
+
+    /**
+     * Save all player data.
+     *
+     * @param async If the saving should be done asynchronously.
+     * @deprecated async is now handled automatically depending on implementation.
+     */
+    @Deprecated
+    default void saveAll(boolean async) {
+        saveAll();
+    }
+
+    /**
+     * Save all player data.
+     */
+    void saveAll();
+}

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

@@ -0,0 +1,24 @@
+package com.willfp.eco.core.data.keys;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Set;
+
+/**
+ * API to register persistent data keys.
+ */
+public interface KeyRegistry {
+    /**
+     * Register a persistent data key to be stored.
+     *
+     * @param key The key.
+     */
+    void registerKey(@NotNull PersistentDataKey<?> key);
+
+    /**
+     * Get all registered keys.
+     *
+     * @return The keys.
+     */
+    Set<PersistentDataKey<?>> getRegisteredKeys();
+}

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

@@ -0,0 +1,68 @@
+package com.willfp.eco.core.data.keys;
+
+import com.willfp.eco.core.Eco;
+import lombok.Getter;
+import org.bukkit.NamespacedKey;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Set;
+
+/**
+ * A persistent data key is a key with a type that can be stored about an offline player.
+ *
+ * @param <T> The type of the data.
+ */
+public class PersistentDataKey<T> {
+    /**
+     * The key of the persistent data value.
+     */
+    @Getter
+    private final NamespacedKey key;
+
+    /**
+     * The default value for the key.
+     */
+    @Getter
+    private final T defaultValue;
+
+    /**
+     * The persistent data key type.
+     */
+    @Getter
+    private final PersistentDataKeyType type;
+
+    /**
+     * Create a new Persistent Data Key.
+     *
+     * @param key          The key.
+     * @param type         The data type.
+     * @param defaultValue The default value.
+     */
+    public PersistentDataKey(@NotNull final NamespacedKey key,
+                             @NotNull final PersistentDataKeyType type,
+                             @NotNull final T defaultValue) {
+        this.key = key;
+        this.defaultValue = defaultValue;
+        this.type = type;
+
+        Eco.getHandler().getKeyRegistry().registerKey(this);
+    }
+
+    @Override
+    public String toString() {
+        return "PersistentDataKey{"
+                + "key=" + key
+                + ", defaultValue=" + defaultValue
+                + ", type=" + type
+                + '}';
+    }
+
+    /**
+     * Get all persistent data keys.
+     *
+     * @return The keys.
+     */
+    public static Set<PersistentDataKey<?>> values() {
+        return Eco.getHandler().getKeyRegistry().getRegisteredKeys();
+    }
+}

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

@@ -0,0 +1,26 @@
+package com.willfp.eco.core.data.keys;
+
+/**
+ * All storable data key types.
+ */
+public enum PersistentDataKeyType {
+    /**
+     * String.
+     */
+    STRING,
+
+    /**
+     * Boolean.
+     */
+    BOOLEAN,
+
+    /**
+     * Integer.
+     */
+    INT,
+
+    /**
+     * Double.
+     */
+    DOUBLE
+}

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

@@ -0,0 +1,179 @@
+package com.willfp.eco.core.display;
+
+import lombok.experimental.UtilityClass;
+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;
+
+/**
+ * Utility class to manage client-side item display.
+ */
+@UtilityClass
+public class Display {
+    /**
+     * The prefix for client-side lore lines.
+     */
+    public static final String PREFIX = "§z";
+
+    /**
+     * The display handler.
+     */
+    private static DisplayHandler handler = null;
+
+    /**
+     * Display on ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    public ItemStack display(@NotNull final ItemStack itemStack) {
+        return display(itemStack, null);
+    }
+
+    /**
+     * Display on ItemStacks.
+     *
+     * @param itemStack The item.
+     * @param player    The player.
+     * @return The ItemStack.
+     */
+    public ItemStack display(@NotNull final ItemStack itemStack,
+                             @Nullable final Player player) {
+        return handler.display(itemStack, player);
+    }
+
+    /**
+     * Display on ItemStacks and then finalize.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    public ItemStack displayAndFinalize(@NotNull final ItemStack itemStack) {
+        return finalize(display(itemStack, null));
+    }
+
+    /**
+     * Display on ItemStacks and then finalize.
+     *
+     * @param itemStack The item.
+     * @param player    The player.
+     * @return The ItemStack.
+     */
+    public ItemStack displayAndFinalize(@NotNull final ItemStack itemStack,
+                                        @Nullable final Player player) {
+        return finalize(display(itemStack, player));
+    }
+
+    /**
+     * Revert on ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    public ItemStack revert(@NotNull final ItemStack itemStack) {
+        return handler.revert(itemStack);
+    }
+
+    /**
+     * Finalize an ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    public ItemStack finalize(@NotNull final ItemStack itemStack) {
+        return handler.finalize(itemStack);
+    }
+
+    /**
+     * Unfinalize an ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    public ItemStack unfinalize(@NotNull final ItemStack itemStack) {
+        return handler.unfinalize(itemStack);
+    }
+
+    /**
+     * If an item is finalized.
+     *
+     * @param itemStack The item.
+     * @return If finalized.
+     */
+    public boolean isFinalized(@NotNull final ItemStack itemStack) {
+        return handler.isFinalized(itemStack);
+    }
+
+    /**
+     * Register a new display module.
+     *
+     * @param module The module.
+     */
+    public void registerDisplayModule(@NotNull final DisplayModule module) {
+        handler.registerDisplayModule(module);
+    }
+
+    /**
+     * Initialize the display system.
+     *
+     * @param handler The handler.
+     */
+    @ApiStatus.Internal
+    public static void init(@NotNull final DisplayHandler handler) {
+        if (Display.handler != null) {
+            throw new IllegalArgumentException("Already Initialized!");
+        }
+        Display.handler = handler;
+    }
+
+    /**
+     * Extremely janky method - also internal, so don't use it. <b>This method is
+     * NOT part of the API and may be removed at any time!</b>
+     * <p>
+     * This calls a display module with the specified parameters, now
+     * you might ask why I need a static java method when the DisplayHandler
+     * implementation could just call it itself? Well, kotlin doesn't really
+     * like dealing with vararg ambiguity, and so while kotlin can't figure out
+     * what is and isn't a vararg when I call display with a player, java can.
+     * <p>
+     * Because of this, I need to have this part of the code in java.
+     *
+     * <b>Don't call this method as part of your plugins!</b>
+     * <p>
+     * No, seriously - don't. This skips a bunch of checks and you'll almost
+     * definitely break something.
+     *
+     * @param module    The display module.
+     * @param itemStack The ItemStack.
+     * @param player    The player.
+     * @param args      The args.
+     */
+    @ApiStatus.Internal
+    public static void callDisplayModule(@NotNull final DisplayModule module,
+                                         @NotNull final ItemStack itemStack,
+                                         @Nullable final Player player,
+                                         @NotNull final Object... args) {
+        module.display(itemStack, args);
+        if (player != null) {
+            module.display(itemStack, player, args);
+        }
+    }
+
+    /**
+     * Set the display handler.
+     * <p>
+     * Internal API component, you will cause bugs if you create your own handler.
+     *
+     * @param handler The handler.
+     */
+    @ApiStatus.Internal
+    public static void setHandler(@NotNull final DisplayHandler handler) {
+        if (Display.handler != null) {
+            throw new IllegalStateException("Display already initialized!");
+        }
+
+        Display.handler = handler;
+    }
+}

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

@@ -0,0 +1,60 @@
+package com.willfp.eco.core.display;
+
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Interface for display implementations.
+ */
+public interface DisplayHandler {
+    /**
+     * Register display module.
+     *
+     * @param module The module.
+     */
+    void registerDisplayModule(@NotNull DisplayModule module);
+
+    /**
+     * Display on ItemStacks.
+     *
+     * @param itemStack The item.
+     * @param player    The player.
+     * @return The ItemStack.
+     */
+    ItemStack display(@NotNull ItemStack itemStack,
+                      @Nullable Player player);
+
+    /**
+     * Revert on ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    ItemStack revert(@NotNull ItemStack itemStack);
+
+    /**
+     * Finalize an ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    ItemStack finalize(@NotNull ItemStack itemStack);
+
+    /**
+     * Unfinalize an ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    ItemStack unfinalize(@NotNull ItemStack itemStack);
+
+    /**
+     * If an item is finalized.
+     *
+     * @param itemStack The item.
+     * @return If finalized.
+     */
+    boolean isFinalized(@NotNull ItemStack itemStack);
+}

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

@@ -0,0 +1,84 @@
+package com.willfp.eco.core.display;
+
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.PluginDependent;
+import lombok.Getter;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Class for all plugin-specific client-side item display modules.
+ */
+public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
+    /**
+     * The priority of the module.
+     */
+    @Getter
+    private final DisplayPriority priority;
+
+    /**
+     * Create a new display module.
+     *
+     * @param plugin   The plugin that the display is for.
+     * @param priority The priority of the module.
+     */
+    protected DisplayModule(@NotNull final EcoPlugin plugin,
+                            @NotNull final DisplayPriority priority) {
+        super(plugin);
+        this.priority = priority;
+    }
+
+    /**
+     * Display an item.
+     *
+     * @param itemStack The item.
+     * @param args      Optional args for display.
+     */
+    public void display(@NotNull final ItemStack itemStack,
+                        @NotNull final Object... args) {
+        // Technically optional.
+    }
+
+    /**
+     * Display an item.
+     *
+     * @param itemStack The item.
+     * @param player    The player.
+     * @param args      Optional args for display.
+     */
+    public void display(@NotNull final ItemStack itemStack,
+                        @Nullable final Player player,
+                        @NotNull final Object... args) {
+        // Technically optional.
+    }
+
+    /**
+     * Revert an item.
+     *
+     * @param itemStack The item.
+     */
+    public void revert(@NotNull final ItemStack itemStack) {
+        // Technically optional.
+    }
+
+    /**
+     * Create varargs to pass back to ItemStack after reverting, but before display.
+     *
+     * @param itemStack The itemStack.
+     * @return The plugin-specific varargs.
+     */
+    public Object[] generateVarArgs(@NotNull final ItemStack itemStack) {
+        return new Object[0];
+    }
+
+    /**
+     * Get name of plugin.
+     *
+     * @return The plugin name.
+     */
+    public final String getPluginName() {
+        return super.getPlugin().getName();
+    }
+}

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

@@ -0,0 +1,26 @@
+package com.willfp.eco.core.display;
+
+/**
+ * The priority (order) of display modules.
+ */
+public enum DisplayPriority {
+    /**
+     * Ran first.
+     */
+    LOWEST,
+
+    /**
+     * Ran second.
+     */
+    LOW,
+
+    /**
+     * Ran third.
+     */
+    HIGH,
+
+    /**
+     * Ran last.
+     */
+    HIGHEST
+}

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

@@ -1,10 +1,6 @@
-package com.willfp.eco.util.drops;
+package com.willfp.eco.core.drops;
 
-import com.willfp.eco.util.drops.internal.AbstractDropQueue;
-import com.willfp.eco.util.drops.internal.DropManager;
-import com.willfp.eco.util.drops.internal.DropQueueType;
-import com.willfp.eco.util.drops.internal.FastCollatedDropQueue;
-import com.willfp.eco.util.drops.internal.InternalDropQueue;
+import com.willfp.eco.core.Eco;
 import org.bukkit.Location;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
@@ -12,21 +8,26 @@ import org.jetbrains.annotations.NotNull;
 
 import java.util.Collection;
 
+/**
+ * A {@link DropQueue} is a set of drops linked to player.
+ * <p>
+ * All drops should be passed through a drop queue for telekinesis integration.
+ * <p>
+ * It functions essentially as a builder class, and runs very quickly.
+ *
+ * @see com.willfp.eco.util.TelekinesisUtils
+ */
 public class DropQueue {
     /**
-     * The internally used {@link AbstractDropQueue}.
+     * The internally used {@link DropQueue}.
      */
-    private final AbstractDropQueue handle;
+    private final InternalDropQueue handle;
 
     /**
-     * Create {@link DropQueue} linked to player.
-     * <p>
-     * All drops should be passed through a drop queue for telekinesis integration.
-     *
      * @param player The player.
      */
     public DropQueue(@NotNull final Player player) {
-        handle = DropManager.getType() == DropQueueType.COLLATED ? new FastCollatedDropQueue(player) : new InternalDropQueue(player);
+        handle = Eco.getHandler().getDropQueueFactory().create(player);
     }
 
     /**

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

@@ -0,0 +1,17 @@
+package com.willfp.eco.core.drops;
+
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Internal component to create backend DropQueue implementations.
+ */
+public interface DropQueueFactory {
+    /**
+     * Create a DropQueue.
+     *
+     * @param player The player.
+     * @return The Queue.
+     */
+    InternalDropQueue create(@NotNull Player player);
+}

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

@@ -1,4 +1,4 @@
-package com.willfp.eco.util.drops.internal;
+package com.willfp.eco.core.drops;
 
 import org.bukkit.Location;
 import org.bukkit.inventory.ItemStack;
@@ -6,14 +6,17 @@ import org.jetbrains.annotations.NotNull;
 
 import java.util.Collection;
 
-public interface AbstractDropQueue {
+/**
+ * Internal interface for backend DropQueue implementations.
+ */
+public interface InternalDropQueue {
     /**
      * Add item to queue.
      *
      * @param item The item to add.
      * @return The DropQueue.
      */
-    AbstractDropQueue addItem(@NotNull ItemStack item);
+    InternalDropQueue addItem(@NotNull ItemStack item);
 
     /**
      * Add multiple items to queue.
@@ -21,7 +24,7 @@ public interface AbstractDropQueue {
      * @param itemStacks The items to add.
      * @return The DropQueue.
      */
-    AbstractDropQueue addItems(@NotNull Collection<ItemStack> itemStacks);
+    InternalDropQueue addItems(@NotNull Collection<ItemStack> itemStacks);
 
     /**
      * Add xp to queue.
@@ -29,7 +32,7 @@ public interface AbstractDropQueue {
      * @param amount The amount to add.
      * @return The DropQueue.
      */
-    AbstractDropQueue addXP(int amount);
+    InternalDropQueue addXP(int amount);
 
     /**
      * Set location of the origin of the drops.
@@ -37,14 +40,14 @@ public interface AbstractDropQueue {
      * @param location The location.
      * @return The DropQueue.
      */
-    AbstractDropQueue setLocation(@NotNull Location location);
+    InternalDropQueue setLocation(@NotNull Location location);
 
     /**
      * Force the queue to act as if player is telekinetic.
      *
      * @return The DropQueue.
      */
-    AbstractDropQueue forceTelekinesis();
+    InternalDropQueue forceTelekinesis();
 
     /**
      * Push the queue.

eco-api/src/main/java/com/willfp/eco/core/events/ArmorChangeEvent.java

@@ -0,0 +1,70 @@
+package com.willfp.eco.core.events;
+
+import lombok.Getter;
+import org.bukkit.entity.Player;
+import org.bukkit.event.HandlerList;
+import org.bukkit.event.player.PlayerEvent;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * The armor change event <b>does</b> contain information about the event.
+ * <p>
+ * Unlike {@link ArmorEquipEvent}, it is called the next tick and contains previous and current armor contents.
+ */
+public class ArmorChangeEvent extends PlayerEvent {
+    /**
+     * Bukkit parity.
+     */
+    private static final HandlerList HANDLERS = new HandlerList();
+
+    /**
+     * The armor contents before. 0 is helmet, 3 is boots.
+     */
+    @Getter
+    private final List<ItemStack> before;
+
+    /**
+     * The armor contents after. 0 is helmet, 3 is boots.
+     */
+    @Getter
+    private final List<ItemStack> after;
+
+    /**
+     * Create a new ArmorChangeEvent.
+     *
+     * @param player The player.
+     * @param before The armor contents before.
+     * @param after The armor contents after.
+     */
+    public ArmorChangeEvent(@NotNull final Player player,
+                            @NotNull final List<ItemStack> before,
+                            @NotNull final List<ItemStack> after) {
+        super(player);
+        this.before = before;
+        this.after = after;
+    }
+
+    /**
+     * Gets a list of handlers handling this event.
+     *
+     * @return A list of handlers handling this event.
+     */
+
+    @Override
+    @NotNull
+    public HandlerList getHandlers() {
+        return HANDLERS;
+    }
+
+    /**
+     * Bukkit parity.
+     *
+     * @return The handler list.
+     */
+    public static HandlerList getHandlerList() {
+        return HANDLERS;
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/events/ArmorEquipEvent.java

@@ -0,0 +1,54 @@
+package com.willfp.eco.core.events;
+
+import org.bukkit.entity.Player;
+import org.bukkit.event.HandlerList;
+import org.bukkit.event.player.PlayerEvent;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * The armor equip event <b>does not contain information about the event.</b>
+ * <p>
+ * It is purely a trigger called whenever a player changes armor, you have to run
+ * your own checks.
+ * <p>
+ * The event is called before the player's inventory actually updates,
+ * so you can check a tick later to see the new contents.
+ *
+ * @see ArmorChangeEvent
+ */
+public class ArmorEquipEvent extends PlayerEvent {
+    /**
+     * Bukkit parity.
+     */
+    private static final HandlerList HANDLERS = new HandlerList();
+
+    /**
+     * Create a new ArmorEquipEvent.
+     *
+     * @param player The player.
+     */
+    public ArmorEquipEvent(@NotNull final Player player) {
+        super(player);
+    }
+
+    /**
+     * Gets a list of handlers handling this event.
+     *
+     * @return A list of handlers handling this event.
+     */
+
+    @Override
+    @NotNull
+    public HandlerList getHandlers() {
+        return HANDLERS;
+    }
+
+    /**
+     * Bukkit parity.
+     *
+     * @return The handler list.
+     */
+    public static HandlerList getHandlerList() {
+        return HANDLERS;
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/events/EntityDeathByEntityEvent.java

@@ -1,4 +1,4 @@
-package com.willfp.eco.util.events.entitydeathbyentity;
+package com.willfp.eco.core.events;
 
 import lombok.Getter;
 import org.bukkit.entity.Entity;
@@ -12,7 +12,9 @@ import org.jetbrains.annotations.NotNull;
 import java.util.List;
 
 /**
- * Event triggered when entity is killed by entity.
+ * Event called when an entity is killed by another entity.
+ * <p>
+ * Not sure why spigot doesn't have this event normally.
  */
 public class EntityDeathByEntityEvent extends Event {
     /**

eco-api/src/main/java/com/willfp/eco/core/events/EventManager.java

@@ -1,7 +1,10 @@
-package com.willfp.eco.util.bukkit.events;
+package com.willfp.eco.core.events;
 
 import org.bukkit.event.Listener;
 
+/**
+ * Manages listeners for a plugin.
+ */
 public interface EventManager {
     /**
      * Register a listener with bukkit.

eco-api/src/main/java/com/willfp/eco/core/events/NaturalExpGainEvent.java

@@ -1,4 +1,4 @@
-package com.willfp.eco.util.events.naturalexpgainevent;
+package com.willfp.eco.core.events;
 
 import lombok.Getter;
 import org.bukkit.event.Event;
@@ -6,6 +6,10 @@ import org.bukkit.event.HandlerList;
 import org.bukkit.event.player.PlayerExpChangeEvent;
 import org.jetbrains.annotations.NotNull;
 
+/**
+ * Event similar to {@link PlayerExpChangeEvent}, except it
+ * isn't called if the exp is from a bottle.
+ */
 public class NaturalExpGainEvent extends Event {
     /**
      * Internal bukkit.

eco-api/src/main/java/com/willfp/eco/core/events/PlayerJumpEvent.java

@@ -0,0 +1,84 @@
+package com.willfp.eco.core.events;
+
+import org.bukkit.Location;
+import org.bukkit.event.HandlerList;
+import org.bukkit.event.player.PlayerMoveEvent;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Event called when a player jumps.
+ */
+public class PlayerJumpEvent extends PlayerMoveEvent {
+    /**
+     * Internal bukkit.
+     */
+    private static final HandlerList HANDLERS = new HandlerList();
+
+    /**
+     * The handled event.
+     */
+    private final PlayerMoveEvent handle;
+
+    /**
+     * Create a new PlayerJumpEvent.
+     *
+     * @param event The PlayerMoveEvent.
+     */
+    public PlayerJumpEvent(@NotNull final PlayerMoveEvent event) {
+        super(event.getPlayer(), event.getFrom(), event.getTo());
+
+        this.handle = event;
+    }
+
+    /**
+     * Internal bukkit.
+     *
+     * @return The handlers.
+     */
+    @Override
+    public @NotNull HandlerList getHandlers() {
+        return HANDLERS;
+    }
+
+    /**
+     * Internal bukkit.
+     *
+     * @return The handlers.
+     */
+    public static @NotNull HandlerList getHandlerList() {
+        return HANDLERS;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return handle.isCancelled();
+    }
+
+    @Override
+    public void setCancelled(final boolean cancel) {
+        handle.setCancelled(cancel);
+    }
+
+    @NotNull
+    @Override
+    public Location getFrom() {
+        return handle.getFrom();
+    }
+
+    @Override
+    public void setFrom(@NotNull final Location from) {
+        handle.setFrom(from);
+    }
+
+    @Nullable
+    @Override
+    public Location getTo() {
+        return handle.getTo();
+    }
+
+    @Override
+    public void setTo(@NotNull final Location to) {
+        handle.setTo(to);
+    }
+}

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

@@ -1,18 +1,41 @@
-package com.willfp.eco.util.extensions;
+package com.willfp.eco.core.extensions;
 
-import com.willfp.eco.util.plugin.AbstractEcoPlugin;
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.PluginLike;
+import com.willfp.eco.core.config.updating.ConfigHandler;
 import lombok.AccessLevel;
 import lombok.Getter;
 import org.apache.commons.lang.Validate;
-import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
-public abstract class Extension {
+import java.io.File;
+
+/**
+ * An extension is a separate jar file that hooks into the base plugin jar.
+ * <p>
+ * If you take PlaceholderAPI as an example, the PAPI expansions are identical to
+ * extensions.
+ * <p>
+ * Syntactically, extensions are very similar to plugins in their own right, except that
+ * they are loaded by another plugin.
+ *
+ * @see <a href="https://auxilor.polymart.org">Extension examples.</a>
+ */
+public abstract class Extension implements PluginLike {
     /**
-     * The {@link AbstractEcoPlugin} that this extension is for.
+     * The {@link EcoPlugin} that this extension is for.
      */
     @Getter(AccessLevel.PROTECTED)
-    private final AbstractEcoPlugin plugin = AbstractEcoPlugin.getInstance();
+    private final EcoPlugin plugin;
+
+    /**
+     * Create a new extension for a plugin.
+     *
+     * @param plugin The plugin.
+     */
+    protected Extension(@NotNull final EcoPlugin plugin) {
+        this.plugin = plugin;
+    }
 
     /**
      * Metadata containing version and name.
@@ -62,7 +85,17 @@ public abstract class Extension {
      */
     public final String getName() {
         Validate.notNull(metadata, "Metadata cannot be null!");
-        return this.metadata.name;
+        return this.metadata.name();
+    }
+
+    /**
+     * Get the author of the extension.
+     *
+     * @return The author of the metadata attached to the extension.
+     */
+    public final String getAuthor() {
+        Validate.notNull(metadata, "Metadata cannot be null!");
+        return this.metadata.author();
     }
 
     /**
@@ -72,36 +105,16 @@ public abstract class Extension {
      */
     public final String getVersion() {
         Validate.notNull(metadata, "Metadata cannot be null!");
-        return this.metadata.version;
+        return this.metadata.version();
     }
 
-    /**
-     * Wrapper for the string and version of the extension.
-     * Contains versions and name.
-     * Designed for internal use.
-     */
-    @ApiStatus.Internal
-    public static final class ExtensionMetadata {
-        /**
-         * The version of the extension.
-         */
-        private final @NotNull String version;
+    @Override
+    public File getDataFolder() {
+        return this.plugin.getDataFolder();
+    }
 
-        /**
-         * The extension's name.
-         */
-        private final @NotNull String name;
-
-        /**
-         * Create a new extension metadata.
-         *
-         * @param version The version for the extension to be.
-         * @param name    The name of the extension.
-         */
-        public ExtensionMetadata(@NotNull final String version,
-                                 @NotNull final String name) {
-            this.version = version;
-            this.name = name;
-        }
+    @Override
+    public ConfigHandler getConfigHandler() {
+        return this.plugin.getConfigHandler();
     }
 }

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

@@ -1,15 +1,11 @@
-package com.willfp.eco.util.extensions.loader;
-
-import com.willfp.eco.util.extensions.Extension;
+package com.willfp.eco.core.extensions;
 
 import java.util.Set;
 
 /**
- * Interface for extension loader.
- * Some external plugins may modify extension loading for internal server purposes.
+ * Internal component to manage loading and unloading extensions.
  */
 public interface ExtensionLoader {
-
     /**
      * Load all extensions.
      */
@@ -20,11 +16,6 @@ public interface ExtensionLoader {
      */
     void unloadExtensions();
 
-    /**
-     * Reload all extensions.
-     */
-    void reloadExtensions();
-
     /**
      * Retrieve a set of all loaded extensions.
      *

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

@@ -0,0 +1,18 @@
+package com.willfp.eco.core.extensions;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * The extension's metadata.
+ * <p>
+ * Stored as a record internally.
+ *
+ * @param version The extension version.
+ * @param name    The extension name.
+ * @param author  The extension's author.
+ */
+public record ExtensionMetadata(@NotNull String version,
+                                @NotNull String name,
+                                @NotNull String author) {
+
+}

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

@@ -1,18 +1,15 @@
-package com.willfp.eco.util.extensions;
+package com.willfp.eco.core.extensions;
 
 import org.jetbrains.annotations.NotNull;
 
 /**
- * Called when the extension is made incorrectly.
+ * Potential causes include:
+ * Missing or invalid extension.yml.
+ * Invalid filetype.
  */
 public class MalformedExtensionException extends RuntimeException {
-
     /**
      * Create a new MalformedExtensionException.
-     * <p>
-     * Potential causes include:
-     * Missing or invalid extension.yml.
-     * Invalid filetype.
      *
      * @param errorMessage The error message to show.
      */

eco-api/src/main/java/com/willfp/eco/core/factory/MetadataValueFactory.java

@@ -0,0 +1,17 @@
+package com.willfp.eco.core.factory;
+
+import org.bukkit.metadata.FixedMetadataValue;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Factory to create metadata values for a specific plugin.
+ */
+public interface MetadataValueFactory {
+    /**
+     * Create a metadata value for a given plugin and object.
+     *
+     * @param value The object to store in metadata.
+     * @return The metadata value.
+     */
+    FixedMetadataValue create(@NotNull Object value);
+}

eco-api/src/main/java/com/willfp/eco/core/factory/NamespacedKeyFactory.java

@@ -0,0 +1,17 @@
+package com.willfp.eco.core.factory;
+
+import org.bukkit.NamespacedKey;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Factory to create {@link NamespacedKey}s for a plugin.
+ */
+public interface NamespacedKeyFactory {
+    /**
+     * Create an {@link NamespacedKey} associated with an {@link com.willfp.eco.core.EcoPlugin}.
+     *
+     * @param key The key in the {@link NamespacedKey}.
+     * @return The created {@link NamespacedKey}.
+     */
+    NamespacedKey create(@NotNull String key);
+}

eco-api/src/main/java/com/willfp/eco/core/factory/RunnableFactory.java

@@ -0,0 +1,20 @@
+package com.willfp.eco.core.factory;
+
+import com.willfp.eco.core.scheduling.RunnableTask;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.function.Consumer;
+
+/**
+ * Factory to create runnables. Much cleaner syntax than instantiating
+ * {@link org.bukkit.scheduler.BukkitRunnable}s.
+ */
+public interface RunnableFactory {
+    /**
+     * Create a {@link RunnableTask}.
+     *
+     * @param consumer Lambda of the code to run, where the parameter represents the instance of the runnable.
+     * @return The created {@link RunnableTask}.
+     */
+    RunnableTask create(@NotNull Consumer<RunnableTask> consumer);
+}

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

@@ -0,0 +1,113 @@
+package com.willfp.eco.core.fast;
+
+import com.willfp.eco.core.Eco;
+import org.bukkit.Material;
+import org.bukkit.enchantments.Enchantment;
+import org.bukkit.inventory.ItemFlag;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * FastItemStack contains methods to modify and read items faster than in default bukkit.
+ */
+public interface FastItemStack {
+    /**
+     * Get all enchantments on an item.
+     *
+     * @param checkStored If stored NBT should also be checked.
+     * @return A map of all enchantments.
+     */
+    Map<Enchantment, Integer> getEnchantmentsOnItem(boolean checkStored);
+
+    /**
+     * Get the level of an enchantment on an item.
+     *
+     * @param enchantment The enchantment.
+     * @param checkStored If the stored NBT should also be checked.
+     * @return The enchantment level, or 0 if not found.
+     */
+    int getLevelOnItem(@NotNull Enchantment enchantment,
+                       boolean checkStored);
+
+    /**
+     * Set the item lore.
+     *
+     * @param lore The lore.
+     */
+    void setLore(@Nullable List<String> lore);
+
+    /**
+     * Get the item lore.
+     *
+     * @return The lore.
+     */
+    List<String> getLore();
+
+
+    /**
+     * Set the rework penalty.
+     *
+     * @param cost The rework penalty to set.
+     */
+    void setRepairCost(int cost);
+
+    /**
+     * Get the rework penalty.
+     * .
+     *
+     * @return The rework penalty found on the item.
+     */
+    int getRepairCost();
+
+    /**
+     * Add ItemFlags.
+     *
+     * @param hideFlags The flags.
+     */
+    void addItemFlags(ItemFlag... hideFlags);
+
+    /**
+     * Remove ItemFlags.
+     *
+     * @param hideFlags The flags.
+     */
+    void removeItemFlags(ItemFlag... hideFlags);
+
+    /**
+     * Get the ItemFlags.
+     *
+     * @return The flags.
+     */
+    Set<ItemFlag> getItemFlags();
+
+    /**
+     * Test the item for a flag.
+     *
+     * @param flag The flag.
+     * @return If the flag is present.
+     */
+    boolean hasItemFlag(ItemFlag flag);
+
+    /**
+     * Get the Bukkit ItemStack again.
+     *
+     * @return The ItemStack.
+     */
+    ItemStack unwrap();
+
+    /**
+     * Wrap an ItemStack to create a FastItemStack.
+     *
+     * @param itemStack The ItemStack.
+     * @return The FastItemStack.
+     */
+    static FastItemStack wrap(@Nullable final ItemStack itemStack) {
+        return Eco.getHandler().createFastItemStack(Objects.requireNonNullElseGet(itemStack, () -> new ItemStack(Material.AIR)));
+    }
+}

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

@@ -0,0 +1,29 @@
+package com.willfp.eco.core.gui;
+
+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.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)}.
+ */
+public interface GUIFactory {
+    /**
+     * Create slot builder.
+     *
+     * @param provider The provider.
+     * @return The builder.
+     */
+    SlotBuilder createSlotBuilder(@NotNull SlotProvider provider);
+
+    /**
+     * Create menu builder.
+     *
+     * @param rows The amount of rows.
+     * @return The builder.
+     */
+    MenuBuilder createMenuBuilder(int rows);
+}

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

@@ -0,0 +1,19 @@
+package com.willfp.eco.core.gui.menu;
+
+import org.bukkit.event.inventory.InventoryCloseEvent;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Interface to run on menu close.
+ */
+@FunctionalInterface
+public interface CloseHandler {
+    /**
+     * Performs this operation on the given arguments.
+     *
+     * @param event The close event.
+     * @param menu  The menu.
+     */
+    void handle(@NotNull InventoryCloseEvent event,
+                @NotNull Menu menu);
+}

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

@@ -0,0 +1,108 @@
+package com.willfp.eco.core.gui.menu;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.gui.slot.Slot;
+import org.bukkit.NamespacedKey;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.Inventory;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.persistence.PersistentDataType;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+import java.util.Set;
+
+/**
+ * GUI version of {@link Inventory}.
+ * <p>
+ * A menu contains slots and is 1-indexed. (Top row has index 1, bottom row has index 6).
+ */
+public interface Menu {
+    /**
+     * Get the amount of rows.
+     *
+     * @return The amount of rows.
+     */
+    int getRows();
+
+    /**
+     * Get slot at given row and column.
+     *
+     * @param row    The row.
+     * @param column The column.
+     * @return The row.
+     */
+    Slot getSlot(int row,
+                 int column);
+
+    /**
+     * Get the menu title.
+     *
+     * @return The title.
+     */
+    String getTitle();
+
+    /**
+     * Open the inventory for the player.
+     *
+     * @param player The player.
+     * @return The inventory.
+     */
+    Inventory open(@NotNull Player player);
+
+    /**
+     * Get captive items.
+     *
+     * @param player The player.
+     * @return The items.
+     */
+    List<ItemStack> getCaptiveItems(@NotNull Player player);
+
+    /**
+     * Write data.
+     *
+     * @param player The player.
+     * @param key    The key.
+     * @param type   The type.
+     * @param value  The value.
+     * @param <T>    The type.
+     * @param <Z>    The type.
+     */
+    <T, Z> void writeData(@NotNull Player player,
+                          @NotNull NamespacedKey key,
+                          @NotNull PersistentDataType<T, Z> type,
+                          @NotNull Z value);
+
+    /**
+     * Read data.
+     *
+     * @param player The player.
+     * @param key    The key.
+     * @param type   The type.
+     * @param <T>    The type.
+     * @param <Z>    The type.
+     * @return The data.
+     */
+    @Nullable <T, Z> T readData(@NotNull Player player,
+                                @NotNull NamespacedKey key,
+                                @NotNull PersistentDataType<T, Z> type);
+
+    /**
+     * Get all data keys for a player.
+     *
+     * @param player The player.
+     * @return The keys.
+     */
+    Set<NamespacedKey> getKeys(@NotNull Player player);
+
+    /**
+     * Create a builder with a given amount of rows.
+     *
+     * @param rows The rows.
+     * @return The builder.
+     */
+    static MenuBuilder builder(final int rows) {
+        return Eco.getHandler().getGUIFactory().createMenuBuilder(rows);
+    }
+}

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

@@ -0,0 +1,75 @@
+package com.willfp.eco.core.gui.menu;
+
+import com.willfp.eco.core.gui.slot.FillerMask;
+import com.willfp.eco.core.gui.slot.Slot;
+import org.bukkit.event.inventory.InventoryCloseEvent;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.function.Consumer;
+
+/**
+ * Builder to create menus.
+ */
+public interface MenuBuilder {
+    /**
+     * Set the menu title.
+     *
+     * @param title The title.
+     * @return The builder.
+     */
+    MenuBuilder setTitle(@NotNull String title);
+
+    /**
+     * Set a slot.
+     *
+     * @param row    The row.
+     * @param column The column.
+     * @param slot   The slot.
+     * @return The builder.
+     */
+    MenuBuilder setSlot(int row,
+                        int column,
+                        @NotNull Slot slot);
+
+    /**
+     * Run function to modify the builder.
+     *
+     * @param modifier The modifier.
+     * @return The builder.
+     */
+    MenuBuilder modfiy(@NotNull Consumer<MenuBuilder> modifier);
+
+    /**
+     * Set the menu mask.
+     *
+     * @param mask The mask.
+     * @return The builder.
+     */
+    MenuBuilder setMask(@NotNull FillerMask mask);
+
+    /**
+     * Set the menu close handler.
+     *
+     * @param action The handler.
+     * @return The builder.
+     */
+    default MenuBuilder onClose(@NotNull Consumer<InventoryCloseEvent> action) {
+        onClose((event, menu) -> action.accept(event));
+        return this;
+    }
+
+    /**
+     * Set the menu close handler.
+     *
+     * @param action The handler.
+     * @return The builder.
+     */
+    MenuBuilder onClose(@NotNull CloseHandler action);
+
+    /**
+     * Build the menu.
+     *
+     * @return The menu.
+     */
+    Menu build();
+}

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

@@ -0,0 +1,85 @@
+package com.willfp.eco.core.gui.slot;
+
+import com.willfp.eco.core.items.builder.ItemStackBuilder;
+import com.willfp.eco.util.ListUtils;
+import lombok.Getter;
+import org.bukkit.Material;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Mask of filler slots.
+ * <p>
+ * A pattern consists of 1s and 0s, where a 1 is a filler slot,
+ * and a 0 isn't.
+ * <p>
+ * For example, creating a filler mask for a single-chest sized menu would look like this:
+ * <p>
+ * new FillerMask(
+ * material,
+ * "11111111"
+ * "10000001"
+ * "11111111"
+ * );
+ */
+public class FillerMask {
+    /**
+     * Mask.
+     */
+    @Getter
+    private final List<List<Slot>> mask;
+
+    /**
+     * Create a new filler mask.
+     *
+     * @param material The mask material.
+     * @param pattern  The pattern.
+     */
+    public FillerMask(@NotNull final Material material,
+                      @NotNull final String... pattern) {
+        this(new MaskMaterials(material), pattern);
+    }
+
+    /**
+     * Create a new filler mask.
+     *
+     * @param materials The mask materials.
+     * @param pattern  The pattern.
+     */
+    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!");
+        }
+
+        mask = ListUtils.create2DList(6, 9);
+
+        for (int i = 0; i < materials.materials().length; i++) {
+            ItemStack itemStack = new ItemStackBuilder(materials.materials()[i])
+                    .setDisplayName("&r")
+                    .build();
+
+            int row = 0;
+
+            for (String patternRow : pattern) {
+                int column = 0;
+                if (patternRow.length() != 9) {
+                    throw new IllegalArgumentException("Invalid amount of columns in pattern!");
+                }
+                for (char c : patternRow.toCharArray()) {
+                    if (c == '0') {
+                        mask.get(row).set(column, null);
+                    } else if (c == Character.forDigit(i + 1, 10)) {
+                        mask.get(row).set(column, new FillerSlot(itemStack));
+                    }
+
+                    column++;
+                }
+                row++;
+            }
+        }
+    }
+}

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

@@ -0,0 +1,38 @@
+package com.willfp.eco.core.gui.slot;
+
+import lombok.Getter;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A filler slot is a slot that does nothing when clicked.
+ * <p>
+ * Useful for backgrounds.
+ */
+public class FillerSlot implements Slot {
+    /**
+     * The ItemStack.
+     */
+    @Getter
+    private final ItemStack itemStack;
+
+    /**
+     * Create new filler slot.
+     *
+     * @param itemStack The ItemStack.
+     */
+    public FillerSlot(@NotNull final ItemStack itemStack) {
+        this.itemStack = itemStack;
+    }
+
+    @Override
+    public ItemStack getItemStack(@NotNull final Player player) {
+        return itemStack;
+    }
+
+    @Override
+    public boolean isCaptive() {
+        return false;
+    }
+}

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

@@ -0,0 +1,14 @@
+package com.willfp.eco.core.gui.slot;
+
+import org.bukkit.Material;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Mask materials store a set of materials which can be accessed by
+ * a filler mask.
+ *
+ * @param materials The materials.
+ */
+public record MaskMaterials(@NotNull Material... materials) {
+
+}

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

@@ -0,0 +1,69 @@
+package com.willfp.eco.core.gui.slot;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.gui.slot.functional.SlotProvider;
+import org.bukkit.Material;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.function.Function;
+
+/**
+ * A slot is an item in a GUI that can handle clicks.
+ */
+public interface Slot {
+    /**
+     * Get the ItemStack that would be shown to a player.
+     *
+     * @param player The player.
+     * @return The ItemStack.
+     */
+    ItemStack getItemStack(@NotNull Player player);
+
+    /**
+     * If the slot is captive. (Can items be placed in it).
+     *
+     * @return If captive.
+     */
+    boolean isCaptive();
+
+    /**
+     * Create a builder for an ItemStack.
+     *
+     * @return The builder.
+     */
+    static SlotBuilder builder() {
+        return Eco.getHandler().getGUIFactory().createSlotBuilder((player, menu) -> new ItemStack(Material.AIR));
+    }
+
+    /**
+     * Create a builder for an ItemStack.
+     *
+     * @param itemStack The ItemStack.
+     * @return The builder.
+     */
+    static SlotBuilder builder(@NotNull final ItemStack itemStack) {
+        return Eco.getHandler().getGUIFactory().createSlotBuilder((player, menu) -> itemStack);
+    }
+
+    /**
+     * Create a builder for a player-specific ItemStack.
+     *
+     * @param provider The provider.
+     * @return The builder.
+     */
+    static SlotBuilder builder(@NotNull final Function<Player, ItemStack> provider) {
+        return Eco.getHandler().getGUIFactory().createSlotBuilder((player, menu) -> provider.apply(player));
+    }
+
+    /**
+     * Create a builder for a player-specific ItemStack.
+     *
+     * @param provider The provider.
+     * @return The builder.
+     */
+    static SlotBuilder builder(@NotNull final SlotProvider provider) {
+        return Eco.getHandler().getGUIFactory().createSlotBuilder(provider);
+    }
+}

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

@@ -0,0 +1,125 @@
+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 org.bukkit.event.inventory.InventoryClickEvent;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.function.BiConsumer;
+
+/**
+ * Builder to create slots.
+ */
+public interface SlotBuilder {
+    /**
+     * Set click handler.
+     *
+     * @param action The handler.
+     * @return The builder.
+     */
+    default SlotBuilder onLeftClick(@NotNull BiConsumer<InventoryClickEvent, Slot> action) {
+        return onLeftClick((event, slot, menu) -> action.accept(event, slot));
+    }
+
+    /**
+     * Set click handler.
+     *
+     * @param handler The handler.
+     * @return The builder.
+     */
+    SlotBuilder onLeftClick(@NotNull SlotHandler handler);
+
+    /**
+     * Set click handler.
+     *
+     * @param action The handler.
+     * @return The builder.
+     */
+    default SlotBuilder onRightClick(@NotNull BiConsumer<InventoryClickEvent, Slot> action) {
+        return onRightClick((event, slot, menu) -> action.accept(event, slot));
+    }
+
+    /**
+     * Set click handler.
+     *
+     * @param handler The handler.
+     * @return The builder.
+     */
+    SlotBuilder onRightClick(@NotNull SlotHandler handler);
+
+    /**
+     * Set click handler.
+     *
+     * @param action The handler.
+     * @return The builder.
+     */
+    default SlotBuilder onShiftLeftClick(@NotNull BiConsumer<InventoryClickEvent, Slot> action) {
+        return onShiftLeftClick((event, slot, menu) -> action.accept(event, slot));
+    }
+
+    /**
+     * Set click handler.
+     *
+     * @param handler The handler.
+     * @return The builder.
+     */
+    SlotBuilder onShiftLeftClick(@NotNull SlotHandler handler);
+
+    /**
+     * Set click handler.
+     *
+     * @param action The handler.
+     * @return The builder.
+     */
+    default SlotBuilder onShiftRightClick(@NotNull BiConsumer<InventoryClickEvent, Slot> action) {
+        return onShiftRightClick((event, slot, menu) -> action.accept(event, slot));
+    }
+
+    /**
+     * Set click handler.
+     *
+     * @param handler The handler.
+     * @return The builder.
+     */
+    SlotBuilder onShiftRightClick(@NotNull SlotHandler handler);
+
+    /**
+     * Set click handler.
+     *
+     * @param action The handler.
+     * @return The builder.
+     */
+    default SlotBuilder onMiddleClick(@NotNull BiConsumer<InventoryClickEvent, Slot> action) {
+        return onMiddleClick((event, slot, menu) -> action.accept(event, slot));
+    }
+
+    /**
+     * Set click handler.
+     *
+     * @param handler The handler.
+     * @return The builder.
+     */
+    SlotBuilder onMiddleClick(@NotNull SlotHandler handler);
+
+    /**
+     * Modify the ItemStack.
+     *
+     * @param modifier The modifier.
+     * @return The builder.
+     */
+    SlotBuilder setModifier(@NotNull SlotModifier modifier);
+
+    /**
+     * Set slot to be a captive slot.
+     *
+     * @return The builder.
+     */
+    SlotBuilder setCaptive();
+
+    /**
+     * Build the slot.
+     *
+     * @return The slot.
+     */
+    Slot build();
+}

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

@@ -0,0 +1,23 @@
+package com.willfp.eco.core.gui.slot.functional;
+
+import com.willfp.eco.core.gui.menu.Menu;
+import com.willfp.eco.core.gui.slot.Slot;
+import org.bukkit.event.inventory.InventoryClickEvent;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Interface to run on slot click.
+ */
+@FunctionalInterface
+public interface SlotHandler {
+    /**
+     * Performs this operation on the given arguments.
+     *
+     * @param event The click event.
+     * @param slot  The slot
+     * @param menu  The menu.
+     */
+    void handle(@NotNull InventoryClickEvent event,
+                @NotNull Slot slot,
+                @NotNull Menu menu);
+}

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

@@ -0,0 +1,23 @@
+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 modify.
+ */
+@FunctionalInterface
+public interface SlotModifier {
+    /**
+     * Performs this operation on the given arguments.
+     *
+     * @param player   The player.
+     * @param menu     The menu.
+     * @param previous The previous ItemStack.
+     */
+    void modify(@NotNull Player player,
+                @NotNull Menu menu,
+                @NotNull ItemStack previous);
+}

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

@@ -0,0 +1,22 @@
+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 display.
+ */
+@FunctionalInterface
+public interface SlotProvider {
+    /**
+     * Performs this operation on the given arguments.
+     *
+     * @param player The player.
+     * @param menu   The menu.
+     * @return The ItemStack.
+     */
+    ItemStack provide(@NotNull Player player,
+                      @NotNull Menu menu);
+}

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

@@ -1,8 +1,12 @@
-package com.willfp.eco.util.integrations;
+package com.willfp.eco.core.integrations;
 
+/**
+ * Abstract class for integrations.
+ */
 public interface Integration {
     /**
      * Get the name of integration.
+     *
      * @return The name.
      */
     String getPluginName();

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

@@ -1,8 +1,13 @@
-package com.willfp.eco.util.integrations;
+package com.willfp.eco.core.integrations;
 
 import lombok.Getter;
 import org.jetbrains.annotations.NotNull;
 
+/**
+ * An integration loader runs a runnable only if a specific plugin is present on the server.
+ * <p>
+ * Used by {@link com.willfp.eco.core.EcoPlugin} to load integrations.
+ */
 public class IntegrationLoader {
     /**
      * The lambda to be ran if the plugin is present.

eco-api/src/main/java/com/willfp/eco/core/integrations/afk/AFKManager.java

@@ -0,0 +1,44 @@
+package com.willfp.eco.core.integrations.afk;
+
+import lombok.experimental.UtilityClass;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Class to handle afk integrations.
+ */
+@UtilityClass
+public class AFKManager {
+    /**
+     * A set of all registered integrations.
+     */
+    private final Set<AFKWrapper> registered = new HashSet<>();
+
+    /**
+     * Register a new integration.
+     *
+     * @param integration The integration to register.
+     */
+    public void register(@NotNull final AFKWrapper integration) {
+        registered.add(integration);
+    }
+
+    /**
+     * Get if a player is afk.
+     *
+     * @param player The player.
+     * @return If afk.
+     */
+    public boolean isAfk(@NotNull final Player player) {
+        for (AFKWrapper afkWrapper : registered) {
+            if (afkWrapper.isAfk(player)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/afk/AFKWrapper.java

@@ -0,0 +1,18 @@
+package com.willfp.eco.core.integrations.afk;
+
+import com.willfp.eco.core.integrations.Integration;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Wrapper class for afk integrations.
+ */
+public interface AFKWrapper extends Integration {
+    /**
+     * Get if a player is afk.
+     *
+     * @param player The player.
+     * @return If afk.
+     */
+    boolean isAfk(@NotNull Player player);
+}

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

@@ -1,6 +1,6 @@
-package com.willfp.eco.util.integrations.anticheat;
+package com.willfp.eco.core.integrations.anticheat;
 
-import com.willfp.eco.util.plugin.AbstractEcoPlugin;
+import com.willfp.eco.core.EcoPlugin;
 import lombok.experimental.UtilityClass;
 import org.bukkit.entity.Player;
 import org.bukkit.event.Listener;
@@ -9,13 +9,11 @@ import org.jetbrains.annotations.NotNull;
 import java.util.HashSet;
 import java.util.Set;
 
+/**
+ * Class to handle anticheat integrations.
+ */
 @UtilityClass
 public class AnticheatManager {
-    /**
-     * The linked {@link AbstractEcoPlugin} to register anticheat listeners to.
-     */
-    private final AbstractEcoPlugin plugin = AbstractEcoPlugin.getInstance();
-
     /**
      * A set of all registered anticheats.
      */
@@ -24,9 +22,11 @@ public class AnticheatManager {
     /**
      * Register a new anticheat.
      *
+     * @param plugin    The plugin.
      * @param anticheat The anticheat to register.
      */
-    public void register(@NotNull final AnticheatWrapper anticheat) {
+    public void register(@NotNull final EcoPlugin plugin,
+                         @NotNull final AnticheatWrapper anticheat) {
         if (anticheat instanceof Listener) {
             plugin.getEventManager().registerListener((Listener) anticheat);
         }
@@ -49,8 +49,6 @@ public class AnticheatManager {
      * @param player The player to remove the exemption.
      */
     public void unexemptPlayer(@NotNull final Player player) {
-        plugin.getScheduler().runLater(() -> {
-            anticheats.forEach(anticheat -> anticheat.unexempt(player));
-        }, 1);
+        anticheats.forEach(anticheat -> anticheat.unexempt(player));
     }
 }

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

@@ -1,9 +1,12 @@
-package com.willfp.eco.util.integrations.anticheat;
+package com.willfp.eco.core.integrations.anticheat;
 
-import com.willfp.eco.util.integrations.Integration;
+import com.willfp.eco.core.integrations.Integration;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 
+/**
+ * Wrapper class for anticheat integrations.
+ */
 public interface AnticheatWrapper extends Integration {
     /**
      * Exempt a player from checks.

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

@@ -1,4 +1,4 @@
-package com.willfp.eco.util.integrations.antigrief;
+package com.willfp.eco.core.integrations.antigrief;
 
 import lombok.experimental.UtilityClass;
 import org.bukkit.Location;
@@ -10,6 +10,9 @@ import org.jetbrains.annotations.NotNull;
 import java.util.HashSet;
 import java.util.Set;
 
+/**
+ * Class to handle antigrief integrations.
+ */
 @UtilityClass
 public class AntigriefManager {
     /**
@@ -26,6 +29,16 @@ public class AntigriefManager {
         registered.add(antigrief);
     }
 
+    /**
+     * Unregister an AntiGrief/Land Management integration.
+     *
+     * @param antigrief The integration to unregister.
+     */
+    public void unregister(@NotNull final AntigriefWrapper antigrief) {
+        registered.removeIf(it -> it.getPluginName().equalsIgnoreCase(antigrief.getPluginName()));
+        registered.remove(antigrief);
+    }
+
     /**
      * Can player break block.
      *

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

@@ -1,18 +1,21 @@
-package com.willfp.eco.util.integrations.antigrief;
+package com.willfp.eco.core.integrations.antigrief;
 
-import com.willfp.eco.util.integrations.Integration;
+import com.willfp.eco.core.integrations.Integration;
 import org.bukkit.Location;
 import org.bukkit.block.Block;
 import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Player;
 
+/**
+ * Wrapper class for antigrief integrations.
+ */
 public interface AntigriefWrapper extends Integration {
     /**
      * Can player break block.
      *
      * @param player The player.
      * @param block  The block.
-     * @return If player cna break block.
+     * @return If player can break block.
      */
     boolean canBreakBlock(Player player, Block block);
 

eco-api/src/main/java/com/willfp/eco/core/integrations/customitems/CustomItemsManager.java

@@ -0,0 +1,38 @@
+package com.willfp.eco.core.integrations.customitems;
+
+import lombok.experimental.UtilityClass;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Class to handle custom item integrations.
+ */
+@UtilityClass
+public class CustomItemsManager {
+    /**
+     * A set of all registered integrations.
+     */
+    private final Set<CustomItemsWrapper> registered = new HashSet<>();
+
+    /**
+     * Register a new integration.
+     *
+     * @param integration The integration to register.
+     */
+    public void register(@NotNull final CustomItemsWrapper integration) {
+        registered.add(integration);
+    }
+
+    /**
+     * Register all the custom items for a specific plugin into eco.
+     *
+     * @see com.willfp.eco.core.items.Items
+     */
+    public void registerAllItems() {
+        for (CustomItemsWrapper customItemsWrapper : registered) {
+            customItemsWrapper.registerAllItems();
+        }
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/customitems/CustomItemsWrapper.java

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

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

@@ -0,0 +1,99 @@
+package com.willfp.eco.core.integrations.economy;
+
+import lombok.experimental.UtilityClass;
+import org.bukkit.OfflinePlayer;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Class to handle economy.
+ */
+@UtilityClass
+public class EconomyManager {
+    /**
+     * A set of all registered integrations.
+     */
+    private final Set<EconomyWrapper> registered = new HashSet<>();
+
+    /**
+     * Register a new integration.
+     *
+     * @param integration The integration to register.
+     */
+    public void register(@NotNull final EconomyWrapper integration) {
+        registered.add(integration);
+    }
+
+    /**
+     * Get if any economy registrations are registered.
+     *
+     * @return If any economy.
+     */
+    public boolean hasRegistrations() {
+        return !registered.isEmpty();
+    }
+
+    /**
+     * Get if a player has a certain amount.
+     *
+     * @param player The player.
+     * @param amount The amount.
+     * @return If the player has the amount.
+     */
+    public boolean hasAmount(@NotNull final OfflinePlayer player,
+                             final double amount) {
+        for (EconomyWrapper wrapper : registered) {
+            return wrapper.hasAmount(player, amount);
+        }
+
+        return false;
+    }
+
+    /**
+     * Give money to a player.
+     *
+     * @param player The player.
+     * @param amount The amount to give.
+     * @return If the transaction was a success.
+     */
+    public boolean giveMoney(@NotNull final OfflinePlayer player,
+                             final double amount) {
+        for (EconomyWrapper wrapper : registered) {
+            return wrapper.giveMoney(player, amount);
+        }
+
+        return false;
+    }
+
+    /**
+     * Remove money from a player.
+     *
+     * @param player The player.
+     * @param amount The amount to remove.
+     * @return If the transaction was a success.
+     */
+    public boolean removeMoney(@NotNull final OfflinePlayer player,
+                               final double amount) {
+        for (EconomyWrapper wrapper : registered) {
+            return wrapper.removeMoney(player, amount);
+        }
+
+        return false;
+    }
+
+    /**
+     * Get the balance of a player.
+     *
+     * @param player The player.
+     * @return The balance.
+     */
+    public double getBalance(@NotNull final OfflinePlayer player) {
+        for (EconomyWrapper wrapper : registered) {
+            return wrapper.getBalance(player);
+        }
+
+        return 0;
+    }
+}

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

@@ -0,0 +1,48 @@
+package com.willfp.eco.core.integrations.economy;
+
+import com.willfp.eco.core.integrations.Integration;
+import org.bukkit.OfflinePlayer;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Wrapper class for economy integrations.
+ */
+public interface EconomyWrapper extends Integration {
+    /**
+     * Get if a player has a certain amount.
+     *
+     * @param player The player.
+     * @param amount The amount.
+     * @return If the player has the amount.
+     */
+    boolean hasAmount(@NotNull OfflinePlayer player,
+                      double amount);
+
+    /**
+     * Give money to a player.
+     *
+     * @param player The player.
+     * @param amount The amount to give.
+     * @return If the transaction was a success.
+     */
+    boolean giveMoney(@NotNull OfflinePlayer player,
+                      double amount);
+
+    /**
+     * Remove money from a player.
+     *
+     * @param player The player.
+     * @param amount The amount to remove.
+     * @return If the transaction was a success.
+     */
+    boolean removeMoney(@NotNull OfflinePlayer player,
+                        double amount);
+
+    /**
+     * Get the balance of a player.
+     *
+     * @param player The player.
+     * @return The balance.
+     */
+    double getBalance(@NotNull OfflinePlayer player);
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/hologram/DummyHologram.java

@@ -0,0 +1,20 @@
+package com.willfp.eco.core.integrations.hologram;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * Dummy hologram, created if no integrations are present on the server.
+ */
+class DummyHologram implements Hologram {
+    @Override
+    public void remove() {
+        // Do nothing.
+    }
+
+    @Override
+    public void setContents(@NotNull final List<String> contents) {
+        // Do nothing.
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/hologram/Hologram.java

@@ -0,0 +1,22 @@
+package com.willfp.eco.core.integrations.hologram;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * Wrapper class for plugin-specific holograms.
+ */
+public interface Hologram {
+    /**
+     * Remove the hologram.
+     */
+    void remove();
+
+    /**
+     * Set the hologram contents.
+     *
+     * @param contents The contents.
+     */
+    void setContents(@NotNull List<String> contents);
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/hologram/HologramManager.java

@@ -0,0 +1,45 @@
+package com.willfp.eco.core.integrations.hologram;
+
+import lombok.experimental.UtilityClass;
+import org.bukkit.Location;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Class to handle hologram integrations.
+ */
+@UtilityClass
+public class HologramManager {
+    /**
+     * A set of all registered integrations.
+     */
+    private final Set<HologramWrapper> registered = new HashSet<>();
+
+    /**
+     * Register a new integration.
+     *
+     * @param integration The integration to register.
+     */
+    public void register(@NotNull final HologramWrapper integration) {
+        registered.add(integration);
+    }
+
+    /**
+     * Create hologram.
+     *
+     * @param location The location.
+     * @param contents The contents for the hologram.
+     * @return The hologram.
+     */
+    public Hologram createHologram(@NotNull final Location location,
+                                   @NotNull final List<String> contents) {
+        for (HologramWrapper wrapper : registered) {
+            return wrapper.createHologram(location, contents);
+        }
+
+        return new DummyHologram();
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/hologram/HologramWrapper.java

@@ -0,0 +1,22 @@
+package com.willfp.eco.core.integrations.hologram;
+
+import com.willfp.eco.core.integrations.Integration;
+import org.bukkit.Location;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * Wrapper class for hologram integrations.
+ */
+public interface HologramWrapper extends Integration {
+    /**
+     * Create hologram.
+     *
+     * @param location The location.
+     * @param contents The contents for the hologram.
+     * @return The hologram.
+     */
+    Hologram createHologram(@NotNull Location location,
+                            @NotNull List<String> contents);
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/mcmmo/McmmoManager.java

@@ -0,0 +1,55 @@
+package com.willfp.eco.core.integrations.mcmmo;
+
+import lombok.experimental.UtilityClass;
+import org.bukkit.block.Block;
+import org.bukkit.event.Event;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Class to handle mcmmo integrations.
+ */
+@UtilityClass
+public class McmmoManager {
+    /**
+     * A set of all registered integrations.
+     */
+    private final Set<McmmoWrapper> registered = new HashSet<>();
+
+    /**
+     * Register a new integration.
+     *
+     * @param integration The integration to register.
+     */
+    public void register(@NotNull final McmmoWrapper integration) {
+        registered.add(integration);
+    }
+
+    /**
+     * Get bonus drop count from block.
+     *
+     * @param block The block.
+     * @return The bonus drop count.
+     */
+    public int getBonusDropCount(@NotNull final Block block) {
+        for (McmmoWrapper mcmmoWrapper : registered) {
+            return mcmmoWrapper.getBonusDropCount(block);
+        }
+        return 0;
+    }
+
+    /**
+     * Get if event is fake.
+     *
+     * @param event The event to check.
+     * @return If the event is fake.
+     */
+    public boolean isFake(@NotNull final Event event) {
+        for (McmmoWrapper mcmmoWrapper : registered) {
+            return mcmmoWrapper.isFake(event);
+        }
+        return false;
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/mcmmo/McmmoWrapper.java

@@ -0,0 +1,27 @@
+package com.willfp.eco.core.integrations.mcmmo;
+
+import com.willfp.eco.core.integrations.Integration;
+import org.bukkit.block.Block;
+import org.bukkit.event.Event;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Wrapper class for mcmmo integrations.
+ */
+public interface McmmoWrapper extends Integration {
+    /**
+     * Get bonus drop count of block.
+     *
+     * @param block The block.
+     * @return The drop multiplier.
+     */
+    int getBonusDropCount(@NotNull Block block);
+
+    /**
+     * Get if event is fake.
+     *
+     * @param event The event.
+     * @return If is fake.
+     */
+    boolean isFake(@NotNull Event event);
+}