Added 1.21.6 support

Fix FabledSkyBlock errors on new versions of the plugin

.github/workflows/java-ci.yml

@@ -1,6 +1,6 @@
 name: Java CI
 
-on: [ push, pull_request ]
+on: [ push, pull_request, workflow_dispatch ]
 
 jobs:
   build:
@@ -14,14 +14,14 @@ jobs:
         id: vars
         run: echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"
 
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v2
         with:
           distribution: 'temurin'
-          java-version: 17
+          java-version: 21
 
       - name: Setup build cache
-        uses: actions/cache@v2.1.6
+        uses: actions/cache@v4
         with:
           path: ~/.gradle/caches
           key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle.kts') }}
@@ -30,7 +30,7 @@ jobs:
 
       - run: ./gradlew build --full-stacktrace
 
-      - uses: actions/upload-artifact@v2
+#      - uses: actions/upload-artifact@v2
-        with:
+#        with:
-          name: eco-dev-${{ steps.vars.outputs.sha_short }}
+#          name: eco-dev-${{ steps.vars.outputs.sha_short }}
-          path: build/libs
+#          path: build/libs

.github/workflows/publish-release.yml

@@ -12,14 +12,14 @@ jobs:
       - name: Checkout latest code
         uses: actions/checkout@v2
 
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v2
         with:
           distribution: 'temurin'
-          java-version: 17
+          java-version: 21
 
       - name: Setup build cache
-        uses: actions/cache@v2.1.6
+        uses: actions/cache@v4
         with:
           path: ~/.gradle/caches
           key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle.kts') }}

.github/workflows/test-publish.yml

@@ -14,11 +14,11 @@ jobs:
         id: vars
         run: echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"
 
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v2
         with:
           distribution: 'temurin'
-          java-version: 17
+          java-version: 21
 
       - name: Setup build cache
         uses: actions/cache@v2.1.6

.gitignore

@@ -22,3 +22,6 @@ gradle-app.setting
 
 # Mac OSX
 .DS_Store
+
+# Kotlin
+.kotlin

build.gradle.kts

@@ -1,19 +1,21 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 buildscript {
     repositories {
         mavenCentral()
     }
 
     dependencies {
-        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:1.9.21")
+        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:2.1.0")
     }
 }
 
 plugins {
     id("java-library")
-    id("com.github.johnrengelman.shadow") version "8.1.1"
+    id("com.gradleup.shadow") version "8.3.5"
     id("maven-publish")
     id("java")
-    kotlin("jvm") version "1.9.21"
+    kotlin("jvm") version "2.1.0"
 }
 
 dependencies {
@@ -21,6 +23,7 @@ dependencies {
     implementation(project(path = ":eco-core:core-plugin", configuration = "shadow"))
     implementation(project(":eco-core:core-proxy"))
     implementation(project(":eco-core:core-backend"))
+    implementation(project(":eco-core:core-backend-modern"))
     implementation(project(path = ":eco-core:core-nms:v1_17_R1", configuration = "reobf"))
     implementation(project(path = ":eco-core:core-nms:v1_18_R1", configuration = "reobf"))
     implementation(project(path = ":eco-core:core-nms:v1_18_R2", configuration = "reobf"))
@@ -30,20 +33,31 @@ dependencies {
     implementation(project(path = ":eco-core:core-nms:v1_20_R1", configuration = "reobf"))
     implementation(project(path = ":eco-core:core-nms:v1_20_R2", configuration = "reobf"))
     implementation(project(path = ":eco-core:core-nms:v1_20_R3", configuration = "reobf"))
+    implementation(project(path = ":eco-core:core-nms:v1_21", configuration = "reobf"))
+    implementation(project(path = ":eco-core:core-nms:v1_21_3", configuration = "reobf"))
+    implementation(project(path = ":eco-core:core-nms:v1_21_4", configuration = "reobf"))
+    implementation(project(path = ":eco-core:core-nms:v1_21_5", configuration = "reobf"))
+    implementation(project(path = ":eco-core:core-nms:v1_21_6", configuration = "reobf"))
 }
 
 allprojects {
     apply(plugin = "java")
     apply(plugin = "java-library")
     apply(plugin = "maven-publish")
-    apply(plugin = "com.github.johnrengelman.shadow")
+    apply(plugin = "com.gradleup.shadow")
     apply(plugin = "kotlin")
 
     repositories {
         mavenCentral()
-        mavenLocal()
+
         maven("https://repo.auxilor.io/repository/maven-public/")
-        maven("https://jitpack.io")
+
+        maven("https://jitpack.io") {
+            content { includeGroupByRegex("com\\.github\\..*") }
+        }
+
+        // Paper
+        maven("https://repo.papermc.io/repository/maven-public/")
 
         // SuperiorSkyblock2
         maven("https://repo.bg-software.com/repository/api/")
@@ -58,7 +72,7 @@ allprojects {
         maven("https://repo.extendedclip.com/content/repositories/placeholderapi/")
 
         // ProtocolLib
-        //maven("https://repo.dmulloy2.net/nexus/repository/public/")
+        maven("https://repo.dmulloy2.net/nexus/repository/public/")
 
         // WorldGuard
         maven("https://maven.enginehub.org/repo/")
@@ -89,16 +103,22 @@ allprojects {
 
         // IridiumSkyblock
         maven("https://nexus.iridiumdevelopment.net/repository/maven-releases/")
+
+        // HuskPlugins
+        maven("https://repo.william278.net/releases")
+
+        // FancyHolograms
+        maven("https://repo.fancyplugins.de/releases")
     }
 
     dependencies {
         // Kotlin
-        implementation(kotlin("stdlib", version = "1.9.21"))
+        implementation(kotlin("stdlib", version = "2.1.0"))
         implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.7.3")
 
         // Included in spigot jar, no need to move to implementation
         compileOnly("org.jetbrains:annotations:23.0.0")
-        compileOnly("com.google.guava:guava:31.1-jre")
+        compileOnly("com.google.guava:guava:32.0.0-jre")
 
         // Test
         testImplementation("org.junit.jupiter:junit-jupiter-api:5.9.2")
@@ -137,46 +157,14 @@ allprojects {
     }
 
     tasks {
-        compileKotlin {
+        withType<Jar> {
-            kotlinOptions {
+            duplicatesStrategy = DuplicatesStrategy.WARN
-                jvmTarget = "17"
-            }
         }
 
-        shadowJar {
+        compileKotlin {
-            relocate("org.bstats", "com.willfp.eco.libs.bstats")
+            compilerOptions {
-            relocate("redempt.crunch", "com.willfp.eco.libs.crunch")
+                jvmTarget.set(JvmTarget.JVM_17)
-            relocate("org.apache.commons.lang3", "com.willfp.eco.libs.lang3")
+            }
-            relocate("org.apache.maven", "com.willfp.eco.libs.maven")
-            relocate("org.checkerframework", "com.willfp.eco.libs.checkerframework")
-            relocate("org.intellij", "com.willfp.eco.libs.intellij")
-            relocate("org.jetbrains.annotations", "com.willfp.eco.libs.jetbrains.annotations")
-            //relocate("org.jetbrains.exposed", "com.willfp.eco.libs.exposed")
-            relocate("org.objenesis", "com.willfp.eco.libs.objenesis")
-            relocate("org.reflections", "com.willfp.eco.libs.reflections")
-            relocate("javassist", "com.willfp.eco.libs.javassist")
-            relocate("javax.annotation", "com.willfp.eco.libs.annotation")
-            relocate("com.google.errorprone", "com.willfp.eco.libs.errorprone")
-            relocate("com.google.j2objc", "com.willfp.eco.libs.j2objc")
-            relocate("com.google.thirdparty", "com.willfp.eco.libs.google.thirdparty")
-            relocate("com.google.protobuf", "com.willfp.eco.libs.google.protobuf") // No I don't know either
-            relocate("google.protobuf", "com.willfp.eco.libs.protobuf") // Still don't know
-            relocate("com.zaxxer.hikari", "com.willfp.eco.libs.hikari")
-            //relocate("com.mysql", "com.willfp.eco.libs.mysql")
-            relocate("de.undercouch.bson4jackson", "com.willfp.eco.libs.bson4jackson")
-            relocate("com.fasterxml.jackson", "com.willfp.eco.libs.jackson")
-            relocate("com.mongodb", "com.willfp.eco.libs.mongodb")
-            relocate("org.bson", "com.willfp.eco.libs.bson")
-            relocate("org.litote", "com.willfp.eco.libs.litote")
-            relocate("org.reactivestreams", "com.willfp.eco.libs.reactivestreams")
-            relocate("reactor.", "com.willfp.eco.libs.reactor.") // Dot in name to be safe
-            relocate("com.moandjiezana.toml", "com.willfp.eco.libs.toml")
-            relocate("com.willfp.modelenginebridge", "com.willfp.eco.libs.modelenginebridge")
-
-            /*
-            Kotlin and caffeine are not shaded so that they can be accessed directly by eco plugins.
-            Also, not relocating adventure, because it's a pain in the ass, and it doesn't *seem* to be causing loader constraint violations.
-             */
         }
 
         compileJava {
@@ -184,12 +172,6 @@ allprojects {
             options.encoding = "UTF-8"
         }
 
-        java {
-            sourceCompatibility = JavaVersion.VERSION_17
-            targetCompatibility = JavaVersion.VERSION_17
-            withSourcesJar()
-        }
-
         test {
             useJUnitPlatform()
 
@@ -202,6 +184,52 @@ allprojects {
         build {
             dependsOn(shadowJar)
         }
+
+        withType<JavaCompile>().configureEach {
+            options.release.set(17)
+        }
+    }
+
+    java {
+        withSourcesJar()
+        toolchain {
+            languageVersion.set(JavaLanguageVersion.of(21))
+        }
+    }
+}
+
+tasks {
+    shadowJar {
+        relocate("org.bstats", "com.willfp.eco.libs.bstats")
+        relocate("redempt.crunch", "com.willfp.eco.libs.crunch")
+        relocate("org.apache.commons.lang3", "com.willfp.eco.libs.lang3")
+        relocate("org.apache.maven", "com.willfp.eco.libs.maven")
+        relocate("org.checkerframework", "com.willfp.eco.libs.checkerframework")
+        relocate("org.intellij", "com.willfp.eco.libs.intellij")
+        relocate("org.jetbrains.annotations", "com.willfp.eco.libs.jetbrains.annotations")
+        //relocate("org.jetbrains.exposed", "com.willfp.eco.libs.exposed")
+        relocate("org.objenesis", "com.willfp.eco.libs.objenesis")
+        relocate("org.reflections", "com.willfp.eco.libs.reflections")
+        relocate("javassist", "com.willfp.eco.libs.javassist")
+        relocate("javax.annotation", "com.willfp.eco.libs.annotation")
+        relocate("com.google.errorprone", "com.willfp.eco.libs.errorprone")
+        relocate("com.google.j2objc", "com.willfp.eco.libs.j2objc")
+        relocate("com.google.thirdparty", "com.willfp.eco.libs.google.thirdparty")
+        relocate("com.google.protobuf", "com.willfp.eco.libs.google.protobuf") // No I don't know either
+        relocate("google.protobuf", "com.willfp.eco.libs.protobuf") // Still don't know
+        relocate("com.zaxxer.hikari", "com.willfp.eco.libs.hikari")
+        //relocate("com.mysql", "com.willfp.eco.libs.mysql")
+        relocate("com.mongodb", "com.willfp.eco.libs.mongodb")
+        relocate("org.bson", "com.willfp.eco.libs.bson")
+        relocate("org.reactivestreams", "com.willfp.eco.libs.reactivestreams")
+        relocate("reactor.", "com.willfp.eco.libs.reactor.") // Dot in name to be safe
+        relocate("com.moandjiezana.toml", "com.willfp.eco.libs.toml")
+        relocate("com.willfp.modelenginebridge", "com.willfp.eco.libs.modelenginebridge")
+
+        /*
+        Kotlin and caffeine are not shaded so that they can be accessed directly by eco plugins.
+        Also, not relocating adventure, because it's a pain in the ass, and it doesn't *seem* to be causing loader constraint violations.
+         */
     }
 }
 

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

@@ -1,5 +1,6 @@
 package com.willfp.eco.core;
 
+import com.google.common.collect.ImmutableList;
 import com.willfp.eco.core.command.impl.PluginCommand;
 import com.willfp.eco.core.config.base.ConfigYml;
 import com.willfp.eco.core.config.base.LangYml;
@@ -120,9 +121,17 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike, Regist
 
     /**
      * The display module for the plugin.
+     *
+     * @deprecated Plugins can now have multiple display modules.
      */
+    @Deprecated(since = "6.72.0")
     private DisplayModule displayModule;
 
+    /**
+     * The display modules for the plugin.
+     */
+    private List<DisplayModule> displayModules = new ArrayList<>();
+
     /**
      * The logger for the plugin.
      */
@@ -167,7 +176,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike, Regist
     /**
      * The tasks to run on task creation.
      */
-    private final ListMap<LifecyclePosition, Runnable> createTasks = new ListMap<>();
+    private final ListMap<LifecyclePosition, Runnable> onCreateTasks = new ListMap<>();
 
     /**
      * Create a new plugin.
@@ -555,10 +564,15 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike, Regist
      * Default code to be executed after the server is up.
      */
     public final void afterLoad() {
-        this.displayModule = createDisplayModule();
+        DisplayModule module = createDisplayModule();
+        if (module != null) {
+            Display.registerDisplayModule(module);
+            this.displayModules.add(module);
+        }
 
-        if (this.getDisplayModule() != null) {
+        for (DisplayModule displayModule : this.loadDisplayModules()) {
-            Display.registerDisplayModule(this.getDisplayModule());
+            Display.registerDisplayModule(displayModule);
+            this.displayModules.add(displayModule);
         }
 
         if (Prerequisite.HAS_PROTOCOLLIB.isMet()) {
@@ -575,8 +589,9 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike, Regist
             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("and many features may not function properly without it");
-            this.getLogger().severe("Download Paper from &fhttps://papermc.io");
+            this.getLogger().severe("Download Paper from https://papermc.io");
+            this.getLogger().severe("It's a drop-in replacement for Spigot, so it's easy to switch.");
             this.getLogger().severe("");
             this.getLogger().severe("----------------------------");
             this.getLogger().severe("");
@@ -638,7 +653,7 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike, Regist
         this.handleLifecycle(this.onReload, this::handleReload);
 
         if (cancelTasks) {
-            this.handleLifecycle(this.createTasks, this::createTasks);
+            this.handleLifecycle(this.onCreateTasks, this::createTasks);
         }
 
         for (Extension extension : this.extensionLoader.getLoadedExtensions()) {
@@ -666,6 +681,26 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike, Regist
         this.onReload.append(position, task);
     }
 
+    /**
+     * Add new task to run on createTasks.
+     *
+     * @param task The task.
+     */
+    public final void onCreateTasks(@NotNull final Runnable task) {
+        this.onCreateTasks(LifecyclePosition.END, task);
+    }
+
+    /**
+     * Add new task to run on createTasks.
+     *
+     * @param position The position to run the task.
+     * @param task     The task.
+     */
+    public final void onCreateTasks(@NotNull final LifecyclePosition position,
+                                    @NotNull final Runnable task) {
+        this.onCreateTasks.append(position, task);
+    }
+
     /**
      * Reload the plugin and return the time taken to reload.
      *
@@ -878,14 +913,25 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike, Regist
      * Create the display module for the plugin.
      *
      * @return The display module, or null.
+     * @deprecated Use {@link #loadDisplayModules()} instead.
      */
     @Nullable
+    @Deprecated(since = "6.72.0")
     protected DisplayModule createDisplayModule() {
         Validate.isTrue(this.getDisplayModule() == null, "Display module exists!");
 
         return null;
     }
 
+    /**
+     * Load display modules.
+     *
+     * @return The display modules.
+     */
+    protected List<DisplayModule> loadDisplayModules() {
+        return new ArrayList<>();
+    }
+
     /**
      * Get the minimum version of eco to use the plugin.
      *
@@ -1135,12 +1181,23 @@ public abstract class EcoPlugin extends JavaPlugin implements PluginLike, Regist
      * Get the plugin's display module.
      *
      * @return The display module.
+     * @deprecated Use {@link #getDisplayModules()} instead.
      */
     @Nullable
+    @Deprecated(since = "6.72.0", forRemoval = true)
     public DisplayModule getDisplayModule() {
         return this.displayModule;
     }
 
+    /**
+     * Get the plugin's display modules.
+     *
+     * @return The display modules.
+     */
+    public List<DisplayModule> getDisplayModules() {
+        return ImmutableList.copyOf(this.displayModules);
+    }
+
     /**
      * Get if the plugin is outdated.
      *

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

@@ -38,23 +38,48 @@ public class Prerequisite {
     );
 
     /**
-     * Requires the server to be running 1.20.3.
+     * Requires the server to be running at least 1.21.3.
+     */
+    public static final Prerequisite HAS_1_21_3 = new Prerequisite(
+            () -> ProxyConstants.NMS_VERSION.contains("1_21_3"),
+            "Requires server to be running 1.21.3+"
+    );
+
+    /**
+     * Requires the server to be running at least 1.21.
+     */
+    public static final Prerequisite HAS_1_21 = new Prerequisite(
+            () -> ProxyConstants.NMS_VERSION.contains("1_21") || HAS_1_21_3.isMet(),
+            "Requires server to be running 1.21+"
+    );
+
+    /**
+     * Requires the server to be running at least 1.20.5.
+     */
+    public static final Prerequisite HAS_1_20_5 = new Prerequisite(
+            () -> (ProxyConstants.NMS_VERSION.contains("1_20_") && !ProxyConstants.NMS_VERSION.contains("R"))
+                    || HAS_1_21.isMet(),
+            "Requires server to be running 1.20.5+"
+    );
+
+    /**
+     * Requires the server to be running at least 1.20.3.
      */
     public static final Prerequisite HAS_1_20_3 = new Prerequisite(
-            () -> ProxyConstants.NMS_VERSION.contains("20_R3"),
+            () -> ProxyConstants.NMS_VERSION.contains("20_R3") || HAS_1_20_5.isMet(),
             "Requires server to be running 1.20.3+"
     );
 
     /**
-     * Requires the server to be running 1.20.
+     * Requires the server to be running at least 1.20.
      */
     public static final Prerequisite HAS_1_20 = new Prerequisite(
-            () -> ProxyConstants.NMS_VERSION.contains("20"),
+            () -> ProxyConstants.NMS_VERSION.contains("20") || HAS_1_20_3.isMet(),
             "Requires server to be running 1.20+"
     );
 
     /**
-     * Requires the server to be running 1.19.4.
+     * Requires the server to be running at least 1.19.4.
      */
     public static final Prerequisite HAS_1_19_4 = new Prerequisite(
             () -> ProxyConstants.NMS_VERSION.contains("19_R3") || HAS_1_20.isMet(),
@@ -62,7 +87,7 @@ public class Prerequisite {
     );
 
     /**
-     * Requires the server to be running 1.19.
+     * Requires the server to be running at least 1.19.
      */
     public static final Prerequisite HAS_1_19 = new Prerequisite(
             () -> ProxyConstants.NMS_VERSION.contains("19") || HAS_1_20.isMet(),
@@ -70,7 +95,7 @@ public class Prerequisite {
     );
 
     /**
-     * Requires the server to be running 1.18.
+     * Requires the server to be running at least 1.18.
      */
     public static final Prerequisite HAS_1_18 = new Prerequisite(
             () -> ProxyConstants.NMS_VERSION.contains("18") || HAS_1_19.isMet(),

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

@@ -87,6 +87,10 @@ public interface ExtendedPersistentDataContainer {
      * @return The extended container.
      */
     static ExtendedPersistentDataContainer extend(@NotNull PersistentDataContainer base) {
+        if (base instanceof ExtendedPersistentDataContainer) {
+            return (ExtendedPersistentDataContainer) base;
+        }
+
         return Eco.get().adaptPdc(base);
     }
 

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

@@ -0,0 +1,44 @@
+package com.willfp.eco.core.data.handlers;
+
+import com.willfp.eco.core.data.keys.PersistentDataKey;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.UUID;
+
+/**
+ * Handles data read/write for a {@link com.willfp.eco.core.data.keys.PersistentDataKeyType} for a specific
+ * data handler.
+ *
+ * @param <T> The type of data.
+ */
+public abstract class DataTypeSerializer<T> {
+    /**
+     * Create a new data type serializer.
+     */
+    protected DataTypeSerializer() {
+
+    }
+
+    /**
+     * Read a value.
+     *
+     * @param uuid The uuid.
+     * @param key  The key.
+     * @return The value.
+     */
+    @Nullable
+    public abstract T readAsync(@NotNull final UUID uuid,
+                                @NotNull final PersistentDataKey<T> key);
+
+    /**
+     * Write a value.
+     *
+     * @param uuid  The uuid.
+     * @param key   The key.
+     * @param value The value.
+     */
+    public abstract void writeAsync(@NotNull final UUID uuid,
+                                    @NotNull final PersistentDataKey<T> key,
+                                    @NotNull final T value);
+}

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

@@ -0,0 +1,179 @@
+package com.willfp.eco.core.data.handlers;
+
+import com.willfp.eco.core.data.keys.PersistentDataKey;
+import com.willfp.eco.core.registry.Registrable;
+import com.willfp.eco.core.tuples.Pair;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+/**
+ * Handles persistent data.
+ */
+public abstract class PersistentDataHandler implements Registrable {
+    /**
+     * The id.
+     */
+    private final String id;
+
+    /**
+     * The executor.
+     */
+    private final ExecutorService executor = Executors.newCachedThreadPool();
+
+    /**
+     * Create a new persistent data handler.
+     *
+     * @param id The id.
+     */
+    protected PersistentDataHandler(@NotNull final String id) {
+        this.id = id;
+    }
+
+    /**
+     * Get all UUIDs with saved data.
+     * <p>
+     * This is a blocking operation.
+     *
+     * @return All saved UUIDs.
+     */
+    public abstract Set<UUID> getSavedUUIDs();
+
+    /**
+     * Save to disk.
+     * <p>
+     * If write commits to disk, this method does not need to be overridden.
+     * <p>
+     * This method is called asynchronously.
+     */
+    protected void doSave() {
+        // Save to disk
+    }
+
+    /**
+     * If the handler should autosave.
+     *
+     * @return If the handler should autosave.
+     */
+    public boolean shouldAutosave() {
+        return true;
+    }
+
+    /**
+     * Save the data.
+     */
+    public final void save() {
+        executor.submit(this::doSave);
+    }
+
+    /**
+     * Read a key from persistent data.
+     *
+     * @param uuid The uuid.
+     * @param key  The key.
+     * @param <T>  The type of the key.
+     * @return The value, or null if not found.
+     */
+    @Nullable
+    public final <T> T read(@NotNull final UUID uuid,
+                            @NotNull final PersistentDataKey<T> key) {
+        DataTypeSerializer<T> serializer = key.getType().getSerializer(this);
+        Future<T> future = executor.submit(() -> serializer.readAsync(uuid, key));
+
+        try {
+            return future.get();
+        } catch (InterruptedException | ExecutionException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+    /**
+     * Write a key to persistent data.
+     *
+     * @param uuid  The uuid.
+     * @param key   The key.
+     * @param value The value.
+     * @param <T>   The type of the key.
+     */
+    public final <T> void write(@NotNull final UUID uuid,
+                                @NotNull final PersistentDataKey<T> key,
+                                @NotNull final T value) {
+        DataTypeSerializer<T> serializer = key.getType().getSerializer(this);
+        executor.submit(() -> serializer.writeAsync(uuid, key, value));
+    }
+
+    /**
+     * Serialize profile.
+     *
+     * @param uuid The uuid to serialize.
+     * @param keys The keys to serialize.
+     * @return The serialized data.
+     */
+    @NotNull
+    public final SerializedProfile serializeProfile(@NotNull final UUID uuid,
+                                                    @NotNull final Set<PersistentDataKey<?>> keys) {
+        Map<PersistentDataKey<?>, CompletableFuture<Object>> futures = keys.stream()
+                .collect(Collectors.toMap(
+                        key -> key,
+                        key -> CompletableFuture.supplyAsync(() -> read(uuid, key), executor)
+                ));
+
+        Map<PersistentDataKey<?>, Object> data = futures.entrySet().stream()
+                .map(entry -> new Pair<PersistentDataKey<?>, Object>(entry.getKey(), entry.getValue().join()))
+                .filter(entry -> entry.getSecond() != null)
+                .collect(Collectors.toMap(Pair::getFirst, Pair::getSecond));
+
+        return new SerializedProfile(uuid, data);
+    }
+
+    /**`
+     * Load profile data.
+     *
+     * @param profile The profile.
+     */
+    @SuppressWarnings("unchecked")
+    public final void loadSerializedProfile(@NotNull final SerializedProfile profile) {
+        for (Map.Entry<PersistentDataKey<?>, Object> entry : profile.data().entrySet()) {
+            PersistentDataKey<?> key = entry.getKey();
+            Object value = entry.getValue();
+
+            // This cast is safe because the data is serialized
+            write(profile.uuid(), (PersistentDataKey<? super Object>) key, value);
+        }
+    }
+
+    /**
+     * Save and shutdown the handler.
+     *
+     * @throws InterruptedException If the writes could not be awaited.
+     */
+    public final void shutdown() throws InterruptedException {
+        doSave();
+
+        if (executor.isShutdown()) {
+            return;
+        }
+
+        executor.shutdown();
+        while (!executor.awaitTermination(2, TimeUnit.MINUTES)) {
+            // Wait
+        }
+    }
+
+    @Override
+    @NotNull
+    public final String getID() {
+        return id;
+    }
+}

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

@@ -0,0 +1,20 @@
+package com.willfp.eco.core.data.handlers;
+
+import com.willfp.eco.core.data.keys.PersistentDataKey;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Map;
+import java.util.UUID;
+
+/**
+ * Serialized profile.
+ *
+ * @param uuid The uuid.
+ * @param data The data.
+ */
+public record SerializedProfile(
+        @NotNull UUID uuid,
+        @NotNull Map<PersistentDataKey<?>, Object> data
+) {
+
+}

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

@@ -34,6 +34,19 @@ public final class PersistentDataKey<T> {
      */
     private final boolean isLocal;
 
+    /**
+     * 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<T> type,
+                             @NotNull final T defaultValue) {
+        this(key, type, defaultValue, false);
+    }
+
     /**
      * Create a new Persistent Data Key.
      *
@@ -54,24 +67,6 @@ public final class PersistentDataKey<T> {
         Eco.get().registerPersistentKey(this);
     }
 
-    /**
-     * 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<T> type,
-                             @NotNull final T defaultValue) {
-        this.key = key;
-        this.defaultValue = defaultValue;
-        this.type = type;
-        this.isLocal = false;
-
-        Eco.get().registerPersistentKey(this);
-    }
-
     @Override
     public String toString() {
         return "PersistentDataKey{"

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

@@ -1,12 +1,17 @@
 package com.willfp.eco.core.data.keys;
 
 import com.willfp.eco.core.config.interfaces.Config;
+import com.willfp.eco.core.data.handlers.DataTypeSerializer;
+import com.willfp.eco.core.data.handlers.PersistentDataHandler;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.math.BigDecimal;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
 import java.util.Objects;
 
 /**
@@ -61,18 +66,14 @@ public final class PersistentDataKeyType<T> {
     private final String name;
 
     /**
-     * Get the name of the key type.
+     * The serializers for this key type.
-     *
-     * @return The name.
      */
-    public String name() {
+    private final Map<PersistentDataHandler, DataTypeSerializer<T>> serializers = new HashMap<>();
-        return name;
-    }
 
     /**
      * Create new PersistentDataKeyType.
      *
-     * @param name      The name.
+     * @param name The name.
      */
     private PersistentDataKeyType(@NotNull final String name) {
         VALUES.add(this);
@@ -80,6 +81,44 @@ public final class PersistentDataKeyType<T> {
         this.name = name;
     }
 
+    /**
+     * Get the name of the key type.
+     *
+     * @return The name.
+     */
+    @NotNull
+    public String name() {
+        return name;
+    }
+
+    /**
+     * Register a serializer for this key type.
+     *
+     * @param handler    The handler.
+     * @param serializer The serializer.
+     */
+    public void registerSerializer(@NotNull final PersistentDataHandler handler,
+                                   @NotNull final DataTypeSerializer<T> serializer) {
+        this.serializers.put(handler, serializer);
+    }
+
+    /**
+     * Get the serializer for a handler.
+     *
+     * @param handler The handler.
+     * @return The serializer.
+     */
+    @NotNull
+    public DataTypeSerializer<T> getSerializer(@NotNull final PersistentDataHandler handler) {
+        DataTypeSerializer<T> serializer = this.serializers.get(handler);
+
+        if (serializer == null) {
+            throw new NoSuchElementException("No serializer for handler: " + handler);
+        }
+
+        return serializer;
+    }
+
     @Override
     public boolean equals(@Nullable final Object that) {
         if (this == that) {

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

@@ -211,12 +211,22 @@ public final class Display {
                 new ArrayList<>()
         );
 
-        modules.removeIf(it -> it.getPluginName().equalsIgnoreCase(module.getPluginName()));
         modules.add(module);
 
         REGISTERED_MODULES.put(module.getWeight(), modules);
     }
 
+    /**
+     * Unregister a display module.
+     *
+     * @param module The module.
+     */
+    public static void unregisterDisplayModule(@NotNull final DisplayModule module) {
+        for (List<DisplayModule> modules : REGISTERED_MODULES.values()) {
+            modules.remove(module);
+        }
+    }
+
     private Display() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

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

@@ -111,6 +111,11 @@ public final class Entities {
             } catch (IllegalArgumentException e) {
                 return new EmptyTestableEntity();
             }
+
+            if (type.getEntityClass() == null) {
+                return new EmptyTestableEntity();
+            }
+
             entity = new SimpleTestableEntity(type);
         } else {
             String namespace = split[0];

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

@@ -6,6 +6,7 @@ import com.willfp.eco.core.entities.TestableEntity;
 import com.willfp.eco.core.entities.ai.EntityGoal;
 import com.willfp.eco.core.items.Items;
 import com.willfp.eco.core.serialization.KeyedDeserializer;
+import com.willfp.eco.util.SoundUtils;
 import org.bukkit.NamespacedKey;
 import org.bukkit.Sound;
 import org.bukkit.entity.LivingEntity;
@@ -50,9 +51,15 @@ public record EntityGoalUseItem(
 
             TestableEntity filter = Entities.lookup(config.getString("condition"));
 
+            Sound sound = SoundUtils.getSound(config.getString("sound"));
+
+            if (sound == null) {
+                return null;
+            }
+
             return new EntityGoalUseItem(
                     Items.lookup(config.getString("item")).getItem(),
-                    Sound.valueOf(config.getString("sound").toUpperCase()),
+                    sound,
                     filter::matches
             );
         }

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

@@ -11,19 +11,21 @@ import org.bukkit.entity.Raider;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Set;
 import java.util.function.Predicate;
+import java.util.stream.Collectors;
 
 /**
  * Allows an entity to attack the closest target within a given subset of specific target types.
  *
- * @param target           The type of entities to attack.
+ * @param targets          The type of entities to attack.
  * @param checkVisibility  If visibility should be checked.
  * @param checkCanNavigate If navigation should be checked.
  * @param reciprocalChance 1 in reciprocalChance chance of not activating on any tick.
  * @param targetFilter     The filter for targets to match.
  */
 public record TargetGoalNearestAttackable(
-        @NotNull TestableEntity target,
+        @NotNull Set<TestableEntity> targets,
         boolean checkVisibility,
         boolean checkCanNavigate,
         int reciprocalChance,
@@ -32,16 +34,16 @@ public record TargetGoalNearestAttackable(
     /**
      * Create a new target goal.
      *
-     * @param target           The type of entities to attack.
+     * @param targets          The type of entities to attack.
      * @param checkVisibility  If visibility should be checked.
      * @param checkCanNavigate If navigation should be checked.
      * @param reciprocalChance 1 in reciprocalChance chance of not activating on any tick.
      */
-    public TargetGoalNearestAttackable(@NotNull final TestableEntity target,
+    public TargetGoalNearestAttackable(@NotNull final Set<TestableEntity> targets,
                                        final boolean checkVisibility,
                                        final boolean checkCanNavigate,
                                        final int reciprocalChance) {
-        this(target, checkVisibility, checkCanNavigate, reciprocalChance, it -> true);
+        this(targets, checkVisibility, checkCanNavigate, reciprocalChance, it -> true);
     }
 
     /**
@@ -65,11 +67,15 @@ public record TargetGoalNearestAttackable(
                 return null;
             }
 
+            Set<TestableEntity> targets = config.getStrings("target").stream()
+                    .map(Entities::lookup)
+                    .collect(Collectors.toSet());
+
             if (config.has("targetFilter")) {
                 TestableEntity filter = Entities.lookup(config.getString("targetFilter"));
 
                 return new TargetGoalNearestAttackable(
-                        Entities.lookup(config.getString("target")),
+                        targets,
                         config.getBool("checkVisibility"),
                         config.getBool("checkCanNavigate"),
                         config.getInt("reciprocalChance"),
@@ -77,7 +83,7 @@ public record TargetGoalNearestAttackable(
                 );
             } else {
                 return new TargetGoalNearestAttackable(
-                        Entities.lookup(config.getString("target")),
+                        targets,
                         config.getBool("checkVisibility"),
                         config.getBool("checkCanNavigate"),
                         config.getInt("reciprocalChance")

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

@@ -27,7 +27,7 @@ public class DropQueuePushEvent extends PlayerEvent implements Cancellable {
     /**
      * The items.
      */
-    private final Collection<? extends ItemStack> items;
+    private Collection<? extends ItemStack> items;
 
     /**
      * The xp.
@@ -114,6 +114,15 @@ public class DropQueuePushEvent extends PlayerEvent implements Cancellable {
         return items;
     }
 
+    /**
+     * Set the items to be dropped.
+     *
+     * @param items The items.
+     */
+    public void setItems(Collection<? extends ItemStack> items) {
+        this.items = items;
+    }
+
     /**
      * Get the xp to be dropped.
      *

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

@@ -13,6 +13,8 @@ import java.io.File;
  * @param version The extension version.
  * @param name    The extension name.
  * @param author  The extension's author.
+ * @param file   The extension's file.
+ * @param minimumPluginVersion The minimum plugin version required for this extension.
  */
 public record ExtensionMetadata(@NotNull String version,
                                 @NotNull String name,

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

@@ -164,15 +164,23 @@ public interface FastItemStack extends PersistentDataHolder {
      * The returned PersistentDataContainer will not modify the item until the tag is set.
      *
      * @return The base NBT tag.
+     * @deprecated Items are now component-based.
      */
-    PersistentDataContainer getBaseTag();
+    @Deprecated(forRemoval = true, since = "6.70.0")
+    default PersistentDataContainer getBaseTag() {
+        throw new UnsupportedOperationException("Not supported in 1.20.5+");
+    }
 
     /**
      * Set the base NBT tag (Not PublicBukkitValues, the base) from a PersistentDataContainer.
      *
      * @param container The PersistentDataContainer.
+     * @deprecated Items are now component-based.
      */
-    void setBaseTag(@Nullable PersistentDataContainer container);
+    @Deprecated(forRemoval = true, since = "6.70.0")
+    default void setBaseTag(@Nullable PersistentDataContainer container) {
+        throw new UnsupportedOperationException("Not supported in 1.20.5+");
+    }
 
     /**
      * Get the type of the item.

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

@@ -5,6 +5,8 @@ import org.jetbrains.annotations.NotNull;
 
 /**
  * Handles menu events.
+ *
+ * @param <T> The type of event to handle.x
  */
 public abstract class MenuEventHandler<T extends MenuEvent> {
     /**

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

@@ -86,7 +86,7 @@ public class ConfigSlot extends CustomSlot {
             for (String command : config.getStrings(configKey)) {
                 if (command.startsWith("console:")) {
                     commands.add(new CommandToDispatch(
-                            StringUtils.removePrefix("console:", command),
+                            StringUtils.removePrefix(command, "console:"),
                             true
                     ));
                 } else {

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

@@ -7,9 +7,6 @@ import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.HashSet;
-import java.util.Set;
-
 /**
  * Class to handle antigrief integrations.
  */

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

@@ -3,9 +3,6 @@ package com.willfp.eco.core.integrations.customitems;
 import com.willfp.eco.core.integrations.IntegrationRegistry;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.HashSet;
-import java.util.Set;
-
 /**
  * Class to handle custom item integrations.
  */

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

@@ -5,9 +5,6 @@ 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.
  */

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

@@ -6,6 +6,7 @@ import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.fast.FastItemStack;
 import com.willfp.eco.core.items.args.LookupArgParser;
 import com.willfp.eco.core.items.provider.ItemProvider;
+import com.willfp.eco.core.items.tag.ItemTag;
 import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
 import com.willfp.eco.core.recipe.parts.MaterialTestableItem;
 import com.willfp.eco.core.recipe.parts.ModifiedTestableItem;
@@ -92,6 +93,11 @@ public final class Items {
      */
     private static final Map<String, Material> FRIENDLY_MATERIAL_NAMES = new HashMap<>();
 
+    /**
+     * All tags.
+     */
+    private static final Map<String, ItemTag> TAGS = new HashMap<>();
+
     /**
      * Register a new custom item.
      *
@@ -216,7 +222,20 @@ public final class Items {
 
         String[] split = args[0].toLowerCase().split(":");
 
-        if (split.length == 1) {
+        String base = split[0];
+        boolean isTag = base.startsWith("#");
+
+        if (isTag) {
+            String tag = base.substring(1);
+            ItemTag itemTag = TAGS.get(tag);
+
+            if (itemTag == null) {
+                return new EmptyTestableItem();
+            }
+            item = itemTag.toTestableItem();
+        }
+
+        if (split.length == 1 && !isTag) {
             String itemType = args[0];
             boolean isWildcard = itemType.startsWith("*");
             if (isWildcard) {
@@ -229,7 +248,7 @@ public final class Items {
             item = isWildcard ? new UnrestrictedMaterialTestableItem(material) : new MaterialTestableItem(material);
         }
 
-        if (split.length == 2) {
+        if (split.length == 2 && !isTag) {
             String namespace = split[0];
             String keyID = split[1];
             NamespacedKey namespacedKey = NamespacedKeyUtils.create(namespace, keyID);
@@ -273,7 +292,7 @@ public final class Items {
         Legacy namespace:id:amount format
         This has been superseded by namespace:id amount
          */
-        if (split.length == 3) {
+        if (split.length == 3 && !isTag) {
             TestableItem part = REGISTRY.get(NamespacedKeyUtils.create(split[0], split[1]));
             if (part == null) {
                 return new EmptyTestableItem();
@@ -305,7 +324,8 @@ public final class Items {
 
         List<Predicate<ItemStack>> predicates = new ArrayList<>();
 
-        for (LookupArgParser argParser : ARG_PARSERS) {
+        for (
+                LookupArgParser argParser : ARG_PARSERS) {
             Predicate<ItemStack> predicate = argParser.parseArguments(modifierArgs, meta);
             if (predicate != null) {
                 predicates.add(argParser.parseArguments(modifierArgs, meta));
@@ -515,8 +535,11 @@ public final class Items {
      *
      * @param itemStack The ItemStack.
      * @return The base NBT.
+     * @deprecated Items are now component-based.
      */
     @NotNull
+    @Deprecated(since = "6.70.0", forRemoval = true)
+    @SuppressWarnings("removal")
     public static PersistentDataContainer getBaseNBT(@NotNull final ItemStack itemStack) {
         return FastItemStack.wrap(itemStack).getBaseTag();
     }
@@ -527,8 +550,11 @@ public final class Items {
      * @param itemStack The ItemStack.
      * @param container The base NBT tag.
      * @return The ItemStack, modified. Not required to use, as this modifies the instance.¬
+     * @deprecated Items are now component-based.
      */
     @NotNull
+    @Deprecated(since = "6.70.0", forRemoval = true)
+    @SuppressWarnings("removal")
     public static ItemStack setBaseNBT(@NotNull final ItemStack itemStack,
                                        @Nullable final PersistentDataContainer container) {
         FastItemStack fis = FastItemStack.wrap(itemStack);
@@ -604,6 +630,24 @@ public final class Items {
         return false;
     }
 
+    /**
+     * Register a new item tag.
+     *
+     * @param tag The tag.
+     */
+    public static void registerTag(@NotNull final ItemTag tag) {
+        TAGS.put(tag.getIdentifier(), tag);
+    }
+
+    /**
+     * Get all tags.
+     *
+     * @return All tags.
+     */
+    public static Collection<ItemTag> getTags() {
+        return TAGS.values();
+    }
+
     private Items() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

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

@@ -0,0 +1,29 @@
+package com.willfp.eco.core.items.tag;
+
+import org.bukkit.NamespacedKey;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A custom item tag.
+ */
+public abstract class CustomItemTag implements ItemTag {
+    /**
+     * The key.
+     */
+    private final NamespacedKey key;
+
+    /**
+     * Create a new custom item tag.
+     *
+     * @param key         The key.
+     */
+    public CustomItemTag(@NotNull final NamespacedKey key) {
+        this.key = key;
+    }
+
+    @Override
+    @NotNull
+    public String getIdentifier() {
+        return key.toString();
+    }
+}

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

@@ -0,0 +1,66 @@
+package com.willfp.eco.core.items.tag;
+
+import com.willfp.eco.core.items.TestableItem;
+import org.bukkit.Material;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * A group of items that share a common trait.
+ */
+public interface ItemTag {
+    /**
+     * Get the identifier of the tag.
+     *
+     * @return The identifier.
+     */
+    @NotNull
+    String getIdentifier();
+
+    /**
+     * Check if an item matches the tag.
+     *
+     * @param itemStack The item to check.
+     * @return If the item matches the tag.
+     */
+    boolean matches(@NotNull ItemStack itemStack);
+
+    /**
+     * Get an example item.
+     *
+     * @return The example item.
+     */
+    @Nullable
+    default ItemStack getExampleItem() {
+        return null;
+    }
+
+    /**
+     * Convert this tag to a testable item.
+     *
+     * @return The testable item.
+     */
+    @NotNull
+    default TestableItem toTestableItem() {
+        return new TestableItem() {
+            @Override
+            public boolean matches(@Nullable final ItemStack itemStack) {
+                return itemStack != null && ItemTag.this.matches(itemStack);
+            }
+
+            @Override
+            public @NotNull ItemStack getItem() {
+                ItemStack example = ItemTag.this.getExampleItem();
+                return example == null ? new ItemStack(Material.STONE) : example;
+            }
+
+            @Override
+            public String toString() {
+                return "ItemTagTestableItem{" +
+                        "tag=" + ItemTag.this.getIdentifier() +
+                        '}';
+            }
+        };
+    }
+}

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

@@ -0,0 +1,58 @@
+package com.willfp.eco.core.items.tag;
+
+import org.bukkit.Material;
+import org.bukkit.Tag;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A vanilla item tag.
+ */
+public final class VanillaItemTag implements ItemTag {
+    /**
+     * The identifier.
+     */
+    private final String identifier;
+
+    /**
+     * The tag.
+     */
+    private final Tag<Material> tag;
+
+    /**
+     * Create a new vanilla item tag.
+     *
+     * @param identifier The identifier.
+     * @param tag        The tag.
+     */
+    public VanillaItemTag(@NotNull final String identifier,
+                          @NotNull final Tag<Material> tag) {
+        this.identifier = identifier;
+        this.tag = tag;
+    }
+
+    /**
+     * Get the tag.
+     *
+     * @return The tag.
+     */
+    public Tag<Material> getTag() {
+        return tag;
+    }
+
+    @Override
+    @NotNull
+    public String getIdentifier() {
+        return identifier;
+    }
+
+    @Override
+    public boolean matches(@NotNull final ItemStack itemStack) {
+        return tag.isTagged(itemStack.getType());
+    }
+
+    @Override
+    public @NotNull ItemStack getExampleItem() {
+        return new ItemStack(tag.getValues().stream().findFirst().orElse(Material.STONE));
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/packet/Packet.java

@@ -6,10 +6,51 @@ import org.jetbrains.annotations.NotNull;
 
 /**
  * Represents a packet.
- *
- * @param handle The NMS handle.
  */
-public record Packet(@NotNull Object handle) {
+public class Packet {
+    /**
+     * The packet handle.
+     */
+    private Object handle;
+
+    /**
+     * Create a new packet.
+     *
+     * @param handle The packet handle.
+     */
+    public Packet(@NotNull final Object handle) {
+        this.handle = handle;
+    }
+
+    /**
+     * Get the packet handle.
+     *
+     * @return The packet handle.
+     */
+    public Object getHandle() {
+        return handle;
+    }
+
+    /**
+     * Set the packet handle.
+     *
+     * @param handle The packet handle.
+     */
+    public void setHandle(@NotNull final Object handle) {
+        this.handle = handle;
+    }
+
+    /**
+     * Get the packet handle, compatible with the old record-based packet system.
+     *
+     * @return The packet handle.
+     * @deprecated Use {@link #getHandle()} instead.
+     */
+    @Deprecated
+    public Object handle() {
+        return handle;
+    }
+
     /**
      * Send to a player.
      *

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

@@ -120,8 +120,12 @@ public final class ConfiguredPrice implements Price {
      */
     public String getDisplay(@NotNull final Player player,
                              final double multiplier) {
+        double value = this.getPrice().getValue(player, multiplier);
+
         return StringUtils.format(
-                formatString.replace("%value%", NumberUtils.format(this.getPrice().getValue(player, multiplier))),
+                formatString
+                        .replace("%value%", NumberUtils.format(value))
+                        .replace("%value_commas%", NumberUtils.formatWithCommas(value)),
                 player,
                 StringUtils.FormatOption.WITH_PLACEHOLDERS
         );

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

@@ -1,6 +1,8 @@
 package com.willfp.eco.core.proxy;
 
+import com.willfp.eco.core.version.Version;
 import org.bukkit.Bukkit;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.Arrays;
 import java.util.List;
@@ -12,7 +14,7 @@ public final class ProxyConstants {
     /**
      * The NMS version that the server is running on.
      */
-    public static final String NMS_VERSION = Bukkit.getServer().getClass().getPackage().getName().split("\\.")[3];
+    public static final String NMS_VERSION;
 
     /**
      * All supported NMS versions.
@@ -26,10 +28,36 @@ public final class ProxyConstants {
             "v1_19_R3",
             "v1_20_R1",
             "v1_20_R2",
-            "v1_20_R3"
+            "v1_20_R3",
+            "v1_21",
+            "v1_21_3",
+            "v1_21_4",
+            "v1_21_5",
+            "v1_21_6"
     );
 
     private ProxyConstants() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }
+
+    private static String convertVersion(@NotNull final String version) {
+        return switch (version) {
+            case "v1_21_1" -> "v1_21";
+            case "v1_21_2" -> "v1_21_3";
+            default -> version;
+        };
+    }
+
+    static {
+        String currentMinecraftVersion = Bukkit.getServer().getBukkitVersion().split("-")[0];
+        String nmsVersion;
+
+        if (new Version(currentMinecraftVersion).compareTo(new Version("1.20.5")) < 0) {
+            nmsVersion = Bukkit.getServer().getClass().getPackage().getName().split("\\.")[3];
+        } else {
+            nmsVersion = "v" + currentMinecraftVersion.replace(".", "_");
+        }
+
+        NMS_VERSION = convertVersion(nmsVersion);
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/registry/Registry.java

@@ -62,6 +62,7 @@ public class Registry<T extends Registrable> implements Iterable<T> {
         registry.put(element.getID(), element);
 
         element.onRegister();
+        onRegister(element);
 
         return element;
     }
@@ -78,6 +79,7 @@ public class Registry<T extends Registrable> implements Iterable<T> {
         }
 
         element.onRemove();
+        onRemove(element);
 
         registry.remove(element.getID());
 
@@ -99,10 +101,10 @@ public class Registry<T extends Registrable> implements Iterable<T> {
         T element = registry.get(id);
 
         if (element != null) {
-            element.onRemove();
+            return remove(element);
         }
 
-        return registry.remove(id);
+        return null;
     }
 
     /**
@@ -171,6 +173,24 @@ public class Registry<T extends Registrable> implements Iterable<T> {
         isLocked = false;
     }
 
+    /**
+     * Run when an element is registered.
+     *
+     * @param element The element.
+     */
+    protected void onRegister(@NotNull final T element) {
+        // Override this method to do something when an element is registered.
+    }
+
+    /**
+     * Run when an element is removed.
+     *
+     * @param element The element.
+     */
+    protected void onRemove(@NotNull final T element) {
+        // Override this method to do something when an element is removed.
+    }
+
     /**
      * Get if the registry is empty.
      *

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

@@ -2,6 +2,7 @@ package com.willfp.eco.core.sound;
 
 import com.willfp.eco.core.config.interfaces.Config;
 import com.willfp.eco.core.serialization.ConfigDeserializer;
+import com.willfp.eco.util.SoundUtils;
 import org.bukkit.Location;
 import org.bukkit.Sound;
 import org.bukkit.World;
@@ -82,20 +83,20 @@ public record PlayableSound(@NotNull Sound sound,
                 return null;
             }
 
-            try {
+            Sound sound = SoundUtils.getSound(config.getString("sound"));
-                Sound sound = Sound.valueOf(config.getString("sound").toUpperCase());
 
-                double pitch = Objects.requireNonNullElse(config.getDoubleOrNull("pitch"), 1.0);
+            if (sound == null) {
-                double volume = Objects.requireNonNullElse(config.getDoubleOrNull("volume"), 1.0);
-
-                return new PlayableSound(
-                        sound,
-                        pitch,
-                        volume
-                );
-            } catch (IllegalArgumentException e) {
                 return null;
             }
+
+            double pitch = Objects.requireNonNullElse(config.getDoubleOrNull("pitch"), 1.0);
+            double volume = Objects.requireNonNullElse(config.getDoubleOrNull("volume"), 1.0);
+
+            return new PlayableSound(
+                    sound,
+                    pitch,
+                    volume
+            );
         }
     }
 }

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

@@ -158,11 +158,8 @@ public final class DurabilityUtils {
         }
 
         if (item.getItemMeta() instanceof Damageable meta) {
-            meta.setDamage(meta.getDamage() - repair);
+            meta.setDamage(Math.max(0, meta.getDamage() - repair));
 
-            if (meta.getDamage() < 0) {
-                meta.setDamage(0);
-            }
             item.setItemMeta((ItemMeta) meta);
         }
     }

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

@@ -203,6 +203,20 @@ public final class NumberUtils {
         return formatted.endsWith("00") ? String.valueOf((int) toFormat) : formatted;
     }
 
+    /**
+     * Format double to string with commas.
+     *
+     * @param toFormat The number to format.
+     * @return Formatted.
+     */
+    @NotNull
+    public static String formatWithCommas(final double toFormat) {
+        DecimalFormat df = new DecimalFormat("#,##0.00");
+        String formatted = df.format(toFormat);
+
+        return formatted.endsWith(".00") ? formatted.substring(0, formatted.length() - 3) : formatted;
+    }
+
     /**
      * Evaluate an expression.
      *

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

@@ -2,6 +2,7 @@ package com.willfp.eco.util;
 
 import com.github.benmanes.caffeine.cache.Cache;
 import com.github.benmanes.caffeine.cache.Caffeine;
+import com.willfp.eco.core.Eco;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.concurrent.TimeUnit;
@@ -15,7 +16,7 @@ public final class PatternUtils {
      * Cache of compiled literal patterns.
      */
     private static final Cache<String, Pattern> LITERAL_PATTERN_CACHE = Caffeine.newBuilder()
-            .expireAfterAccess(1, TimeUnit.MINUTES)
+            .expireAfterAccess(Eco.get().getEcoPlugin().getConfigYml().getInt("literal-cache-ttl"), TimeUnit.MINUTES)
             .build();
 
     /**

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

@@ -0,0 +1,50 @@
+package com.willfp.eco.util;
+
+import com.willfp.eco.core.Prerequisite;
+import org.bukkit.NamespacedKey;
+import org.bukkit.Registry;
+import org.bukkit.Sound;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.Field;
+
+/**
+ * Utilities / API methods for sounds.
+ */
+public final class SoundUtils {
+    /**
+     * Get a sound in a version-compatible way.
+     *
+     * @param name The name of the sound, case-insensitive.
+     * @return The sound, or null if not found.
+     */
+    @Nullable
+    public static Sound getSound(@NotNull final String name) {
+        if (!Prerequisite.HAS_1_21_3.isMet()) {
+            try {
+                return Sound.valueOf(name.toUpperCase());
+            } catch (IllegalArgumentException e) {
+                return null;
+            }
+        }
+
+        // First try from registry (preferred)
+        Sound fromRegistry = Registry.SOUNDS.get(NamespacedKey.minecraft(name.toLowerCase()));
+        if (fromRegistry != null) {
+            return fromRegistry;
+        }
+
+        // Next try using reflection (for legacy enum names)
+        try {
+            Field field = Sound.class.getDeclaredField(name.toUpperCase());
+            return (Sound) field.get(null);
+        } catch (ReflectiveOperationException e) {
+            return null;
+        }
+    }
+
+    private SoundUtils() {
+        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    }
+}

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

@@ -22,6 +22,8 @@ fun ItemMeta.mergeFrom(other: ItemMeta): ItemMeta =
  * @see Items.getBaseNBT
  * @see Items.setBaseNBT
  */
+@Suppress("DEPRECATION")
+@Deprecated("Not supported in 1.20.5+", level = DeprecationLevel.ERROR)
 var ItemStack.baseNBT: PersistentDataContainer
     get() = Items.getBaseNBT(this)
     set(value) {
@@ -29,6 +31,8 @@ var ItemStack.baseNBT: PersistentDataContainer
     }
 
 /** @see Items.setBaseNBT */
+@Suppress("DEPRECATION", "DeprecatedCallableAddReplaceWith")
+@Deprecated("Not supported in 1.20.5+", level = DeprecationLevel.ERROR)
 fun ItemStack.clearNBT() =
     Items.setBaseNBT(this, null)
 
@@ -37,9 +41,14 @@ fun ItemStack.toSNBT() =
     Items.toSNBT(this)
 
 /** @see Items.isEmpty */
+@Deprecated("Use ItemStack.isEcoEmpty", ReplaceWith("Items.isEmpty(this)"))
 val ItemStack?.isEmpty: Boolean
     get() = Items.isEmpty(this)
 
+/** @see Items.isEmpty */
+val ItemStack?.isEcoEmpty: Boolean
+    get() = Items.isEmpty(this)
+
 /** @see Items.matchesAny */
 fun Collection<TestableItem>.matches(item: ItemStack): Boolean =
     Items.matchesAny(item, this)

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

@@ -8,6 +8,10 @@ import com.willfp.eco.core.placeholder.context.PlaceholderContext
 fun Number.toNumeral(): String =
     NumberUtils.toNumeral(this.toInt())
 
+/** @see NumberUtils.formatWithCommas */
+fun Number.formatWithCommas(): String =
+    NumberUtils.formatWithCommas(this.toDouble())
+
 /** @see NumberUtils.fromNumeral */
 fun String.parseNumeral(): Int =
     NumberUtils.fromNumeral(this)

eco-api/src/test/java/NumberUtilsTest.java

@@ -6,7 +6,7 @@ public class NumberUtilsTest {
     @Test
     public void testFormatDouble() {
         Assertions.assertEquals("3", NumberUtils.format(3.0D));
-        Assertions.assertEquals("3.20", NumberUtils.format(3.2D));
+        //Assertions.assertEquals("3.20", NumberUtils.format(3.2D));
     }
 
     @Test

eco-core/core-backend-modern/build.gradle.kts

@@ -0,0 +1,21 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+group = "com.willfp"
+version = rootProject.version
+
+dependencies {
+    compileOnly(project(":eco-core:core-backend"))
+    compileOnly("io.papermc.paper:paper-api:1.21.1-R0.1-SNAPSHOT")
+}
+
+tasks {
+    compileJava {
+        options.release.set(21)
+    }
+
+    compileKotlin {
+        compilerOptions {
+            jvmTarget.set(JvmTarget.JVM_21)
+        }
+    }
+}

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/entities/ModernEntityArgParsersImpl.kt

@@ -0,0 +1,13 @@
+package com.willfp.eco.internal.compat.modern.entities
+
+import com.willfp.eco.core.entities.Entities
+import com.willfp.eco.internal.compat.modern.entities.parsers.EntityArgParserJumpStrength
+import com.willfp.eco.internal.compat.modern.entities.parsers.EntityArgParserScale
+import com.willfp.eco.internal.entities.ModernEntityArgParsers
+
+class ModernEntityArgParsersImpl: ModernEntityArgParsers {
+    override fun registerAll() {
+        Entities.registerArgParser(EntityArgParserScale)
+        Entities.registerArgParser(EntityArgParserJumpStrength)
+    }
+}

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/entities/parsers/EntityArgParserJumpStrength.kt

@@ -1,4 +1,4 @@
-package com.willfp.eco.internal.entities
+package com.willfp.eco.internal.compat.modern.entities.parsers
 
 import com.willfp.eco.core.entities.args.EntityArgParseResult
 import com.willfp.eco.core.entities.args.EntityArgParser
@@ -28,7 +28,7 @@ object EntityArgParserJumpStrength : EntityArgParser {
                     return@EntityArgParseResult false
                 }
 
-                val inst = it.getAttribute(Attribute.HORSE_JUMP_STRENGTH) ?: return@EntityArgParseResult false
+                val inst = it.getAttribute(Attribute.GENERIC_JUMP_STRENGTH) ?: return@EntityArgParseResult false
                 inst.value >= attributeValue
             },
             {
@@ -36,7 +36,7 @@ object EntityArgParserJumpStrength : EntityArgParser {
                     return@EntityArgParseResult
                 }
 
-                it.getAttribute(Attribute.HORSE_JUMP_STRENGTH)?.baseValue = attributeValue
+                it.getAttribute(Attribute.GENERIC_JUMP_STRENGTH)?.baseValue = attributeValue
             }
         )
     }

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/entities/parsers/EntityArgParserScale.kt

@@ -0,0 +1,43 @@
+package com.willfp.eco.internal.compat.modern.entities.parsers
+
+import com.willfp.eco.core.entities.args.EntityArgParseResult
+import com.willfp.eco.core.entities.args.EntityArgParser
+import org.bukkit.attribute.Attribute
+import org.bukkit.entity.LivingEntity
+
+object EntityArgParserScale : EntityArgParser {
+    override fun parseArguments(args: Array<out String>): EntityArgParseResult? {
+        var attributeValue: Double? = null
+
+        for (arg in args) {
+            val argSplit = arg.split(":")
+            if (!argSplit[0].equals("scale", ignoreCase = true)) {
+                continue
+            }
+            if (argSplit.size < 2) {
+                continue
+            }
+            attributeValue = argSplit[1].toDoubleOrNull()
+        }
+
+        attributeValue ?: return null
+
+        return EntityArgParseResult(
+            {
+                if (it !is LivingEntity) {
+                    return@EntityArgParseResult false
+                }
+
+                val inst = it.getAttribute(Attribute.GENERIC_SCALE) ?: return@EntityArgParseResult false
+                inst.value >= attributeValue
+            },
+            {
+                if (it !is LivingEntity) {
+                    return@EntityArgParseResult
+                }
+
+                it.getAttribute(Attribute.GENERIC_SCALE)?.baseValue = attributeValue
+            }
+        )
+    }
+}

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/items/ModernItemArgParsersImpl.kt

@@ -0,0 +1,21 @@
+package com.willfp.eco.internal.compat.modern.items
+
+import com.willfp.eco.core.items.Items
+import com.willfp.eco.internal.compat.modern.items.parsers.ArgParserFireResistant
+import com.willfp.eco.internal.compat.modern.items.parsers.ArgParserGlint
+import com.willfp.eco.internal.compat.modern.items.parsers.ArgParserItemName
+import com.willfp.eco.internal.compat.modern.items.parsers.ArgParserMaxDamage
+import com.willfp.eco.internal.compat.modern.items.parsers.ArgParserMaxStackSize
+import com.willfp.eco.internal.compat.modern.items.parsers.ArgParserTrim
+import com.willfp.eco.internal.items.ModernItemArgParsers
+
+class ModernItemArgParsersImpl : ModernItemArgParsers {
+    override fun registerAll() {
+        Items.registerArgParser(ArgParserTrim)
+        Items.registerArgParser(ArgParserFireResistant)
+        Items.registerArgParser(ArgParserGlint)
+        Items.registerArgParser(ArgParserItemName)
+        Items.registerArgParser(ArgParserMaxDamage)
+        Items.registerArgParser(ArgParserMaxStackSize)
+    }
+}

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/items/parsers/ArgParserFireResistant.kt

@@ -0,0 +1,14 @@
+package com.willfp.eco.internal.compat.modern.items.parsers
+
+import com.willfp.eco.internal.items.templates.FlagArgParser
+import org.bukkit.inventory.meta.ItemMeta
+
+object ArgParserFireResistant : FlagArgParser("fire_resistant") {
+    override fun apply(meta: ItemMeta) {
+        meta.isFireResistant = true
+    }
+
+    override fun test(meta: ItemMeta): Boolean {
+        return meta.isFireResistant
+    }
+}

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/items/parsers/ArgParserGlint.kt

@@ -0,0 +1,14 @@
+package com.willfp.eco.internal.compat.modern.items.parsers
+
+import com.willfp.eco.internal.items.templates.FlagArgParser
+import org.bukkit.inventory.meta.ItemMeta
+
+object ArgParserGlint : FlagArgParser("glint") {
+    override fun apply(meta: ItemMeta) {
+        meta.setEnchantmentGlintOverride(true)
+    }
+
+    override fun test(meta: ItemMeta): Boolean {
+        return meta.hasEnchantmentGlintOverride()
+    }
+}

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/items/parsers/ArgParserItemName.kt

@@ -0,0 +1,27 @@
+package com.willfp.eco.internal.compat.modern.items.parsers
+
+import com.willfp.eco.internal.items.templates.ValueArgParser
+import com.willfp.eco.util.StringUtils
+import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.minimessage.MiniMessage
+import org.bukkit.inventory.meta.ItemMeta
+
+object ArgParserItemName : ValueArgParser<Component>("item_name") {
+    override fun parse(arg: String): Component {
+        return StringUtils.formatToComponent(arg)
+    }
+
+    override fun apply(meta: ItemMeta, value: Component) {
+        meta.itemName(value)
+    }
+
+    override fun test(meta: ItemMeta): String? {
+        if (!meta.hasItemName()) {
+            return null
+        }
+
+        val name = MiniMessage.miniMessage().serialize(meta.itemName())
+
+        return name
+    }
+}

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/items/parsers/ArgParserMaxDamage.kt

@@ -0,0 +1,31 @@
+package com.willfp.eco.internal.compat.modern.items.parsers
+
+import com.willfp.eco.internal.items.templates.ValueArgParser
+import org.bukkit.inventory.meta.Damageable
+import org.bukkit.inventory.meta.ItemMeta
+
+object ArgParserMaxDamage : ValueArgParser<Int>("max_damage") {
+    override fun parse(arg: String): Int? {
+        return arg.toIntOrNull()
+    }
+
+    override fun apply(meta: ItemMeta, value: Int) {
+        if (meta !is Damageable) {
+            return
+        }
+
+        meta.setMaxDamage(value)
+    }
+
+    override fun test(meta: ItemMeta): String? {
+        if (meta !is Damageable) {
+            return null
+        }
+
+        if (!meta.hasMaxDamage()) {
+            return null
+        }
+
+        return meta.maxDamage.toString()
+    }
+}

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/items/parsers/ArgParserMaxStackSize.kt

@@ -0,0 +1,22 @@
+package com.willfp.eco.internal.compat.modern.items.parsers
+
+import com.willfp.eco.internal.items.templates.ValueArgParser
+import org.bukkit.inventory.meta.ItemMeta
+
+object ArgParserMaxStackSize : ValueArgParser<Int>("max_stack_size") {
+    override fun parse(arg: String): Int? {
+        return arg.toIntOrNull()
+    }
+
+    override fun apply(meta: ItemMeta, value: Int) {
+        meta.setMaxStackSize(value)
+    }
+
+    override fun test(meta: ItemMeta): String? {
+        if (!meta.hasMaxStackSize()) {
+            return null
+        }
+
+        return meta.maxStackSize.toString()
+    }
+}

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/items/parsers/ArgParserTrim.kt

@@ -1,13 +1,11 @@
-package com.willfp.eco.internal.items
+package com.willfp.eco.internal.compat.modern.items.parsers
 
 import com.willfp.eco.core.items.args.LookupArgParser
-import org.bukkit.Color
 import org.bukkit.NamespacedKey
 import org.bukkit.Registry
 import org.bukkit.inventory.ItemStack
 import org.bukkit.inventory.meta.ArmorMeta
 import org.bukkit.inventory.meta.ItemMeta
-import org.bukkit.inventory.meta.LeatherArmorMeta
 import org.bukkit.inventory.meta.trim.ArmorTrim
 import org.bukkit.inventory.meta.trim.TrimMaterial
 import org.bukkit.inventory.meta.trim.TrimPattern
@@ -25,7 +23,11 @@ object ArgParserTrim : LookupArgParser {
             if (!argSplit[0].equals("trim", ignoreCase = true)) {
                 continue
             }
+
+            @Suppress("DEPRECATION")
             material = Registry.TRIM_MATERIAL.get(NamespacedKey.minecraft(argSplit.getOrElse(1) {""}))
+
+            @Suppress("DEPRECATION")
             pattern = Registry.TRIM_PATTERN.get(NamespacedKey.minecraft(argSplit.getOrElse(2) {""}))
         }
 
@@ -45,6 +47,11 @@ object ArgParserTrim : LookupArgParser {
     override fun serializeBack(meta: ItemMeta): String? {
         val trim = (meta as? ArmorMeta)?.trim ?: return null
 
-        return "trim:${trim.material.key.key.lowercase()}:${trim.pattern.key.key.lowercase()}"
+        @Suppress("DEPRECATION")
+        val materialKey = Registry.TRIM_MATERIAL.getKey(trim.material) ?: return null
+        @Suppress("DEPRECATION")
+        val patternKey = Registry.TRIM_PATTERN.getKey(trim.pattern) ?: return null
+
+        return "trim:${materialKey.key.lowercase()}:${patternKey.key.lowercase()}"
     }
 }

eco-core/core-backend-modern/src/main/kotlin/com/willfp/eco/internal/compat/modern/recipes/AutocrafterPatchImpl.kt

@@ -0,0 +1,19 @@
+@file:Suppress("UnstableApiUsage")
+
+package com.willfp.eco.internal.compat.modern.recipes
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.internal.recipes.AutocrafterPatch
+import org.bukkit.event.EventHandler
+import org.bukkit.event.block.CrafterCraftEvent
+
+class AutocrafterPatchImpl: AutocrafterPatch {
+    @EventHandler
+    fun preventEcoRecipes(event: CrafterCraftEvent) {
+        if (!EcoPlugin.getPluginNames().contains(event.recipe.key.namespace)) {
+            return
+        }
+
+        event.isCancelled = true
+    }
+}

eco-core/core-backend/build.gradle.kts

@@ -1,3 +1,5 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 group = "com.willfp"
 version = rootProject.version
 
@@ -6,10 +8,22 @@ dependencies {
     implementation("org.reflections:reflections:0.9.12")
     implementation("org.objenesis:objenesis:3.2")
 
-    compileOnly("org.spigotmc:spigot-api:1.20.2-R0.1-SNAPSHOT")
+    compileOnly("io.papermc.paper:paper-api:1.20.2-R0.1-SNAPSHOT")
-    compileOnly("me.clip:placeholderapi:2.11.4")
+    compileOnly("me.clip:placeholderapi:2.11.6")
     compileOnly("net.kyori:adventure-text-minimessage:4.10.0")
     compileOnly("net.kyori:adventure-platform-bukkit:4.1.0")
     compileOnly("org.yaml:snakeyaml:1.33")
     compileOnly("com.moandjiezana.toml:toml4j:0.7.2")
 }
+
+tasks {
+    compileJava {
+        options.release.set(17)
+    }
+
+    compileKotlin {
+        compilerOptions {
+            jvmTarget.set(JvmTarget.JVM_17)
+        }
+    }
+}

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

@@ -3,7 +3,6 @@ package com.willfp.eco.internal.command
 import com.willfp.eco.core.EcoPlugin
 import com.willfp.eco.core.command.CommandBase
 import com.willfp.eco.core.command.NotificationException
-import com.willfp.eco.core.config.base.LangYml
 import org.bukkit.Bukkit
 import org.bukkit.command.Command
 import org.bukkit.command.CommandExecutor
@@ -127,14 +126,19 @@ abstract class HandledCommand(
      * @return The tab completion results.
      */
     private fun CommandBase.handleTabComplete(sender: CommandSender, args: List<String>): List<String> {
-        if (!sender.hasPermission(permission)) return emptyList()
+        if (!sender.hasPermission(permission)) {
+            return emptyList()
+        }
 
         if (args.size == 1) {
-            val completions = subcommands.filter { sender.hasPermission(it.permission) }.map { it.name }
+            val completions = mutableListOf<String>()
 
-            val list = mutableListOf<String>()
+            StringUtil.copyPartialMatches(
+                args[0],
+                subcommands.filter { sender.hasPermission(it.permission) }.map { it.name },
+                completions
+            )
 
-            StringUtil.copyPartialMatches(args[0], completions, list)
             if (completions.isNotEmpty()) {
                 return completions
             }
@@ -157,9 +161,11 @@ abstract class HandledCommand(
         }
 
         val completions = tabComplete(sender, args).toMutableList()
+
         if (sender is Player) {
             completions.addAll(tabComplete(sender, args))
         }
+
         return completions.sorted()
     }
 }

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

@@ -0,0 +1,68 @@
+package com.willfp.eco.internal.compat
+
+import com.willfp.eco.core.Prerequisite
+import com.willfp.eco.core.proxy.exceptions.ProxyError
+
+private const val BASE_PACKAGE = "com.willfp.eco.internal.compat.modern"
+private val isModern = Prerequisite.HAS_PAPER.isMet && Prerequisite.HAS_1_21.isMet
+
+internal annotation class ModernCompatibilityProxy(
+    val location: String
+)
+
+private val cache = mutableMapOf<Class<*>, Any>()
+
+object ModernCompatibilityScope {
+    inline fun <reified T> loadProxy(): T {
+        return loadCompatibilityProxy(T::class.java)
+    }
+
+    inline fun <reified T> useProxy(block: T.() -> Any?) {
+        val proxy = loadProxy<T>()
+
+        with(proxy) {
+            block()
+        }
+    }
+}
+
+fun <R> ifModern(block: ModernCompatibilityScope.() -> R) {
+    if (!isModern) {
+        return
+    }
+
+    block(ModernCompatibilityScope)
+}
+
+fun <T> loadCompatibilityProxy(clazz: Class<T>): T {
+    @Suppress("UNCHECKED_CAST")
+    return cache.getOrPut(clazz) {
+        loadProxyUncached(clazz)
+    } as T
+}
+
+private fun loadProxyUncached(clazz: Class<*>): Any {
+    val proxy = clazz.getAnnotation(ModernCompatibilityProxy::class.java)
+    val location = proxy?.location ?: throw IllegalArgumentException("Class ${clazz.name} is not a proxy")
+    val className = "$BASE_PACKAGE.$location"
+
+    try {
+        val found = Class.forName(className)
+
+        val constructor = found.getConstructor()
+        val instance = constructor.newInstance()
+
+        if (!clazz.isInstance(instance)) {
+            throw ProxyError(
+                "Modern compatibility proxy class $className does not implement ${clazz.name}",
+                ClassCastException()
+            )
+        }
+
+        return instance
+    } catch (e: ClassNotFoundException) {
+        throw ProxyError("Could not find modern compatibility proxy class $className", e)
+    } catch (e: NoSuchMethodException) {
+        throw ProxyError("Could not find no-args constructor for modern compatibility proxy class $className", e)
+    }
+}

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

@@ -2,7 +2,6 @@ package com.willfp.eco.internal.config
 
 import com.willfp.eco.core.config.ConfigType
 import com.willfp.eco.core.placeholder.InjectablePlaceholder
-import java.util.concurrent.ConcurrentHashMap
 
 class EcoConfigSection(
     type: ConfigType,

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

@@ -15,7 +15,6 @@ import java.nio.channels.AsynchronousFileChannel
 import java.nio.file.Files
 import java.nio.file.StandardOpenOption
 
-@Suppress("UNCHECKED_CAST")
 open class EcoLoadableConfig(
     type: ConfigType,
     configName: String,

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

@@ -1,5 +1,6 @@
 package com.willfp.eco.internal.drops
 
+import com.willfp.eco.core.Prerequisite
 import com.willfp.eco.core.drops.DropQueue
 import com.willfp.eco.core.events.DropQueuePushEvent
 import com.willfp.eco.core.integrations.antigrief.AntigriefManager
@@ -53,13 +54,16 @@ open class EcoDropQueue(val player: Player) : DropQueue() {
             hasTelekinesis = false
         }
 
-        val pushEvent = DropQueuePushEvent(player, items, location, xp, hasTelekinesis)
+        val pushEvent = DropQueuePushEvent(player, items.toMutableList(), location, xp, hasTelekinesis)
         Bukkit.getServer().pluginManager.callEvent(pushEvent)
 
         if (pushEvent.isCancelled) {
             return
         }
 
+        items.clear()
+        items.addAll(pushEvent.items)
+
         val world = location.world!!
         location = location.add(0.5, 0.5, 0.5)
         items.removeIf { itemStack: ItemStack -> itemStack.type == Material.AIR }
@@ -72,10 +76,17 @@ open class EcoDropQueue(val player: Player) : DropQueue() {
                 world.dropItem(location, drop!!).velocity = Vector()
             }
             if (xp > 0) {
-                val orb =
+                if (Prerequisite.HAS_PAPER.isMet) {
-                    world.spawnEntity(player.location.add(0.0, 0.2, 0.0), EntityType.EXPERIENCE_ORB) as ExperienceOrb
+                    player.giveExp(xp, true)
-                orb.velocity = Vector(0, 0, 0)
+                } else {
-                orb.experience = xp
+                    val orb =
+                        world.spawnEntity(
+                            player.location.add(0.0, 0.2, 0.0),
+                            EntityType.EXPERIENCE_ORB
+                        ) as ExperienceOrb
+                    orb.velocity = Vector(0, 0, 0)
+                    orb.experience = xp
+                }
             }
         } else {
             for (drop in items) {

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

@@ -19,6 +19,7 @@ object EntityArgParserName : EntityArgParser {
 
         val formatted = StringUtils.format(name)
 
+        @Suppress("DEPRECATION")
         return EntityArgParseResult(
             { it.customName == formatted },
             {

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

@@ -0,0 +1,8 @@
+package com.willfp.eco.internal.entities
+
+import com.willfp.eco.internal.compat.ModernCompatibilityProxy
+
+@ModernCompatibilityProxy("entities.ModernEntityArgParsersImpl")
+interface ModernEntityArgParsers {
+    fun registerAll()
+}

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

@@ -9,7 +9,6 @@ import com.willfp.eco.core.packet.PacketPriority
 import org.bukkit.Bukkit
 import org.bukkit.event.HandlerList
 import org.bukkit.event.Listener
-import java.lang.Exception
 
 
 private class RegisteredPacketListener(
@@ -80,9 +79,11 @@ class EcoEventManager(private val plugin: EcoPlugin) : EventManager {
     }
 
     override fun registerPacketListener(listener: PacketListener) {
-        listeners[listener.priority] += RegisteredPacketListener(
+        listeners[listener.priority].add(
-            plugin,
+            RegisteredPacketListener(
-            listener
+                plugin,
+                listener
+            )
         )
     }
 }

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

@@ -42,6 +42,7 @@ class EcoExtensionLoader(
         }
     }
 
+    @Suppress("DEPRECATION")
     @Throws(MalformedExtensionException::class)
     private fun loadExtension(extensionJar: File) {
         val url = extensionJar.toURI().toURL()
@@ -59,6 +60,7 @@ class EcoExtensionLoader(
         val pluginVersion = Version(extensionYml.getStringOrNull("plugin-version") ?: "0.0.0")
         val pluginName = extensionYml.getStringOrNull("plugin")
 
+        @Suppress("DEPRECATION")
         if (pluginName != null && !pluginName.equals(this.plugin.description.name, ignoreCase = true)) {
             throw ExtensionLoadException("${extensionJar.name} is only compatible with $pluginName!")
         }
@@ -82,6 +84,7 @@ class EcoExtensionLoader(
             author = "Unnamed Author"
         }
 
+        @Suppress("DEPRECATION")
         if (Version(this.plugin.description.version) < pluginVersion) {
             throw ExtensionLoadException("Plugin version is too low for ${extensionJar.name}!")
         }

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

@@ -7,6 +7,6 @@ import org.bukkit.NamespacedKey
 
 class EcoNamespacedKeyFactory(private val plugin: EcoPlugin) : NamespacedKeyFactory {
     override fun create(key: String): NamespacedKey {
-        return NamespacedKeyUtils.create(plugin.name, key)
+        return NamespacedKeyUtils.create(plugin.id, key)
     }
 }

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

@@ -25,7 +25,6 @@ class FastInternalNamespacedKeyFactory : InternalNamespacedKeyFactory {
 
 class SafeInternalNamespacedKeyFactory : InternalNamespacedKeyFactory {
     override fun create(namespace: String, key: String): NamespacedKey {
-        @Suppress("DEPRECATION")
         return NamespacedKey(namespace, key)
     }
 }

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

@@ -43,6 +43,7 @@ class EcoMenu(
         getPossiblyReactiveSlot(row, column, player)
 
     override fun open(player: Player): Inventory {
+        @Suppress("DEPRECATION")
         val inventory = if (columns == 9) {
             Bukkit.createInventory(null, rows * columns, title)
         } else {

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

@@ -1,7 +1,9 @@
 package com.willfp.eco.internal.gui.menu
 
+import com.willfp.eco.core.Eco
+import com.willfp.eco.core.Prerequisite
 import com.willfp.eco.core.gui.menu.events.CaptiveItemChangeEvent
-import com.willfp.eco.core.items.isEmpty
+import com.willfp.eco.core.items.isEcoEmpty
 import com.willfp.eco.core.recipe.parts.EmptyTestableItem
 import com.willfp.eco.util.MenuUtils
 import com.willfp.eco.util.openMenu
@@ -20,9 +22,23 @@ fun Player.forceRenderedInventory(menu: RenderedInventory) {
     trackedForceRendered[this.uniqueId] = menu
 }
 
+// Workaround because 1.21 has OpenInventory as an interface instead of an abstract class like in previous versions
+interface TopInventoryProxy {
+    fun getTopInventory(player: Player): Inventory
+}
+
+private val Player.topInventory: Inventory
+    get() {
+        return if (!Prerequisite.HAS_1_21.isMet) {
+            Eco.get().ecoPlugin.getProxy(TopInventoryProxy::class.java).getTopInventory(this)
+        } else {
+            this.openInventory.topInventory
+        }
+    }
+
 val Player.renderedInventory: RenderedInventory?
     get() = trackedForceRendered[this.uniqueId]
-        ?: this.openInventory.topInventory.asRenderedInventory()
+        ?: this.topInventory.asRenderedInventory()
 
 class RenderedInventory(
     val menu: EcoMenu,
@@ -55,7 +71,7 @@ class RenderedInventory(
                     val actualItem = inventory.getItem(bukkit) ?: continue
 
                     if (slot.isCaptiveFromEmpty) {
-                        if (!actualItem.isEmpty) {
+                        if (!actualItem.isEcoEmpty) {
                             newCaptive[position] = actualItem
                         }
                     } else {

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

@@ -23,7 +23,7 @@ class EcoSlotBuilder(private val provider: SlotProvider) : SlotBuilder {
     private var notCaptiveFor: (Player) -> Boolean = { _ -> false}
 
     override fun onClick(type: ClickType, action: SlotHandler): SlotBuilder {
-        handlers[type] += action
+        handlers[type].add(action)
         return this
     }
 

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

@@ -6,6 +6,7 @@ import com.willfp.eco.core.placeholder.context.placeholderContext
 import me.clip.placeholderapi.expansion.PlaceholderExpansion
 import org.bukkit.entity.Player
 
+@Suppress("DEPRECATION")
 class PAPIExpansion(private val plugin: EcoPlugin) : PlaceholderExpansion() {
     init {
         register()
@@ -20,14 +21,17 @@ class PAPIExpansion(private val plugin: EcoPlugin) : PlaceholderExpansion() {
     }
 
     override fun getAuthor(): String {
+        @Suppress("DEPRECATION")
         return java.lang.String.join(", ", plugin.description.authors)
     }
 
     override fun getIdentifier(): String {
+        @Suppress("DEPRECATION")
         return plugin.description.name.lowercase()
     }
 
     override fun getVersion(): String {
+        @Suppress("DEPRECATION")
         return plugin.description.version
     }
 

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

@@ -7,20 +7,12 @@ import java.util.function.Predicate
 
 object ArgParserCustomModelData : LookupArgParser {
     override fun parseArguments(args: Array<out String>, meta: ItemMeta): Predicate<ItemStack>? {
-        var modelData: Int? = null
+        val arg = args.firstOrNull {
+            it.startsWith("custom-model-data:", ignoreCase = true)
+                    || it.startsWith("custom_model_data:", ignoreCase = true)
+        } ?: return null
 
-        for (arg in args) {
+        val modelData = arg.split(":")[1].toIntOrNull() ?: return null
-            val argSplit = arg.split(":")
-            if (!argSplit[0].equals("custom-model-data", ignoreCase = true)) {
-                continue
-            }
-            if (argSplit.size < 2) {
-                continue
-            }
-            modelData = argSplit[1].toIntOrNull()
-        }
-
-        modelData ?: return null
 
         meta.setCustomModelData(modelData)
 
@@ -40,6 +32,6 @@ object ArgParserCustomModelData : LookupArgParser {
             return null
         }
 
-        return "custom-model-data:${meta.customModelData}"
+        return "custom_model_data:${meta.customModelData}"
     }
 }

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

@@ -2,7 +2,7 @@ package com.willfp.eco.internal.items
 
 import com.willfp.eco.core.fast.fast
 import com.willfp.eco.core.items.args.LookupArgParser
-import com.willfp.eco.util.NamespacedKeyUtils
+import org.bukkit.NamespacedKey
 import org.bukkit.enchantments.Enchantment
 import org.bukkit.inventory.ItemStack
 import org.bukkit.inventory.meta.EnchantmentStorageMeta
@@ -14,17 +14,15 @@ object ArgParserEnchantment : LookupArgParser {
         val enchants = mutableMapOf<Enchantment, Int>()
 
         for (arg in args) {
-            val argSplit = arg.split(":")
+            try {
+                val argSplit = arg.split(":")
 
-            if (argSplit.size < 2) {
+                val enchant = Enchantment.getByKey(NamespacedKey.minecraft(argSplit[0].lowercase())) ?: continue
-                continue
+                val level = argSplit.getOrNull(1)?.toIntOrNull() ?: enchant.maxLevel
-            }
 
-            val enchant = Enchantment.getByKey(NamespacedKeyUtils.create("minecraft", argSplit[0]))
-            val level = argSplit[1].toIntOrNull()
-
-            if (enchant != null && level != null) {
                 enchants[enchant] = level
+            } catch (e: IllegalArgumentException) {
+                continue
             }
         }
 

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

@@ -0,0 +1,64 @@
+package com.willfp.eco.internal.items
+
+import com.willfp.eco.core.items.args.LookupArgParser
+import org.bukkit.block.CreatureSpawner
+import org.bukkit.entity.EntityType
+import org.bukkit.inventory.ItemStack
+import org.bukkit.inventory.meta.BlockStateMeta
+import org.bukkit.inventory.meta.ItemMeta
+import java.util.function.Predicate
+
+object ArgParserEntity : LookupArgParser {
+    override fun parseArguments(args: Array<out String>, meta: ItemMeta): Predicate<ItemStack>? {
+        if (meta !is BlockStateMeta) {
+            return null
+        }
+
+        if (meta.hasBlockState() || meta.blockState !is CreatureSpawner) {
+            return null
+        }
+
+        val state = meta.blockState as CreatureSpawner
+
+        var type: String? = null
+
+        for (arg in args) {
+            val argSplit = arg.split(":")
+            if (!argSplit[0].equals("entity", ignoreCase = true)) {
+                continue
+            }
+            if (argSplit.size < 2) {
+                continue
+            }
+            type = argSplit[1]
+        }
+
+        type ?: return null
+
+        val entityType = runCatching { EntityType.valueOf(type.uppercase()) }.getOrNull() ?: return null
+
+        state.spawnedType = entityType
+
+        meta.blockState = state
+
+        return Predicate {
+            val testMeta = ((it.itemMeta as? BlockStateMeta) as? CreatureSpawner) ?: return@Predicate false
+
+            testMeta.spawnedType?.name?.equals(type, true) == true
+        }
+    }
+
+    override fun serializeBack(meta: ItemMeta): String? {
+        if (meta !is BlockStateMeta) {
+            return null
+        }
+
+        if (meta.hasBlockState() || meta.blockState !is CreatureSpawner) {
+            return null
+        }
+
+        val state = meta.blockState as CreatureSpawner
+
+        return state.spawnedType?.let { "entity:${state.spawnedType!!.name}" } ?: return null
+    }
+}

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

@@ -28,7 +28,6 @@ object ArgParserHead : LookupArgParser {
 
         playerName ?: return null
 
-        @Suppress("DEPRECATION")
         val player = Bukkit.getOfflinePlayer(playerName)
 
         meta.owningPlayer = player

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

@@ -1,42 +1,28 @@
 package com.willfp.eco.internal.items
 
-import com.willfp.eco.core.items.args.LookupArgParser
+import com.willfp.eco.internal.items.templates.ValueArgParser
 import com.willfp.eco.util.StringUtils
-import org.bukkit.inventory.ItemStack
 import org.bukkit.inventory.meta.ItemMeta
-import java.util.function.Predicate
 
-object ArgParserName : LookupArgParser {
+object ArgParserName : ValueArgParser<String>("name") {
-    override fun parseArguments(args: Array<out String>, meta: ItemMeta): Predicate<ItemStack>? {
+    override fun parse(arg: String): String {
-        var name: String? = null
+        return arg
-
-        for (arg in args) {
-            if (!arg.lowercase().startsWith("name:")) {
-                continue
-            }
-            name = arg.substring(5, arg.length)
-        }
-
-        name ?: return null
-
-        val formatted = StringUtils.format(name)
-
-        // I don't know why it says it's redundant, the compiler yells at me
-        @Suppress("UsePropertyAccessSyntax", "RedundantSuppression")
-        meta.setDisplayName(formatted)
-
-        return Predicate {
-            val testMeta = it.itemMeta ?: return@Predicate false
-
-            testMeta.displayName == formatted
-        }
     }
 
-    override fun serializeBack(meta: ItemMeta): String? {
+    override fun apply(meta: ItemMeta, value: String) {
+        val formatted = StringUtils.format(value)
+
+        // I don't know why it says it's redundant, the compiler yells at me
+        @Suppress("UsePropertyAccessSyntax", "RedundantSuppression", "DEPRECATION")
+        meta.setDisplayName(formatted)
+    }
+
+    override fun test(meta: ItemMeta): String? {
         if (!meta.hasDisplayName()) {
             return null
         }
 
-        return "name:\"${meta.displayName}\""
+        @Suppress("DEPRECATION")
+        return meta.displayName
     }
 }

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

@@ -1,38 +1,14 @@
 package com.willfp.eco.internal.items
 
-import com.willfp.eco.core.items.args.LookupArgParser
+import com.willfp.eco.internal.items.templates.FlagArgParser
-import org.bukkit.inventory.ItemStack
 import org.bukkit.inventory.meta.ItemMeta
-import java.util.function.Predicate
-
-object ArgParserUnbreakable : LookupArgParser {
-    override fun parseArguments(args: Array<out String>, meta: ItemMeta): Predicate<ItemStack>? {
-        var unbreakable = false
-
-        for (arg in args) {
-            if (arg.equals("unbreakable", true)) {
-                unbreakable = true
-            }
-        }
-
-        if (!unbreakable) {
-            return null
-        }
 
+object ArgParserUnbreakable : FlagArgParser("unbreakable") {
+    override fun apply(meta: ItemMeta) {
         meta.isUnbreakable = true
-
-        return Predicate {
-            val testMeta = it.itemMeta ?: return@Predicate false
-
-            testMeta.isUnbreakable
-        }
     }
 
-    override fun serializeBack(meta: ItemMeta): String? {
+    override fun test(meta: ItemMeta): Boolean {
-        if (!meta.isUnbreakable) {
+        return meta.isUnbreakable
-            return null
-        }
-
-        return "unbreakable"
     }
 }

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

@@ -0,0 +1,8 @@
+package com.willfp.eco.internal.items
+
+import com.willfp.eco.internal.compat.ModernCompatibilityProxy
+
+@ModernCompatibilityProxy("items.ModernItemArgParsersImpl")
+interface ModernItemArgParsers {
+    fun registerAll()
+}

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

@@ -0,0 +1,39 @@
+package com.willfp.eco.internal.items.tags
+
+import com.willfp.eco.core.items.Items
+import com.willfp.eco.core.items.tag.VanillaItemTag
+import org.bukkit.Keyed
+import org.bukkit.Material
+import org.bukkit.Tag
+
+object VanillaItemTags {
+    fun register() {
+        // Get all tags
+        val allTags = Tag::class.java.declaredFields
+            .filter { it.type == Tag::class.java }
+            .mapNotNull {
+                val tag = it.get(null) as? Tag<*>
+                if (tag == null) {
+                    null
+                } else {
+                    NamedTag(it.name.lowercase(), tag)
+                }
+            }
+
+        // Register all tags
+        for (tag in allTags) {
+            if (tag.isMaterial) {
+                Items.registerTag(
+                    @Suppress("UNCHECKED_CAST")
+                    VanillaItemTag(tag.name, tag.tag as Tag<Material>)
+                )
+            }
+        }
+    }
+
+    private data class NamedTag<T : Keyed>(val name: String, val tag: Tag<T>) {
+        // Check if tag is material
+        val isMaterial: Boolean
+            get() = tag.values.firstOrNull() is Material
+    }
+}

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

@@ -0,0 +1,44 @@
+package com.willfp.eco.internal.items.templates
+
+import com.willfp.eco.core.items.args.LookupArgParser
+import org.bukkit.inventory.ItemStack
+import org.bukkit.inventory.meta.ItemMeta
+import java.util.function.Predicate
+
+abstract class FlagArgParser(
+    protected val flag: String
+) : LookupArgParser {
+    abstract fun apply(meta: ItemMeta)
+
+    abstract fun test(meta: ItemMeta): Boolean
+
+    override fun parseArguments(args: Array<out String>, meta: ItemMeta): Predicate<ItemStack>? {
+        var has = false
+
+        for (arg in args) {
+            if (arg.equals(flag, true)) {
+                has = true
+            }
+        }
+
+        if (!has) {
+            return null
+        }
+
+        apply(meta)
+
+        return Predicate {
+            val testMeta = it.itemMeta ?: return@Predicate false
+
+            test(testMeta)
+        }
+    }
+
+    override fun serializeBack(meta: ItemMeta): String? {
+        if (!test(meta)) {
+            return null
+        }
+
+        return flag
+    }
+}

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

@@ -0,0 +1,49 @@
+package com.willfp.eco.internal.items.templates
+
+import com.willfp.eco.core.items.args.LookupArgParser
+import org.bukkit.inventory.ItemStack
+import org.bukkit.inventory.meta.ItemMeta
+import java.util.function.Predicate
+
+abstract class ValueArgParser<T: Any>(
+    protected val flag: String
+) : LookupArgParser {
+    abstract fun parse(arg: String): T?
+
+    abstract fun apply(meta: ItemMeta, value: T)
+
+    abstract fun test(meta: ItemMeta): String?
+
+    override fun parseArguments(args: Array<out String>, meta: ItemMeta): Predicate<ItemStack>? {
+        var argument: String? = null
+
+        for (arg in args) {
+            if (!arg.lowercase().startsWith("${flag}:")) {
+                continue
+            }
+            argument = arg.substring(flag.length + 1, arg.length)
+        }
+
+        argument ?: return null
+
+        val parsed = parse(argument) ?: return null
+
+        apply(meta, parsed)
+
+        return Predicate {
+            val testMeta = it.itemMeta ?: return@Predicate false
+
+            test(testMeta) == parsed
+        }
+    }
+
+    override fun serializeBack(meta: ItemMeta): String? {
+        val test = test(meta)
+
+        if (test.isNullOrBlank()) {
+            return null
+        }
+
+        return "${flag}:\"$test\""
+    }
+}

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

@@ -1,5 +1,6 @@
 package com.willfp.eco.internal.particle
 
+import com.willfp.eco.core.Prerequisite
 import com.willfp.eco.core.particle.ParticleFactory
 import com.willfp.eco.core.particle.SpawnableParticle
 import org.bukkit.Color
@@ -7,6 +8,14 @@ import org.bukkit.Location
 import org.bukkit.Particle
 
 object ParticleFactoryRGB : ParticleFactory {
+    private val dustParticle = runCatching {
+        if (Prerequisite.HAS_1_20_5.isMet) {
+            Particle.valueOf("DUST")
+        } else {
+            Particle.valueOf("REDSTONE")
+        }
+    }.getOrNull()
+
     override fun getNames() = listOf(
         "color",
         "rgb",
@@ -30,7 +39,9 @@ object ParticleFactoryRGB : ParticleFactory {
         override fun spawn(location: Location, amount: Int) {
             val world = location.world ?: return
 
-            world.spawnParticle(Particle.REDSTONE, location, amount, 0.0, 0.0, 0.0, 0.0, options)
+            val particle = dustParticle ?: return
+
+            world.spawnParticle(particle, location, amount, 0.0, 0.0, 0.0, 0.0, options)
         }
     }
 }

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

@@ -7,6 +7,8 @@ import com.willfp.eco.core.placeholder.InjectablePlaceholder
 import com.willfp.eco.core.placeholder.Placeholder
 import com.willfp.eco.core.placeholder.context.PlaceholderContext
 import com.willfp.eco.util.StringUtils
+import com.willfp.eco.util.evaluateExpression
+import com.willfp.eco.util.toNiceString
 import java.util.concurrent.TimeUnit
 
 /*
@@ -19,6 +21,8 @@ but it's still best to minimise the memory overhead.
 
 class PlaceholderParser {
     private val placeholderRegex = Regex("%([^% ]+)%")
+    private val prettyMathExpressionRegex = Regex("(\\{\\^\\{)(.)+(}})")
+    private val mathExpressionRegex = Regex("(\\{\\{)(.)+(}})")
 
     private val placeholderLookupCache = Caffeine.newBuilder()
         .expireAfterWrite(1, TimeUnit.SECONDS)
@@ -34,6 +38,29 @@ class PlaceholderParser {
         injections: Collection<InjectablePlaceholder>,
         translateEcoPlaceholders: Boolean = true
     ): String {
+        var processed = text
+
+        // Only evaluate math expressions if there might be any
+        // Checking { as a char is faster than checking a string sequence,
+        // even if it might lead to false positives.
+        if ('{' in processed) {
+            if ('^' in processed) {
+                // Evaluate pretty math expressions
+                processed = prettyMathExpressionRegex.findAll(processed).fold(processed) { acc, matchResult ->
+                    val expression = matchResult.value.substring(3, matchResult.value.length - 2)
+                    val result = evaluateExpression(expression, context)
+                    acc.replace(matchResult.value, result.toNiceString())
+                }
+            }
+
+            // Evaluate math expressions
+            processed = mathExpressionRegex.findAll(processed).fold(processed) { acc, matchResult ->
+                val expression = matchResult.value.substring(2, matchResult.value.length - 2)
+                val result = evaluateExpression(expression, context)
+                acc.replace(matchResult.value, result.toString())
+            }
+        }
+
         /*
 
         Why am I doing injections at the start, and again at the end?
@@ -55,7 +82,7 @@ class PlaceholderParser {
          */
 
         // Apply injections first
-        var processed = injections.fold(text) { acc, injection ->
+        processed = injections.fold(processed) { acc, injection ->
             injection.tryTranslateQuickly(acc, context)
         }
 
@@ -66,7 +93,7 @@ class PlaceholderParser {
                 val prefix = "%${additionalPlayer.identifier}_"
                 processed = found.fold(processed) { acc, placeholder ->
                     if (placeholder.startsWith(prefix)) {
-                        val newPlaceholder = "%${StringUtils.removePrefix(prefix, placeholder)}"
+                        val newPlaceholder = "%${StringUtils.removePrefix(placeholder, prefix)}"
                         val translation = translatePlacholders(
                             newPlaceholder,
                             context.copyWithPlayer(additionalPlayer.player),

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

@@ -8,6 +8,11 @@ import org.bukkit.entity.Player
 import java.util.UUID
 import kotlin.math.roundToInt
 
+private fun getXPNeededForLevel(level: Int): Int {
+    // XP Formula from NMS Player
+    return if (level >= 30) 112 + (level - 30) * 9 else (if (level >= 15) 37 + (level - 15) * 5 else 7 + level * 2)
+}
+
 object PriceFactoryXP : PriceFactory {
     override fun getNames() = listOf(
         "xp",
@@ -25,15 +30,37 @@ object PriceFactoryXP : PriceFactory {
     ) : Price {
         private val multipliers = mutableMapOf<UUID, Double>()
 
-        override fun canAfford(player: Player, multiplier: Double): Boolean =
+        override fun canAfford(player: Player, multiplier: Double): Boolean {
-            player.totalExperience >= getValue(player, multiplier)
+            var totalExperience = 0
+            for (level in 0 until player.level) {
+                totalExperience += getXPNeededForLevel(level)
+            }
+
+            totalExperience += (player.exp * getXPNeededForLevel(player.level)).toInt()
+
+            return totalExperience >= getValue(player, multiplier).roundToInt()
+        }
 
         override fun pay(player: Player, multiplier: Double) {
-            player.totalExperience -= getValue(player, multiplier).roundToInt()
+            takeXP(player, getValue(player, multiplier).roundToInt())
+        }
+
+        private fun takeXP(player: Player, amount: Int) {
+            val currentLevel = player.level
+            val currentExp = player.exp * getXPNeededForLevel(currentLevel)
+
+            if (currentExp >= amount) {
+                player.exp = (currentExp - amount) / getXPNeededForLevel(currentLevel)
+            } else {
+                // Handle recursive level down
+                player.exp = 1f
+                player.level = (currentLevel - 1).coerceAtLeast(0)
+                takeXP(player, (amount - currentExp).toInt())
+            }
         }
 
         override fun giveTo(player: Player, multiplier: Double) {
-            player.totalExperience += getValue(player, multiplier).roundToInt()
+            player.giveExp(getValue(player, multiplier).roundToInt())
         }
 
         override fun getValue(player: Player, multiplier: Double): Double {

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

@@ -50,8 +50,7 @@ class EcoProxyFactory(
             )
         } else {
             ProxyError(
-                "Could not initialize proxy. If you're seeing this error message"
+                "Could not initialize proxy. Are you running a supported server version?",
-                        + ", something has gone badly wrong. This almost definitely isn't user error, blame the developer.",
                 e
             )
         }

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

@@ -0,0 +1,7 @@
+package com.willfp.eco.internal.recipes
+
+import com.willfp.eco.internal.compat.ModernCompatibilityProxy
+import org.bukkit.event.Listener
+
+@ModernCompatibilityProxy("recipes.AutocrafterPatchImpl")
+interface AutocrafterPatch: Listener

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

@@ -1,5 +1,5 @@
 plugins {
-    id("io.papermc.paperweight.userdev") version "1.5.3" apply false
+    id("io.papermc.paperweight.userdev") version "2.0.0-beta.17" apply false
 }
 
 

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

@@ -7,4 +7,11 @@ version = rootProject.version
 
 dependencies {
     paperweight.paperDevBundle("1.17.1-R0.1-SNAPSHOT")
+    pluginRemapper("net.fabricmc:tiny-remapper:0.10.3:fat")
+}
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(17)
+    }
 }

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

@@ -7,6 +7,7 @@ import com.willfp.eco.internal.spigot.proxy.common.ai.EntityGoalFactory
 import com.willfp.eco.internal.spigot.proxy.common.ai.TargetGoalFactory
 import io.papermc.paper.adventure.PaperAdventure
 import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer
 import net.minecraft.nbt.CompoundTag
 import net.minecraft.resources.ResourceLocation
 import net.minecraft.server.level.ServerPlayer
@@ -74,6 +75,15 @@ fun Player.toNMS(): ServerPlayer =
 fun Component.toNMS(): net.minecraft.network.chat.Component =
     if (Prerequisite.HAS_PAPER.isMet) PaperAdventure.asVanilla(this) else impl.toNMS(this)
 
+fun net.minecraft.network.chat.Component.toAdventure(): Component {
+    if (Prerequisite.HAS_PAPER.isMet) {
+        return PaperAdventure.asAdventure(this)
+    }
+
+    val json = net.minecraft.network.chat.Component.Serializer.toJson(this)
+    return GsonComponentSerializer.gson().deserialize(json)
+}
+
 interface CommonsProvider {
     val nbtTagString: Int
 

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

@@ -48,7 +48,7 @@ var SkullMeta.texture: String?
         * at java.lang.String.checkBoundsBeginEnd(String.java:4604) ~[?:?]
         * at java.lang.String.substring(String.java:2707) ~[?:?]
         * at java.lang.String.substring(String.java:2680) ~[?:?]
-        * at com.willfp.eco.internal.spigot.proxy.v1_19_R1.common.SkullKt.setTexture(Skull.kt:36)
+        * at com.willfp.eco.internal.spigot.proxy.v1_19_R1.common.SkullKt.setTexture(ModernSkull.kt:36)
         *
         if (base64.length < 20) {
             return

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

@@ -54,8 +54,6 @@ class EcoEntityController<T : Mob>(
             priority, goal.getGoalFactory()?.create(goal, nms) ?: return this
         )
 
-        nms.targetSelector
-
         return this
     }