Extensions

api/src/main/java/net/luckperms/api/event/extension/ExtensionLoadEvent.java

@@ -0,0 +1,47 @@
+/*
+ * This file is part of LuckPerms, licensed under the MIT License.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+package net.luckperms.api.event.extension;
+
+import net.luckperms.api.event.LuckPermsEvent;
+import net.luckperms.api.event.Param;
+import net.luckperms.api.extension.Extension;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * Called when an {@link Extension} is loaded.
+ */
+public interface ExtensionLoadEvent extends LuckPermsEvent {
+
+    /**
+     * Gets the extension that was loaded.
+     *
+     * @return the extension
+     */
+    @Param(0)
+    @NonNull Extension getExtension();
+
+}

api/src/main/java/net/luckperms/api/extension/Extension.java

@@ -0,0 +1,50 @@
+/*
+ * This file is part of LuckPerms, licensed under the MIT License.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+package net.luckperms.api.extension;
+
+import net.luckperms.api.LuckPerms;
+
+/**
+ * Represents a simple extension "plugin" for LuckPerms.
+ *
+ * <p>Yes, that's right. A plugin for a plugin.</p>
+ *
+ * <p>Extensions should either declare a no-arg constructor, or a constructor
+ * that accepts a single {@link LuckPerms} parameter as it's only argument.</p>
+ */
+public interface Extension {
+
+    /**
+     * Loads the extension.
+     */
+    void load();
+
+    /**
+     * Unloads the extension.
+     */
+    void unload();
+
+}

api/src/main/java/net/luckperms/api/extension/ExtensionManager.java

@@ -0,0 +1,61 @@
+/*
+ * This file is part of luckperms, licensed under the MIT License.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+package net.luckperms.api.extension;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.Collection;
+
+/**
+ * Manages extensions.
+ */
+public interface ExtensionManager {
+
+    /**
+     * Loads the given extension.
+     *
+     * @param extension the extension to load
+     */
+    void loadExtension(Extension extension);
+
+    /**
+     * Loads the extension at the given path.
+     *
+     * @param path the path to the extension
+     * @throws IOException if the extension could not be loaded
+     */
+    @NonNull Extension loadExtension(Path path) throws IOException;
+
+    /**
+     * Gets a collection of all loaded extensions.
+     *
+     * @return the loaded extensions
+     */
+    @NonNull Collection<Extension> getLoadedExtensions();
+
+}

common/src/main/java/me/lucko/luckperms/common/event/EventFactory.java

@@ -48,6 +48,7 @@ import net.luckperms.api.event.Cancellable;
 import net.luckperms.api.event.LuckPermsEvent;
 import net.luckperms.api.event.cause.CreationCause;
 import net.luckperms.api.event.cause.DeletionCause;
+import net.luckperms.api.event.extension.ExtensionLoadEvent;
 import net.luckperms.api.event.group.GroupCacheLoadEvent;
 import net.luckperms.api.event.group.GroupCreateEvent;
 import net.luckperms.api.event.group.GroupDataRecalculateEvent;
@@ -82,6 +83,7 @@ import net.luckperms.api.event.user.UserFirstLoginEvent;
 import net.luckperms.api.event.user.UserLoadEvent;
 import net.luckperms.api.event.user.track.UserDemoteEvent;
 import net.luckperms.api.event.user.track.UserPromoteEvent;
+import net.luckperms.api.extension.Extension;
 import net.luckperms.api.model.DataType;
 import net.luckperms.api.model.PlayerSaveResult;
 import net.luckperms.api.node.Node;
@@ -133,6 +135,10 @@ public final class EventFactory {
         return (T) GeneratedEventSpec.lookup(eventClass).newInstance(this.eventBus.getApiProvider(), params);
     }
 
+    public void handleExtensionLoad(Extension extension) {
+        post(ExtensionLoadEvent.class, () -> generate(ExtensionLoadEvent.class, extension));
+    }
+
     public void handleGroupCacheLoad(Group group, GroupCachedDataManager data) {
         post(GroupCacheLoadEvent.class, () -> generate(GroupCacheLoadEvent.class, group.getApiDelegate(), data));
     }

common/src/main/java/me/lucko/luckperms/common/extension/SimpleExtensionManager.java

@@ -0,0 +1,183 @@
+/*
+ * This file is part of LuckPerms, licensed under the MIT License.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+package me.lucko.luckperms.common.extension;
+
+import com.google.gson.JsonElement;
+
+import me.lucko.luckperms.common.plugin.LuckPermsPlugin;
+import me.lucko.luckperms.common.util.gson.GsonProvider;
+
+import net.luckperms.api.LuckPerms;
+import net.luckperms.api.extension.Extension;
+import net.luckperms.api.extension.ExtensionManager;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.Path;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class SimpleExtensionManager implements ExtensionManager, AutoCloseable {
+    private final LuckPermsPlugin plugin;
+    private final Set<LoadedExtension> extensions = new HashSet<>();
+
+    public SimpleExtensionManager(LuckPermsPlugin plugin) {
+        this.plugin = plugin;
+    }
+
+    @Override
+    public void close() {
+        for (LoadedExtension extension : this.extensions) {
+            try {
+                extension.instance.unload();
+                if (extension.classLoader != null) {
+                    extension.classLoader.close();
+                }
+            } catch (Exception e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    @Override
+    public void loadExtension(Extension extension) {
+        if (this.extensions.stream().anyMatch(e -> e.instance.equals(extension))) {
+            return;
+        }
+        this.extensions.add(new LoadedExtension(extension, null, null));
+        extension.load();
+        this.plugin.getEventFactory().handleExtensionLoad(extension);
+    }
+
+    public void loadExtensions(Path directory) {
+        if (!Files.exists(directory) || !Files.isDirectory(directory)) {
+            return;
+        }
+
+        try (Stream<Path> stream = Files.list(directory)) {
+            stream.forEach(path -> {
+                try {
+                    loadExtension(path);
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            });
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @Override
+    public @NonNull Extension loadExtension(Path path) throws IOException {
+        if (this.extensions.stream().anyMatch(e -> path.equals(e.path))) {
+            throw new IllegalStateException("Extension at path " + path.toString() + " already loaded.");
+        }
+
+        if (!Files.exists(path)) {
+            throw new NoSuchFileException("No file at " + path);
+        }
+
+        URLClassLoader classLoader = new URLClassLoader(new URL[]{path.toUri().toURL()}, getClass().getClassLoader());
+        String className;
+
+        try (InputStream in = classLoader.getResourceAsStream("extension.json")) {
+            if (in == null) {
+                throw new RuntimeException("extension.json not present in " + path.toString());
+            }
+            try (BufferedReader reader = new BufferedReader(new InputStreamReader(in, StandardCharsets.UTF_8))) {
+                JsonElement parsed = GsonProvider.parser().parse(reader);
+                className = parsed.getAsJsonObject().get("class").getAsString();
+            }
+        }
+
+        if (className == null) {
+            throw new IllegalArgumentException("class is null");
+        }
+
+        Class<? extends Extension> extensionClass;
+        try {
+            extensionClass = classLoader.loadClass(className).asSubclass(Extension.class);
+        } catch (ClassNotFoundException e) {
+            throw new RuntimeException(e);
+        }
+
+        Extension extension = null;
+
+        try {
+            Constructor<? extends Extension> constructor = extensionClass.getConstructor(LuckPerms.class);
+            extension = constructor.newInstance(this.plugin.getApiProvider());
+        } catch (NoSuchMethodException e) {
+            // ignore
+        } catch (IllegalAccessException | InstantiationException | InvocationTargetException e) {
+            throw new RuntimeException(e);
+        }
+
+        if (extension == null) {
+            try {
+                Constructor<? extends Extension> constructor = extensionClass.getConstructor();
+                extension = constructor.newInstance();
+            } catch (NoSuchMethodException | IllegalAccessException | InstantiationException | InvocationTargetException e) {
+                throw new RuntimeException(e);
+            }
+        }
+
+        this.extensions.add(new LoadedExtension(extension, classLoader, path));
+        extension.load();
+        this.plugin.getEventFactory().handleExtensionLoad(extension);
+        return extension;
+    }
+
+    @Override
+    public @NonNull Collection<Extension> getLoadedExtensions() {
+        return this.extensions.stream().map(e -> e.instance).collect(Collectors.toSet());
+    }
+
+    private static final class LoadedExtension {
+        private final Extension instance;
+        private final URLClassLoader classLoader;
+        private final Path path;
+
+        private LoadedExtension(Extension instance, URLClassLoader classLoader, Path path) {
+            this.instance = instance;
+            this.classLoader = classLoader;
+            this.path = path;
+        }
+    }
+}

common/src/main/java/me/lucko/luckperms/common/plugin/AbstractLuckPermsPlugin.java

@@ -38,6 +38,7 @@ import me.lucko.luckperms.common.dependencies.Dependency;
 import me.lucko.luckperms.common.dependencies.DependencyManager;
 import me.lucko.luckperms.common.event.AbstractEventBus;
 import me.lucko.luckperms.common.event.EventFactory;
+import me.lucko.luckperms.common.extension.SimpleExtensionManager;
 import me.lucko.luckperms.common.inheritance.InheritanceHandler;
 import me.lucko.luckperms.common.locale.LocaleManager;
 import me.lucko.luckperms.common.locale.message.Message;
@@ -82,6 +83,7 @@ public abstract class AbstractLuckPermsPlugin implements LuckPermsPlugin {
     private CalculatorFactory calculatorFactory;
     private LuckPermsApiProvider apiProvider;
     private EventFactory eventFactory;
+    private SimpleExtensionManager extensionManager;
 
     /**
      * Performs the initial actions to load the plugin
@@ -166,6 +168,10 @@ public abstract class AbstractLuckPermsPlugin implements LuckPermsPlugin {
         ApiRegistrationUtil.registerProvider(this.apiProvider);
         registerApiOnPlatform(this.apiProvider);
 
+        // setup extension manager
+        this.extensionManager = new SimpleExtensionManager(this);
+        this.extensionManager.loadExtensions(getBootstrap().getConfigDirectory().resolve("extensions"));
+
         // schedule update tasks
         int mins = getConfiguration().get(ConfigKeys.SYNC_TIME);
         if (mins > 0) {
@@ -194,6 +200,9 @@ public abstract class AbstractLuckPermsPlugin implements LuckPermsPlugin {
         this.permissionRegistry.stop();
         this.verboseHandler.stop();
 
+        // unload extensions
+        this.extensionManager.close();
+
         // remove any hooks into the platform
         removePlatformHooks();
 
@@ -332,6 +341,11 @@ public abstract class AbstractLuckPermsPlugin implements LuckPermsPlugin {
         return this.apiProvider;
     }
 
+    @Override
+    public SimpleExtensionManager getExtensionManager() {
+        return this.extensionManager;
+    }
+
     @Override
     public EventFactory getEventFactory() {
         return this.eventFactory;

common/src/main/java/me/lucko/luckperms/common/plugin/LuckPermsPlugin.java

@@ -34,6 +34,7 @@ import me.lucko.luckperms.common.config.LuckPermsConfiguration;
 import me.lucko.luckperms.common.context.ContextManager;
 import me.lucko.luckperms.common.dependencies.DependencyManager;
 import me.lucko.luckperms.common.event.EventFactory;
+import me.lucko.luckperms.common.extension.SimpleExtensionManager;
 import me.lucko.luckperms.common.inheritance.InheritanceHandler;
 import me.lucko.luckperms.common.locale.LocaleManager;
 import me.lucko.luckperms.common.messaging.InternalMessagingService;
@@ -146,6 +147,13 @@ public interface LuckPermsPlugin {
      */
     LuckPermsApiProvider getApiProvider();
 
+    /**
+     * Gets the extension manager.
+     *
+     * @return the extension manager
+     */
+    SimpleExtensionManager getExtensionManager();
+
     /**
      * Gets the command manager
      *