/*************************************************************************/
/*  GodotPluginRegistry.java                                             */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
/*************************************************************************/
/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
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/* 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.       */
/*                                                                       */
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package org.godotengine.godot.plugin;

import org.godotengine.godot.Godot;

import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;

import androidx.annotation.Nullable;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Registry used to load and access the registered Godot Android plugins.
 */
public final class GodotPluginRegistry {

	private static final String TAG = GodotPluginRegistry.class.getSimpleName();

	private static final String GODOT_PLUGIN_V1_NAME_PREFIX = "org.godotengine.plugin.v1.";

	/**
	 * Name for the metadata containing the list of Godot plugins to enable.
	 */
	private static final String GODOT_ENABLED_PLUGINS_LABEL = "plugins";

	private static final String PLUGIN_VALUE_SEPARATOR_REGEX = "\\|";

	private static GodotPluginRegistry instance;
	private final ConcurrentHashMap<String, GodotPlugin> registry;

	private GodotPluginRegistry(Godot godot) {
		registry = new ConcurrentHashMap<>();
		loadPlugins(godot);
	}

	/**
	 * Retrieve the plugin tied to the given plugin name.
	 * @param pluginName Name of the plugin
	 * @return {@link GodotPlugin} handle if it exists, null otherwise.
	 */
	@Nullable
	public GodotPlugin getPlugin(String pluginName) {
		return registry.get(pluginName);
	}

	/**
	 * Retrieve the full set of loaded plugins.
	 */
	public Collection<GodotPlugin> getAllPlugins() {
		return registry.values();
	}

	/**
	 * Parse the manifest file and load all included Godot Android plugins.
	 * <p>
	 * A plugin manifest entry is a '<meta-data>' tag setup as described in the {@link GodotPlugin}
	 * documentation.
	 *
	 * @param godot Godot instance
	 * @return A singleton instance of {@link GodotPluginRegistry}. This ensures that only one instance
	 * of each Godot Android plugins is available at runtime.
	 */
	public static GodotPluginRegistry initializePluginRegistry(Godot godot) {
		if (instance == null) {
			instance = new GodotPluginRegistry(godot);
		}

		return instance;
	}

	/**
	 * Return the plugin registry if it's initialized.
	 * Throws a {@link IllegalStateException} exception if not.
	 *
	 * @throws IllegalStateException if {@link GodotPluginRegistry#initializePluginRegistry(Godot)} has not been called prior to calling this method.
	 */
	public static GodotPluginRegistry getPluginRegistry() throws IllegalStateException {
		if (instance == null) {
			throw new IllegalStateException("Plugin registry hasn't been initialized.");
		}

		return instance;
	}

	private void loadPlugins(Godot godot) {
		try {
			ApplicationInfo appInfo = godot
											  .getPackageManager()
											  .getApplicationInfo(godot.getPackageName(), PackageManager.GET_META_DATA);
			Bundle metaData = appInfo.metaData;
			if (metaData == null || metaData.isEmpty()) {
				return;
			}

			// When using the Godot editor for building and exporting the apk, this is used to check
			// which plugins to enable.
			// When using a custom process to generate the apk, the metadata is not needed since
			// it's assumed that the developer is aware of the dependencies included in the apk.
			final Set<String> enabledPluginsSet;
			if (metaData.containsKey(GODOT_ENABLED_PLUGINS_LABEL)) {
				String enabledPlugins = metaData.getString(GODOT_ENABLED_PLUGINS_LABEL, "");
				String[] enabledPluginsList = enabledPlugins.split(PLUGIN_VALUE_SEPARATOR_REGEX);
				if (enabledPluginsList.length == 0) {
					// No plugins to enable. Aborting early.
					return;
				}

				enabledPluginsSet = new HashSet<>();
				for (String enabledPlugin : enabledPluginsList) {
					enabledPluginsSet.add(enabledPlugin.trim());
				}
			} else {
				enabledPluginsSet = null;
			}

			int godotPluginV1NamePrefixLength = GODOT_PLUGIN_V1_NAME_PREFIX.length();
			for (String metaDataName : metaData.keySet()) {
				// Parse the meta-data looking for entry with the Godot plugin name prefix.
				if (metaDataName.startsWith(GODOT_PLUGIN_V1_NAME_PREFIX)) {
					String pluginName = metaDataName.substring(godotPluginV1NamePrefixLength).trim();
					if (enabledPluginsSet != null && !enabledPluginsSet.contains(pluginName)) {
						Log.w(TAG, "Plugin " + pluginName + " is listed in the dependencies but is not enabled.");
						continue;
					}

					Log.i(TAG, "Initializing Godot plugin " + pluginName);

					// Retrieve the plugin class full name.
					String pluginHandleClassFullName = metaData.getString(metaDataName);
					if (!TextUtils.isEmpty(pluginHandleClassFullName)) {
						try {
							// Attempt to create the plugin init class via reflection.
							@SuppressWarnings("unchecked")
							Class<GodotPlugin> pluginClass = (Class<GodotPlugin>)Class
																	 .forName(pluginHandleClassFullName);
							Constructor<GodotPlugin> pluginConstructor = pluginClass
																				 .getConstructor(Godot.class);
							GodotPlugin pluginHandle = pluginConstructor.newInstance(godot);

							// Load the plugin initializer into the registry using the plugin name
							// as key.
							if (!pluginName.equals(pluginHandle.getPluginName())) {
								Log.w(TAG,
										"Meta-data plugin name does not match the value returned by the plugin handle: " + pluginName + " =/= " + pluginHandle.getPluginName());
							}
							registry.put(pluginName, pluginHandle);
							Log.i(TAG, "Completed initialization for Godot plugin " + pluginHandle.getPluginName());
						} catch (ClassNotFoundException e) {
							Log.w(TAG, "Unable to load Godot plugin " + pluginName, e);
						} catch (IllegalAccessException e) {
							Log.w(TAG, "Unable to load Godot plugin " + pluginName, e);
						} catch (InstantiationException e) {
							Log.w(TAG, "Unable to load Godot plugin " + pluginName, e);
						} catch (NoSuchMethodException e) {
							Log.w(TAG, "Unable to load Godot plugin " + pluginName, e);
						} catch (InvocationTargetException e) {
							Log.w(TAG, "Unable to load Godot plugin " + pluginName, e);
						}
					} else {
						Log.w(TAG, "Invalid plugin loader class for " + pluginName);
					}
				}
			}
		} catch (PackageManager.NameNotFoundException e) {
			Log.e(TAG, "Unable load Godot Android plugins from the manifest file.", e);
		}
	}
}
