/*
 * Copyright (c) 2006-2017 DMDirc Developers
 *
 * 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 com.dmdirc.plugins;

import com.dmdirc.events.PluginRefreshEvent;
import com.dmdirc.events.eventbus.EventBus;
import com.dmdirc.interfaces.config.IdentityController;
import com.dmdirc.updater.components.PluginComponent;
import com.dmdirc.updater.manager.UpdateManager;

import com.google.common.collect.Sets;

import java.io.File;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import dagger.ObjectGraph;

import static com.dmdirc.util.LogUtils.USER_ERROR;

/**
 * Searches for and manages plugins and services.
 */
public class PluginManager {

    private static final Logger LOG = LoggerFactory.getLogger(PluginManager.class);

    /** List of known plugins' file names to their corresponding {@link PluginInfo} objects. */
    private final Map<String, PluginInfo> knownPlugins = new HashMap<>();
    /** Set of known plugins' metadata. */
    private final Set<PluginMetaData> plugins = new HashSet<>();
    /** File handler to use for disk-based functions. */
    private final PluginFileHandler fileHandler;
    /** Directory where plugins are stored. */
    private final String directory;
    /** The identity controller to use to find configuration options. */
    private final IdentityController identityController;
    /** The update manager to inform about plugins. */
    private final UpdateManager updateManager;
    /** Global ClassLoader used by plugins from this manager. */
    private final GlobalClassLoader globalClassLoader;
    /** The graph to pass to plugins for DI purposes. */
    private final ObjectGraph objectGraph;
    /** Event bus to pass to plugin info for plugin loaded events. */
    private final EventBus eventBus;
    /** The service manager to use. */
    private final ServiceManager serviceManager;

    /**
     * Creates a new instance of PluginManager.
     *
     * @param eventBus            The event bus to subscribe to events on
     * @param identityController  The identity controller to use for configuration options.
     * @param updateManager       The update manager to inform about plugins.
     * @param objectGraph         The graph to pass to plugins for DI purposes.
     * @param directory           The directory to load plugins from.
     */
    public PluginManager(
            final EventBus eventBus,
            final ServiceManager serviceManager,
            final IdentityController identityController,
            final UpdateManager updateManager,
            final ObjectGraph objectGraph,
            final PluginFileHandler fileHandler,
            final String directory) {
        this.identityController = identityController;
        this.serviceManager = serviceManager;
        this.updateManager = updateManager;
        this.fileHandler = fileHandler;
        this.directory = directory;
        this.globalClassLoader = new GlobalClassLoader(this);
        this.objectGraph = objectGraph;
        this.eventBus = eventBus;
    }

    /**
     * Get the global class loader in use for this plugin manager.
     *
     * @return Global Class Loader
     */
    public GlobalClassLoader getGlobalClassLoader() {
        return globalClassLoader;
    }

    /**
     * Autoloads plugins.
     */
    public void doAutoLoad() {
        for (String plugin : identityController.getGlobalConfiguration().getOptionList("plugins",
                "autoload")) {
            plugin = plugin.trim();
            if (!plugin.isEmpty() && plugin.charAt(0) != '#' && getPluginInfo(plugin) != null) {
                getPluginInfo(plugin).loadPlugin();
            }
        }
    }

    /**
     * Tests and adds the specified plugin to the known plugins list. Plugins will only be added if:
     * <ul><li>The file exists,<li>No other plugin with the same name is known,<li>All requirements
     * are met for the plugin,
     * <li>The plugin has a valid config file that can be read</ul>.
     *
     * @param filename Filename of Plugin jar
     *
     * @return True if the plugin is in the known plugins list (either before this invocation or as
     *         a result of it), false if it was not added for one of the reasons outlined above.
     */
    public boolean addPlugin(final String filename) {
        if (knownPlugins.containsKey(filename.toLowerCase())) {
            return true;
        }

        if (!new File(directory, filename).exists()) {
            LOG.warn(USER_ERROR, "Error loading plugin {}: File does not exist", filename);
            return false;
        }

        try {
            final PluginMetaData metadata = new PluginMetaData(this,
                    Paths.get(directory, filename));
            metadata.load();
            final PluginInfo pluginInfo = new PluginInfo(this, serviceManager, metadata,
                    eventBus, identityController, objectGraph);
            final PluginInfo existing = getPluginInfoByName(metadata.getName());
            if (existing != null) {
                LOG.warn(USER_ERROR, "Duplicate plugin detected, ignoring. ({} is the same as {})",
                        filename, existing.getFilename());
                return false;
            }

            if (metadata.getUpdaterId() > 0 && metadata.getVersion().isValid()
                    || identityController.getGlobalConfiguration()
                    .hasOptionInt("plugin-addonid", metadata.getName())) {
                updateManager.addComponent(new PluginComponent(
                        identityController.getGlobalConfiguration(), pluginInfo));
            }

            knownPlugins.put(filename.toLowerCase(), pluginInfo);

            eventBus.publishAsync(new PluginRefreshEvent());
            return true;
        } catch (PluginException e) {
            LOG.warn(USER_ERROR, "Error loading plugin {}: {}", filename, e.getMessage(), e);
        }

        return false;
    }

    /**
     * Remove a plugin.
     *
     * @param filename Filename of Plugin jar
     *
     * @return True if removed.
     */
    public boolean delPlugin(final String filename) {
        if (!knownPlugins.containsKey(filename.toLowerCase())) {
            return false;
        }

        final PluginInfo pluginInfo = getPluginInfo(filename);
        final boolean wasLoaded = pluginInfo.isLoaded();

        if (wasLoaded && !pluginInfo.isUnloadable()) {
            return false;
        }

        pluginInfo.unloadPlugin();

        knownPlugins.remove(filename.toLowerCase());

        return true;
    }

    /**
     * Reload a plugin.
     *
     * @param filename Filename of Plugin jar
     *
     * @return True if reloaded.
     */
    public boolean reloadPlugin(final String filename) {
        if (!knownPlugins.containsKey(filename.toLowerCase())) {
            return false;
        }

        final PluginInfo pluginInfo = getPluginInfo(filename);
        final boolean wasLoaded = pluginInfo.isLoaded();

        if (wasLoaded && !pluginInfo.isUnloadable()) {
            return false;
        }

        delPlugin(filename);
        boolean result = addPlugin(filename);

        if (wasLoaded && result) {
            getPluginInfo(filename).loadPlugin();
            result = getPluginInfo(filename).isLoaded();
        }

        return result;
    }

    /**
     * Get a plugin instance.
     *
     * @param filename File name of plugin jar
     *
     * @return PluginInfo instance, or null
     */
    public PluginInfo getPluginInfo(final String filename) {
        return knownPlugins.get(filename.toLowerCase());
    }

    /**
     * Get a plugin instance by plugin name.
     *
     * @param name Name of plugin to find.
     *
     * @return PluginInfo instance, or null
     */
    public PluginInfo getPluginInfoByName(final String name) {
        for (PluginInfo pluginInfo : getPluginInfos()) {
            if (pluginInfo.getMetaData().getName().equalsIgnoreCase(name)) {
                return pluginInfo;
            }
        }

        return null;
    }

    /**
     * Get directory where plugins are stored.
     *
     * @return Directory where plugins are stored.
     *
     * @deprecated Should be injected.
     */
    @Deprecated
    public String getDirectory() {
        return directory;
    }

    /**
     * Get directory where plugin files are stored.
     *
     * @return Directory where plugin files are stored.
     */
    public String getFilesDirectory() {
        final String fs = System.getProperty("file.separator");
        String filesDir = directory + "files" + fs;
        if (identityController.getGlobalConfiguration().hasOptionString("plugins", "filesdir")) {
            final String fdopt = identityController.getGlobalConfiguration()
                    .getOptionString("plugins", "filesdir");

            if (fdopt != null && !fdopt.isEmpty() && new File(fdopt).exists()) {
                filesDir = fdopt;
            }
        }

        return filesDir;
    }

    /**
     * Refreshes the list of known plugins.
     */
    public void refreshPlugins() {
        final Set<PluginMetaData> newPlugins = fileHandler.refresh(this);

        Sets.difference(plugins, newPlugins).forEach(this::handlePluginDeleted);
        Sets.difference(newPlugins, plugins).forEach(this::handleNewPluginFound);

        eventBus.publishAsync(new PluginRefreshEvent());
    }

    /**
     * Called when a new plugin has been located on disk.
     *
     * @param metaData The metadata of the new plugin.
     */
    private void handleNewPluginFound(final PluginMetaData metaData) {
        plugins.add(metaData);
        addPlugin(metaData.getRelativeFilename());
    }

    /**
     * Called when an existing plugin has gone missing from disk.
     *
     * @param metaData The metadata of the deleted plugin.
     */
    private void handlePluginDeleted(final PluginMetaData metaData) {
        plugins.remove(metaData);
        delPlugin(metaData.getRelativeFilename());
    }

    /**
     * Retrieves a list of all installed plugins. Any file under the main plugin directory
     * (~/.DMDirc/plugins or similar) that matches *.jar is deemed to be a valid plugin.
     *
     * @return A list of all installed or known plugins
     */
    public Collection<PluginMetaData> getAllPlugins() {
        return fileHandler.getKnownPlugins();
    }

    /**
     * Update the autoLoadList
     *
     * @param plugin to add/remove (Decided automatically based on isLoaded())
     */
    public void updateAutoLoad(final PluginInfo plugin) {
        final List<String> list = identityController.getGlobalConfiguration()
                .getOptionList("plugins", "autoload");
        final String path = plugin.getMetaData().getRelativeFilename();

        if (plugin.isLoaded() && !list.contains(path)) {
            list.add(path);
        } else if (!plugin.isLoaded() && list.contains(path)) {
            list.remove(path);
        }

        identityController.getUserSettings().setOption("plugins", "autoload", list);
    }

    /**
     * Get Collection&lt;PluginInf&gt; of known plugins.
     *
     * @return Collection&lt;PluginInfo&gt; of known plugins.
     */
    public Collection<PluginInfo> getPluginInfos() {
        return new ArrayList<>(knownPlugins.values());
    }

}