/*
 * Syncany, www.syncany.org
 * Copyright (C) 2011-2016 Philipp C. Heckel <philipp.heckel@gmail.com> 
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.syncany.plugins;

import java.io.InputStream;
import java.util.Properties;

import org.syncany.plugins.transfer.TransferManager;
import org.syncany.plugins.transfer.TransferSettings;

/**
 * A plugin can be used to store Syncany's repository files on any remote location. 
 * Implementations of the <tt>Plugin</tt> class identify a storage/transfer plugin.
 * 
 * <p>Using the 'id' attribute, plugins can be loaded by the {@link Plugins} class. 
 * Once a plugin is loaded, a corresponding {@link TransferSettings} object must be created and 
 * initialized. From the connection object, a {@link TransferManager} can then be used to
 * upload/download files to the repository.
 * 
 * <p>Per <b>naming convention</b>, plugins must end by the name <b>Plugin</b> and extend this class. 
 * Furthermore, all plugin classes must reside in a package <b>org.syncany.plugins.<i>plugin-id</i></b>,
 * where <i>plugin-id</i> is the identifier specified by {@link #getId()}. 
 * 
 * @author Philipp C. Heckel <philipp.heckel@gmail.com>
 */
public abstract class Plugin {
	private static final String PLUGIN_PROPERTIES_NAME_KEY = "pluginName";
	private static final String PLUGIN_PROPERTIES_VERSION_KEY = "pluginVersion";
	private static final String PLUGIN_PROPERTIES_DATE_KEY = "pluginDate";

	private String pluginId;
	private Properties pluginProperties;

	public Plugin(String pluginId) {
		this.pluginId = pluginId;
		this.pluginProperties = loadPluginProperties(pluginId);
	}

	/**
	 * Returns a unique plugin identifier.
	 * 
	 * <p>This identifier must correspond to the to the fully qualified package name in
	 * which the plugin classes reside. all plugin classes must reside in a package 
	 * 'org.syncany.connection.plugins.<i>plugin-id</i>'. 
	 */
	public String getId() {
		return pluginId;
	}

	/**
	 * Returns a short name of the plugin
	 */
	public String getName() {
		return pluginProperties.getProperty(PLUGIN_PROPERTIES_NAME_KEY);
	}

	/**
	 * Returns the version of the plugin
	 */
	public String getVersion() {
		return pluginProperties.getProperty(PLUGIN_PROPERTIES_VERSION_KEY);
	}
	
	/**
	 * Returns the date the plugin was compiled
	 */
	public String getDateStr() {
		return pluginProperties.getProperty(PLUGIN_PROPERTIES_DATE_KEY);
	}

	/**
	 * Loads the plugin properties (ID, name, version)
	 * from the resource
	 */
	private Properties loadPluginProperties(String pluginId) {
		String pluginInfoResource = "/" + Plugin.class.getPackage().getName().replace('.', '/') + "/" + pluginId + "/plugin.properties";
		
		InputStream pluginPropertiesInputStream = Plugin.class.getResourceAsStream(pluginInfoResource);

		try {
			Properties pluginProperties = new Properties();
			pluginProperties.load(pluginPropertiesInputStream);

			return pluginProperties;
		}
		catch (Exception e) {
			throw new RuntimeException("Cannot load application properties.", e);
		}
	}	
}