/*

  *   SONEWS News Server

  *   see AUTHORS for the list of contributors

  *

  *   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.sonews.daemon;

 import java.util.HashMap;

 import java.util.Map;

 import java.util.Set;

 import java.util.concurrent.ConcurrentHashMap;

 import org.sonews.daemon.command.Command;

 import org.sonews.daemon.command.UnsupportedCommand;

 import org.sonews.util.Log;

 import org.sonews.util.io.Resource;

 /**

  * Selects the correct command processing class.

  * @author Christian Lins

  * @since sonews/1.0

  */

 public class CommandSelector

 {

 	private static Map<Thread, CommandSelector> instances = new ConcurrentHashMap<Thread, CommandSelector>();

 	private static Map<String, Class<?>> commandClassesMapping = new ConcurrentHashMap<String, Class<?>>();

 	static {

 		String[] classes = Resource.getAsString("helpers/commands.list", true).split("\n");

 		for (String className : classes) {

 			if (className.charAt(0) == '#') {

 				// Skip comments

 				continue;

 			}

 			try {

 				addCommandHandler(className);

 			} catch (ClassNotFoundException ex) {

 				Log.get().warning("Could not load command class: " + ex);

 			} catch (InstantiationException ex) {

 				Log.get().severe("Could not instantiate command class: " + ex);

 			} catch (IllegalAccessException ex) {

 				Log.get().severe("Could not access command class: " + ex);

 			}

 		}

 	}

 	public static void addCommandHandler(String className)

 		throws ClassNotFoundException, InstantiationException,

 		IllegalAccessException

 	{

 		Class<?> clazz = Class.forName(className);

 		Command cmd = (Command) clazz.newInstance();

 		String[] cmdStrs = cmd.getSupportedCommandStrings();

 		for (String cmdStr : cmdStrs) {

 			commandClassesMapping.put(cmdStr, clazz);

 		}

 	}

 	public static Set<String> getCommandNames()

 	{

 		return commandClassesMapping.keySet();

 	}

 	public static CommandSelector getInstance()

 	{

 		CommandSelector csel = instances.get(Thread.currentThread());

 		if (csel == null) {

 			csel = new CommandSelector();

 			instances.put(Thread.currentThread(), csel);

 		}

 		return csel;

 	}

 	private Map<String, Command> commandMapping = new HashMap<String, Command>();

 	private Command unsupportedCmd = new UnsupportedCommand();

 	private CommandSelector()

 	{

 	}

 	public Command get(String commandName)

 	{

 		try {

 			commandName = commandName.toUpperCase();

 			Command cmd = this.commandMapping.get(commandName);

 			if (cmd == null) {

 				Class<?> clazz = commandClassesMapping.get(commandName);

 				if (clazz == null) {

 					cmd = this.unsupportedCmd;

 				} else {

 					cmd = (Command) clazz.newInstance();

 					this.commandMapping.put(commandName, cmd);

 				}

 			} else if (cmd.isStateful()) {

 				cmd = cmd.getClass().newInstance();

 			}

 			return cmd;

 		} catch (Exception ex) {

 			ex.printStackTrace();

 			return this.unsupportedCmd;

 		}

 	}

 }