/*
 * Copyright (c) 2010, Manuel Mausz. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - The names of the authors may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import java.util.HashMap;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

/*
 * CommandHandler
 * Allows you to register and invoke methods based on keywords/commands
 * Method registed with keyword "unknown" will be invoked if there's no
 * matching keyword
 *
 * @author Manuel Mausz (0728348)
 */
public class CommandHandler
{
  class Exception
    extends java.lang.RuntimeException
  {
    public Exception()
    {
      super();
    }

    public Exception(String message)
    {
      super(message);
    }
  }

  /*==========================================================================*/

  private HashMap<String, Object[]> commands;

  /*--------------------------------------------------------------------------*/

  public CommandHandler()
  {
    commands = new HashMap<String, Object[]>();
  }

  /*--------------------------------------------------------------------------*/

  public void register(String cmd, Object obj, String method)
    throws NoSuchMethodException
  {
    Class[] params = { String.class, String[].class };
    Method meth = obj.getClass().getMethod(method, params);
    Object[] tmp = { obj, meth };
    commands.put(cmd, tmp);
  }

  /*--------------------------------------------------------------------------*/

  public void call(String cmd, String[] args)
    throws Exception
  {
    try
    {
      Object[] meth = commands.get(cmd);
      if (meth == null)
        meth = commands.get("unknown");
      if (meth == null)
      {
        unknown(cmd, args);
        return;
      }

      Object[] params = { cmd, args };
      ((Method) meth[1]).invoke(meth[0], (Object[]) params);
    }
    catch (IllegalAccessException e)
    {
      throw new Exception(e.getMessage());
    }
    catch (InvocationTargetException e)
    {
      throw new Exception(e.getCause().getMessage());
    }
    catch (IllegalArgumentException e)
    {
      throw new Exception(e.getMessage());
    }
  }

  /*--------------------------------------------------------------------------*/

  public void unknown(String cmd, String[] args)
  {
    System.out.println("Error: Unknown command: " + cmd);
    return;
  }
}