/*
 * Copyright (C) 2008  Manish Pandya, [manish at meetamanish dot com]
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * 
 */
package org.hooliguns.ninja.telnet;

/**
 * An abstract stub of command execution unit for mod specific implementation to
 * extend. It must know how to abort current execution (implement
 * {@link AbortExecutionListener}), must know how to parse mod specific
 * commands and must implement {@link Runnable} (i.e. allow run method executing
 * command queue.
 * 
 * @author Manish Pandya (July 1 2008)
 * 
 */
public abstract class CommandExecutionUnit implements AbortExecutionListener,
		CommandParser, Runnable, Statefull {

  protected static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
  
  /**
	 * The Queue holding commands
	 */
	protected CommandQueue commandQueue = null;

	/**
	 * place holder of desired azimuth
	 */
	protected int destinationX = Integer.MIN_VALUE;

	/**
	 * place holder of desired altitude
	 */
	protected int destinationY = Integer.MIN_VALUE;

	/**
	 * current velocity for azimuth
	 */
	protected int velocity = 0;

	/**
	 * current command that is being executed
	 */
	protected Command currentCommand = null;

	/**
	 * Creates a CommandExecutionUnit with supplied CommandQueue
	 * 
	 * @param commandQueue
	 *          the command queue for the execution unit
	 */
	public CommandExecutionUnit(CommandQueue commandQueue) {
		this.commandQueue = commandQueue;
	}

	/**
	 * A method to query the internal state of the execution unit
	 * 
	 * @return a comma seperated name=value formated name and value pairs of
	 *         internal state registers
	 */
	public String getState() {
		StringBuffer sb = new StringBuffer();

		if (this instanceof RealtimeStateReporter) {
			RealtimeStateReporter realTimeStateReporter =
					(RealtimeStateReporter) this;
			sb.append("inMotion=" + realTimeStateReporter.isInMotion() + ",");
			sb.append("currentX=" + realTimeStateReporter.getCurrentX() + ",");
			sb.append("currentY=" + realTimeStateReporter.getCurrentY() + ",");
		} else {
			sb.append("inMotion=?,");
			sb.append("currentX=?,");
			sb.append("currentY=?,");
		}

		sb.append("destinationX=" + destinationX + ",");
		sb.append("destinationY=" + destinationY + ",");
		sb.append("destVelocityX=" + velocity + ",");
		sb.append("currentCommand=" + currentCommand);
		sb.append("queue.size=" + commandQueue.size());
		return sb.toString();
	}

	/**
	 * A method to write bytes to real hardware.
	 * It takes care of exceptions, port simultions and other
	 * complexities.

	 * @param bytes bytes to be written to hardware port
	 * @return response bytes from hardware
	 */
	public abstract byte[] writeToHardware(byte[] bytes);

	/* (non-Javadoc)
	 * @see org.hooliguns.ninja.telnet.Statefull#getDestinationX()
	 */
	public int getDestinationX() {
		return destinationX;
	}

	/* (non-Javadoc)
	 * @see org.hooliguns.ninja.telnet.Statefull#setDestinationX(int)
	 */
	public void setDestinationX(int destinationX) {
		this.destinationX = destinationX;
	}

	/* (non-Javadoc)
	 * @see org.hooliguns.ninja.telnet.Statefull#getDestinationY()
	 */
	public int getDestinationY() {
		return destinationY;
	}

	/* (non-Javadoc)
	 * @see org.hooliguns.ninja.telnet.Statefull#setDestinationY(int)
	 */
	public void setDestinationY(int destinationY) {
		this.destinationY = destinationY;
	}

	/* (non-Javadoc)
	 * @see org.hooliguns.ninja.telnet.Statefull#getVelocity()
	 */
	public int getVelocity() {
		return velocity;
	}

  /* (non-Javadoc)
   * @see org.hooliguns.ninja.telnet.Statefull#setVelocity(int)
   */
  public void setVelocity(int velocity) {
    this.velocity = velocity;
  }

	/* (non-Javadoc)
	 * @see org.hooliguns.ninja.telnet.Statefull#getCurrentCommand()
	 */
	public Command getCurrentCommand() {
		return currentCommand;
	}

	/* (non-Javadoc)
	 * @see org.hooliguns.ninja.telnet.Statefull#setCurrentCommand(org.hooliguns.ninja.telnet.Command)
	 */
	public void setCurrentCommand(Command currentCommand) {
		this.currentCommand = currentCommand;
	}
}