/*
 *   Author:       David Loudon (Converted from Sun microsystems JavaTanks Demonstration)
 *   Description:  Handles low level sending and receiving of messages via the infrared tower.    
 *			 Makes use of the Java communications API to control the serial port.
 */

import java.io.*;
import java.util.*;
import javax.comm.*;

public class IRProtocol implements SerialPortEventListener
{

  private SerialPort port;
  private OutputStream out;
  private InputStream in;
  private MessageBuffer mbuf;

  public IRProtocol()
  {
  //initialises serial port with correct parameters for communication with RCX  
    CommPortIdentifier portID= null;
    try {
      portID= CommPortIdentifier.getPortIdentifier("COM1");
      System.out.println("COM ID: "+ portID);

      port= (SerialPort) portID.open("IRProtocol", 1000);
      out= port.getOutputStream();
      in= port.getInputStream();
      port.setSerialPortParams( 2400,
                                SerialPort.DATABITS_8,
                                SerialPort.STOPBITS_1,
                                SerialPort.PARITY_ODD );
      port.addEventListener(this);
      port.notifyOnDataAvailable(true);
    }
    catch (Exception e) {
      e.printStackTrace();
    }

    mbuf= new MessageBuffer();

    System.out.println("\nUsing port: " + portID.getName());
    System.out.println("Parity is set to: " + (port.getParity() == SerialPort.PARITY_ODD ? "ODD" : "NONE"));
    System.out.println("Receive buffer size is: " + port.getInputBufferSize());

  }//IRProtocol constructor


  private String toHex(byte x) {
    return ((x & 0xff) < 16 ? "0" : "") + Integer.toHexString(x & 0xff).toUpperCase();
  }//toHex


 /*
  * SerialPortEventListener method. Only responds to data being
  * available on the input buffer.
  */
  public void serialEvent(SerialPortEvent e)
  {
    int type= e.getEventType();

    if(type == SerialPortEvent.DATA_AVAILABLE){
      int available= 0;
      try{

      //Read in all data on the input buffer
        available= in.available();
        byte[] chunk= new byte[available];
        in.read(chunk);

      //Send data to the message buffer
        mbuf.append(chunk);

/*
        for(int i=0;i<chunk.length;i++){
          System.out.print(toHex(chunk[i]) + " ");
        }
        System.out.println();
*/
      }
      catch(Exception x){
      	x.printStackTrace();
      }
    }
  }//serialEvent


 /*
  * Provides layer above with the capability of receiving messages from the message buffer.
  */
  public void addMessageListener(MessageListener l) {
    mbuf.addMessageListener(l);
  }//addMessageListener


 /*
  * Send a message using the Lego IR protocol. All messages are
  * prefaced with a three byte header (0x55, 0xff, 0x00). Each
  * data byte is followed by its two's complement. The message
  * is followed by a simple checksum, and the two's complement
  * of that checksum. The checksum is computed by doing an 8-bit
  * accumulation of all the data bytes. Messages look like this:
  *
  * 0x55 0xff 0x00 D1 ~D1 D2 ~D2 ... Dn ~Dn CS ~CS
  */
  public void send(byte[] data) throws IOException
  {
    byte[] buf = new byte[2 * data.length + 5];
    byte sum = 0;
    int i;

  //Add header information
    buf[0] = (byte)0x55;
    buf[1] = (byte)0xff;
    buf[2] = (byte)0x00;

  //Insert the data and two's complement of the data in to the buffer
    for (i = 0; i < data.length; i++) {
      buf[2 * i + 3] = data[i];
      buf[2 * i + 4] = (byte)~data[i];
      sum += data[i];  //Keep the sum of all data for use in checksum.
    }

    buf[buf.length - 2] = sum;
    buf[buf.length - 1] = (byte)~sum;

    out.write(buf);
    out.flush();
  }//send

  public void close()
  {
    port.close();
  }//close


  public static void main(String args[])
  {
    byte b[]={(byte)0xf7, (byte)0x01};

    IRProtocol ir= new IRProtocol();

    try{
      char ch=(char)System.in.read();
      while(ch!='q'){
        ir.send(b);
        ch=(char)System.in.read();
      }
    }
    catch(IOException ex){
      System.out.println("Couldn't send");
    }

    ir.close();
  }

}