/***********************************************************************
 * Ce programme emet a destination du port argv[1] sur la machine
 * argv[0], argv[3] messages (datagramme UDP) constitues chacun
 * de argv[2] caracteres.
 * 
 * ex: java DgramSend linux03 2005 1000 10
 *
 * L'emission se fait par send sur un DatagramSocket dans le domaine
 * INET.
 ***********************************************************************/

package tftp;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.channels.FileChannel;



/*
 * $Id: TftpClientMain.java 29 2016-06-02 13:29:57Z conan $
 */
public class TftpClientMain {
	public static void main(String[] argv) {
		DatagramChannel sndChan;
		ByteBuffer dataBuf[];
		InetAddress destAddr;
		InetSocketAddress rcvAddress;
		long sent;
		if (argv.length != 3) {
			System.out.println("usage: java TftpClientMain <machine> <port> <file> ");
			return;
		}
		dataBuf = new ByteBuffer[2];
		// we will send 1k byte at a time
		dataBuf[1] = ByteBuffer.allocate(1024);

		// calculate size of the Bytebuffer to store the Header
		// header is composed of : one int to describe the number of bytes necessary for the name
		// the array of bytes, one long for the starting point and the size of the data (1024)
		byte [] s2b = argv[2].getBytes();
		int headerSize = s2b.length + Long.SIZE/Byte.SIZE + 2*Integer.SIZE/Byte.SIZE;
		dataBuf[0] = ByteBuffer.allocate(headerSize);


		try {
			FileInputStream fin = new FileInputStream(argv[2]);
			FileChannel fc = fin.getChannel();
//			long fileSize = fc.size();
			sndChan = DatagramChannel.open();
			// on recupere l'adresse IP de la machine cible
			destAddr = InetAddress.getByName(argv[0]);
			rcvAddress = new InetSocketAddress(destAddr,
					Integer.parseInt(argv[1]));
			sndChan.connect(rcvAddress);
			int count;
			long curpos = 0;
			do {
				dataBuf[0].clear();
				dataBuf[1].clear();
				count = fc.read(dataBuf[1]);
				dataBuf[0].putInt(s2b.length);
				dataBuf[0].put(s2b);
			//	dataBuf[0].putLong(fileSize);
				dataBuf[0].putLong(curpos);
				dataBuf[0].putInt(count);
				dataBuf[0].flip();
				dataBuf[1].flip();
				sent = sndChan.write(dataBuf);
				System.out.println("Sending a datagram of size " + sent);
				curpos += count;
			} while (count == 1024);

		} catch(FileNotFoundException fnf){
			fnf.printStackTrace();
			return;
		}
		catch (SocketException se) {
			se.printStackTrace();
			return;
		} catch (UnknownHostException ue) {
			ue.printStackTrace();
			return;
		} catch (IOException ie) {
			ie.printStackTrace();
			return;
		}
	}
}