import java.io.*;
import java.net.*;


public class Sender extends Thread
{

    private static final int PORT_NUMBER = 42730;
    private DatagramSocket sock;
    private String clientfile;
    private String targethost;
    private int windowsize;
    private int timeout;
    private int payload;

    public Sender(String clientfile, String targethost, int windowsize, int timeout, int payload)
    {
        try
        {
            this.clientfile = clientfile;
            this.targethost = targethost;
            this.windowsize = windowsize;
            this.timeout = timeout;
            this.payload = payload;
        }
        catch(Exception e)
        {
            System.out.println("Unable to set up sender.");
        }
    }


    public void run()
    {
        try
        {
            sock = new DatagramSocket(PORT_NUMBER);
            String file = new String("F:\\eclipse\\workspace\\Assignment\\test.txt");

            byte[] data = getBytesFromFile(file); //convert file into bytes
            ByteArrayOutputStream byteArray = new ByteArrayOutputStream();
            DataOutputStream dos = new DataOutputStream(byteArray);

            int seqnum = 0; //initialize sequence number

            byte[] buffSend = new byte[payload];    //data to send
            byte[] buffReceive = new byte[4];       //ACK

            System.out.println("Sending to " + targethost);
            while (true)
            {
                //yield thread here until there is data to send


                //increment sequence number
                seqnum++;

                //create packet
                Packet packet = new Packet(data, seqnum, payload);

                dos.write(packet.getBytes());
                buffSend = packet.getBytes();

                //construct packet and send
                DatagramPacket dp = new DatagramPacket(buffSend, buffSend.length, InetAddress.getByName(targethost), PORT_NUMBER);
                sock.send(dp);

                //set packet timeout
                //sock.setSoTimeout( timeout );

                //construct ACK
                //DatagramPacket rp = new DatagramPacket(buffReceive, buffReceive.length);
                //sock.receive(rp);

                //receive ACK;

                System.out.println("Sender sent packet #" + seqnum);
            }
        }
        catch(Exception e)
        {
            System.out.println("Sender send packet failed: " + e.toString());
        }
    }

    private byte[] getBytesFromFile(String file) throws IOException
    {
        InputStream stream = new FileInputStream(file);

        long length = clientfile.length();

        byte[] bytes = new byte[(int)length];

        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length && (numRead=stream.read(bytes, offset, bytes.length-offset)) >= 0)
        {
            offset += numRead;
        }

        if (offset < bytes.length) {
            throw new IOException("Could not completely read file "+clientfile);
        }

        stream.close();
        return bytes;
    }
}