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



public class Sender
{

    private static final int PORT_NUMBER = 42730;
        //dragon.cs.uni.edu = 134.161.241.111
    private File clientfile;
    private String targethost;
    private int windowsize;
    private int timeout;
    private int payload;

    public Sender(File 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;

            File file = new File("C:\\Program Files\\eclipse\\workspace\\Assignment\\test.txt");
            byte[] fileData = getBytesFromFile(); //convert file into bytes
            DatagramSocket sock = new DatagramSocket(PORT_NUMBER);
            //ByteArrayOutputStream byteArray = new ByteArrayOutputStream();
            //DataOutputStream dos = new DataOutputStream(byteArray);
            int seqnum = 0; //initialize sequence number
            //byte[] buffReceive = new byte[512];
            byte[] buffSend = new byte[512];


            //checksum payload
            //MessageDigest md = MessageDigest.getInstance("MD5");
            //md.update(fileData);
            //byte[] hash = md.digest();

            //make packet[seq#, length, data, checksum]
            //dos.writeInt(seqnum);
            //dos.writeInt(fileData.length);
            //dos.write(fileData);
            //dos.write(hash);
            //buffSend = byteArray.toByteArray();
            while (true)
            {
                //increment sequence number
                seqnum++;
                Packet newpack = new Packet(fileData, seqnum);

                buffSend = newpack.digest();

                // read min(segment size, remaining file size)
                DatagramPacket dp = new DatagramPacket(buffSend, buffSend.length, InetAddress.getByName("dragon.cs.uni.edu"), PORT_NUMBER);
                sock.send(dp);

                //checksum payload
                //md.update(fileData);
                //hash = md.digest();

                //make packet[seq#, length, data, checksum]
                //dos.writeInt(seqnum);
                //dos.writeInt(fileData.length);
                //dos.write(fileData);
                //dos.write(hash);
                //buffSend = byteArray.toByteArray();
                //buffSend = newpack.digest();
            }
        }
        catch(Exception e)
        {
            System.out.println("Unable to set up sender.");
            System.exit(0);
        }
    }

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

        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.getName());
        }

        stream.close();
        return bytes;
    }

    /**
    private void sendData(DatagramSocket sock, DatagramPacket packet)
    {
        InetAddress IPAddress = packet.getAddress();
        int port = packet.getPort();
        DatagramPacket sendPacket = new DatagramPacket ("Hello", 5, IPAddress, port);
        sock.send(sendPacket);
    }
    */
}