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

public class SlidingWindowReceiver {
    private static int BUFFERSIZE = 5;
    private static int PORT = 5555;

    public static void main(String[] args) throws Exception
    {
        // create serversocket to listen for incoming connections
        ServerSocket serverSocket = null;
        serverSocket = new ServerSocket(PORT);

        // connect to client
        Socket clientSocket = null;
        clientSocket = serverSocket.accept();

        PrintWriter out = new PrintWriter(clientSocket.getOutputStream(),
                                          true);

        BufferedReader in = new BufferedReader(
                                new InputStreamReader(
                                    clientSocket.getInputStream()));
        // create buffer
        RecvBuffer rbuf = new RecvBuffer(BUFFERSIZE);

        String inputLine;
        String outputLine;
        while ((inputLine = in.readLine()) != null) {
            // let our Packet object parse the inputLine into ID and DATA:
            Packet packet = new Packet (inputLine);
            int packet_id = packet.id();
            String data = packet.data();

            int ack = rbuf.storepacket(packet_id, data);

            if (ack>=0) {
                /* send ack back */
                out.println (Packet.formatACK(ack));
            } else {
                /* ignore packet */
            }

            // try to read next data packets
            while ((outputLine = (String)rbuf.getnextpacket()) != null) {
                System.out.print (outputLine);
            }
        }
        // when the client closed the connection, print all we got left
        while ((outputLine = (String)rbuf.getnextpacket()) != null) {
            System.out.print (outputLine);
        }

        System.err.print("Client closed connection!");

        // clean-up
        out.close();
        in.close();
        clientSocket.close();
        serverSocket.close();
    }
}