package edu.vt.marian.uip;

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

import edu.vt.marian.common.*;



//--------------------------------------------------------------------------------------------------------
//  Class name: packet_input_stream
//  Class description: kind of wrapper of DatagramPacket and the DatagramSocket, used
//			for udp communication
//  Author: Jianxin Zhao
//  Finished time: June 2, 1998
//  Known bugs: none
//  Platform: jdk1.1.5 under UNIX
//--------------------------------------------------------------------------------------------------------
public class packet_input_stream
{
	// used for debugging
	private Debug debug = null;

	// this is the sender's address
	private InetAddress address = null;
	private int port = -1;

	// this is used to read data
	private String data = null;
	private int start_index = 0;


	// this constructor will create a packet_input_stream object
	public packet_input_stream(DatagramSocket socket, Debug debug)
	{
		this.debug = debug;

		try
		{
			// first receive a packet from the sender
			byte[] buffer = new byte[9000];
			DatagramPacket dp = new DatagramPacket(buffer, 9000);
			socket.receive(dp);

			// get the data from the packet
			data = new String(dp.getData(), 0, dp.getLength());

			// get number of packets
			start_index = data.indexOf('\n');
			if (start_index == -1)
			{
				debug.dumpTrace("class packet_input_stream, constructor, no number of packets");
				return;
			}

			int number_of_packets = 0;
			try
			{
				number_of_packets = Integer.parseInt(data.substring(0, start_index));
			}
			catch (Exception e)
			{
				debug.dumpTrace("class packet_input_stream, constructor, number_of_packets not integer");
				return;
			}

			if (number_of_packets < 1)
			{
				debug.dumpTrace("class packet_input_stream, constructor, number_of_packets not valid");
				return;
			}


			// read out all the remaining packets if possible
			for (int i = 1; i < number_of_packets; i++)
			{
				buffer = new byte[9000];
				dp = new DatagramPacket(buffer, 9000);
				socket.receive(dp);
				data += new String(dp.getData(), 0, dp.getLength());
			}

			socket.close();

			// jump over the '\n'
			start_index++;

			// get the address of the sender
			address = dp.getAddress();
			port = dp.getPort();
//debug.dumpTrace("class packet input stream, constructor, data is ");
//debug.dumpTrace(data);
		
		}
		catch (Exception e)
		{
			debug.dumpTrace("class packet_input_stream, constructor, error create socket or read from it");
		}
	}


	// this constructor will create a packet_input_stream object 
	public packet_input_stream(DatagramPacket dp, Debug debug)
	{
		this.debug = debug;

		if (dp == null)
		{
			debug.dumpTrace("class packet_input_stream, constructor, null parameter identified");
			return;
		}

		// first get the data from the packet
		data = new String(dp.getData(), 0, dp.getLength());

		// set the start index to jump over the first line
		start_index = data.indexOf('\n');
		start_index++;

		// get the address of the sender
		address = dp.getAddress();
		port = dp.getPort();
	}


	// this method will read a line from the data of this stream
	public String readLine()
	{
		if (start_index == data.length())
		{
			// we reached the end of the data
			return null;
		}

		int end_index = data.indexOf('\n', start_index);
		if (end_index == -1)
		{
			// we just reached the end of the data after this read
			String return_string = data.substring(start_index);
			start_index = data.length();
			return return_string;
		}

		String return_string = data.substring(start_index, end_index);
		start_index = end_index + 1;
		return return_string;
	}


	// the method will return the address of the sender
	public InetAddress get_ip_address()
	{
		return address;
	}

	
	// the method will return the address of the sender
	public int get_port()
	{
		return port;
	}
}