/**
 * Code based on code from Computer Networking: A Top-Down Approach Featuring 
 * the Internet.  J.F Kurose and K.W. Ross. Extended to multi-threads
 *
 **/

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

class RequestServer extends Thread {

    Socket connSocket;

    public RequestServer( Socket connectionSocket ) {
	connSocket  = connectionSocket;
    }

    public void run () {
	
	try {
	    // read the request from client

	    BufferedReader inFromClient =
		new BufferedReader(new InputStreamReader(connSocket.getInputStream()));

	    String requestMessageLine;
	    requestMessageLine = inFromClient.readLine();
	
	    // process the request
	    StringTokenizer tokenizedLine =
		new StringTokenizer(requestMessageLine);
	
	    if (tokenizedLine.nextToken().equals("GET")) {
	    
		String fileName;
		// parse URL to retrieve file name
		fileName = tokenizedLine.nextToken();
	    
		if (fileName.startsWith("/") == true )
		    fileName  = fileName.substring(1);
	    
		File file = new File(fileName);
		int numOfBytes = (int) file.length();
		
		FileInputStream inFile  = new FileInputStream (fileName);
	    
		byte[] fileInBytes = new byte[numOfBytes];
		inFile.read(fileInBytes);

		// get output stream
		DataOutputStream outToClient =
		    new DataOutputStream(connSocket.getOutputStream());
	    
		// generate response header
		outToClient.writeBytes("HTTP/1.0 200 Document Follows\r\n");
	    
		if (fileName.endsWith(".jpg"))
		    outToClient.writeBytes("Content-Type: image/jpeg\r\n");
		if (fileName.endsWith(".gif"))
		    outToClient.writeBytes("Content-Type: image/gif\r\n");
	    
		outToClient.writeBytes("Content-Length: " + numOfBytes + "\r\n");
		outToClient.writeBytes("\r\n");
	    
		// send file content
		outToClient.write(fileInBytes, 0, numOfBytes);
	    
		// close connection
		connSocket.close();
	    } // end of if
	    else 
		System.out.println("Bad Request Message");
	} // end of try
	catch (Exception e) {
	    System.out.println("Error");
	} // end of catch
	    
    } // end of run()

} // end of RequestServer

class mtHTTPServer {
    
    public static void main(String args[]) throws Exception  {
	
	// see if we do not use default server port
	int serverPort = 6789;
	if (args.length >= 1)
	    serverPort = Integer.parseInt(args[0]);

	// create server socket
	ServerSocket listenSocket = new ServerSocket(serverPort);
	System.out.println("server listening at " + listenSocket);

	while (true) {

	    // take a ready connection from the accepted queue
	    Socket connectionSocket = listenSocket.accept();
	    System.out.println("receive request from " + connectionSocket);

	    // dispatch a request server
	    Thread t = new RequestServer( connectionSocket );
	    t.start();

	} // end of while (true)
	
    } // end of main

} // end of mtHTTPServer