/* This is an example of a multithreaded server in Java.
It listens for connections on port 1357 (use telnet to make such connections
once you have the server running) and echos any information sent to it to
anyone else who's logged in at the time - a very simple talker application.

See also http://www.wellho.net/solutions/java-a-multithreaded-server-in-java.html
*/

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

public class Leanne implements Runnable {

// A simple talker - Sample written by Graham Ellis, July 2010 (update)
// No login needed. Connect on port 1357.
// commands:
// .q quit
// .w who

// Variables for each thread

Socket linkto; // the socket
PrintWriter out; // the output and input streams
BufferedReader in;
int id; // i.d. of the connection
String from_name; // name of host connecting

// Class Variables

static Vector connectiontable; // current connections
static int nextid = 1; // Increasing i.d.

/////////////////////////////// Main method ////////////////////////

public static void main(String [] args) {
// Parent thread - create a server socket and await a connection
ServerSocket ss = null;
Socket s = null;
connectiontable = new Vector();

try {
ss = new ServerSocket(1357);
while ((s=ss.accept())!= null) {

// Connection received - create a thread
Leanne now;
Thread current = new Thread(now = new Leanne(s));
current.setDaemon(true);
connectiontable.addElement(now); // Save talker into vector ..
current.start(); // start the user's thread
}
}
catch (Exception e) {
        System.out.println(e);
        }

// should add finally block to close down
}
///////////////// Constructor for a new thread //////////////////////

Leanne (Socket from) {
        id = nextid++;
        linkto = from;
        InetAddress source = linkto.getInetAddress();
        from_name = source.getHostName();
        try {
        out = new PrintWriter(new OutputStreamWriter
                        (linkto.getOutputStream()));
        in = new BufferedReader(new InputStreamReader
                        (linkto.getInputStream()));
        }
        catch (Exception e) {}
        }

public void run () {

        String line = " [User has just logged in] ";

        while (true) {
                boolean done=false;

                // read a line from the user

                if (line == null) {
                        try {
                                out.print(">: "); //prompt,flush,read
                                out.flush();
                                line = in.readLine();
                        } catch (Exception e) {
                                System.out.println(e);
                                done = true; // force exit if there's a problem
                        }
                }

                // Handle special cases - user input starts with "."
                // You get a NULL back if connection lost and we should
                // pick up that exception!

                try {
                        if (line.startsWith(".q")) done = true;
        } catch (Exception e) { // e.g. null
        done = true;
        line = "[exiting]";
        }

                if (line.startsWith(".w")) { // build up list of host names
                        int k;
                        StringBuffer fred = new StringBuffer("WHO HERE?\n");
                        for (k=0;k<connectiontable.size();k++) {
                                Leanne person = (Leanne)connectiontable.elementAt(k);
                                fred.append(person.from_name);
                                fred.append(" ");
                                }
                        line = fred.toString();
                        }

                // echo the line (with a header) to all users

                String outline = from_name+" "+id+": "+line;
                int k;
                for (k=0;k<connectiontable.size();k++) {
                        Leanne person = (Leanne)connectiontable.elementAt(k);
                        person.out.println(outline);
                        person.out.flush(); // Vital - ensure it is sent!
                        }

                // clear out the user if they're done

                if (done) {
                        connectiontable.removeElement(this);
                        try {
                                out.close(); // closes needed to terminate connection
                                in.close(); // otherwise user's window goes mute
                                linkto.close();
                        } catch (Exception e) {}
                                break;
                        }
                line = null;
                }
        }
}