package myChat;

/**
 *
 * @author Patrick Neubauer
 * @version 1.0 alpha
 * 
 * Course: Distributed Systems
 * Project P1: Internet Chat System
 * 
 * Team members:
 * Tenzin Dakpa, Patrick Neubauer
 * 
 */

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

public class TCPServer implements Runnable {
    
    // defining private properties
    private int clientCounter = 0;
    
    private ServerSocket server = null;
    
    private Thread thread = null;
    public boolean runThread= true;
    // clients[] is an array that saves all the clients connected to the server
    // clients are TCPServerThread's
    private TCPServerThread clients[] = new TCPServerThread[50];
    
    /* 
     constructor for the server setting up on starting it.
    */
    public TCPServer(int port) {
        try {
            System.out.println("Server: doing the set up ...");
            System.out.println("Server: setting port at " + port);
            server = new ServerSocket(port);
            System.out.println("Server: started server on " + server);
            start(); // create new thread for client
        } catch (IOException ioe) {
            System.out.println("Server: cannot start server at port " + port + ".\n Error: " + ioe.getMessage());
        }
    }
    
    /* creating a new thread and starting it
     */
    public void start() {
    	
        if (runThread) {
            thread = new Thread(this); 
            thread.start();
        }
   }
   
   /* stop a thread
    * 
    */
   public void stop() {
       if (runThread) {
           runThread=false;
       }
   }
 
   /* start waiting for clients, accepting and adding new threads
    */
   public void run() {
       while (runThread) {
           try {
               System.out.println("Server: waiting for clients ...\n");
               addThread(server.accept());
           } catch (IOException ioe) {
               System.out.println("Server:erroe in accepting client: " + ioe + "\n");
               stop();
               System.out.println("Server: stopped server.\n");
           }
       }
       System.out.println("Server Terminating.");
       System.exit(0);
       /*this is a good place to clean up after server.We get here if the boolean runThread becomes false.*/
   }
   
   /* findClient inside the client array
    */
   private int findClient(int ID) {
       for (int i=0; i<clientCounter; i++) {
           if (clients[i].getID() == ID)
               return i; // returns the position of the client with a certain ID
       }
       return -1; // if client ID not found
   }
   
   
   
   /* handle messages, broadcast it to all connected clients
    synchronized
    */
   public synchronized void handle(int ID, String input) {
       if (input.contains("/exit")) {
           // find the client ID in the array of TCPServerThread clients
           // and send him the leaving command
           clients[findClient(ID)].send("/exit");
           remove(ID); // finally remove the client out of the array
       } else {
           // send all the connected clients the input from the client,
           // broadcast messages to all connected clients ...
           for (int i=0; i<clientCounter; i++) {
               clients[i].send(input);
           }
       }
   }
   
   
   
   /* terminate client and remove it from server
    */
   public synchronized void remove(int ID) {
       int pos = findClient(ID); // get position
       if (pos >= 0) {
           // get the client out of the array that has to be terminated
           TCPServerThread toTerminate = clients[pos];
           System.out.println("Server: TERMINATING CLIENT thread with ID " + ID + " at position " + pos);
           if (pos < clientCounter-1) {
               for (int i=pos+1; i<clientCounter; i++) {
                   clients[i-1] = clients[i];
               }
               clientCounter--; // decrease clientCounter after removed client
           }
           try {
               toTerminate.close(); // closes socket and data streams
           } catch (IOException ioe){
               System.out.println("Server: error while closing thread: " + ioe);
           }
           toTerminate.stopClient(); // stop client thread
       }
   }
   
   
   /* add new tcp server threads to the client array on server 
    */
   private void addThread(Socket socket) {
       if (clientCounter < clients.length) {
           System.out.println("Server: new CLIENT ACCEPTED on " + socket);
           // add new client to TCPServerThread array of clients
           clients[clientCounter] = new TCPServerThread(this, socket);
           try {
               clients[clientCounter].open(); // open connection to client
               clients[clientCounter].start(); // starting connection to client
               clientCounter++;
           } catch (IOException ioe) {
               System.out.println("Server: error while opening thread: " + ioe);
           }
       } else {
           System.out.println("Server: client refused, because maximum length of " + clients.length + " reached.");
       }
   }
    
/*we need a graceful method to stop the server.*/
    public static void main (String args[]) {
        
        TCPServer server = null;
        int port;
        port = 7896;
        server = new TCPServer(port);
        Scanner myScan= new Scanner(System.in);
        System.out.println("Server succesfully started.type enter q to stop");
        String q;
    	do{	
    		q= myScan.nextLine();
    	} while(!q.equals("q"));{
    		server.runThread= false;	
        };
        System.exit(0);
    }
}