/***
 * @author Callum Innes, Jon Bilsbury
 * @title ChatServer
 * @description Controls the chat server
 */

import java.net.*;
import java.util.ArrayList;
import java.util.regex.Pattern;
import java.io.*;

public class ChatServer implements Runnable {

	private ChatServerThread clients[] = new ChatServerThread[50]; // array of current clients connected
	private ServerSocket serverSocket = null; // socket of the server
	private Thread t = null; // thread for each connected server
	private int noOfClients = 0; // number of clients

	/**
	 * Constructor
	 * @param port port of the server
	 */
	public ChatServer(int port) {
		try {
			System.out.println("Binding to port " + port + ", please wait  ...");
			serverSocket = new ServerSocket(port); // server socket binds to port
			System.out.println("serverSocket started: " + serverSocket);
			start(); // start thread
		} catch (IOException ioe) {
			System.out.println("Can not bind to port " + port + ": " + ioe.getMessage());
		}
	}

	/**
	 * Always called by thread
	 */
	public void run() {
		while (t != null) {
			try {
				System.out.println("Waiting for a client ...");
				addThread(serverSocket.accept());
			} catch (IOException ioe) {
				System.out.println("serverSocket accept error: " + ioe);
				stop();
			}
		}
	}

	/**
	 * Called at the start of the thread
	 */
	public void start() {
		if (t == null) {
			t = new Thread(this);
			t.start();
		}
	}

	/**
	 * Stops the thread
	 */
	public void stop() {
		if (t != null) {
			t.stop();
			t = null;
		}
	}

	/**
	 * finds the client from list of clients
	 * @param ID ID of client to find
	 * @return the location of found client
	 */
	private int findClient(int ID) {
		for (int i = 0; i < noOfClients; i++)
			if (clients[i].getID() == ID)
				return i;
		return -1;
	}

	/**
	 * handles messages to the server and what to do with them
	 * @param ID id of the user sending them
	 * @param input what they are sending
	 */
	public synchronized void handle(int ID, String input) {
		ChatServerThread client = clients[findClient(ID)];
		String userName = null, password = null, message = null;
		if (input.contains(".register")) {
			System.out.println("Registering " + input);
			String parsedInfo[] = input.split(Pattern.quote(" "));
			userName = parsedInfo[1];
			password = parsedInfo[2];
			registerUser(userName, password);
		} else if (input.contains(".login")) {
			String parsedInfo[] = input.split(Pattern.quote(" "));
			userName = parsedInfo[1];
			password = parsedInfo[2];
			if (checkLogin(userName, password) == false) {
				System.out.println("Telling user " + userName + " to register");
				client.send(".register");
			}
			client.send("SERVER: Login successful, welcome " + userName);
		} else if (input.charAt(0) != '.') {
			System.out.println(input);
			String parsedInfo[] = input.split(Pattern.quote("☼"));
			userName = parsedInfo[0];
			password = parsedInfo[1];
			message = parsedInfo[2];
			if (message.equals(".bye")) {
				client.send("Disconnecting now ...");
				client.send(".bye");
				remove(ID);
			} else if (message.contains("fuck")) {
				client.send("Rude! Timeout!\nDisconnecting now ...");
				client.send(".bye");
				remove(ID);
			} else if (message.length() > 160) {
				client.send("Client " + ID + " - too prolix!!!\nDisconnecting now ...");
				client.send(".bye");
				remove(ID);
			} else {
				for (int i = 0; i < noOfClients; i++) {
					clients[i].send(userName + ": " + message);
					System.out.println("Sending message");
				}
			}
		}

	}

	/**
	 * registers a user by writing them to text file
	 * @param username their username
	 * @param password their password
	 */
	public void registerUser(String username, String password) {
		try (FileWriter fw = new FileWriter("user_pass.txt", true);
				BufferedWriter bw = new BufferedWriter(fw);
				PrintWriter out = new PrintWriter(bw)) {
			out.println(username + ":" + password);
		} catch (IOException e) {
			// File writing/opening failed at some stage.
		}
	}

	/**
	 * Checks the login info given by the user
	 * @param username username of the user
	 * @param password password of the user
	 * @return whether they are a member or not
	 */
	public boolean checkLogin(String username, String password) {
		boolean valid = false;

		ArrayList<String> lines = new ArrayList<String>();
		String line;
	    try {
	        BufferedReader reader = new BufferedReader(new FileReader("user_pass.txt"));
	        while((line = reader.readLine()) != null){
	        	  lines.add(line);
	        	}
	    } catch (Exception e) {
	        e.printStackTrace();
	    }

	    String[] users = new String[lines.size()];
	    String[] pass = new String[lines.size()];

	    for(int i = 0; i < lines.size(); i++){
	    	String[] output = lines.get(i).split("\\:");
	    	users[i] = output[0];
	    	pass[i] = output[1];
	    }

	    for (int i = 0; i < lines.size(); i++){
	    	System.out.println(users[i] + ":" + pass[i]);
	    	if(users[i].equals(username) && pass[i].equals(password)){
	    		System.out.println("found a match");
	    		valid = true;
	    		break;
	    	}
	    }

		return valid;
	}

	/**
	 * removes a user from the list
	 * @param ID user to remove
	 */
	public synchronized void remove(int ID) {
		int pos = findClient(ID);
		if (pos >= 0) {
			ChatServerThread toTerminate = clients[pos];
			System.out.println("Removing client " + ID + " at " + pos);
			if (pos < noOfClients - 1)
				for (int i = pos + 1; i < noOfClients; i++)
					clients[i - 1] = clients[i];
			noOfClients--;
			try {
				toTerminate.close();
			} catch (IOException ioe) {
				System.out.println("Error closing t: " + ioe);
			}
			toTerminate.stop();
		}
	}

	/**
	 * adds a thread and pairs with user
	 * @param socket socket of server
	 */
	private void addThread(Socket socket) {
		if (noOfClients < clients.length) {
			System.out.println("Client accepted: " + socket);
			clients[noOfClients] = new ChatServerThread(this, socket);
			try {
				clients[noOfClients].open();
				clients[noOfClients].start();
				noOfClients++;
			} catch (IOException ioe) {
				System.out.println("Error opening thread: " + ioe);
			}
		} else
			System.out.println("Client refused: maximum " + clients.length + " reached.");
	}

	/**
	 * main method
	 * @param args starting info
	 */
	public static void main(String args[]) {
		ChatServer serverSocket = null;
		if (args.length != 1)
			System.out.println("Usage: java ChatServer port");
		else
			serverSocket = new ChatServer(Integer.parseInt(args[0])); // instantiate class
	}

}