Party-Parrots-At-Sea/src/main/java/seng302/gameServer/HeartbeatThread.java

package seng302.gameServer;

import java.io.IOException;
import java.util.Stack;
import java.util.Timer;
import java.util.TimerTask;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import seng302.model.Player;
import seng302.gameServer.messages.Heartbeat;
import seng302.gameServer.messages.Message;

/**
 * Send Heartbeat messages to connected player at a specified interval
 * Will call .clientDisconnected on the delegate when a heartbeat message
 * cannot be sent to a player
 */
public class HeartbeatThread implements Runnable {

    private Logger logger = LoggerFactory.getLogger(HeartbeatThread.class);

    private final int HEARTBEAT_PERIOD = 200;
    private ClientConnectionDelegate delegate;
    private Integer seqNum;
    private Stack<Player> disconnectedPlayers;

    public HeartbeatThread(ClientConnectionDelegate delegate){
        this.delegate =  delegate;
        seqNum = 0;
        disconnectedPlayers = new Stack<>();

        Thread thread = new Thread(this, "HeartBeat");
        thread.start();
    }

    /**
     * A player has lost connection to the server
     * The player is added to a stack so that the delegate
     * can be notified
     *
     * @param player The player that has disconnected
     */
    private void playerLostConnection(Player player){
        disconnectedPlayers.push(player);
    }

    /**
     * Sends a heartbeat message to each connected player
     * The delegate is notified if a player has disconnected
     */
    private void sendHeartbeatToAllPlayers(){
        try {
            Message heartbeat = new Heartbeat(seqNum);
            for (Player player : GameState.getPlayers()) {
                if (!player.getSocket().isConnected()) {
                    playerLostConnection(player);
                }
                try {
                    player.getSocket().getOutputStream().write(heartbeat.getBuffer());
                } catch (IOException e) {
                    playerLostConnection(player);
                }
            }
            updateDelegate();
            seqNum++;
        } catch (NullPointerException ne) {
            logger.debug("Socket closed between checking for connection and sending heartbeat");
        }
    }

    /**
     * Notifies the delegate about
     * each disconnected player
     */
    private void updateDelegate() {
        while (!disconnectedPlayers.empty()){
            delegate.clientDisconnected(disconnectedPlayers.pop());
        }
    }

    public void run(){
        Timer t = new Timer();
        t.schedule(new TimerTask() {
            @Override
            public void run() {
                sendHeartbeatToAllPlayers();
            }
        }, 0, HEARTBEAT_PERIOD);
    }
}