Packets are sent out when collision happens and receiver is able to interpret and display as visual alert. Updated visual alert to looks better.

- Created yacht event code message to be sent out as packet.
- Added observers to main server thread on yacht so when collision detected, main server thread will send out yacht event message to all server to client threads.
- Updated collision visual alert using circle and animation timer.

#story[1117]

src/main/java/seng302/gameServer/MainServerThread.java

@@ -1,10 +1,12 @@
 package seng302.gameServer;
 
+import com.sun.corba.se.spi.activation.Server;
 import java.io.IOException;
 import java.net.ServerSocket;
 import java.time.LocalDateTime;
 import java.util.ArrayList;
 import java.util.Observable;
+import java.util.Observer;
 import java.util.Timer;
 import java.util.TimerTask;
 import seng302.model.GeoPoint;
@@ -18,7 +20,8 @@ import seng302.visualiser.GameClient;
  * A class describing the overall server, which creates and collects server threads for each client
  * Created by wmu16 on 13/07/17.
  */
-public class MainServerThread extends Observable implements Runnable, ClientConnectionDelegate {
+public class MainServerThread extends Observable implements Runnable, ClientConnectionDelegate,
+    Observer {
 
     private static final int PORT = 4942;
     private static final Integer CLIENT_UPDATES_PER_SECOND = 10;
@@ -112,7 +115,7 @@ public class MainServerThread extends Observable implements Runnable, ClientConn
         serverToClientThreads.add(serverToClientThread);
         this.addObserver(serverToClientThread);
         setChanged();
-        notifyObservers();
+        notifyObservers("send setup message");
     }
 
     /**
@@ -136,11 +139,12 @@ public class MainServerThread extends Observable implements Runnable, ClientConn
             }
         }
         setChanged();
-        notifyObservers();
+        notifyObservers("send setup message");
     }
 
     public void startGame() {
         initialiseBoatPositions();
+        setupYachtObserver();
 
         Timer t = new Timer();
 
@@ -210,4 +214,17 @@ public class MainServerThread extends Observable implements Runnable, ClientConn
             boatIndex++;
         }
     }
+
+    @Override
+    public void update(Observable o, Object arg) {
+        for (ServerToClientThread serverToClientThread : serverToClientThreads) {
+            serverToClientThread.sendCollisionMessage((Integer) arg);
+        }
+    }
+
+    private void setupYachtObserver() {
+        for (ServerToClientThread serverToClientThread : serverToClientThreads) {
+            serverToClientThread.getYacht().addObserver(this);
+        }
+    }
 }

src/main/java/seng302/gameServer/ServerToClientThread.java

@@ -18,6 +18,7 @@ import java.util.concurrent.ThreadLocalRandom;
 import java.util.stream.Collectors;
 import java.util.zip.CRC32;
 import java.util.zip.Checksum;
+import seng302.gameServer.server.messages.YachtEventCodeMessage;
 import seng302.model.Player;
 import seng302.model.Yacht;
 import seng302.model.stream.packets.PacketType;
@@ -126,7 +127,9 @@ public class ServerToClientThread implements Runnable, Observer {
 
     @Override
     public void update(Observable o, Object arg) {
-        sendSetupMessages();
+        if (arg.equals("send setup message")) {
+            sendSetupMessages();
+        }
     }
 
     public void run() {
@@ -372,4 +375,8 @@ public class ServerToClientThread implements Runnable, Observer {
     public Yacht getYacht() {
         return yacht;
     }
+
+    public void sendCollisionMessage(Integer yachtId) {
+        sendMessage(new YachtEventCodeMessage(yachtId));
+    }
 }

src/main/java/seng302/gameServer/server/messages/YachtEventCodeMessage.java

@@ -0,0 +1,52 @@
+package seng302.gameServer.server.messages;
+
+/**
+ * Created by zyt10 on 10/08/17.
+ */
+public class YachtEventCodeMessage extends Message {
+
+    private final MessageType MESSAGE_TYPE = MessageType.YACHT_EVENT_CODE;
+    private final int MESSAGE_VERSION = 1; //Always set to 1
+    private final int MESSAGE_SIZE = 22;
+
+    // Message fields
+    private long timeStamp;
+    private long ack = 0x00; //Unused
+    private int raceId;
+    private int destSourceId;
+    private int incidentId;
+    private int eventId;
+
+
+    public YachtEventCodeMessage(Integer subjectId) {
+        timeStamp = System.currentTimeMillis() / 1000L;
+        ack = 0;
+        raceId = 1;
+        destSourceId = subjectId;  // collision boat source id
+        incidentId = 0;
+        eventId = 33;
+
+        setHeader(new Header(MESSAGE_TYPE, 0x01, (short) getSize()));
+        allocateBuffer();
+        writeHeaderToBuffer();
+
+        // Write message fields
+        putUnsignedByte((byte) MESSAGE_VERSION);
+        putInt((int) timeStamp, 6);
+        putInt((int) ack, 2);
+        putInt((int) raceId, 4);
+        putInt((int) destSourceId, 4);
+        putInt((int) incidentId, 4);
+        putInt((int) eventId, 1);
+
+        writeCRC();
+        rewind();
+    }
+
+    /**
+     * @return The length of this message
+     */
+    public int getSize() {
+        return MESSAGE_SIZE;
+    }
+}