Add Eventsystem; Update Entity to reflect changes

src/main/java/com/yes/yes/utils/Entity.java

@@ -1,9 +1,14 @@
 package com.yes.yes.utils;
 
 import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.function.Function;
 
 public abstract class Entity extends javafx.scene.Group {
     private ArrayList<Component> behaviours = new ArrayList<>();
+    private final HashMap<String, Object> data = new HashMap<String, Object>();
+    private final EventHandler handler = new EventHandler();
+    private int rotation;
 
     public final void addBehaviour(Component behaviour) {
         behaviours.add(behaviour);
@@ -26,4 +31,24 @@ public abstract class Entity extends javafx.scene.Group {
             behaviour.update();
         }
     }
+
+    public final void setData(String key, Object value) {
+        data.put(key, value);
+    }
+
+    public final <T> T getData(String key) {
+        return (T) data.get(key);
+    }
+
+    public final void addListener(String eventName, Function<Object, Void> function) {
+        handler.addListener(eventName, function);
+    }
+
+    public final void removeListener(String eventName, Function<Object, Void> function) {
+        handler.removeListener(eventName, function);
+    }
+
+    public final void trigger(String eventName, Object parameter) {
+        handler.trigger(eventName, parameter);
+    }
 }

src/main/java/com/yes/yes/utils/EventHandler.java

@@ -0,0 +1,33 @@
+package com.yes.yes.utils;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.function.Function;
+
+public class EventHandler {
+    private final HashMap<String, ArrayList<Function<Object, Void>>> events = new HashMap<>();
+
+
+
+    public void addListener(String eventName, Function<Object, Void> function) {
+        if (!events.containsKey(eventName)) {
+            events.put(eventName, new ArrayList<>());
+        }
+        events.get(eventName).add(function);
+    }
+
+    public void removeListener(String eventName, Function<Object, Void> function) throws IllegalArgumentException {
+        //NOTE: This needs to be called otherwise memory leak
+        if (!events.containsKey(eventName)) {
+            throw new IllegalArgumentException("Event " + eventName + " does not exist!");
+        }
+        events.get(eventName).remove(function);
+    }
+
+    public void trigger(String eventName, Object parameter) {
+        //TODO: Check if this needs null checking
+        if (events.containsKey(eventName)) {
+            events.get(eventName).forEach(e -> e.apply(parameter));
+        }
+    }
+}

src/main/java/com/yes/yes/utils/GlobalEventHandler.java

@@ -0,0 +1,19 @@
+package com.yes.yes.utils;
+
+import java.util.function.Function;
+
+public abstract class GlobalEventHandler {
+    private static final EventHandler handler = new EventHandler();
+
+    public static void addListener(String eventName, Function<Object, Void> function) {
+        handler.addListener(eventName, function);
+    }
+
+    public static void removeListener(String eventName, Function<Object, Void> function) {
+        handler.removeListener(eventName, function);
+    }
+
+    public static void trigger(String eventName, Object parameter) {
+        handler.trigger(eventName, parameter);
+    }
+}