feat: implement GameState.snapshot and make entities cloneable

src/main/java/uulm/teamname/marvelous/gamelibrary/entities/Character.java

@@ -58,4 +58,16 @@ public class Character extends Entity {
     public boolean isAlive() {
         return hp.getValue() > 0;
     }
+
+    @Override
+    public Character clone() {
+        Character clone = new Character(id, position, name, hp.max, mp.max, ap.max, attackRange, rangedDamage, meleeDamage);
+        for(StoneType stone: inventory) {
+            clone.inventory.addStone(stone);
+        }
+        clone.hp.setValue(hp.getValue());
+        clone.mp.setValue(mp.getValue());
+        clone.ap.setValue(ap.getValue());
+        return clone;
+    }
 }

src/main/java/uulm/teamname/marvelous/gamelibrary/entities/Entity.java

@@ -5,10 +5,10 @@ import uulm.teamname.marvelous.gamelibrary.IntVector2;
 /** Represents an abstract entity. */
 public abstract class Entity {
     /** Whether or not the entity is currently active in the game */
-    private boolean active = true;
+    protected boolean active = true;
 
     /** The position of the entity */
-    private IntVector2 position;
+    protected IntVector2 position;
 
     /** The {@link EntityID} of the entity */
     public final EntityID id;
@@ -23,6 +23,12 @@ public abstract class Entity {
         this.id = id;
     }
 
+    /**
+     * Clones the {@link Entity}.
+     * @return A new entity cloned from this one
+     */
+    public abstract Entity clone();
+
     public boolean isActive() {
         return active;
     }

src/main/java/uulm/teamname/marvelous/gamelibrary/entities/EntityID.java

@@ -27,6 +27,14 @@ public class EntityID {
         return type == other;
     }
 
+    /**
+     * Clones this entity id.
+     * @return The cloned {@link EntityID}
+     */
+    public EntityID clone() {
+        return new EntityID(this.id, this.type);
+    }
+
     /**
      * Serializes the id for debugging.
      * @return A debug string containing all the necessary information about the id

src/main/java/uulm/teamname/marvelous/gamelibrary/entities/InfinityStone.java

@@ -17,4 +17,9 @@ public class InfinityStone extends Entity {
         super(id, position);
         this.type = type;
     }
+
+    @Override
+    public InfinityStone clone() {
+        return new InfinityStone(id, position, type);
+    }
 }

src/main/java/uulm/teamname/marvelous/gamelibrary/entities/Inventory.java

@@ -21,7 +21,7 @@ public class Inventory implements Iterable<StoneType> {
             throw new IllegalArgumentException("Attempted to construct an inventory with more than "+size+" initial stones.");
         }
 
-        for(StoneType stone : content) {
+        for(StoneType stone: content) {
             if(content.contains(stone)) {
                 throw new IllegalArgumentException("Attempted to construct an inventory with duplicate entries.");
             }

src/main/java/uulm/teamname/marvelous/gamelibrary/entities/NPC.java

@@ -29,4 +29,13 @@ public class NPC extends Entity {
         super(id, position);
         this.inventory = new Inventory();
     }
+
+    @Override
+    public NPC clone() {
+        NPC clone = new NPC(id, position);
+        for(StoneType stone: inventory) {
+            clone.inventory.addStone(stone);
+        }
+        return clone;
+    }
 }

src/main/java/uulm/teamname/marvelous/gamelibrary/entities/Rock.java

@@ -29,4 +29,11 @@ public class Rock extends Entity {
     public void decreaseHp(int damage) {
         this.hp -= damage;
     }
+
+    @Override
+    public Rock clone() {
+        Rock clone = new Rock(id, position, maxHP);
+        clone.hp = hp;
+        return clone;
+    }
 }