Add game ticks

src/engine/builders/item.js

@@ -40,6 +40,11 @@ export default class ItemBuilder {
         return this;
     }
 
+    withTickCallback(callback) {
+        this.item.addTickCallback(callback);
+        return this;
+    }
+
     create() {
         return this.item;
     }

src/engine/index.js

@@ -5,6 +5,7 @@ import Output from './output';
 import Input from './input';
 import Commands from './commands';
 
+
 export default class Game {
     constructor() {
         this.player = new Player();
@@ -15,6 +16,7 @@ export default class Game {
         this.commandHandler = new Commands(this);
         this.input = new Input(this.commandHandler, this.output);
         this.visitedRooms = new Map();
+        this.interval = null;
     }
 
     print(string) {
@@ -36,6 +38,21 @@ export default class Game {
         this.player = new Player();
         this.player.context = this;
         this.move(this.player.currentRoom);
+        this.start();
+    }
+
+    advanceTick() {
+        this.items.forEach((item) => item.onTick());
+        this.rooms.forEach((room) => room.onTick());
+    }
+
+    start() {
+        this.interval = setInterval(() => this.advanceTick(), 1000);
+    }
+    
+    stop() {
+        clearInterval(this.interval);
+        this.interval = null;
     }
 
     examineRoom() {

src/engine/item.js

@@ -8,6 +8,7 @@ export default class Item {
         this.useCallback = null;
         this.takeCallback = null;
         this.dropCallback = null;
+        this.tickCallback = null;
         this.context = null;
     }
 
@@ -19,6 +20,10 @@ export default class Item {
         if (this.takeCallback) return this.takeCallback();
     }
 
+    async onTick() {
+        if (this.tickCallback) return this.tickCallback(this.context);
+    }
+
     addUseCallback(callback) {
         this.useCallback = callback.bind(this);
     }
@@ -30,4 +35,8 @@ export default class Item {
     addDropCallback(callback) {
         this.dropCallback = callback.bind(this);
     }
+
+    addTickCallback(callback) {
+        this.tickCallback = callback.bind(this);
+    }
 }

src/engine/room.js

@@ -76,4 +76,8 @@ export default class Room {
     getItems() {
         return this.objects.map((item) => this.context.getItem(item));
     }
+
+    async onTick() {
+        if (this.tickCallback) return this.tickCallback(this.context);
+    }
 }