fix: getSceneName use scenes #3022 (#3023)

Closes #3022

## Changes:

- Fixed `getSceneName` to use `scene`.

I didn't know how to use `_sceneToInstance` cache, so I replaced it with something simpler.

src/engine/Director/Director.ts

@@ -277,13 +277,35 @@ export class Director<TKnownScenes extends string = any> {
     return undefined;
   }
 
-  getSceneName(scene: Scene) {
-    for (const [name, sceneInstance] of this._sceneToInstance) {
-      if (scene === sceneInstance) {
-        return name;
+  /**
+   * Returns the name of the registered scene, null if none can be found
+   * @param scene
+   */
+  getSceneName(scene: Scene): string | null {
+    for (const [name, maybeScene] of Object.entries(this.scenes)) {
+      if (maybeScene instanceof Scene) {
+        if (scene === maybeScene) {
+          return name;
+        }
+      } else if (!isSceneConstructor(maybeScene)) {
+        if (scene === maybeScene.scene) {
+          return name;
+        }
       }
     }
-    return 'unknown scene name';
+
+    for (const [name, maybeScene] of Object.entries(this.scenes)) {
+      if (isSceneConstructor(maybeScene)) {
+        if (scene.constructor === maybeScene) {
+          return name;
+        }
+      } else if (!(maybeScene instanceof Scene)) {
+        if (scene.constructor === maybeScene.scene) {
+          return name;
+        }
+      }
+    }
+    return null;
   }
 
   /**

src/spec/DirectorSpec.ts

@@ -97,6 +97,36 @@ describe('A Director', () => {
     engine.dispose();
   });
 
+  it('can get a scene name', () => {
+    const engine = TestUtils.engine();
+    const clock = engine.clock as ex.TestClock;
+    clock.start();
+    const scene1 = new ex.Scene();
+    scene1._initialize(engine);
+    const scene2 = new ex.Scene();
+    scene2._initialize(engine);
+    const scene3 = new ex.Scene();
+    scene3._initialize(engine);
+
+    class SceneCtor1 extends ex.Scene {}
+    class SceneCtor2 extends ex.Scene {}
+
+    const sut = new ex.Director(engine, {
+      scene1,
+      scene2,
+      myScene: { scene: scene3 },
+      sceneWithCtor: { scene: SceneCtor1 },
+      ctor: SceneCtor2
+    });
+
+    expect(sut.getSceneName(scene1)).toBe('scene1');
+    expect(sut.getSceneName(scene2)).toBe('scene2');
+    expect(sut.getSceneName(scene3)).toBe('myScene');
+    expect(sut.getSceneName(new SceneCtor1())).toBe('sceneWithCtor');
+    expect(sut.getSceneName(new SceneCtor2())).toBe('ctor');
+    expect(sut.getSceneName(new ex.Scene())).toBe(null);
+  });
+
   it('will draw a start scene transition', async () => {
     const engine = TestUtils.engine();
     const clock = engine.clock as ex.TestClock;