[Bug] Fix #5029 Memory leak when saving and exiting (#5128)

* Add destroy function to ui handlers

* Implement destroy() for StarterSelectUiHandler

* Update battlescene to free memory when resetting

* Document destroy for starter select

---------

Co-authored-by: damocleas <damocleas25@gmail.com>

src/battle-scene.ts

@@ -1191,6 +1191,9 @@ export default class BattleScene extends SceneBase {
         onComplete: () => {
           this.clearPhaseQueue();
 
+          this.ui.freeUIData();
+          this.uiContainer.remove(this.ui, true);
+          this.uiContainer.destroy();
           this.children.removeAll(true);
           this.game.domContainer.innerHTML = "";
           this.launchBattle();

src/ui/settings/navigationMenu.ts

@@ -89,6 +89,13 @@ export class NavigationManager {
     }
   }
 
+  /**
+   * Removes menus from the manager in preparation for reset
+   */
+  public clearNavigationMenus() {
+    this.navigationMenus.length = 0;
+  }
+
 }
 
 export default class NavigationMenu extends Phaser.GameObjects.Container {

src/ui/starter-select-ui-handler.ts

@@ -2698,6 +2698,11 @@ export default class StarterSelectUiHandler extends MessageUiHandler {
     this.updateScroll();
   };
 
+  override destroy(): void {
+    // Without this the reference gets hung up and no startercontainers get GCd
+    this.starterContainers = [];
+  }
+
   updateScroll = () => {
     const maxColumns = 9;
     const maxRows = 9;

src/ui/ui-handler.ts

@@ -62,4 +62,9 @@ export default abstract class UiHandler {
   clear() {
     this.active = false;
   }
+  /**
+   * To be implemented by individual handlers when necessary to free memory
+   * Called when {@linkcode BattleScene} is reset
+   */
+  destroy(): void {}
 }

src/ui/ui.ts

@@ -53,6 +53,7 @@ import TestDialogueUiHandler from "#app/ui/test-dialogue-ui-handler";
 import AutoCompleteUiHandler from "./autocomplete-ui-handler";
 import { Device } from "#enums/devices";
 import MysteryEncounterUiHandler from "./mystery-encounter-ui-handler";
+import { NavigationManager } from "./settings/navigationMenu";
 
 export enum Mode {
   MESSAGE,
@@ -614,4 +615,14 @@ export default class UI extends Phaser.GameObjects.Container {
       return globalScene.inputMethod;
     }
   }
+
+  /**
+   * Attempts to free memory held by UI handlers
+   * and clears menus from {@linkcode NavigationManager} to prepare for reset
+   */
+  public freeUIData(): void {
+    this.handlers.forEach(h => h.destroy());
+    this.handlers = [];
+    NavigationManager.getInstance().clearNavigationMenus();
+  }
 }