import { CocosStorage } from '../modules/save/CocosStorage';
import { SaveManager } from '../modules/save/SaveManager';
import { StatsSection } from '../modules/save/StatsSection';

/**
 * The application's services, created once by the loader scene.
 *
 * Cocos components are built by the engine, so there is nowhere to inject
 * dependencies through a constructor; a small explicit locator is the honest
 * alternative to every component reaching for its own singleton. Everything it
 * holds is engine-independent apart from the storage adapter, so a test can
 * build one over `MemoryStorage` and drive the whole thing headlessly.
 */
export class App {
    private static _instance: App | null = null;

    readonly save: SaveManager;
    readonly stats: StatsSection;

    private constructor(save: SaveManager, stats: StatsSection) {
        this.save = save;
        this.stats = stats;
    }

    /** Builds the services and loads saved progress. Called once, from `Bootstrap`. */
    static create(): App {
        if (App._instance) {
            return App._instance;
        }

        const stats = new StatsSection();
        const save = new SaveManager(new CocosStorage());
        save.register(stats);
        save.load();

        App._instance = new App(save, stats);
        return App._instance;
    }

    static get instance(): App {
        if (!App._instance) {
            throw new Error('App.create() has not run — is the loader scene the start scene?');
        }
        return App._instance;
    }

    static get exists(): boolean {
        return App._instance !== null;
    }

    /** Records the result of a match and writes it out immediately. */
    recordMatch(outcome: 'win' | 'loss' | 'draw'): void {
        this.stats.recordResult(outcome);
        this.save.save();
    }
}