/**
 * database.ts
 * Dexie (IndexedDB) singleton for the P2P Survey App.
 *
 * All survey data — surveys, participant tokens, and responses — lives
 * exclusively in the creator's browser. Dexie wraps the raw IndexedDB API
 * with a clean, Promise-based interface and live-query support.
 *
 * Usage (inject via InjectionToken, see main.ts):
 *   constructor(@Inject(DATABASE_TOKEN) private db: AppDatabase) {}
 */

import Dexie, { type Table } from 'dexie';
import type { Survey, Participant, Response } from '../shared/models/survey.models';

/** Typed Dexie database class */
export class AppDatabase extends Dexie {
  /** All surveys created by this user */
  surveys!: Table<Survey, string>;

  /**
   * Pre-generated participant tokens.
   * Primary key: token (UUID string).
   */
  participants!: Table<Participant, string>;

  /**
   * Submitted responses.
   * Primary key: id (UUID string).
   */
  responses!: Table<Response, string>;

  constructor() {
    super('P2PSurveyDB');

    this.version(1).stores({
      // Indexed fields: primary key first, then fields used in queries
      surveys:      'id, status, createdAt',
      participants: 'token, surveyId, locked',
      responses:    'id, surveyId, participantToken, submittedAt',
    });
  }
}

/** Module-level singleton — import this wherever you need direct DB access */
export const db = new AppDatabase();