tasks.repository.ts

import { Task } from './entities/task.entity';
import { TaskPage, TaskQuery, TaskStats } from './tasks.types';

/**
 * Storage port for tasks. The service depends only on this abstraction; the
 * concrete adapter is bound in {@link TasksModule}.
 *
 * Two deliberate decisions make it future-proof against a real database:
 *
 *  1. **Every method is async.** In-memory work resolves immediately, but the
 *     signatures already return Promises — so introducing a DB never ripples
 *     `await`s through the service and controller.
 *  2. **Querying lives here, not in the service.** `findMany` takes a domain
 *     {@link TaskQuery} and is responsible for filtering, sorting, pagination
 *     and counting; `getStats` does aggregation. A SQL adapter pushes these
 *     down to `WHERE/ORDER BY/LIMIT/GROUP BY` instead of loading every row.
 *
 * Net effect: adding Postgres is a new class implementing these four methods
 * plus a one-line provider swap — the service, controller and DTOs are untouched.
 */
export abstract class TasksRepository {
  abstract findById(id: string): Promise<Task | null>;
  abstract findMany(query: TaskQuery): Promise<TaskPage>;
  abstract save(task: Task): Promise<Task>;
  abstract getStats(): Promise<TaskStats>;
}