/**
 * Feature-flag config for the Phase 1 async notifications path (RFC-004 / GOO-173).
 *
 * When NOTIFICATIONS_ASYNC_ENABLED is `true`, producers route through
 * `NotificationsPublisher` → outbox → Redis Streams → BullMQ consumer.
 * When `false` (default until parity is confirmed in production), producers
 * continue to execute `SendNotificationCommand` directly in-process.
 *
 * Kept as a tiny injectable so:
 *   - callers don't read process.env directly (testability)
 *   - we have one place to evolve the flag shape (per-category rollout,
 *     percentage shadowing, etc.) without ripping through listeners again
 */

import { Injectable } from '@nestjs/common';

const FLAG_ENV = 'NOTIFICATIONS_ASYNC_ENABLED';

@Injectable()
export class NotificationsAsyncConfig {
  /** True when the async outbox path should be used for new notifications. */
  get asyncEnabled(): boolean {
    const raw = process.env[FLAG_ENV];
    if (raw === undefined) return false;
    const v = raw.trim().toLowerCase();
    return v === '1' || v === 'true' || v === 'yes' || v === 'on';
  }

  /** Exposed for observability / startup logs. */
  describe(): string {
    return `${FLAG_ENV}=${this.asyncEnabled ? 'enabled' : 'disabled'}`;
  }
}