import {
  Inject,
  Injectable,
  Logger,
  type OnModuleInit,
  type OnModuleDestroy,
} from '@nestjs/common';
import { SummarizationService } from './summarization.service.js';
import { SessionGCService } from '../gc/session-gc.service.js';
import {
  QueueService,
  QUEUE_SUMMARIZATION,
  QUEUE_GC,
  QUEUE_TIER_MANAGEMENT,
} from '../queue/queue.service.js';
import type { Worker } from 'bullmq';
import type { MosaicJobData } from '../queue/queue.service.js';

@Injectable()
export class CronService implements OnModuleInit, OnModuleDestroy {
  private readonly logger = new Logger(CronService.name);
  private readonly registeredWorkers: Worker<MosaicJobData>[] = [];

  constructor(
    @Inject(SummarizationService) private readonly summarization: SummarizationService,
    @Inject(SessionGCService) private readonly sessionGC: SessionGCService,
    @Inject(QueueService) private readonly queueService: QueueService,
  ) {}

  async onModuleInit(): Promise<void> {
    const summarizationSchedule = process.env['SUMMARIZATION_CRON'] ?? '0 */6 * * *'; // every 6 hours
    const tierManagementSchedule = process.env['TIER_MANAGEMENT_CRON'] ?? '0 3 * * *'; // daily at 3am
    const gcSchedule = process.env['SESSION_GC_CRON'] ?? '0 4 * * *'; // daily at 4am

    // M6-003: Summarization repeatable job
    await this.queueService.addRepeatableJob(
      QUEUE_SUMMARIZATION,
      'summarization',
      {},
      summarizationSchedule,
    );
    const summarizationWorker = this.queueService.registerWorker(QUEUE_SUMMARIZATION, async () => {
      await this.summarization.runSummarization();
    });
    this.registeredWorkers.push(summarizationWorker);

    // M6-005: Tier management repeatable job
    await this.queueService.addRepeatableJob(
      QUEUE_TIER_MANAGEMENT,
      'tier-management',
      {},
      tierManagementSchedule,
    );
    const tierWorker = this.queueService.registerWorker(QUEUE_TIER_MANAGEMENT, async () => {
      await this.summarization.runTierManagement();
    });
    this.registeredWorkers.push(tierWorker);

    // M6-004: GC repeatable job
    await this.queueService.addRepeatableJob(QUEUE_GC, 'session-gc', {}, gcSchedule);
    const gcWorker = this.queueService.registerWorker(QUEUE_GC, async () => {
      await this.sessionGC.sweepOrphans();
    });
    this.registeredWorkers.push(gcWorker);

    this.logger.log(
      `BullMQ jobs scheduled: summarization="${summarizationSchedule}", tier="${tierManagementSchedule}", gc="${gcSchedule}"`,
    );
  }

  async onModuleDestroy(): Promise<void> {
    // Workers are closed by QueueService.onModuleDestroy — nothing extra needed here.
    this.registeredWorkers.length = 0;
    this.logger.log('CronService destroyed (workers managed by QueueService)');
  }
}