import { Injectable, Logger } from '@nestjs/common';
import { EventPublisherService } from './event-publisher.service';
import { DeadLetterService } from './dead-letter.service';

@Injectable()
export class EventRetryService {
  private readonly logger = new Logger(EventRetryService.name);
  private readonly maxRetries = 3;
  private isRunning = false;

  constructor(
    private readonly eventPublisher: EventPublisherService,
    private readonly deadLetterService: DeadLetterService,
  ) {}

  // 可以通过 API 手动触发或由外部调度器调用
  async retryFailedEvents(): Promise<void> {
    if (this.isRunning) {
      this.logger.debug('Retry job already running, skipping');
      return;
    }

    this.isRunning = true;
    this.logger.log('Starting failed events retry job');

    try {
      const failedEvents = await this.deadLetterService.getFailedEvents(50);
      let successCount = 0;
      let failCount = 0;

      for (const event of failedEvents) {
        if (event.retryCount >= this.maxRetries) {
          this.logger.warn(
            `Event ${event.eventId} exceeded max retries (${this.maxRetries}), skipping`,
          );
          continue;
        }

        try {
          await this.eventPublisher.publish(event.topic, {
            eventId: event.eventId,
            occurredAt: event.createdAt.toISOString(),
            aggregateId: event.aggregateId,
            aggregateType: event.aggregateType,
            eventType: event.eventType,
            payload: event.payload,
          });

          await this.deadLetterService.markAsProcessed(event.id);
          successCount++;
          this.logger.log(`Successfully retried event: ${event.eventId}`);
        } catch (error) {
          failCount++;
          await this.deadLetterService.incrementRetryCount(event.id);
          this.logger.error(`Failed to retry event: ${event.eventId}`, error);
        }
      }

      this.logger.log(
        `Finished retry job: ${successCount} succeeded, ${failCount} failed`,
      );
    } finally {
      this.isRunning = false;
    }
  }

  async manualRetry(eventId: string): Promise<boolean> {
    const events = await this.deadLetterService.getFailedEvents(1000);
    const event = events.find((e) => e.eventId === eventId);

    if (!event) {
      this.logger.warn(`Event not found: ${eventId}`);
      return false;
    }

    try {
      await this.eventPublisher.publish(event.topic, {
        eventId: event.eventId,
        occurredAt: event.createdAt.toISOString(),
        aggregateId: event.aggregateId,
        aggregateType: event.aggregateType,
        eventType: event.eventType,
        payload: event.payload,
      });

      await this.deadLetterService.markAsProcessed(event.id);
      this.logger.log(`Manually retried event: ${eventId}`);
      return true;
    } catch (error) {
      this.logger.error(`Failed to manually retry event: ${eventId}`, error);
      return false;
    }
  }
}