# Code coverage report for modules/notifications/services/notification-queue.service.ts

# All files / modules/notifications/services notification-queue.service.ts

98.57% Statements 69/70
95.65% Branches 22/23
100% Functions 13/13
98.52% Lines 67/68

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     import {
      Injectable,
      Logger,
    } from '@nestjs/common';
    import { InjectRepository } from '@nestjs/typeorm';
    import { Repository, LessThanOrEqual, In } from 'typeorm';
    import {
      NotificationQueue,
      NotificationLog,
      Notification,
      QueueStatus,
      NotificationChannel,
    } from '../entities';

    export interface QueueItem {
      id: string;
      notification_id: string;
      channel: NotificationChannel;
      priority_value: number;
      attempts: number;
      notification: Notification;
    }

    export interface QueueStats {
      queued: number;
      processing: number;
      sent: number;
      failed: number;
      retrying: number;
    }

    @Injectable()
    export class NotificationQueueService {
      private readonly logger = new Logger(NotificationQueueService.name);

      constructor(
        @InjectRepository(NotificationQueue)
        private readonly queueRepository: Repository<NotificationQueue>,
        @InjectRepository(NotificationLog)
        private readonly logRepository: Repository<NotificationLog>,
        @InjectRepository(Notification)
        private readonly notificationRepository: Repository<Notification>,
      ) {}

      async enqueue(
        notificationId: string,
        channel: NotificationChannel,
        priority: 'low' | 'normal' | 'high' | 'urgent' = 'normal',
        scheduledFor?: Date,
      ): Promise<NotificationQueue> {
        const priorityValue = this.getPriorityValue(priority);

        const queueItem = this.queueRepository.create({
          notification_id: notificationId,
          channel,
          priority_value: priorityValue,
          scheduled_for: scheduledFor || new Date(),
          status: 'queued',
          attempts: 0,
          max_attempts: 3,
        });

        const saved = await this.queueRepository.save(queueItem);
        this.logger.debug(
          `Enqueued notification ${notificationId} for channel ${channel}`,
        );

        return saved;
      }

      async enqueueBatch(
        notificationId: string,
        channels: NotificationChannel[],
        priority: 'low' | 'normal' | 'high' | 'urgent' = 'normal',
      ): Promise<NotificationQueue[]> {
        const priorityValue = this.getPriorityValue(priority);
        const now = new Date();

        const items = channels.map((channel) =>
          this.queueRepository.create({
            notification_id: notificationId,
            channel,
            priority_value: priorityValue,
            scheduled_for: now,
            status: 'queued',
            attempts: 0,
            max_attempts: 3,
          }),
        );

        const saved = await this.queueRepository.save(items);
        this.logger.debug(
          `Enqueued notification ${notificationId} for ${channels.length} channels`,
        );

        return saved;
      }

      async getPendingItems(
        limit: number = 100,
        channel?: NotificationChannel,
      ): Promise<QueueItem[]> {
        const now = new Date();

        const queryBuilder = this.queueRepository
          .createQueryBuilder('q')
          .leftJoinAndSelect('q.notification', 'n')
          .where('q.status IN (:...statuses)', {
            statuses: ['queued', 'retrying'],
          })
          .andWhere('(q.scheduled_for IS NULL OR q.scheduled_for <= :now)', { now })
          .andWhere('(q.next_retry_at IS NULL OR q.next_retry_at <= :now)', { now })
          .orderBy('q.priority_value', 'DESC')
          .addOrderBy('q.created_at', 'ASC')
          .take(limit);

        if (channel) {
          queryBuilder.andWhere('q.channel = :channel', { channel });
        }

        return queryBuilder.getMany() as Promise<QueueItem[]>;
      }

      async markAsProcessing(queueId: string): Promise<void> {
        await this.queueRepository.update(queueId, {
          status: 'processing',
          last_attempt_at: new Date(),
        });
      }

      async markAsSent(
        queueId: string,
        provider?: string,
        providerMessageId?: string,
        providerResponse?: Record<string, any>,
      ): Promise<void> {
        const queueItem = await this.queueRepository.findOne({
          where: { id: queueId },
        });

        if (!queueItem) {
          return;
        }

        // Update queue item
        await this.queueRepository.update(queueId, {
          status: 'sent',
          completed_at: new Date(),
          attempts: queueItem.attempts + 1,
        });

        // Update notification status
        await this.notificationRepository.update(queueItem.notification_id, {
          delivery_status: 'sent',
          sent_at: new Date(),
        });

        // Create log
        await this.logRepository.save({
          notification_id: queueItem.notification_id,
          queue_id: queueId,
          channel: queueItem.channel,
          status: 'sent',
          provider,
          provider_message_id: providerMessageId,
          provider_response: providerResponse,
          delivered_at: new Date(),
        });

        this.logger.debug(`Queue item ${queueId} marked as sent`);
      }

      async markAsFailed(
        queueId: string,
        errorMessage: string,
        provider?: string,
      ): Promise<void> {
        const queueItem = await this.queueRepository.findOne({
          where: { id: queueId },
        });

        if (!queueItem) {
          return;
        }

        const newAttempts = queueItem.attempts + 1;
        const shouldRetry = newAttempts < queueItem.max_attempts;

        if (shouldRetry) {
          // Schedule retry with exponential backoff
          const retryDelay = Math.pow(2, queueItem.attempts) * 60 * 1000; // 1, 2, 4 minutes
          const nextRetryAt = new Date(Date.now() + retryDelay);

          await this.queueRepository.update(queueId, {
            status: 'retrying',
            attempts: newAttempts,
            error_message: errorMessage,
            error_count: queueItem.error_count + 1,
            next_retry_at: nextRetryAt,
          });

          this.logger.debug(
            `Queue item ${queueId} scheduled for retry at ${nextRetryAt.toISOString()}`,
          );
        } else {
          // Final failure
          await this.queueRepository.update(queueId, {
            status: 'failed',
            attempts: newAttempts,
            error_message: errorMessage,
            error_count: queueItem.error_count + 1,
            completed_at: new Date(),
          });

          // Update notification status
          await this.notificationRepository.update(queueItem.notification_id, {
            delivery_status: 'failed',
          });

          this.logger.warn(
            `Queue item ${queueId} failed permanently after ${newAttempts} attempts`,
          );
        }

        // Create log
        await this.logRepository.save({
          notification_id: queueItem.notification_id,
          queue_id: queueId,
          channel: queueItem.channel,
          status: 'failed',
          provider,
          error_message: errorMessage,
        });
      }

      async getStats(): Promise<QueueStats> {
        const stats = await this.queueRepository
          .createQueryBuilder('q')
          .select('q.status', 'status')
          .addSelect('COUNT(*)', 'count')
          .groupBy('q.status')
          .getRawMany();

        const result: QueueStats = {
          queued: 0,
          processing: 0,
          sent: 0,
          failed: 0,
          retrying: 0,
        };

        for (const row of stats) {
          result[row.status as keyof QueueStats] = parseInt(row.count, 10);
        }

        return result;
      }

      async getStatsByChannel(): Promise<
        Array<{ channel: string; status: string; count: number }>
      > {
        return this.queueRepository
          .createQueryBuilder('q')
          .select('q.channel', 'channel')
          .addSelect('q.status', 'status')
          .addSelect('COUNT(*)', 'count')
          .groupBy('q.channel')
          .addGroupBy('q.status')
          .getRawMany();
      }

      async cleanupOldItems(daysToKeep: number = 30): Promise<number> {
        const cutoffDate = new Date();
        cutoffDate.setDate(cutoffDate.getDate() - daysToKeep);

        const result = await this.queueRepository
          .createQueryBuilder()
          .delete()
          .where('status IN (:...statuses)', { statuses: ['sent', 'failed'] })
          .andWhere('completed_at < :cutoff', { cutoff: cutoffDate })
          .execute();

        if (result.affected && result.affected > 0) {
          this.logger.log(`Cleaned up ${result.affected} old queue items`);
        }

        return result.affected || 0;
      }

      async cancelPending(notificationId: string): Promise<number> {
        const result = await this.queueRepository.update(
          {
            notification_id: notificationId,
            status: In(['queued', 'retrying']),
          },
          {
            status: 'failed',
            error_message: 'Cancelled',
            completed_at: new Date(),
          },
        );

        return result.affected || 0;
      }

      private getPriorityValue(
        priority: 'low' | 'normal' | 'high' | 'urgent',
      ): number {
        switch (priority) {
          case 'urgent':
            return 10;
          case 'high':
            return 5;
          case 'normal':
            return 0;
          case 'low':
            return -5;
          default:
            return 0;
        }
      }
    }