// File: src/modules/ai/workers/cleanup-temp-files.worker.ts
// Change Log:
// - 2026-05-22: อัปเดตและสร้างตัวล้างไฟล์ชั่วคราว (T016) เพื่อลบไฟล์ที่หมดอายุ 24 ชม.
// - 2026-06-02: ข้าม cleanup อย่างปลอดภัยเมื่อ schema migration_review_queue ยังไม่มี temp_attachment_id

import { Injectable, Logger } from '@nestjs/common';
import { Cron, CronExpression } from '@nestjs/schedule';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import * as fs from 'fs-extra';
import { Attachment } from '../../../common/file-storage/entities/attachment.entity';
import {
  MigrationReviewQueue,
  MigrationReviewStatus,
} from '../../migration/entities/migration-review-queue.entity';

@Injectable()
export class CleanupTempFilesWorker {
  private readonly logger = new Logger(CleanupTempFilesWorker.name);
  private static readonly MISSING_TEMP_ATTACHMENT_COLUMN_MESSAGE =
    'temp_attachment_id';

  constructor(
    @InjectRepository(Attachment)
    private readonly attachmentRepository: Repository<Attachment>,
    @InjectRepository(MigrationReviewQueue)
    private readonly reviewQueueRepository: Repository<MigrationReviewQueue>
  ) {}

  /**
   * รันทุกชั่วโมงเพื่อลบไฟล์แนบชั่วคราวที่ครบ 24 ชั่วโมงและไม่ได้ถูกคอมมิต
   * ยกเว้นไฟล์ที่ถูกอ้างอิงโดยรายการที่สถานะเป็น PENDING ใน Migration Review Queue
   */
  @Cron(CronExpression.EVERY_HOUR)
  async handleCleanup(): Promise<void> {
    this.logger.log('Starting temporary files cleanup worker...');
    try {
      const oneDayAgo = new Date();
      oneDayAgo.setHours(oneDayAgo.getHours() - 24);
      const pendingAttachmentIds = await this.getPendingAttachmentIds();
      if (pendingAttachmentIds === null) {
        return;
      }
      const query = this.attachmentRepository
        .createQueryBuilder('attachment')
        .where('attachment.isTemporary = :isTemporary', { isTemporary: true })
        .andWhere('attachment.createdAt < :oneDayAgo', { oneDayAgo });
      if (pendingAttachmentIds.length > 0) {
        query.andWhere('attachment.id NOT IN (:...pendingAttachmentIds)', {
          pendingAttachmentIds,
        });
      }
      const expiredAttachments = await query.getMany();
      if (expiredAttachments.length === 0) {
        this.logger.log('No expired temporary files found.');
        return;
      }
      this.logger.log(
        `Found ${expiredAttachments.length} expired temporary files. Deleting...`
      );
      let deletedCount = 0;
      let failedCount = 0;
      for (const att of expiredAttachments) {
        try {
          if (await fs.pathExists(att.filePath)) {
            await fs.remove(att.filePath);
          }
          await this.attachmentRepository.remove(att);
          deletedCount++;
        } catch (error) {
          const errMessage = (error as Error).message;
          this.logger.error(
            `Failed to delete temporary file ID ${att.id}: ${errMessage}`
          );
          failedCount++;
        }
      }
      this.logger.log(
        `Temporary files cleanup completed. Deleted: ${deletedCount}, Failed: ${failedCount}`
      );
    } catch (err) {
      const errMsg = (err as Error).message;
      this.logger.error(
        `Error occurred during temporary files cleanup: ${errMsg}`
      );
    }
  }

  /**
   * อ่านรายการ temp attachment ที่ยังถูกใช้งานโดย migration review status=PENDING
   * ถ้า schema ยังไม่พร้อม ให้ข้าม cleanup รอบนี้เพื่อป้องกันการลบไฟล์ที่ยังถูกอ้างอิง
   */
  private async getPendingAttachmentIds(): Promise<number[] | null> {
    try {
      const pendingRecords = await this.reviewQueueRepository.find({
        select: ['tempAttachmentId'],
        where: { status: MigrationReviewStatus.PENDING },
      });
      return pendingRecords
        .map((record) => record.tempAttachmentId)
        .filter((id): id is number => id !== undefined && id !== null);
    } catch (error) {
      if (this.isMissingTempAttachmentIdColumnError(error)) {
        this.logger.warn(
          'Skipping temporary files cleanup because migration_review_queue.temp_attachment_id is missing. Apply delta specs/03-Data-and-Storage/deltas/2026-06-02-add-temp-attachment-id-to-migration-review-queue.sql first.'
        );
        return null;
      }
      throw error;
    }
  }

  private isMissingTempAttachmentIdColumnError(error: unknown): boolean {
    if (!(error instanceof Error)) {
      return false;
    }
    return error.message.includes(
      CleanupTempFilesWorker.MISSING_TEMP_ATTACHMENT_COLUMN_MESSAGE
    );
  }
}