import { Injectable, BadRequestException } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { OssService } from '../oss/oss.service';
import * as fs from 'fs';
import * as path from 'path';
import { randomBytes } from 'crypto';

@Injectable()
export class UploadService {
  private readonly uploadDir: string;
  private readonly useOss: boolean;

  constructor(
    private configService: ConfigService,
    private ossService: OssService,
  ) {
    // 本地上传文件存储目录（作为 COS 的备用方案）
    this.uploadDir = path.join(process.cwd(), 'uploads');

    // 确保本地上传目录存在
    if (!fs.existsSync(this.uploadDir)) {
      fs.mkdirSync(this.uploadDir, { recursive: true });
    }

    // 检查是否使用 COS
    this.useOss = this.ossService.isEnabled();

    if (this.useOss) {
      console.log('文件上传将使用腾讯云 COS');
    } else {
      console.log('文件上传将使用本地存储，目录:', this.uploadDir);
    }
  }

  async uploadFile(
    file: Express.Multer.File,
    tenantId?: number,
    userId?: number,
  ): Promise<{ url: string; fileName: string; size: number }> {
    if (!file) {
      throw new BadRequestException('文件不存在');
    }

    // 优先使用 COS
    if (this.useOss) {
      return this.uploadToOss(file, tenantId, userId);
    }

    // 备用方案：本地存储
    return this.uploadToLocal(file, tenantId, userId);
  }

  /**
   * 上传到腾讯云 COS
   */
  private async uploadToOss(
    file: Express.Multer.File,
    tenantId?: number,
    userId?: number,
  ): Promise<{ url: string; fileName: string; size: number }> {
    try {
      const result = await this.ossService.uploadFile(
        file.buffer,
        file.originalname,
        tenantId,
        userId,
      );

      return {
        url: result.url,
        fileName: result.fileName,
        size: file.size,
      };
    } catch (error: any) {
      console.error('COS 上传失败，尝试本地存储:', error.message);
      // COS 失败时回退到本地存储
      return this.uploadToLocal(file, tenantId, userId);
    }
  }

  /**
   * 上传到本地存储
   */
  private async uploadToLocal(
    file: Express.Multer.File,
    tenantId?: number,
    userId?: number,
  ): Promise<{ url: string; fileName: string; size: number }> {
    // 生成唯一文件名
    const fileExt = path.extname(file.originalname);
    const uniqueId = randomBytes(16).toString('hex');
    const fileName = `${uniqueId}${fileExt}`;

    // 根据租户ID和用户ID创建目录结构：uploads/tenantId/userId/
    let targetDir = this.uploadDir;
    if (tenantId) {
      targetDir = path.join(targetDir, `tenant_${tenantId}`);
      if (!fs.existsSync(targetDir)) {
        fs.mkdirSync(targetDir, { recursive: true });
      }

      if (userId) {
        targetDir = path.join(targetDir, `user_${userId}`);
        if (!fs.existsSync(targetDir)) {
          fs.mkdirSync(targetDir, { recursive: true });
        }
      }
    }

    // 文件保存路径
    const filePath = path.join(targetDir, fileName);

    // 保存文件
    fs.writeFileSync(filePath, file.buffer);

    // 生成访问URL
    // 格式：/api/uploads/tenantId/userId/fileName 或 /api/uploads/fileName
    let urlPath = '/api/uploads';
    if (tenantId) {
      urlPath += `/tenant_${tenantId}`;
      if (userId) {
        urlPath += `/user_${userId}`;
      }
    }
    urlPath += `/${fileName}`;

    return {
      url: urlPath,
      fileName: file.originalname,
      size: file.size,
    };
  }
}