import { Injectable } from '@nestjs/common';
import sharp from 'sharp';

/**
 * Sharp 图片处理服务
 * 基于 NestJS 官方示例实现
 * 参考: https://docs.nestjs.cn/fundamentals/dependency-injection
 * 对应 Java: ImageUtils
 */
@Injectable()
export class SharpService {
  /**
   * 获取 sharp 实例
   */
  getSharp() {
    return sharp;
  }

  /**
   * 调整图片大小
   */
  async resize(
    input: Buffer | string,
    width: number,
    height?: number,
    options?: sharp.ResizeOptions,
  ): Promise<Buffer> {
    return sharp(input).resize(width, height, options).toBuffer();
  }

  /**
   * 生成缩略图
   */
  async thumbnail(
    input: Buffer | string,
    size: number,
    options?: sharp.ResizeOptions,
  ): Promise<Buffer> {
    return sharp(input)
      .resize(size, size, { ...options, fit: 'cover' })
      .toBuffer();
  }

  /**
   * 压缩图片
   */
  async compress(
    input: Buffer | string,
    quality: number = 80,
  ): Promise<Buffer> {
    return sharp(input).jpeg({ quality }).toBuffer();
  }

  /**
   * 转换图片格式
   */
  async convert(
    input: Buffer | string,
    format: 'jpeg' | 'png' | 'webp' | 'gif' | 'tiff',
  ): Promise<Buffer> {
    return sharp(input).toFormat(format).toBuffer();
  }

  /**
   * 获取图片信息
   */
  async metadata(input: Buffer | string): Promise<sharp.Metadata> {
    return sharp(input).metadata();
  }

  /**
   * 裁剪图片
   */
  async crop(
    input: Buffer | string,
    left: number,
    top: number,
    width: number,
    height: number,
  ): Promise<Buffer> {
    return sharp(input).extract({ left, top, width, height }).toBuffer();
  }

  /**
   * 旋转图片
   */
  async rotate(input: Buffer | string, angle: number): Promise<Buffer> {
    return sharp(input).rotate(angle).toBuffer();
  }

  /**
   * 翻转图片
   */
  async flip(input: Buffer | string): Promise<Buffer> {
    return sharp(input).flip().toBuffer();
  }

  /**
   * 镜像图片
   */
  async flop(input: Buffer | string): Promise<Buffer> {
    return sharp(input).flop().toBuffer();
  }

  /**
   * 模糊图片
   */
  async blur(input: Buffer | string, sigma: number): Promise<Buffer> {
    return sharp(input).blur(sigma).toBuffer();
  }

  /**
   * 锐化图片
   */
  async sharpen(
    input: Buffer | string,
    sigma?: number,
    flat?: number,
    jagged?: number,
  ): Promise<Buffer> {
    return sharp(input).sharpen(sigma, flat, jagged).toBuffer();
  }

  /**
   * 调整亮度
   */
  async modulate(
    input: Buffer | string,
    brightness: number = 1,
  ): Promise<Buffer> {
    return sharp(input).modulate({ brightness }).toBuffer();
  }

  /**
   * 调整对比度
   */
  async linear(input: Buffer | string, a: number, b: number): Promise<Buffer> {
    return sharp(input).linear(a, b).toBuffer();
  }

  /**
   * 添加水印
   */
  async composite(
    input: Buffer | string,
    overlay: Buffer | string,
    options?: sharp.OverlayOptions,
  ): Promise<Buffer> {
    return sharp(input)
      .composite([{ input: overlay, ...options }])
      .toBuffer();
  }

  /**
   * 生成图片哈希
   */
  async hash(input: Buffer | string): Promise<string> {
    const metadata = await sharp(input).metadata();
    return `${metadata.width}x${metadata.height}-${metadata.format}`;
  }
}