gongxiangp2/lib/psd-processor.ts

import { readPsd } from 'ag-psd'
import sharp from 'sharp'
import fs from 'fs/promises'

interface PsdProcessResult {
  success: boolean
  previewPath?: string
  width?: number
  height?: number
  error?: string
}

/**
 * 从PSD文件生成预览图
 * @param psdFilePath PSD文件路径
 * @param outputPath 输出预览图路径
 * @param maxSize 最大尺寸（宽或高），默认800px
 * @param maxHeight 最大高度限制，长图裁剪，默认1200px
 * @returns 处理结果
 */
export async function generatePsdPreview(
  psdFilePath: string,
  outputPath: string,
  maxSize: number = 800,
  maxHeight: number = 1200
): Promise<PsdProcessResult> {
  try {
    // 读取PSD文件
    const psdBuffer = await fs.readFile(psdFilePath)
    
    // 解析PSD
    const psd = readPsd(psdBuffer, {
      skipLayerImageData: true, // 跳过图层数据，只读取合成图像
      skipThumbnail: false
    })

    if (!psd) {
      return {
        success: false,
        error: 'Failed to parse PSD file'
      }
    }

    // 获取PSD的宽高
    const width = psd.width || 0
    const height = psd.height || 0

    if (width === 0 || height === 0) {
      return {
        success: false,
        error: 'Invalid PSD dimensions'
      }
    }

    // 如果PSD有缩略图，优先使用缩略图
    if (psd.imageData) {
      const imageData = psd.imageData
      const channels = 4 // RGBA
      
      // 将PSD图像数据转换为Buffer
      const rawBuffer = Buffer.from(imageData.data)

      // 创建Sharp实例
      let sharpInstance = sharp(rawBuffer, {
        raw: {
          width: imageData.width,
          height: imageData.height,
          channels: channels
        }
      })

      // 如果是长图（高度超过maxHeight），先裁剪顶部区域
      if (imageData.height > maxHeight) {
        console.log(`[PSD] 检测到长图 ${imageData.width}x${imageData.height}，裁剪到顶部${maxHeight}px`)
        sharpInstance = sharpInstance.extract({
          left: 0,
          top: 0,
          width: imageData.width,
          height: maxHeight
        })
      }

      // 然后进行缩放处理
      await sharpInstance
        .resize(maxSize, maxSize, {
          fit: 'inside',
          withoutEnlargement: true
        })
        .jpeg({
          quality: 90,
          mozjpeg: true
        })
        .toFile(outputPath)

      return {
        success: true,
        previewPath: outputPath,
        width,
        height
      }
    }

    return {
      success: false,
      error: 'No image data found in PSD file'
    }
  } catch (error) {
    console.error('Error generating PSD preview:', error)
    return {
      success: false,
      error: error instanceof Error ? error.message : 'Unknown error'
    }
  }
}

/**
 * 检查文件是否为PSD格式
 * @param filePath 文件路径
 * @returns 是否为PSD文件
 */
export async function isPsdFile(filePath: string): Promise<boolean> {
  try {
    const buffer = await fs.readFile(filePath, { encoding: null })
    // PSD文件签名：8BPS
    return buffer.length > 4 && 
           buffer[0] === 0x38 && // '8'
           buffer[1] === 0x42 && // 'B'
           buffer[2] === 0x50 && // 'P'
           buffer[3] === 0x53    // 'S'
  } catch {
    return false
  }
}

/**
 * 从文件扩展名判断是否为PSD
 * @param filename 文件名
 * @returns 是否为PSD文件
 */
export function hasPsdExtension(filename: string): boolean {
  return filename.toLowerCase().endsWith('.psd')
}