/**
 * PDF素材上传处理工具
 * 
 * 专门处理品牌VI灵感（PDF）类型的上传逻辑
 * 包括：PDF预览图提取、文件处理等
 */

import { promises as fs } from 'fs'
import { generatePdfPreview, isPdfFile } from './pdf-processor'
import { uploadToS3 } from './s3'

/**
 * 生成唯一文件名
 */
function generateUniqueFilename(prefix: string, ext: string): string {
  const timestamp = Date.now()
  const random = require('crypto').randomBytes(8).toString('hex')
  return `${prefix}-${timestamp}-${random}${ext}`
}

/**
 * PDF上传处理结果
 */
export interface PdfUploadResult {
  success: boolean
  previewUrl?: string
  error?: string
}

/**
 * 处理PDF文件上传
 * 从PDF文件提取第一页作为预览图
 * 
 * @param pdfFilePath PDF文件路径
 * @param existingPreviewUrl 已存在的预览图URL（如果用户手动上传了预览图）
 * @returns 处理结果
 */
export async function processPdfUpload(
  pdfFilePath: string,
  existingPreviewUrl?: string
): Promise<PdfUploadResult> {
  try {
    // 如果已经有预览图，直接返回
    if (existingPreviewUrl && existingPreviewUrl.trim()) {
      return {
        success: true,
        previewUrl: existingPreviewUrl,
      }
    }

    // 检查是否为PDF文件
    const isPdf = await isPdfFile(pdfFilePath)
    if (!isPdf) {
      return {
        success: false,
        error: '文件不是有效的PDF格式',
      }
    }

    console.log('[PDF Upload] PDF file detected, extracting first page as preview...')
    console.log('[PDF Upload] PDF file path:', pdfFilePath)
    
    // 提取PDF第一页作为预览图
    const pdfPreviewResult = await generatePdfPreview(pdfFilePath)
    
    console.log('[PDF Upload] PDF预览图提取结果:', {
      success: pdfPreviewResult.success,
      hasPreviewPath: !!pdfPreviewResult.previewPath,
      previewPath: pdfPreviewResult.previewPath,
      error: pdfPreviewResult.error,
      width: pdfPreviewResult.width,
      height: pdfPreviewResult.height
    })
    
    if (!pdfPreviewResult.success || !pdfPreviewResult.previewPath) {
      const errorMsg = pdfPreviewResult.error || 'PDF预览图提取失败'
      console.error('[PDF Upload] ❌ PDF预览图提取失败:', errorMsg)
      return {
        success: false,
        error: errorMsg,
      }
    }

    try {
      // 读取预览图并上传到S3
      const previewBuffer = await fs.readFile(pdfPreviewResult.previewPath)
      const previewFilename = generateUniqueFilename('pdf-preview', '.jpg')
      const previewUrl = await uploadToS3(previewBuffer, previewFilename, 'image/jpeg')
      
      console.log('[PDF Upload] PDF preview extracted and uploaded:', previewUrl)
      
      // 清理临时预览图文件
      await fs.unlink(pdfPreviewResult.previewPath).catch(() => {})
      
      return {
        success: true,
        previewUrl,
      }
    } catch (uploadError) {
      console.error('[PDF Upload] Failed to upload PDF preview:', uploadError)
      return {
        success: false,
        error: uploadError instanceof Error ? uploadError.message : '上传预览图失败',
      }
    }
  } catch (error) {
    console.error('[PDF Upload] Error processing PDF upload:', error)
    return {
      success: false,
      error: error instanceof Error ? error.message : 'PDF处理失败',
    }
  }
}