import express, { type Request, type Response } from 'express'
import multer from 'multer'
import path from 'path'
import fs from 'fs/promises'
import { existsSync } from 'fs'
import { asyncHandler } from '../../utils/asyncHandler.js'
import { successResponse } from '../../utils/response.js'
import { resolveNotebookPath } from '../../utils/pathSafety.js'
import { getUniqueFilename } from '../../utils/file.js'
import { formatTimestamp } from '../../../shared/utils/date.js'
import { getTempDir } from '../../utils/tempDir.js'
import {
  createJobContext,
  spawnPythonScript,
  findImageDestinations,
  applyReplacements,
  cleanupJob,
  getScriptPath,
  ensureScriptExists,
} from './documentParser.js'
import type { ImageReplacement } from './documentParser.js'
import { ValidationError, InternalError } from '../../../shared/errors/index.js'
import { logger } from '../../utils/logger.js'

const router = express.Router()

const tempDir = getTempDir()

const upload = multer({ 
  dest: tempDir,
  limits: {
    fileSize: 50 * 1024 * 1024
  }
})

router.post(
  '/parse',
  upload.single('file'),
  asyncHandler(async (req: Request, res: Response) => {
    if (!req.file) {
      throw new ValidationError('File is required')
    }

    const { targetPath } = req.body as { targetPath?: string }
    if (!targetPath) {
      await fs.unlink(req.file.path).catch(() => {})
      throw new ValidationError('Target path is required')
    }

    let fullTargetPath: string
    try {
      const resolved = resolveNotebookPath(targetPath)
      fullTargetPath = resolved.fullPath
    } catch (error) {
      await fs.unlink(req.file.path).catch(() => {})
      throw error
    }

    const scriptPath = getScriptPath('mineru', 'mineru_parser.py')
    if (!ensureScriptExists(scriptPath)) {
      await fs.unlink(req.file.path).catch(() => {})
      throw new InternalError('Parser script not found')
    }

    processPdfInBackground(req.file.path, fullTargetPath, path.dirname(scriptPath))
      .catch(err => {
        logger.error('Background PDF processing failed:', err)
        fs.writeFile(fullTargetPath, `# 解析失败\n\n> 错误信息: ${err.message}`, 'utf-8').catch(() => {})
      })

    successResponse(res, {
      message: 'PDF upload successful. Parsing started in background.',
      status: 'processing'
    })
  }),
)

async function processPdfInBackground(filePath: string, targetPath: string, cwd: string) {
  try {
    const output = await spawnPythonScript({
      scriptPath: 'mineru_parser.py',
      args: [filePath],
      cwd,
    })

    const match = output.match(/JSON_RESULT:(.*)/)
    if (!match) {
      throw new Error('Failed to parse Python script output: JSON_RESULT not found')
    }

    const result = JSON.parse(match[1])
    const markdownPath = result.markdown_file
    const outputDir = result.output_dir

    if (!existsSync(markdownPath)) {
      throw new Error('Markdown result file not found')
    }

    let mdContent = await fs.readFile(markdownPath, 'utf-8')

    const imagesDir = path.join(outputDir, 'images')
    if (existsSync(imagesDir)) {
      const jobContext = await createJobContext('pdf_images')

      const destinations = findImageDestinations(mdContent)
      const replacements: ImageReplacement[] = []

      for (const dest of destinations) {
        const originalSrc = dest.url
        if (!originalSrc) continue

        const possibleFilenames = [originalSrc, path.basename(originalSrc)]
        let foundFile: string | null = null

        for (const fname of possibleFilenames) {
          const localPath = path.join(imagesDir, fname)
          if (existsSync(localPath)) {
            foundFile = localPath
            break
          }

          const directPath = path.join(outputDir, originalSrc)
          if (existsSync(directPath)) {
            foundFile = directPath
            break
          }
        }

        if (foundFile) {
          const ext = path.extname(foundFile)
          const baseName = formatTimestamp(jobContext.now)
          const newFilename = await getUniqueFilename(jobContext.destImagesDir, baseName, ext)
          const newPath = path.join(jobContext.destImagesDir, newFilename)
          await fs.copyFile(foundFile, newPath)
          replacements.push({
            start: dest.start,
            end: dest.end,
            original: originalSrc,
            replacement: `${jobContext.imagesSubDir}/${newFilename}`
          })
        }
      }

      mdContent = applyReplacements(mdContent, replacements)
    }

    await fs.writeFile(targetPath, mdContent, 'utf-8')
    await fs.unlink(markdownPath).catch(() => {})

    if (outputDir && outputDir.includes('temp')) {
      await fs.rm(outputDir, { recursive: true, force: true }).catch(() => {})
    }
  } finally {
    await fs.unlink(filePath).catch(() => {})
  }
}

export default router