const crypto = require('crypto')
const fs = require('fs')
const path = require('path')
const multer = require('multer')
const { ok, fail } = require('./http')

const uploadDir = process.env.UPLOAD_DIR
  ? path.resolve(process.env.UPLOAD_DIR)
  : path.join(__dirname, '..', 'public', 'uploads')

const IMAGE_RE = /^image\/(png|jpe?g|webp)$/i
const VIDEO_RE = /^video\/(mp4|quicktime|webm)$/i

const storage = multer.diskStorage({
  destination(req, file, cb) {
    fs.mkdirSync(uploadDir, { recursive: true })
    cb(null, uploadDir)
  },
  filename(req, file, cb) {
    const ext = path.extname(file.originalname || '').toLowerCase() || '.bin'
    cb(null, `${Date.now().toString(36)}${crypto.randomBytes(3).toString('hex')}${ext}`)
  }
})

function uploader(options) {
  const imagesOnly = !!(options && options.imagesOnly)
  const middleware = multer({
    storage,
    limits: { fileSize: imagesOnly ? 5 * 1024 * 1024 : 80 * 1024 * 1024 },
    fileFilter(req, file, cb) {
      const mime = file.mimetype || ''
      const allowed = IMAGE_RE.test(mime) || (!imagesOnly && VIDEO_RE.test(mime))
      cb(null, allowed)
    }
  }).single('file')

  return (req, res) => {
    middleware(req, res, (error) => {
      if (error) {
        const tooLarge = error.code === 'LIMIT_FILE_SIZE'
        return fail(res, 400, tooLarge ? (imagesOnly ? '图片需小于 5MB' : '文件需小于 80MB') : '上传失败')
      }
      if (!req.file) {
        return fail(res, 400, imagesOnly ? '仅支持 png/jpg/webp 图片' : '仅支持 png/jpg/webp 图片或 mp4/mov/webm 视频')
      }
      const type = VIDEO_RE.test(req.file.mimetype) ? 'video' : 'image'
      ok(res, { url: `/static/uploads/${req.file.filename}`, type })
    })
  }
}

module.exports = { uploader, uploadDir }