const fs = require('fs')
const path = require('path')

function decodeBase64Buffer(data) {
  if (!data || typeof data !== 'string') {
    throw new Error('داده فایل نامعتبر است')
  }
  const payload = data.includes(',') ? data.split(',')[1] : data
  if (!payload) {
    throw new Error('داده base64 خالی است')
  }
  return Buffer.from(payload, 'base64')
}

async function saveBase64PostFiles(files, imageDir, videoDir, { allowEmpty = false } = {}) {
  if (!Array.isArray(files) || files.length === 0) {
    if (allowEmpty) return []
    throw new Error('هیچ فایلی ارسال نشده است')
  }

  return Promise.all(
    files.map(async (file, index) => {
      if (!file?.data || !file?.type) {
        throw new Error(`فایل ${index + 1} ناقص است`)
      }

      const buffer = decodeBase64Buffer(file.data)
      if (!buffer.length) {
        throw new Error(`فایل ${index + 1} خالی است`)
      }

      const dir = String(file.type).startsWith('video/') ? videoDir : imageDir
      const safeName = path
        .basename(file.name || `upload-${index}`)
        .replace(/[^\w.\-()+\s]/g, '_')
      const filename = `${Date.now()}-${index}-${safeName}`
      const filePath = path.join(dir, filename)

      await fs.promises.writeFile(filePath, buffer)

      return {
        path: filePath,
        filename,
        mimetype: file.type,
      }
    })
  )
}

module.exports = {
  decodeBase64Buffer,
  saveBase64PostFiles,
}