import { Router } from 'express'
import path from 'node:path'
import fs from 'node:fs'
import crypto from 'node:crypto'
import { fileURLToPath } from 'node:url'
import { adminAuth } from '../middleware/adminAuth.js'

const __dirname = path.dirname(fileURLToPath(import.meta.url))
const UPLOAD_DIR = path.join(__dirname, '..', '..', 'public', 'images')

export const uploadRouter = Router()
uploadRouter.use(adminAuth)

// Ensure upload directory exists
if (!fs.existsSync(UPLOAD_DIR)) {
  fs.mkdirSync(UPLOAD_DIR, { recursive: true })
}

const MAX_SIZE = 5 * 1024 * 1024 // 5MB
const ALLOWED_TYPES = ['image/jpeg', 'image/png', 'image/webp', 'image/avif']

uploadRouter.post('/', async (req, res) => {
  try {
    const contentType = req.headers['content-type'] || ''

    if (!contentType.startsWith('multipart/form-data')) {
      res.status(400).json({ error: { code: 'INVALID_CONTENT_TYPE', message: 'Expected multipart/form-data' } })
      return
    }

    // Parse multipart manually using web-standard approach
    const chunks: Buffer[] = []
    let size = 0

    for await (const chunk of req) {
      size += chunk.length
      if (size > MAX_SIZE) {
        res.status(413).json({ error: { code: 'FILE_TOO_LARGE', message: 'File must be under 5MB' } })
        return
      }
      chunks.push(chunk)
    }

    const body = Buffer.concat(chunks)
    const boundary = contentType.split('boundary=')[1]
    if (!boundary) {
      res.status(400).json({ error: { code: 'NO_BOUNDARY', message: 'Missing multipart boundary' } })
      return
    }

    // Find file data between boundaries
    const boundaryBuf = Buffer.from(`--${boundary}`)
    const parts = splitBuffer(body, boundaryBuf).filter((p) => p.length > 4)

    const files: string[] = []

    for (const part of parts) {
      const headerEnd = part.indexOf('\r\n\r\n')
      if (headerEnd === -1) continue

      const headers = part.subarray(0, headerEnd).toString()
      const fileData = part.subarray(headerEnd + 4, part.length - 2) // trim trailing \r\n

      const filenameMatch = headers.match(/filename="([^"]+)"/)
      const typeMatch = headers.match(/Content-Type:\s*(\S+)/i)
      if (!filenameMatch || !typeMatch) continue

      const mimeType = typeMatch[1]
      if (!ALLOWED_TYPES.includes(mimeType)) continue

      const ext = path.extname(filenameMatch[1]).toLowerCase() || mimeExtension(mimeType)
      const filename = `${crypto.randomBytes(16).toString('hex')}${ext}`
      const filepath = path.join(UPLOAD_DIR, filename)

      fs.writeFileSync(filepath, fileData)
      files.push(`/images/${filename}`)
    }

    if (files.length === 0) {
      res.status(400).json({ error: { code: 'NO_FILES', message: 'No valid image files found' } })
      return
    }

    res.json({ urls: files })
  } catch (err) {
    console.error('Upload failed:', err)
    res.status(500).json({ error: { code: 'UPLOAD_FAILED', message: 'File upload failed' } })
  }
})

function mimeExtension(mime: string): string {
  const map: Record<string, string> = {
    'image/jpeg': '.jpg',
    'image/png': '.png',
    'image/webp': '.webp',
    'image/avif': '.avif',
  }
  return map[mime] || '.jpg'
}

function splitBuffer(buf: Buffer, delimiter: Buffer): Buffer[] {
  const parts: Buffer[] = []
  let start = 0
  while (true) {
    const idx = buf.indexOf(delimiter, start)
    if (idx === -1) {
      if (start < buf.length) parts.push(buf.subarray(start))
      break
    }
    if (idx > start) parts.push(buf.subarray(start, idx))
    start = idx + delimiter.length
  }
  return parts
}