// Shared multer middleware for the two admin image-upload routes:
// POST /admin/posts/upload (posts.router.js) and POST /admin/uploads
// (uploads.router.js). It lived inline in admin.routes.js while both routes did;
// the PR 3 split put them in different files, so the config moved here rather
// than being duplicated — one upload directory, one mimetype allowlist.
//
// Kept in this directory on purpose: UPLOAD_DIR is resolved relative to
// __dirname, so moving the file to another folder would silently repoint the
// upload directory.

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

const UPLOAD_DIR =
  process.env.UPLOAD_DIR || path.join(__dirname, '..', '..', '..', '..', 'uploads')
fs.mkdirSync(UPLOAD_DIR, { recursive: true })

// Whitelisted image mimetypes → the extension we store the file under. The
// stored extension is derived from this map (keyed by the accepted mimetype),
// never from originalname — so a spoofed `Content-Type: image/png` paired with
// `originalname: x.html` can never land an executable .html file in /uploads.
const MIME_EXT = {
  'image/png': '.png',
  'image/jpeg': '.jpg',
  'image/gif': '.gif',
  'image/webp': '.webp',
  'image/avif': '.avif',
}

const storage = multer.diskStorage({
  destination: (req, file, cb) => cb(null, UPLOAD_DIR),
  filename: (req, file, cb) => {
    const ext = MIME_EXT[file.mimetype] || ''
    cb(null, `${Date.now()}-${crypto.randomBytes(8).toString('hex')}${ext}`)
  },
})
const upload = multer({
  storage,
  limits: { fileSize: 8 * 1024 * 1024 },
  fileFilter: (req, file, cb) => {
    // Single source of truth: only mimetypes we can map to a safe extension pass.
    if (MIME_EXT[file.mimetype]) cb(null, true)
    else cb(new Error('Only image uploads are allowed'))
  },
})

module.exports = { upload, UPLOAD_DIR, MIME_EXT }