import { NextRequest, NextResponse } from 'next/server'
import { writeFile, mkdir } from 'fs/promises'
import path from 'path'
import { randomUUID } from 'crypto'
import { auth } from '@/auth'
import { writeUploadMeta } from '@/lib/upload-access'

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

export async function POST(request: NextRequest) {
  try {
    const session = await auth()
    if (!session?.user?.id) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    const userId = session.user.id
    const formData = await request.formData()
    const file = formData.get('file') as File

    if (!file) {
      return NextResponse.json({ error: 'No file uploaded' }, { status: 400 })
    }

    if (!ALLOWED_TYPES.includes(file.type)) {
      return NextResponse.json({ error: 'Invalid file type' }, { status: 400 })
    }

    if (file.size > MAX_SIZE) {
      return NextResponse.json({ error: 'File too large (max 5MB)' }, { status: 400 })
    }

    const buffer = Buffer.from(await file.arrayBuffer())
    let ext = path.extname(file.name).toLowerCase()
    if (!['.jpg', '.jpeg', '.png', '.gif', '.webp'].includes(ext)) {
      const mimeToExt: Record<string, string> = {
        'image/jpeg': '.jpg',
        'image/png': '.png',
        'image/gif': '.gif',
        'image/webp': '.webp',
      }
      ext = mimeToExt[file.type] || '.png'
    }

    const filename = `${randomUUID()}${ext}`
    // Ownership in path: /uploads/notes/{userId}/{filename}
    const relativeUnderNotes = `${userId}/${filename}`
    const uploadDir = path.join(process.cwd(), 'data', 'uploads', 'notes', userId)
    await mkdir(uploadDir, { recursive: true })

    const filePath = path.join(uploadDir, filename)
    await writeFile(filePath, buffer)
    await writeUploadMeta(relativeUnderNotes, userId)

    const url = `/uploads/notes/${relativeUnderNotes}`

    return NextResponse.json({
      success: true,
      url,
    })
  } catch (error) {
    console.error('[upload]', error)
    return NextResponse.json(
      { error: 'Failed to upload file' },
      { status: 500 },
    )
  }
}