import type { NextApiRequest } from 'next'
import { IncomingForm, File as FormidableFile } from 'formidable'
import type { Files } from 'formidable'
import fs from 'fs'
import type { ParseResult, UploadedFile } from './types'

const MAX_FILE_SIZE = 50 * 1024 * 1024 // 50MB

export async function parseFileFromMultipartRequest(req: NextApiRequest): Promise<UploadedFile | null> {
  const form = new IncomingForm({ maxFileSize: MAX_FILE_SIZE, keepExtensions: true })
  const parseResult = await new Promise<ParseResult>((resolve, reject) => {
    form.parse(req, (err, fields, files) => {
      if (err) {
        console.error('Formidable parse error:', err)
        reject(err)
        return
      }
      resolve({ fields, files })
    })
  })
  return getFirstFile(parseResult.files, 'file')
}

function getFirstFile(files: Files, fieldName: string): FormidableFile | null {
  const value = files[fieldName]
  if (!value) {
    return null
  }
  if (Array.isArray(value)) {
    const first = value[0]
    return first ?? null
  }
  return value
}

export function safeUnlink(filepath: string): void {
  try {
    fs.unlinkSync(filepath)
  } catch (unlinkError) {
    console.error('Error deleting temp file:', unlinkError)
  }
}