import type {
  FastifyInstance,
  FastifyPluginCallback,
  FastifyPluginOptions,
  FastifyRequest,
} from 'fastify'
import fp from 'fastify-plugin'
import { IncomingMessage } from 'http'

const kMultipart = Symbol('multipart')

function setMultipart(
  req: FastifyRequest,
  _payload: IncomingMessage,
  done: (err: Error | null) => void,
) {
  // nothing to do, it will be done by multer in beforeHandler method
  ;(req as any)[kMultipart] = true
  done(null)
}

export function isMultipart(this: FastifyRequest): boolean {
  return (this.raw as any)[kMultipart] || false
}

const fastifyMulter: FastifyPluginCallback<FastifyPluginOptions> = (
  instance: FastifyInstance,
  _options: FastifyPluginOptions,
  done: (err?: Error) => void,
): void => {
  instance.addContentTypeParser('multipart', setMultipart)
  instance.decorateRequest('isMultipart', isMultipart)

  done()
}

const multer = fp(fastifyMulter, {
  fastify: '4.x',
  name: 'fastify-multer',
})

export default multer