import { NextApiRequest, NextApiResponse } from 'next'
import { Prisma, BookingStatus } from '@prisma/client';
import { patchBooking } from '../../../../db/index'
import {
  sendBookingConfirmed,
  sendBookingRejected,
  sendBookingCanceled,
} from '../../../../helpers/mail'
import { log } from '../../../../helpers/log'

function changedStatus(
  previous: Prisma.BookingUpdateInput,
  current: Prisma.BookingUpdateInput,
  status: BookingStatus
): boolean {
  return (
    BookingStatus.REQUESTED === previous.status &&
    current.status === status
  )
}
function wasRejected(previous: Prisma.BookingUpdateInput, current: Prisma.BookingUpdateInput): boolean {
  return changedStatus(previous, current, BookingStatus.REJECTED)
}

function wasConfirmed(previous: Prisma.BookingUpdateInput, current: Prisma.BookingUpdateInput): boolean {
  return changedStatus(previous, current, BookingStatus.CONFIRMED)
}

function wasCanceled(previous: Prisma.BookingUpdateInput, current: Prisma.BookingUpdateInput): boolean {
  return (
    [BookingStatus.REQUESTED, BookingStatus.CONFIRMED].find(s => s === previous.status)
    && current.status === BookingStatus.CANCELED
  )
}

export default async function userHandler(
  req: NextApiRequest,
  res: NextApiResponse
): Promise<void> {
  const {
    method,
    query: { uuid: uuids },
  } = req

  const uuid = Array.isArray(uuids) ? uuids[0] : uuids

  switch (method) {
    case 'PATCH':
      if (!Object.values(BookingStatus).includes(req.body.status)) {
        res
          .status(400)
          .end(
            `The attribute status can only be: ${Object.values(
              BookingStatus
            ).join(', ')}`
          )
        break
      }

      try {
        const { current, previous } = await patchBooking(uuid, req.body)

        // TODO: this should really go into the schema
        if (wasRejected(previous, current)) {
          sendBookingRejected(current)
        } else if (wasConfirmed(previous, current)) {
          sendBookingConfirmed(current)
        } else if (wasCanceled(previous, current)) {
          sendBookingCanceled(current)
        }

        res.status(200).json(current)
      } catch (error) {
        log.error('failed patch booking', error)
        res.status(400).end(`Failed to save booking: ${error.message}`)
      }
      break
    default:
      res.setHeader('Allow', ['PATCH'])
      res.status(405).end(`Method ${method} Not Allowed`)
  }
}