import { IncomingMessage } from 'http'
import { NextApiRequest } from '../shared/lib/utils'
import { PaginationArgumentError } from '../stdlib/errors'

export * from './middleware'
export * from './auth-sessions'
export * from './auth-utils'
export * from './passport-adapter'
export * from './resolver'

export function isLocalhost(req: NextApiRequest | IncomingMessage): boolean {
  let { host } = req.headers
  let localhost = false
  if (host) {
    host = host.split(':')[0]
    localhost = host === 'localhost'
  }
  return localhost
}

export type PaginateArgs<QueryResult> = {
  skip?: number
  take?: number
  maxTake?: number
  count: () => Promise<number>
  query: (args: { skip: number; take: number }) => Promise<QueryResult>
}

const isInteger = (value: unknown) =>
  typeof value === 'number' && value % 1 === 0

export async function paginate<QueryResult>({
  skip = 0,
  take = 0,
  maxTake = 250,
  count: countQuery,
  query,
}: PaginateArgs<QueryResult>) {
  if (!isInteger(skip)) {
    throw new PaginationArgumentError('`skip` argument must be a integer')
  }
  if (!isInteger(take)) {
    throw new PaginationArgumentError('`take` argument must be a integer')
  }
  if (!isInteger(maxTake)) {
    throw new PaginationArgumentError('`maxTake` argument must be a integer')
  }
  if (typeof countQuery !== 'function') {
    throw new PaginationArgumentError('`count` argument must be a function')
  }
  if (typeof query !== 'function') {
    throw new PaginationArgumentError('`query` argument must be a function')
  }
  if (skip < 0) {
    throw new PaginationArgumentError(
      '`skip` argument must be a positive number'
    )
  }
  if (take < 0) {
    throw new PaginationArgumentError(
      '`take` argument must be a positive number'
    )
  }
  if (take > maxTake) {
    throw new PaginationArgumentError(
      '`take` argument must less than `maxTake` which is currently ' + maxTake
    )
  }

  const [count, items] = await Promise.all([
    countQuery(),
    query({ skip, take }),
  ])

  const hasMore = skip + take < count
  const nextPage = hasMore ? { take, skip: skip + take } : null

  return {
    items,
    nextPage,
    hasMore,
    count,
  }
}