import { Credentials, CredentialsArray } from '../typings'

function validateCredentials(creds: Credentials) {
  if (typeof creds === 'string') {
    if (creds.includes(':') === false) {
      throw new TypeError(
        'auth must have `:` (user:password) when providing a string'
      )
    }
    return
  }
  if (!Array.isArray(creds)) {
    throw new Error('credentials should have been transformed')
  }
  if (typeof creds[0] !== 'string') {
    throw new TypeError('auth option `user` must be a string')
  }
  if (typeof creds[1] !== 'string') {
    throw new TypeError('auth option `pass` must be a string')
  }
  if (creds.length > 2) {
    throw new Error('auth option can only have two keys `[user, pass]`')
  }
}

function fromStringToCredentials(creds: string) {
  const index = creds.indexOf(':')
  return [creds.substr(0, index), creds.substr(index + 1)]
}

function ensureLengthTwo(creds: CredentialsArray) {
  if (creds.length === 1) {
    if (process.env.NODE_ENV !== 'production') {
      console.warn('giving no password for user request')
    }

    creds.push('')
  }
}

export function toAuth(creds: Credentials = ['', '']) {
  if (process.env.NODE_ENV !== 'production') {
    validateCredentials(creds)
  }

  if (typeof creds === 'string' && creds.includes(':') === true) {
    return fromStringToCredentials(creds)
  }

  ensureLengthTwo(creds as CredentialsArray)
  const authString = (creds as CredentialsArray).join(':')
  const buffer = Buffer.from(authString)
  return `Basic ${buffer.toString('base64')}`
}