// @flow

import fetch from 'node-fetch'

import log from './log'

import type { Config, BotContext } from './types'

export const createContext = (config: Config): BotContext => {
  const callMainframe = (endpoint: string, data: ?Object = {}) => {
    const url = config.mainframe_url + endpoint
    log('call %s', url)
    return fetch(url, {
      body: JSON.stringify(data),
      method: 'post',
      headers: {
        Authorization: `Mainframe-Bot ${config.mainframe_secret}`,
        'Content-Type': 'application/json',
      },
    }).then(res => {
      if (res.ok) {
        return res.status === 204 ? null : res.json()
      }

      const error: Object = new Error(res.statusText)
      error.status = res.status
      error.enpoint = endpoint
      error.data = data

      if (res.headers.get('Content-Type').indexOf('application/json') !== -1) {
        return res.json().then(json => {
          error.response = json
          throw error
        })
      } else {
        return res.text().then(text => {
          error.response = text
          throw error
        })
      }
    })
  }

  const sendMessage = (payload: {
    conversation_id: string,
    message?: string,
    data?: Object,
  }) => callMainframe('/send_message', payload)

  const setupSubscription = (payload: {
    subscription_token: string,
    label: string,
  }) => callMainframe('/setup_subscription', payload)

  const editSubscription = (payload: {
    subscription_token: string,
    label?: string,
  }) => callMainframe('/edit_subscription', payload)

  return {
    config,
    callMainframe,
    sendMessage,
    setupSubscription,
    editSubscription,
  }
}