request.js

const identity = require('ramda/src/identity')
const qs       = require('qs')

const Task = require('./task')

const parseHeaders = identity

const request = opts => Task((reject, resolve) => {
  var {
    data,
    deserialize = identity,
    headers = {},
    json = false,
    method = 'GET',
    onUploadProgress,
    serialize = identity,
    url
  } = opts

  if (json) {
    deserialize = JSON.parse
    serialize   = JSON.stringify
    headers['Content-Type'] = 'application/json'
  }

  if (method === 'GET' && data) url = `${url}?${qs.stringify(data)}`

  const xhr = new XMLHttpRequest()

  xhr.addEventListener('error', reject)

  xhr.addEventListener('load', () => {
    resolve({
      body:    deserialize(xhr.response),
      headers: parseHeaders(xhr.getResponseHeader('Content-Length')),
      status:  xhr.status
    })
  })

  if (xhr.upload && typeof onUploadProgress === 'function')
    xhr.upload.addEventListener('progress', onUploadProgress)

  xhr.open(method, url)

  for (var key in headers) xhr.setRequestHeader(key, headers[key])

  if (method !== 'GET' && data) {
    xhr.send(serialize(data))
  } else {
    xhr.send()
  }
})

module.exports = request