'use strict';

var utils = require('./../utils');
var buildURL = require('./../helpers/buildURL');
var parseHeaders = require('./../helpers/parseHeaders');
var transformData = require('./../helpers/transformData');
var isURLSameOrigin = require('./../helpers/isURLSameOrigin');
var btoa = (typeof window !== 'undefined' && window.btoa) || require('./../helpers/btoa');
var settle = require('../helpers/settle');

module.exports = function xhrAdapter(resolve, reject, config) {
  var requestData = config.data;
  var requestHeaders = config.headers;

  if (utils.isFormData(requestData)) {
    delete requestHeaders['Content-Type']; // Let the browser set it
  }

  var request = new XMLHttpRequest();
  var loadEvent = 'onreadystatechange';
  var xDomain = false;

  // For IE 8/9 CORS support
  // Only supports POST and GET calls and doesn't returns the response headers.
  // DON'T do this for testing b/c XMLHttpRequest is mocked, not XDomainRequest.
  if (process.env.NODE_ENV !== 'test' && typeof window !== 'undefined' && window.XDomainRequest && !('withCredentials' in request) && !isURLSameOrigin(config.url)) {
    request = new window.XDomainRequest();
    loadEvent = 'onload';
    xDomain = true;
    request.onprogress = function handleProgress() {};
    request.ontimeout = function handleTimeout() {};
  }

  // HTTP basic authentication
  if (config.auth) {
    var username = config.auth.username || '';
    var password = config.auth.password || '';
    requestHeaders.Authorization = 'Basic ' + btoa(username + ':' + password);
  }

  request.open(config.method.toUpperCase(), buildURL(config.url, config.params, config.paramsSerializer), true);

  // Set the request timeout in MS
  request.timeout = config.timeout;

  // Listen for ready state
  request[loadEvent] = function handleLoad() {
    if (!request || (request.readyState !== 4 && !xDomain)) {
      return;
    }

    // The request errored out and we didn't get a response, this will be
    // handled by onerror instead
    if (request.status === 0) {
      return;
    }

    // Prepare the response
    var responseHeaders = 'getAllResponseHeaders' in request ? parseHeaders(request.getAllResponseHeaders()) : null;
    var responseData = !config.responseType || config.responseType === 'text' ? request.responseText : request.response;
    var response = {
      data: transformData(
        responseData,
        responseHeaders,
        config.transformResponse
      ),
      // IE sends 1223 instead of 204 (https://github.com/mzabriskie/axios/issues/201)
      status: request.status === 1223 ? 204 : request.status,
      statusText: request.status === 1223 ? 'No Content' : request.statusText,
      headers: responseHeaders,
      config: config,
      request: request
    };

    settle(resolve, reject, response);

    // Clean up request
    request = null;
  };

  // Handle low level network errors
  request.onerror = function handleError() {
    // Real errors are hidden from us by the browser
    // onerror should only fire if it's a network error
    reject(new Error('Network Error'));

    // Clean up request
    request = null;
  };

  // Handle timeout
  request.ontimeout = function handleTimeout() {
    var err = new Error('timeout of ' + config.timeout + 'ms exceeded');
    err.timeout = config.timeout;
    err.code = 'ECONNABORTED';
    reject(err);

    // Clean up request
    request = null;
  };

  // Add xsrf header
  // This is only done if running in a standard browser environment.
  // Specifically not if we're in a web worker, or react-native.
  if (utils.isStandardBrowserEnv()) {
    var cookies = require('./../helpers/cookies');

    // Add xsrf header
    var xsrfValue = config.withCredentials || isURLSameOrigin(config.url) ?
        cookies.read(config.xsrfCookieName) :
        undefined;

    if (xsrfValue) {
      requestHeaders[config.xsrfHeaderName] = xsrfValue;
    }
  }

  // Add headers to the request
  if ('setRequestHeader' in request) {
    utils.forEach(requestHeaders, function setRequestHeader(val, key) {
      if (typeof requestData === 'undefined' && key.toLowerCase() === 'content-type') {
        // Remove Content-Type if data is undefined
        delete requestHeaders[key];
      } else {
        // Otherwise add header to the request
        request.setRequestHeader(key, val);
      }
    });
  }

  // Add withCredentials to request if needed
  if (config.withCredentials) {
    request.withCredentials = true;
  }

  // Add responseType to request if needed
  if (config.responseType) {
    try {
      request.responseType = config.responseType;
    } catch (e) {
      if (request.responseType !== 'json') {
        throw e;
      }
    }
  }

  // Handle progress if needed
  if (config.progress) {
    if (config.method === 'post' || config.method === 'put') {
      request.upload.addEventListener('progress', config.progress);
    } else if (config.method === 'get') {
      request.addEventListener('progress', config.progress);
    }
  }

  if (requestData === undefined) {
    requestData = null;
  }

  // Send the request
  request.send(requestData);
};