'use strict';

var createBlob = require('./blob.js');
var utils = require('../utils');

module.exports = function(options, callback) {

  var xhr, timer, hasUpload;

  var abortReq = function () {
    xhr.abort();
  };

  if (options.xhr) {
    xhr = new options.xhr();
  } else {
    xhr = new XMLHttpRequest();
  }

  // cache-buster, specifically designed to work around IE's aggressive caching
  // see http://www.dashbay.com/2011/05/internet-explorer-caches-ajax/
  if (options.method === 'GET' && !options.cache) {
    var hasArgs = options.url.indexOf('?') !== -1;
    options.url += (hasArgs ? '&' : '?') + '_nonce=' + Date.now();
  }

  xhr.open(options.method, options.url);
  xhr.withCredentials = true;

  if (options.json) {
    options.headers.Accept = 'application/json';
    options.headers['Content-Type'] = options.headers['Content-Type'] ||
      'application/json';
    if (options.body &&
        options.processData &&
        typeof options.body !== "string") {
      options.body = JSON.stringify(options.body);
    }
  }

  if (options.binary) {
    xhr.responseType = 'arraybuffer';
  }

  if (!('body' in options)) {
    options.body = null;
  }

  for (var key in options.headers) {
    if (options.headers.hasOwnProperty(key)) {
      xhr.setRequestHeader(key, options.headers[key]);
    }
  }

  if (options.timeout > 0) {
    timer = setTimeout(abortReq, options.timeout);
    xhr.onprogress = function () {
      clearTimeout(timer);
      timer = setTimeout(abortReq, options.timeout);
    };
    if (typeof hasUpload === 'undefined') {
      // IE throws an error if you try to access it directly
      hasUpload = Object.keys(xhr).indexOf('upload') !== -1;
    }
    if (hasUpload) { // does not exist in ie9
      xhr.upload.onprogress = xhr.onprogress;
    }
  }

  xhr.onreadystatechange = function () {
    if (xhr.readyState !== 4) {
      return;
    }

    var response = {
      statusCode: xhr.status
    };

    if (xhr.status >= 200 && xhr.status < 300) {
      var data;
      if (options.binary) {
        data = createBlob([xhr.response || ''], {
          type: xhr.getResponseHeader('Content-Type')
        });
      } else {
        data = xhr.responseText;
      }
      callback(null, response, data);
    } else {
      var err = {};
      try {
        err = JSON.parse(xhr.response);
      } catch(e) {}
      callback(err, response);
    }
  };

  if (options.body && (options.body instanceof Blob)) {
    utils.readAsBinaryString(options.body, function (binary) {
      xhr.send(utils.fixBinary(binary));
    });
  } else {
    xhr.send(options.body);
  }

  return {abort: abortReq};
};