/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

const EXPORTED_SYMBOLS = ["httpRequest", "percentEncode"];

Cu.importGlobalProperties(["XMLHttpRequest"]);

// Strictly follow RFC 3986 when encoding URI components.

// Accepts a unescaped string and returns the URI encoded string for use in

// an HTTP request.

function percentEncode(aString) {

  return encodeURIComponent(aString).replace(/[!'()]/g, escape).replace(/\*/g, "%2A");

}

/*

 * aOptions can have a variety of fields:

 *  headers, an array of headers

 *  postData, this can be:

 *    a string: send it as is

 *    an array of parameters: encode as form values

 *    null/undefined: no POST data.

 *  method, GET, POST or PUT (this is set automatically if postData exists).

 *  onLoad, a function handle to call when the load is complete, it takes two

 *          parameters: the responseText and the XHR object.

 *  onError, a function handle to call when an error occcurs, it takes three

 *          parameters: the error, the responseText and the XHR object.

 *  logger, an object that implements the debug and log methods (e.g. log.jsm).

 *

 * Headers or post data are given as an array of arrays, for each each inner

 * array the first value is the key and the second is the value, e.g.

 *  [["key1", "value1"], ["key2", "value2"]].

 */

function httpRequest(aUrl, aOptions) {

  let xhr = new XMLHttpRequest();

  xhr.mozBackgroundRequest = true; // no error dialogs

  xhr.open(aOptions.method || (aOptions.postData ? "POST" : "GET"), aUrl);

  xhr.channel.loadFlags = Ci.nsIChannel.LOAD_ANONYMOUS | // don't send cookies

                          Ci.nsIChannel.LOAD_BYPASS_CACHE |

                          Ci.nsIChannel.INHIBIT_CACHING;

  xhr.onerror = function(aProgressEvent) {

    if (aOptions.onError) {

      // adapted from toolkit/mozapps/extensions/nsBlocklistService.js

      let request = aProgressEvent.target;

      let status;

      try {

        // may throw (local file or timeout)

        status = request.status;

      } catch (e) {

        request = request.channel.QueryInterface(Ci.nsIRequest);

        status = request.status;

      }

      // When status is 0 we don't have a valid channel.

      let statusText = status ? request.statusText : "offline";

      aOptions.onError(statusText, null, this);

    }

  };

  xhr.onload = function(aRequest) {

    try {

      let target = aRequest.target;

      if (aOptions.logger)

        aOptions.logger.debug("Received response: " + target.responseText);

      if (target.status < 200 || target.status >= 300) {

        let errorText = target.responseText;

        if (!errorText || /<(ht|\?x)ml\b/i.test(errorText))

          errorText = target.statusText;

        throw target.status + " - " + errorText;

      }

      if (aOptions.onLoad)

        aOptions.onLoad(target.responseText, this);

    } catch (e) {

      if (aOptions.onError)

        aOptions.onError(e, aRequest.target.responseText, this);

    }

  };

  if (aOptions.headers) {

    aOptions.headers.forEach(function(header) {

      xhr.setRequestHeader(header[0], header[1]);

    });

  }

  // Handle adding postData as defined above.

  let POSTData = aOptions.postData || null;

  if (POSTData && Array.isArray(POSTData)) {

    xhr.setRequestHeader("Content-Type",

                         "application/x-www-form-urlencoded; charset=utf-8");

    POSTData = POSTData.map(p => p[0] + "=" + percentEncode(p[1]))

                       .join("&";;

  }

  if (aOptions.logger) {

    aOptions.logger.log("sending request to " + aUrl + " (POSTData = " +

                        POSTData + ")");

  }

  xhr.send(POSTData);

  return xhr;

}