// Copyright 2009 Google Inc.  All Rights Reserved.

function Webhook(formId) {

  this.formId = formId;

  this.action = null;

  this.headers = {};

  this.method = null;

  this.payload = null;

};

Webhook.prototype.HEADER_KEY = 'header:';

Webhook.prototype.parse = function() {

  var form = document.getElementById(this.formId);

  if (form == null) {

    return 'could not find form with id "' + this.formId + '"';

  };

  this.action = form.action;

  this.method = form.method;

  for (var i = 0, n = form.elements.length; i < n; i++) {

    var currentElement = form.elements[i];

    if (currentElement.tagName != 'INPUT' ||

        currentElement.type.toUpperCase() != 'HIDDEN') {

      continue;

    }

    var key = currentElement.name;

    var value = currentElement.value;

    var headerIndex = key.indexOf(this.HEADER_KEY);

    if (headerIndex == 0) {

      var header = key.substr(this.HEADER_KEY.length);

      this.headers[header] = value;

    } else if (key == 'payload') {

      this.payload = value;

    }

  }

  if (this.action == '') {

    return 'action not found';

  }

  if (this.method == '') {

    return 'method not found';

  }

  return '';

};

Webhook.prototype.send = function(callback) {

  var req = null;

  if (window.XMLHttpRequest) {

    req = new XMLHttpRequest();

  } else if (window.ActiveXObject) {

    req = new ActiveXObject('MSXML2.XMLHTTP.3.0');

  }

  try {

    req.open(this.method, this.action, false);

    for (var key in this.headers) {

      req.setRequestHeader(key, this.headers[key]);

    };

    req.send(this.payload);

  } catch (e) {

    callback(this, req, e);

    return;

  }

};

Webhook.prototype.run = function(callback) {

  var error = this.parse();

  if (error != '') {

    callback(this, null, error);

  } else {

    this.send(callback);

  }

};