/**
* Object assign is required, so ensure that browsers know how to execute this method
*
* @method Object.assign
* @returns {Function}
*/
if (typeof Object.assign != 'function') {
  // Must be writable: true, enumerable: false, configurable: true
  Object.defineProperty(Object, "assign", {
    value: function assign(target, varArgs) { // .length of function is 2
      'use strict';
      if (target == null) { // TypeError if undefined or null
        throw new TypeError('Cannot convert undefined or null to object');
      }

      var to = Object(target);

      for (var index = 1; index < arguments.length; index++) {
        var nextSource = arguments[index];

        if (nextSource != null) { // Skip over if undefined or null
          for (var nextKey in nextSource) {
            // Avoid bugs when hasOwnProperty is shadowed
            if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
              to[nextKey] = nextSource[nextKey];
            }
          }
        }
      }
      return to;
    },
    writable: true,
    configurable: true
  });
}


/**
* Object to convert XML into a structured JSON object
*
* @method xmlToJson
* @returns {Object}
*/
var xmlToJson = (function () {
  var self = this;


	/**
	* Adds an object value to a parent object
	*
	* @method addToParent
	* @param {Object} parent
	* @param {String} nodeName
	* @param {Mixed} obj
	* @returns none
	*/
  self.addToParent = function (parent, nodeName, obj) {
    // If this is the first or only instance of the node name, assign it as
    // an object on the parent.
    if (!parent[nodeName]) {
      parent[nodeName] = obj;
    }
    // Else the parent knows about other nodes of the same name
    else {
      // If the parent has a property with the node name, but it is not an array,
      // store the contents of that property, convert the property to an array, and
      // assign what was formerly an object on the parent to the first member of the
      // array
      if (!Array.isArray(parent[nodeName])) {
        var tmp = parent[nodeName];
        parent[nodeName] = [];
        parent[nodeName].push(tmp);
      }

      // Push the current object to the collection
      parent[nodeName].push(obj);
    }
  };




  self.convertXMLStringToDoc = function (str) {
    var xmlDoc = null;

    if (str && typeof str === 'string') {
      // Create a DOMParser
      var parser = new DOMParser();

      // Use it to turn your xmlString into an XMLDocument
      xmlDoc = parser.parseFromString(str, 'application/xml');
    }

    return xmlDoc;
  }


	/**
	* Validates if an data is an XMLDocument
	*
	* @method isXML
	* @param {Mixed} data
	* @returns {Boolean}
	*/
  self.isXML = function (data) {
    var documentElement = (data ? data.ownerDocument || data : 0).documentElement;

    return documentElement ? documentElement.nodeName.toLowerCase() !== 'html' : false;
  };


	/**
	* Reads through a node's attributes and assigns the values to a new object
	*
	* @method parseAttributes
	* @param {XMLNode} node
	* @returns {Object}
	*/
  self.parseAttributes = function (node) {
    var attributes = node.attributes,
      obj = {};

    // If the node has attributes, assign the new object properties
    // corresponding to each attribute
    if (node.hasAttributes()) {
      for (var i = 0; i < attributes.length; i++) {
        obj[attributes[i].name] = self.parseValue(attributes[i].value);
      }
    }

    // return the new object
    return obj;
  };


	/**
	* Rips through child nodes and parses them
	*
	* @method parseChildren
	* @param {Object} parent
	* @param {XMLNodeMap} childNodes
	* @returns none
	*/
  self.parseChildren = function (parent, childNodes) {
    // If there are child nodes...
    if (childNodes.length > 0) {
      // Loop over all the child nodes
      for (var i = 0; i < childNodes.length; i++) {
        // If the child node is a XMLNode, parse the node
        if (childNodes[i].nodeType == 1) {
          self.parseNode(parent, childNodes[i]);
        }
      }
    }
  };


	/**
	* Converts a node into an object with properties
	*
	* @method parseNode
	* @param {Object} parent
	* @param {XMLNode} node
	* @returns {Object}
	*/
  self.parseNode = function (parent, node) {
    var nodeName = node.nodeName,
      obj = Object.assign({}, self.parseAttributes(node)),
      tmp = null;

    // If there is only one text child node, there is no need to process the children
    if (node.childNodes.length == 1 && node.childNodes[0].nodeType == 3) {
      // If the node has attributes, then the object will already have properties.
      // Add a new property 'text' with the value of the text content
      if (node.hasAttributes()) {
        obj['text'] = self.parseValue(node.childNodes[0].nodeValue);
      }
      // If there are no attributes, then the parent[nodeName] property value is
      // simply the interpreted textual content
      else {
        obj = self.parseValue(node.childNodes[0].nodeValue);
      }
    }
    // Otherwise, there are child XMLNode elements, so process them
    else {
      self.parseChildren(obj, node.childNodes);
    }

    // Once the object has been processed, add it to the parent
    self.addToParent(parent, nodeName, obj)

    // Return the parent
    return parent;
  };


	/**
	* Interprets a value and converts it to Boolean, Number or String based on content
	*
	* @method parseValue
	* @param {Mixed} val
	* @returns {Mixed}
	*/
  this.parseValue = function (val) {
    // Create a numeric value from the passed parameter
    var num = Number(val);

    // If the value is 'true' or 'false', parse it as a Boolean and return it
    if (val.toLowerCase() === 'true' || val.toLowerCase() === 'false') {
      return (val.toLowerCase() == 'true');
    }

    // If the num parsed to a Number, return the numeric value
    // Else if the valuse passed has no length (an attribute without value) return null,
    // Else return the param as is
    return (isNaN(num)) ? val.trim() : (val.length == 0) ? null : num;
  };

  // Expose the API
  return {
    parse: function (xml) {
      if (xml && typeof xml === 'string') {
        xml = self.convertXMLStringToDoc(xml);
      }
      return (xml && self.isXML(xml)) ? self.parseNode({}, xml.firstChild) : null;
    }
  }
})();