/**
 * Template provides directions an how to bind to a given element.
 * It contains a list of init functions which need to be called to
 * bind to a new instance of elements. It also provides a list
 * of child paths which contain child templates
 */
function Template() {
  this.paths = [];
  this.children = [];
  this.inits = [];
}

Template.prototype = {
  init: function(element, scope) {
    element = jqLite(element);
    foreach(this.inits, function(fn) {
      scope.apply(fn, element);
    });

    var i,
        childNodes = element[0].childNodes,
        children = this.children,
        paths = this.paths,
        length = paths.length;
    for (i = 0; i < length; i++) {
      children[i].init(childNodes[paths[i]], scope);
    }
  },


  addInit:function(init) {
    if (init) {
      this.inits.push(init);
    }
  },


  addChild: function(index, template) {
    if (template) {
      this.paths.push(index);
      this.children.push(template);
    }
  },

  empty: function() {
    return this.inits.length == 0 && this.paths.length == 0;
  }
};

///////////////////////////////////
//Compiler
//////////////////////////////////
function isTextNode(node) {
  return node.nodeType == Node.TEXT_NODE;
}

function eachTextNode(element, fn){
  var i, chldNodes = element[0].childNodes || [], size = chldNodes.length, chld;
  for (i = 0; i < size; i++) {
    if(isTextNode(chld = chldNodes[i])) {
      fn(jqLite(chld), i);
    }
  }
}

function eachNode(element, fn){
  var i, chldNodes = element[0].childNodes || [], size = chldNodes.length, chld;
  for (i = 0; i < size; i++) {
    if(!isTextNode(chld = chldNodes[i])) {
      fn(jqLite(chld), i);
    }
  }
}

function eachAttribute(element, fn){
  var i, attrs = element[0].attributes || [], size = attrs.length, chld, attr;
  for (i = 0; i < size; i++) {
    var attr = attrs[i];
    fn(attr.name, attr.value);
  }
}

function Compiler(textMarkup, attrMarkup, directives, widgets){
  this.textMarkup = textMarkup;
  this.attrMarkup = attrMarkup;
  this.directives = directives;
  this.widgets = widgets;
}

Compiler.prototype = {
  compile: function(rawElement) {
    rawElement = jqLite(rawElement);
    var template = this.templatize(rawElement) || new Template();
    return function(element, parentScope){
      var scope = new Scope(parentScope);
      scope.element = element;
      // todo return should be a scope with everything already set on it as element
      return {
        scope: scope,
        element:element,
        init: bind(template, template.init, element, scope)
      };
    };
  },

  templatize: function(element){
    var self = this,
        widget = self.widgets[element[0].nodeName],
        directives = self.directives,
        descend = true,
        exclusive = false,
        directiveQueue = [],
        template = new Template(),
        selfApi = {
          compile: bind(self, self.compile),
          comment:function(text) {return jqLite(document.createComment(text));},
          element:function(type) {return jqLite(document.createElement(type));},
          text:function(text) {return jqLite(document.createTextNode(text));},
          descend: function(value){ if(isDefined(value)) descend = value; return descend;}
        };

    if (widget) {
      template.addInit(widget.call(selfApi, element));
    } else {
      // process markup for text nodes only
      eachTextNode(element, function(textNode){
        var text = textNode.text();
        foreach(self.textMarkup, function(markup){
          markup.call(selfApi, text, textNode, element);
        });
      });

      // Process attributes/directives
      eachAttribute(element, function(name, value){
        foreach(self.attrMarkup, function(markup){
          markup.call(selfApi, value, name, element);
        });
      });
      eachAttribute(element, function(name, value){
        var directive  = directives[name];
        if (!exclusive && directive) {
          if (directive.exclusive) {
            exclusive = true;
            directiveQueue = [];
          }
          directiveQueue.push(bindTry(selfApi, directive, value, element, errorHandlerFor(element)));
        }
      });

      // Execute directives
      foreach(directiveQueue, function(directive){
        template.addInit(directive());
      });

      // Process non text child nodes
      if (descend) {
        eachNode(element, function(child, i){
          template.addChild(i, self.templatize(child));
        });
      }
    }
    return template.empty() ? null : template;
  }
};