angularDirective("ng:init", function(expression){
  return function(element){
    this.$tryEval(expression, element);
  };
});

angularDirective("ng:controller", function(expression){
  this.scope(true);
  return function(element){
    var controller = getter(window, expression, true) || getter(this, expression, true);
    if (!controller)
      throw "Can not find '"+expression+"' controller.";
    if (!isFunction(controller))
      throw "Reference '"+expression+"' is not a class.";
    this.$become(controller);
  };
});

angularDirective("ng:eval", function(expression){
  return function(element){
    this.$onEval(expression, element);
  };
});

angularDirective("ng:bind", function(expression){
  return function(element) {
    var lastValue = noop, lastError = noop;
    this.$onEval(function() {
      var error, value, isHtml, isDomElement,
          oldElement = this.hasOwnProperty($$element) ? this.$element : _undefined;
      this.$element = element;
      value = this.$tryEval(expression, function(e){
        error = toJson(e);
      });
      this.$element = oldElement;
      if (lastValue === value && lastError == error) return;
      isHtml = value instanceof HTML;
      isDomElement = isElement(value);
      if (!isHtml && !isDomElement && isObject(value)) {
        value = toJson(value);
      }
      if (value != lastValue || error != lastError) {
        lastValue = value;
        lastError = error;
        elementError(element, NG_EXCEPTION, error);
        if (error) value = error;
        if (isHtml) {
          element.html(value.html);
        } else if (isDomElement) {
          element.html('');
          element.append(value);
        } else {
          element.text(value === _undefined ? '' : value);
        }
      }
    }, element);
  };
});

var bindTemplateCache = {};
function compileBindTemplate(template){
  var fn = bindTemplateCache[template];
  if (!fn) {
    var bindings = [];
    foreach(parseBindings(template), function(text){
      var exp = binding(text);
      bindings.push(exp ? function(element){
        var error, value = this.$tryEval(exp, function(e){
          error = toJson(e);
        });
        elementError(element, NG_EXCEPTION, error);
        return error ? error : value;
      } : function() {
        return text;
      });
    });
    bindTemplateCache[template] = fn = function(element){
      var parts = [], self = this,
         oldElement = this.hasOwnProperty($$element) ? self.$element : _undefined;
      self.$element = element;
      for ( var i = 0; i < bindings.length; i++) {
        var value = bindings[i].call(self, element);
        if (isElement(value))
          value = '';
        else if (isObject(value))
          value = toJson(value, true);
        parts.push(value);
      }
      self.$element = oldElement;
      return parts.join('');
    };
  }
  return fn;
}

angularDirective("ng:bind-template", function(expression){
  var templateFn = compileBindTemplate(expression);
  return function(element) {
    var lastValue;
    this.$onEval(function() {
      var value = templateFn.call(this, element);
      if (value != lastValue) {
        element.text(value);
        lastValue = value;
      }
    }, element);
  };
});

var REMOVE_ATTRIBUTES = {
  'disabled':'disabled',
  'readonly':'readOnly',
  'checked':'checked'
};
angularDirective("ng:bind-attr", function(expression){
  return function(element){
    var lastValue = {};
    var updateFn = element.parent().data('$update');
    this.$onEval(function(){
      var values = this.$eval(expression);
      for(var key in values) {
        var value = compileBindTemplate(values[key]).call(this, element),
            specialName = REMOVE_ATTRIBUTES[lowercase(key)];
        if (lastValue[key] !== value) {
          lastValue[key] = value;
          if (specialName) {
            if (element[specialName] = toBoolean(value)) {
              element.attr(specialName, value);
            } else {
              element.removeAttr(key);
            }
            (element.data('$validate')||noop)();
          } else {
            element.attr(key, value);
          }
          this.$postEval(updateFn);
        }
      }
    }, element);
  };
});

angularWidget("@ng:non-bindable", noop);

angularWidget("@ng:repeat", function(expression, element){
  element.removeAttr('ng:repeat');
  element.replaceWith(this.comment("ng:repeat: " + expression));
  var template = this.compile(element);
  return function(reference){
    var match = expression.match(/^\s*(.+)\s+in\s+(.*)\s*$/),
        lhs, rhs, valueIdent, keyIdent;
    if (! match) {
      throw "Expected ng:repeat in form of 'item in collection' but got '" +
      expression + "'.";
    }
    lhs = match[1];
    rhs = match[2];
    match = lhs.match(/^([\$\w]+)|\(([\$\w]+)\s*,\s*([\$\w]+)\)$/);
    if (!match) {
      throw "'item' in 'item in collection' should be identifier or (key, value) but got '" +
      keyValue + "'.";
    }
    valueIdent = match[3] || match[1];
    keyIdent = match[2];

    var children = [], currentScope = this;
    this.$onEval(function(){
      var index = 0, childCount = children.length, childScope, lastElement = reference,
          collection = this.$tryEval(rhs, reference), is_array = isArray(collection);
      for ( var key in collection) {
        if (!is_array || collection.hasOwnProperty(key)) {
          if (index < childCount) {
            // reuse existing child
            childScope = children[index];
            childScope[valueIdent] = collection[key];
            if (keyIdent) childScope[keyIdent] = key;
          } else {
            // grow children
            childScope = template(quickClone(element), createScope(currentScope));
            childScope[valueIdent] = collection[key];
            if (keyIdent) childScope[keyIdent] = key;
            lastElement.after(childScope.$element);
            childScope.$index = index;
            childScope.$element.attr('ng:repeat-index', index);
            childScope.$init();
            children.push(childScope);
          }
          childScope.$eval();
          lastElement = childScope.$element;
          index ++;
        }
      }
      // shrink children
      while(children.length > index) {
        children.pop().$element.remove();
      }
    }, reference);
  };
});


/*
 * A directive that allows creation of custom onclick handlers that are defined as angular
 * expressions and are compiled and executed within the current scope.
 *
 * Events that are handled via these handler are always configured not to propagate further.
 *
 * TODO: maybe we should consider allowing users to control even propagation in the future.
 */
angularDirective("ng:click", function(expression, element){
  return function(element){
    var self = this;
    element.bind('click', function(event){
      self.$tryEval(expression, element);
      self.$root.$eval();
      event.stopPropagation();
    });
  };
});

angularDirective("ng:watch", function(expression, element){
  return function(element){
    var self = this;
    parser(expression).watch()({
      addListener:function(watch, exp){
        self.$watch(watch, function(){
          return exp(self);
        }, element);
      }
    });
  };
});

function ngClass(selector) {
  return function(expression, element){
    var existing = element[0].className + ' ';
    return function(element){
      this.$onEval(function(){
        if (selector(this.$index)) {
          var value = this.$eval(expression);
          if (isArray(value)) value = value.join(' ');
          element[0].className = trim(existing + value);
        }
      }, element);
    };
  };
}

angularDirective("ng:class", ngClass(function(){return true;}));
angularDirective("ng:class-odd", ngClass(function(i){return i % 2 === 0;}));
angularDirective("ng:class-even", ngClass(function(i){return i % 2 === 1;}));

angularDirective("ng:show", function(expression, element){
  return function(element){
    this.$onEval(function(){
      element.css($display, toBoolean(this.$eval(expression)) ? '' : $none);
    }, element);
  };
});

angularDirective("ng:hide", function(expression, element){
  return function(element){
    this.$onEval(function(){
      element.css($display, toBoolean(this.$eval(expression)) ? $none : '');
    }, element);
  };
});

angularDirective("ng:style", function(expression, element){
  return function(element){
    var resetStyle = getStyle(element);
    this.$onEval(function(){
      var style = this.$eval(expression) || {}, key, mergedStyle = {};
      for(key in style) {
        if (resetStyle[key] === _undefined) resetStyle[key] = '';
        mergedStyle[key] = style[key];
      }
      for(key in resetStyle) {
        mergedStyle[key] = mergedStyle[key] || resetStyle[key];
      }
      element.css(mergedStyle);
    }, element);
  };
});