'use strict';

/* global

    -VALID_CLASS,
    -INVALID_CLASS,
    -PRISTINE_CLASS,
    -DIRTY_CLASS
*/

var URL_REGEXP = /^(ftp|http|https):\/\/(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?$/;
var EMAIL_REGEXP = /^[a-z0-9!#$%&'*+/=?^_`{|}~.-]+@[a-z0-9-]+(\.[a-z0-9-]+)*$/i;
var NUMBER_REGEXP = /^\s*(\-|\+)?(\d+|(\d*(\.\d*)))\s*$/;

var inputType = {

  /**
   * @ngdoc input
   * @name input[text]
   *
   * @description
   * Standard HTML text input with angular data binding.
   *
   * @param {string} ngModel Assignable angular expression to data-bind to.
   * @param {string=} name Property name of the form under which the control is published.
   * @param {string=} required Adds `required` validation error key if the value is not entered.
   * @param {string=} ngRequired Adds `required` attribute and `required` validation constraint to
   *    the element when the ngRequired expression evaluates to true. Use `ngRequired` instead of
   *    `required` when you want to data-bind to the `required` attribute.
   * @param {number=} ngMinlength Sets `minlength` validation error key if the value is shorter than
   *    minlength.
   * @param {number=} ngMaxlength Sets `maxlength` validation error key if the value is longer than
   *    maxlength.
   * @param {string=} ngPattern Sets `pattern` validation error key if the value does not match the
   *    RegExp pattern expression. Expected value is `/regexp/` for inline patterns or `regexp` for
   *    patterns defined as scope expressions.
   * @param {string=} ngChange Angular expression to be executed when input changes due to user
   *    interaction with the input element.
   * @param {boolean=} [ngTrim=true] If set to false Angular will not automatically trim the input.
   *
   * @example
      <example name="text-input-directive">
        <file name="index.html">
         <script>
           function Ctrl($scope) {
             $scope.text = 'guest';
             $scope.word = /^\s*\w*\s*$/;
           }
         </script>
         <form name="myForm" ng-controller="Ctrl">
           Single word: <input type="text" name="input" ng-model="text"
                               ng-pattern="word" required ng-trim="false">
           <span class="error" ng-show="myForm.input.$error.required">
             Required!</span>
           <span class="error" ng-show="myForm.input.$error.pattern">
             Single word only!</span>

           <tt>text = {{text}}</tt><br/>
           <tt>myForm.input.$valid = {{myForm.input.$valid}}</tt><br/>
           <tt>myForm.input.$error = {{myForm.input.$error}}</tt><br/>
           <tt>myForm.$valid = {{myForm.$valid}}</tt><br/>
           <tt>myForm.$error.required = {{!!myForm.$error.required}}</tt><br/>
          </form>
        </file>
        <file name="protractor.js" type="protractor">
          var text = element(by.binding('text'));
          var valid = element(by.binding('myForm.input.$valid'));
          var input = element(by.model('text'));

          it('should initialize to model', function() {
            expect(text.getText()).toContain('guest');
            expect(valid.getText()).toContain('true');
          });

          it('should be invalid if empty', function() {
            input.clear();
            input.sendKeys('');

            expect(text.getText()).toEqual('text =');
            expect(valid.getText()).toContain('false');
          });

          it('should be invalid if multi word', function() {
            input.clear();
            input.sendKeys('hello world');

            expect(valid.getText()).toContain('false');
          });
        </file>
      </example>
   */
  'text': textInputType,


  /**
   * @ngdoc input
   * @name input[number]
   *
   * @description
   * Text input with number validation and transformation. Sets the `number` validation
   * error if not a valid number.
   *
   * @param {string} ngModel Assignable angular expression to data-bind to.
   * @param {string=} name Property name of the form under which the control is published.
   * @param {string=} min Sets the `min` validation error key if the value entered is less than `min`.
   * @param {string=} max Sets the `max` validation error key if the value entered is greater than `max`.
   * @param {string=} required Sets `required` validation error key if the value is not entered.
   * @param {string=} ngRequired Adds `required` attribute and `required` validation constraint to
   *    the element when the ngRequired expression evaluates to true. Use `ngRequired` instead of
   *    `required` when you want to data-bind to the `required` attribute.
   * @param {number=} ngMinlength Sets `minlength` validation error key if the value is shorter than
   *    minlength.
   * @param {number=} ngMaxlength Sets `maxlength` validation error key if the value is longer than
   *    maxlength.
   * @param {string=} ngPattern Sets `pattern` validation error key if the value does not match the
   *    RegExp pattern expression. Expected value is `/regexp/` for inline patterns or `regexp` for
   *    patterns defined as scope expressions.
   * @param {string=} ngChange Angular expression to be executed when input changes due to user
   *    interaction with the input element.
   *
   * @example
      <example name="number-input-directive">
        <file name="index.html">
         <script>
           function Ctrl($scope) {
             $scope.value = 12;
           }
         </script>
         <form name="myForm" ng-controller="Ctrl">
           Number: <input type="number" name="input" ng-model="value"
                          min="0" max="99" required>
           <span class="error" ng-show="myForm.input.$error.required">
             Required!</span>
           <span class="error" ng-show="myForm.input.$error.number">
             Not valid number!</span>
           <tt>value = {{value}}</tt><br/>
           <tt>myForm.input.$valid = {{myForm.input.$valid}}</tt><br/>
           <tt>myForm.input.$error = {{myForm.input.$error}}</tt><br/>
           <tt>myForm.$valid = {{myForm.$valid}}</tt><br/>
           <tt>myForm.$error.required = {{!!myForm.$error.required}}</tt><br/>
          </form>
        </file>
        <file name="protractor.js" type="protractor">
          var value = element(by.binding('value'));
          var valid = element(by.binding('myForm.input.$valid'));
          var input = element(by.model('value'));

          it('should initialize to model', function() {
            expect(value.getText()).toContain('12');
            expect(valid.getText()).toContain('true');
          });

          it('should be invalid if empty', function() {
            input.clear();
            input.sendKeys('');
            expect(value.getText()).toEqual('value =');
            expect(valid.getText()).toContain('false');
          });

          it('should be invalid if over max', function() {
            input.clear();
            input.sendKeys('123');
            expect(value.getText()).toEqual('value =');
            expect(valid.getText()).toContain('false');
          });
        </file>
      </example>
   */
  'number': numberInputType,


  /**
   * @ngdoc input
   * @name input[url]
   *
   * @description
   * Text input with URL validation. Sets the `url` validation error key if the content is not a
   * valid URL.
   *
   * @param {string} ngModel Assignable angular expression to data-bind to.
   * @param {string=} name Property name of the form under which the control is published.
   * @param {string=} required Sets `required` validation error key if the value is not entered.
   * @param {string=} ngRequired Adds `required` attribute and `required` validation constraint to
   *    the element when the ngRequired expression evaluates to true. Use `ngRequired` instead of
   *    `required` when you want to data-bind to the `required` attribute.
   * @param {number=} ngMinlength Sets `minlength` validation error key if the value is shorter than
   *    minlength.
   * @param {number=} ngMaxlength Sets `maxlength` validation error key if the value is longer than
   *    maxlength.
   * @param {string=} ngPattern Sets `pattern` validation error key if the value does not match the
   *    RegExp pattern expression. Expected value is `/regexp/` for inline patterns or `regexp` for
   *    patterns defined as scope expressions.
   * @param {string=} ngChange Angular expression to be executed when input changes due to user
   *    interaction with the input element.
   *
   * @example
      <example name="url-input-directive">
        <file name="index.html">
         <script>
           function Ctrl($scope) {
             $scope.text = 'http://google.com';
           }
         </script>
         <form name="myForm" ng-controller="Ctrl">
           URL: <input type="url" name="input" ng-model="text" required>
           <span class="error" ng-show="myForm.input.$error.required">
             Required!</span>
           <span class="error" ng-show="myForm.input.$error.url">
             Not valid url!</span>
           <tt>text = {{text}}</tt><br/>
           <tt>myForm.input.$valid = {{myForm.input.$valid}}</tt><br/>
           <tt>myForm.input.$error = {{myForm.input.$error}}</tt><br/>
           <tt>myForm.$valid = {{myForm.$valid}}</tt><br/>
           <tt>myForm.$error.required = {{!!myForm.$error.required}}</tt><br/>
           <tt>myForm.$error.url = {{!!myForm.$error.url}}</tt><br/>
          </form>
        </file>
        <file name="protractor.js" type="protractor">
          var text = element(by.binding('text'));
          var valid = element(by.binding('myForm.input.$valid'));
          var input = element(by.model('text'));

          it('should initialize to model', function() {
            expect(text.getText()).toContain('http://google.com');
            expect(valid.getText()).toContain('true');
          });

          it('should be invalid if empty', function() {
            input.clear();
            input.sendKeys('');

            expect(text.getText()).toEqual('text =');
            expect(valid.getText()).toContain('false');
          });

          it('should be invalid if not url', function() {
            input.clear();
            input.sendKeys('box');

            expect(valid.getText()).toContain('false');
          });
        </file>
      </example>
   */
  'url': urlInputType,


  /**
   * @ngdoc input
   * @name input[email]
   *
   * @description
   * Text input with email validation. Sets the `email` validation error key if not a valid email
   * address.
   *
   * @param {string} ngModel Assignable angular expression to data-bind to.
   * @param {string=} name Property name of the form under which the control is published.
   * @param {string=} required Sets `required` validation error key if the value is not entered.
   * @param {string=} ngRequired Adds `required` attribute and `required` validation constraint to
   *    the element when the ngRequired expression evaluates to true. Use `ngRequired` instead of
   *    `required` when you want to data-bind to the `required` attribute.
   * @param {number=} ngMinlength Sets `minlength` validation error key if the value is shorter than
   *    minlength.
   * @param {number=} ngMaxlength Sets `maxlength` validation error key if the value is longer than
   *    maxlength.
   * @param {string=} ngPattern Sets `pattern` validation error key if the value does not match the
   *    RegExp pattern expression. Expected value is `/regexp/` for inline patterns or `regexp` for
   *    patterns defined as scope expressions.
   * @param {string=} ngChange Angular expression to be executed when input changes due to user
   *    interaction with the input element.
   *
   * @example
      <example name="email-input-directive">
        <file name="index.html">
         <script>
           function Ctrl($scope) {
             $scope.text = 'me@example.com';
           }
         </script>
           <form name="myForm" ng-controller="Ctrl">
             Email: <input type="email" name="input" ng-model="text" required>
             <span class="error" ng-show="myForm.input.$error.required">
               Required!</span>
             <span class="error" ng-show="myForm.input.$error.email">
               Not valid email!</span>
             <tt>text = {{text}}</tt><br/>
             <tt>myForm.input.$valid = {{myForm.input.$valid}}</tt><br/>
             <tt>myForm.input.$error = {{myForm.input.$error}}</tt><br/>
             <tt>myForm.$valid = {{myForm.$valid}}</tt><br/>
             <tt>myForm.$error.required = {{!!myForm.$error.required}}</tt><br/>
             <tt>myForm.$error.email = {{!!myForm.$error.email}}</tt><br/>
           </form>
         </file>
        <file name="protractor.js" type="protractor">
          var text = element(by.binding('text'));
          var valid = element(by.binding('myForm.input.$valid'));
          var input = element(by.model('text'));

          it('should initialize to model', function() {
            expect(text.getText()).toContain('me@example.com');
            expect(valid.getText()).toContain('true');
          });

          it('should be invalid if empty', function() {
            input.clear();
            input.sendKeys('');
            expect(text.getText()).toEqual('text =');
            expect(valid.getText()).toContain('false');
          });

          it('should be invalid if not email', function() {
            input.clear();
            input.sendKeys('xxx');

            expect(valid.getText()).toContain('false');
          });
        </file>
      </example>
   */
  'email': emailInputType,


  /**
   * @ngdoc input
   * @name input[radio]
   *
   * @description
   * HTML radio button.
   *
   * @param {string} ngModel Assignable angular expression to data-bind to.
   * @param {string} value The value to which the expression should be set when selected.
   * @param {string=} name Property name of the form under which the control is published.
   * @param {string=} ngChange Angular expression to be executed when input changes due to user
   *    interaction with the input element.
   * @param {string} ngValue Angular expression which sets the value to which the expression should
   *    be set when selected.
   *
   * @example
      <example name="radio-input-directive">
        <file name="index.html">
         <script>
           function Ctrl($scope) {
             $scope.color = 'blue';
             $scope.specialValue = {
               "id": "12345",
               "value": "green"
             };
           }
         </script>
         <form name="myForm" ng-controller="Ctrl">
           <input type="radio" ng-model="color" value="red">  Red <br/>
           <input type="radio" ng-model="color" ng-value="specialValue"> Green <br/>
           <input type="radio" ng-model="color" value="blue"> Blue <br/>
           <tt>color = {{color | json}}</tt><br/>
          </form>
          Note that `ng-value="specialValue"` sets radio item's value to be the value of `$scope.specialValue`.
        </file>
        <file name="protractor.js" type="protractor">
          it('should change state', function() {
            var color = element(by.binding('color'));

            expect(color.getText()).toContain('blue');

            element.all(by.model('color')).get(0).click();

            expect(color.getText()).toContain('red');
          });
        </file>
      </example>
   */
  'radio': radioInputType,


  /**
   * @ngdoc input
   * @name input[checkbox]
   *
   * @description
   * HTML checkbox.
   *
   * @param {string} ngModel Assignable angular expression to data-bind to.
   * @param {string=} name Property name of the form under which the control is published.
   * @param {string=} ngTrueValue The value to which the expression should be set when selected.
   * @param {string=} ngFalseValue The value to which the expression should be set when not selected.
   * @param {string=} ngChange Angular expression to be executed when input changes due to user
   *    interaction with the input element.
   *
   * @example
      <example name="checkbox-input-directive">
        <file name="index.html">
         <script>
           function Ctrl($scope) {
             $scope.value1 = true;
             $scope.value2 = 'YES'
           }
         </script>
         <form name="myForm" ng-controller="Ctrl">
           Value1: <input type="checkbox" ng-model="value1"> <br/>
           Value2: <input type="checkbox" ng-model="value2"
                          ng-true-value="YES" ng-false-value="NO"> <br/>
           <tt>value1 = {{value1}}</tt><br/>
           <tt>value2 = {{value2}}</tt><br/>
          </form>
        </file>
        <file name="protractor.js" type="protractor">
          it('should change state', function() {
            var value1 = element(by.binding('value1'));
            var value2 = element(by.binding('value2'));

            expect(value1.getText()).toContain('true');
            expect(value2.getText()).toContain('YES');

            element(by.model('value1')).click();
            element(by.model('value2')).click();

            expect(value1.getText()).toContain('false');
            expect(value2.getText()).toContain('NO');
          });
        </file>
      </example>
   */
  'checkbox': checkboxInputType,

  'hidden': noop,
  'button': noop,
  'submit': noop,
  'reset': noop,
  'file': noop
};

// A helper function to call $setValidity and return the value / undefined,
// a pattern that is repeated a lot in the input validation logic.
function validate(ctrl, validatorName, validity, value){
  ctrl.$setValidity(validatorName, validity);
  return validity ? value : undefined;
}


function addNativeHtml5Validators(ctrl, validatorName, element) {
  var validity = element.prop('validity');
  if (isObject(validity)) {
    var validator = function(value) {
      // Don't overwrite previous validation, don't consider valueMissing to apply (ng-required can
      // perform the required validation)
      if (!ctrl.$error[validatorName] && (validity.badInput || validity.customError ||
          validity.typeMismatch) && !validity.valueMissing) {
        ctrl.$setValidity(validatorName, false);
        return;
      }
      return value;
    };
    ctrl.$parsers.push(validator);
    ctrl.$formatters.push(validator);
  }
}

function textInputType(scope, element, attr, ctrl, $sniffer, $browser) {
  var validity = element.prop('validity');
  // In composition mode, users are still inputing intermediate text buffer,
  // hold the listener until composition is done.
  // More about composition events: https://developer.mozilla.org/en-US/docs/Web/API/CompositionEvent
  if (!$sniffer.android) {
    var composing = false;

    element.on('compositionstart', function(data) {
      composing = true;
    });

    element.on('compositionend', function() {
      composing = false;
      listener();
    });
  }

  var listener = function() {
    if (composing) return;
    var value = element.val();

    // By default we will trim the value
    // If the attribute ng-trim exists we will avoid trimming
    // e.g. <input ng-model="foo" ng-trim="false">
    if (toBoolean(attr.ngTrim || 'T')) {
      value = trim(value);
    }

    if (ctrl.$viewValue !== value ||
        // If the value is still empty/falsy, and there is no `required` error, run validators
        // again. This enables HTML5 constraint validation errors to affect Angular validation
        // even when the first character entered causes an error.
        (validity && value === '' && !validity.valueMissing)) {
      if (scope.$$phase) {
        ctrl.$setViewValue(value);
      } else {
        scope.$apply(function() {
          ctrl.$setViewValue(value);
        });
      }
    }
  };

  // if the browser does support "input" event, we are fine - except on IE9 which doesn't fire the
  // input event on backspace, delete or cut
  if ($sniffer.hasEvent('input')) {
    element.on('input', listener);
  } else {
    var timeout;

    var deferListener = function() {
      if (!timeout) {
        timeout = $browser.defer(function() {
          listener();
          timeout = null;
        });
      }
    };

    element.on('keydown', function(event) {
      var key = event.keyCode;

      // ignore
      //    command            modifiers                   arrows
      if (key === 91 || (15 < key && key < 19) || (37 <= key && key <= 40)) return;

      deferListener();
    });

    // if user modifies input value using context menu in IE, we need "paste" and "cut" events to catch it
    if ($sniffer.hasEvent('paste')) {
      element.on('paste cut', deferListener);
    }
  }

  // if user paste into input using mouse on older browser
  // or form autocomplete on newer browser, we need "change" event to catch it
  element.on('change', listener);

  ctrl.$render = function() {
    element.val(ctrl.$isEmpty(ctrl.$viewValue) ? '' : ctrl.$viewValue);
  };

  // pattern validator
  var pattern = attr.ngPattern,
      patternValidator,
      match;

  if (pattern) {
    var validateRegex = function(regexp, value) {
      return validate(ctrl, 'pattern', ctrl.$isEmpty(value) || regexp.test(value), value);
    };
    match = pattern.match(/^\/(.*)\/([gim]*)$/);
    if (match) {
      pattern = new RegExp(match[1], match[2]);
      patternValidator = function(value) {
        return validateRegex(pattern, value);
      };
    } else {
      patternValidator = function(value) {
        var patternObj = scope.$eval(pattern);

        if (!patternObj || !patternObj.test) {
          throw minErr('ngPattern')('noregexp',
            'Expected {0} to be a RegExp but was {1}. Element: {2}', pattern,
            patternObj, startingTag(element));
        }
        return validateRegex(patternObj, value);
      };
    }

    ctrl.$formatters.push(patternValidator);
    ctrl.$parsers.push(patternValidator);
  }

  // min length validator
  if (attr.ngMinlength) {
    var minlength = int(attr.ngMinlength);
    var minLengthValidator = function(value) {
      return validate(ctrl, 'minlength', ctrl.$isEmpty(value) || value.length >= minlength, value);
    };

    ctrl.$parsers.push(minLengthValidator);
    ctrl.$formatters.push(minLengthValidator);
  }

  // max length validator
  if (attr.ngMaxlength) {
    var maxlength = int(attr.ngMaxlength);
    var maxLengthValidator = function(value) {
      return validate(ctrl, 'maxlength', ctrl.$isEmpty(value) || value.length <= maxlength, value);
    };

    ctrl.$parsers.push(maxLengthValidator);
    ctrl.$formatters.push(maxLengthValidator);
  }
}

function numberInputType(scope, element, attr, ctrl, $sniffer, $browser) {
  textInputType(scope, element, attr, ctrl, $sniffer, $browser);

  ctrl.$parsers.push(function(value) {
    var empty = ctrl.$isEmpty(value);
    if (empty || NUMBER_REGEXP.test(value)) {
      ctrl.$setValidity('number', true);
      return value === '' ? null : (empty ? value : parseFloat(value));
    } else {
      ctrl.$setValidity('number', false);
      return undefined;
    }
  });

  addNativeHtml5Validators(ctrl, 'number', element);

  ctrl.$formatters.push(function(value) {
    return ctrl.$isEmpty(value) ? '' : '' + value;
  });

  if (attr.min) {
    var minValidator = function(value) {
      var min = parseFloat(attr.min);
      return validate(ctrl, 'min', ctrl.$isEmpty(value) || value >= min, value);
    };

    ctrl.$parsers.push(minValidator);
    ctrl.$formatters.push(minValidator);
  }

  if (attr.max) {
    var maxValidator = function(value) {
      var max = parseFloat(attr.max);
      return validate(ctrl, 'max', ctrl.$isEmpty(value) || value <= max, value);
    };

    ctrl.$parsers.push(maxValidator);
    ctrl.$formatters.push(maxValidator);
  }

  ctrl.$formatters.push(function(value) {
    return validate(ctrl, 'number', ctrl.$isEmpty(value) || isNumber(value), value);
  });
}

function urlInputType(scope, element, attr, ctrl, $sniffer, $browser) {
  textInputType(scope, element, attr, ctrl, $sniffer, $browser);

  var urlValidator = function(value) {
    return validate(ctrl, 'url', ctrl.$isEmpty(value) || URL_REGEXP.test(value), value);
  };

  ctrl.$formatters.push(urlValidator);
  ctrl.$parsers.push(urlValidator);
}

function emailInputType(scope, element, attr, ctrl, $sniffer, $browser) {
  textInputType(scope, element, attr, ctrl, $sniffer, $browser);

  var emailValidator = function(value) {
    return validate(ctrl, 'email', ctrl.$isEmpty(value) || EMAIL_REGEXP.test(value), value);
  };

  ctrl.$formatters.push(emailValidator);
  ctrl.$parsers.push(emailValidator);
}

function radioInputType(scope, element, attr, ctrl) {
  // make the name unique, if not defined
  if (isUndefined(attr.name)) {
    element.attr('name', nextUid());
  }

  element.on('click', function() {
    if (element[0].checked) {
      scope.$apply(function() {
        ctrl.$setViewValue(attr.value);
      });
    }
  });

  ctrl.$render = function() {
    var value = attr.value;
    element[0].checked = (value == ctrl.$viewValue);
  };

  attr.$observe('value', ctrl.$render);
}

function checkboxInputType(scope, element, attr, ctrl) {
  var trueValue = attr.ngTrueValue,
      falseValue = attr.ngFalseValue;

  if (!isString(trueValue)) trueValue = true;
  if (!isString(falseValue)) falseValue = false;

  element.on('click', function() {
    scope.$apply(function() {
      ctrl.$setViewValue(element[0].checked);
    });
  });

  ctrl.$render = function() {
    element[0].checked = ctrl.$viewValue;
  };

  // Override the standard `$isEmpty` because a value of `false` means empty in a checkbox.
  ctrl.$isEmpty = function(value) {
    return value !== trueValue;
  };

  ctrl.$formatters.push(function(value) {
    return value === trueValue;
  });

  ctrl.$parsers.push(function(value) {
    return value ? trueValue : falseValue;
  });
}


/**
 * @ngdoc directive
 * @name textarea
 * @restrict E
 *
 * @description
 * HTML textarea element control with angular data-binding. The data-binding and validation
 * properties of this element are exactly the same as those of the
 * {@link ng.directive:input input element}.
 *
 * @param {string} ngModel Assignable angular expression to data-bind to.
 * @param {string=} name Property name of the form under which the control is published.
 * @param {string=} required Sets `required` validation error key if the value is not entered.
 * @param {string=} ngRequired Adds `required` attribute and `required` validation constraint to
 *    the element when the ngRequired expression evaluates to true. Use `ngRequired` instead of
 *    `required` when you want to data-bind to the `required` attribute.
 * @param {number=} ngMinlength Sets `minlength` validation error key if the value is shorter than
 *    minlength.
 * @param {number=} ngMaxlength Sets `maxlength` validation error key if the value is longer than
 *    maxlength.
 * @param {string=} ngPattern Sets `pattern` validation error key if the value does not match the
 *    RegExp pattern expression. Expected value is `/regexp/` for inline patterns or `regexp` for
 *    patterns defined as scope expressions.
 * @param {string=} ngChange Angular expression to be executed when input changes due to user
 *    interaction with the input element.
 */


/**
 * @ngdoc directive
 * @name input
 * @restrict E
 *
 * @description
 * HTML input element control with angular data-binding. Input control follows HTML5 input types
 * and polyfills the HTML5 validation behavior for older browsers.
 *
 * @param {string} ngModel Assignable angular expression to data-bind to.
 * @param {string=} name Property name of the form under which the control is published.
 * @param {string=} required Sets `required` validation error key if the value is not entered.
 * @param {boolean=} ngRequired Sets `required` attribute if set to true
 * @param {number=} ngMinlength Sets `minlength` validation error key if the value is shorter than
 *    minlength.
 * @param {number=} ngMaxlength Sets `maxlength` validation error key if the value is longer than
 *    maxlength.
 * @param {string=} ngPattern Sets `pattern` validation error key if the value does not match the
 *    RegExp pattern expression. Expected value is `/regexp/` for inline patterns or `regexp` for
 *    patterns defined as scope expressions.
 * @param {string=} ngChange Angular expression to be executed when input changes due to user
 *    interaction with the input element.
 *
 * @example
    <example name="input-directive">
      <file name="index.html">
       <script>
         function Ctrl($scope) {
           $scope.user = {name: 'guest', last: 'visitor'};
         }
       </script>
       <div ng-controller="Ctrl">
         <form name="myForm">
           User name: <input type="text" name="userName" ng-model="user.name" required>
           <span class="error" ng-show="myForm.userName.$error.required">
             Required!</span><br>
           Last name: <input type="text" name="lastName" ng-model="user.last"
             ng-minlength="3" ng-maxlength="10">
           <span class="error" ng-show="myForm.lastName.$error.minlength">
             Too short!</span>
           <span class="error" ng-show="myForm.lastName.$error.maxlength">
             Too long!</span><br>
         </form>
         <hr>
         <tt>user = {{user}}</tt><br/>
         <tt>myForm.userName.$valid = {{myForm.userName.$valid}}</tt><br>
         <tt>myForm.userName.$error = {{myForm.userName.$error}}</tt><br>
         <tt>myForm.lastName.$valid = {{myForm.lastName.$valid}}</tt><br>
         <tt>myForm.lastName.$error = {{myForm.lastName.$error}}</tt><br>
         <tt>myForm.$valid = {{myForm.$valid}}</tt><br>
         <tt>myForm.$error.required = {{!!myForm.$error.required}}</tt><br>
         <tt>myForm.$error.minlength = {{!!myForm.$error.minlength}}</tt><br>
         <tt>myForm.$error.maxlength = {{!!myForm.$error.maxlength}}</tt><br>
       </div>
      </file>
      <file name="protractor.js" type="protractor">
        var user = element(by.binding('{{user}}'));
        var userNameValid = element(by.binding('myForm.userName.$valid'));
        var lastNameValid = element(by.binding('myForm.lastName.$valid'));
        var lastNameError = element(by.binding('myForm.lastName.$error'));
        var formValid = element(by.binding('myForm.$valid'));
        var userNameInput = element(by.model('user.name'));
        var userLastInput = element(by.model('user.last'));

        it('should initialize to model', function() {
          expect(user.getText()).toContain('{"name":"guest","last":"visitor"}');
          expect(userNameValid.getText()).toContain('true');
          expect(formValid.getText()).toContain('true');
        });

        it('should be invalid if empty when required', function() {
          userNameInput.clear();
          userNameInput.sendKeys('');

          expect(user.getText()).toContain('{"last":"visitor"}');
          expect(userNameValid.getText()).toContain('false');
          expect(formValid.getText()).toContain('false');
        });

        it('should be valid if empty when min length is set', function() {
          userLastInput.clear();
          userLastInput.sendKeys('');

          expect(user.getText()).toContain('{"name":"guest","last":""}');
          expect(lastNameValid.getText()).toContain('true');
          expect(formValid.getText()).toContain('true');
        });

        it('should be invalid if less than required min length', function() {
          userLastInput.clear();
          userLastInput.sendKeys('xx');

          expect(user.getText()).toContain('{"name":"guest"}');
          expect(lastNameValid.getText()).toContain('false');
          expect(lastNameError.getText()).toContain('minlength');
          expect(formValid.getText()).toContain('false');
        });

        it('should be invalid if longer than max length', function() {
          userLastInput.clear();
          userLastInput.sendKeys('some ridiculously long name');

          expect(user.getText()).toContain('{"name":"guest"}');
          expect(lastNameValid.getText()).toContain('false');
          expect(lastNameError.getText()).toContain('maxlength');
          expect(formValid.getText()).toContain('false');
        });
      </file>
    </example>
 */
var inputDirective = ['$browser', '$sniffer', function($browser, $sniffer) {
  return {
    restrict: 'E',
    require: '?ngModel',
    link: function(scope, element, attr, ctrl) {
      if (ctrl) {
        (inputType[lowercase(attr.type)] || inputType.text)(scope, element, attr, ctrl, $sniffer,
                                                            $browser);
      }
    }
  };
}];

var VALID_CLASS = 'ng-valid',
    INVALID_CLASS = 'ng-invalid',
    PRISTINE_CLASS = 'ng-pristine',
    DIRTY_CLASS = 'ng-dirty';

/**
 * @ngdoc type
 * @name ngModel.NgModelController
 *
 * @property {string} $viewValue Actual string value in the view.
 * @property {*} $modelValue The value in the model, that the control is bound to.
 * @property {Array.<Function>} $parsers Array of functions to execute, as a pipeline, whenever
       the control reads value from the DOM.  Each function is called, in turn, passing the value
       through to the next. The last return value is used to populate the model.
       Used to sanitize / convert the value as well as validation. For validation,
       the parsers should update the validity state using
       {@link ngModel.NgModelController#$setValidity $setValidity()},
       and return `undefined` for invalid values.

 *
 * @property {Array.<Function>} $formatters Array of functions to execute, as a pipeline, whenever
       the model value changes. Each function is called, in turn, passing the value through to the
       next. Used to format / convert values for display in the control and validation.
 *      ```js
 *      function formatter(value) {
 *        if (value) {
 *          return value.toUpperCase();
 *        }
 *      }
 *      ngModel.$formatters.push(formatter);
 *      ```
 *
 * @property {Array.<Function>} $viewChangeListeners Array of functions to execute whenever the
 *     view value has changed. It is called with no arguments, and its return value is ignored.
 *     This can be used in place of additional $watches against the model value.
 *
 * @property {Object} $error An object hash with all errors as keys.
 *
 * @property {boolean} $pristine True if user has not interacted with the control yet.
 * @property {boolean} $dirty True if user has already interacted with the control.
 * @property {boolean} $valid True if there is no error.
 * @property {boolean} $invalid True if at least one error on the control.
 *
 * @description
 *
 * `NgModelController` provides API for the `ng-model` directive. The controller contains
 * services for data-binding, validation, CSS updates, and value formatting and parsing. It
 * purposefully does not contain any logic which deals with DOM rendering or listening to
 * DOM events. Such DOM related logic should be provided by other directives which make use of
 * `NgModelController` for data-binding.
 *
 * ## Custom Control Example
 * This example shows how to use `NgModelController` with a custom control to achieve
 * data-binding. Notice how different directives (`contenteditable`, `ng-model`, and `required`)
 * collaborate together to achieve the desired result.
 *
 * Note that `contenteditable` is an HTML5 attribute, which tells the browser to let the element
 * contents be edited in place by the user.  This will not work on older browsers.
 *
 * <example name="NgModelController" module="customControl">
    <file name="style.css">
      [contenteditable] {
        border: 1px solid black;
        background-color: white;
        min-height: 20px;
      }

      .ng-invalid {
        border: 1px solid red;
      }

    </file>
    <file name="script.js">
      angular.module('customControl', []).
        directive('contenteditable', function() {
          return {
            restrict: 'A', // only activate on element attribute
            require: '?ngModel', // get a hold of NgModelController
            link: function(scope, element, attrs, ngModel) {
              if(!ngModel) return; // do nothing if no ng-model

              // Specify how UI should be updated
              ngModel.$render = function() {
                element.html(ngModel.$viewValue || '');
              };

              // Listen for change events to enable binding
              element.on('blur keyup change', function() {
                scope.$apply(read);
              });
              read(); // initialize

              // Write data to the model
              function read() {
                var html = element.html();
                // When we clear the content editable the browser leaves a <br> behind
                // If strip-br attribute is provided then we strip this out
                if( attrs.stripBr && html == '<br>' ) {
                  html = '';
                }
                ngModel.$setViewValue(html);
              }
            }
          };
        });
    </file>
    <file name="index.html">
      <form name="myForm">
       <div contenteditable
            name="myWidget" ng-model="userContent"
            strip-br="true"
            required>Change me!</div>
        <span ng-show="myForm.myWidget.$error.required">Required!</span>
       <hr>
       <textarea ng-model="userContent"></textarea>
      </form>
    </file>
    <file name="protractor.js" type="protractor">
    it('should data-bind and become invalid', function() {
      if (browser.params.browser == 'safari' || browser.params.browser == 'firefox') {
        // SafariDriver can't handle contenteditable
        // and Firefox driver can't clear contenteditables very well
        return;
      }
      var contentEditable = element(by.css('[contenteditable]'));
      var content = 'Change me!';

      expect(contentEditable.getText()).toEqual(content);

      contentEditable.clear();
      contentEditable.sendKeys(protractor.Key.BACK_SPACE);
      expect(contentEditable.getText()).toEqual('');
      expect(contentEditable.getAttribute('class')).toMatch(/ng-invalid-required/);
    });
    </file>
 * </example>
 *
 *
 */
var NgModelController = ['$scope', '$exceptionHandler', '$attrs', '$element', '$parse', '$animate',
    function($scope, $exceptionHandler, $attr, $element, $parse, $animate) {
  this.$viewValue = Number.NaN;
  this.$modelValue = Number.NaN;
  this.$parsers = [];
  this.$formatters = [];
  this.$viewChangeListeners = [];
  this.$pristine = true;
  this.$dirty = false;
  this.$valid = true;
  this.$invalid = false;
  this.$name = $attr.name;

  var ngModelGet = $parse($attr.ngModel),
      ngModelSet = ngModelGet.assign;

  if (!ngModelSet) {
    throw minErr('ngModel')('nonassign', "Expression '{0}' is non-assignable. Element: {1}",
        $attr.ngModel, startingTag($element));
  }

  /**
   * @ngdoc method
   * @name ngModel.NgModelController#$render
   *
   * @description
   * Called when the view needs to be updated. It is expected that the user of the ng-model
   * directive will implement this method.
   */
  this.$render = noop;

  /**
   * @ngdoc method
   * @name ngModel.NgModelController#$isEmpty
   *
   * @description
   * This is called when we need to determine if the value of the input is empty.
   *
   * For instance, the required directive does this to work out if the input has data or not.
   * The default `$isEmpty` function checks whether the value is `undefined`, `''`, `null` or `NaN`.
   *
   * You can override this for input directives whose concept of being empty is different to the
   * default. The `checkboxInputType` directive does this because in its case a value of `false`
   * implies empty.
   *
   * @param {*} value Reference to check.
   * @returns {boolean} True if `value` is empty.
   */
  this.$isEmpty = function(value) {
    return isUndefined(value) || value === '' || value === null || value !== value;
  };

  var parentForm = $element.inheritedData('$formController') || nullFormCtrl,
      invalidCount = 0, // used to easily determine if we are valid
      $error = this.$error = {}; // keep invalid keys here


  // Setup initial state of the control
  $element.addClass(PRISTINE_CLASS);
  toggleValidCss(true);

  // convenience method for easy toggling of classes
  function toggleValidCss(isValid, validationErrorKey) {
    validationErrorKey = validationErrorKey ? '-' + snake_case(validationErrorKey, '-') : '';
    $animate.removeClass($element, (isValid ? INVALID_CLASS : VALID_CLASS) + validationErrorKey);
    $animate.addClass($element, (isValid ? VALID_CLASS : INVALID_CLASS) + validationErrorKey);
  }

  /**
   * @ngdoc method
   * @name ngModel.NgModelController#$setValidity
   *
   * @description
   * Change the validity state, and notifies the form when the control changes validity. (i.e. it
   * does not notify form if given validator is already marked as invalid).
   *
   * This method should be called by validators - i.e. the parser or formatter functions.
   *
   * @param {string} validationErrorKey Name of the validator. the `validationErrorKey` will assign
   *        to `$error[validationErrorKey]=isValid` so that it is available for data-binding.
   *        The `validationErrorKey` should be in camelCase and will get converted into dash-case
   *        for class name. Example: `myError` will result in `ng-valid-my-error` and `ng-invalid-my-error`
   *        class and can be bound to as  `{{someForm.someControl.$error.myError}}` .
   * @param {boolean} isValid Whether the current state is valid (true) or invalid (false).
   */
  this.$setValidity = function(validationErrorKey, isValid) {
    // Purposeful use of ! here to cast isValid to boolean in case it is undefined
    // jshint -W018
    if ($error[validationErrorKey] === !isValid) return;
    // jshint +W018

    if (isValid) {
      if ($error[validationErrorKey]) invalidCount--;
      if (!invalidCount) {
        toggleValidCss(true);
        this.$valid = true;
        this.$invalid = false;
      }
    } else {
      toggleValidCss(false);
      this.$invalid = true;
      this.$valid = false;
      invalidCount++;
    }

    $error[validationErrorKey] = !isValid;
    toggleValidCss(isValid, validationErrorKey);

    parentForm.$setValidity(validationErrorKey, isValid, this);
  };

  /**
   * @ngdoc method
   * @name ngModel.NgModelController#$setPristine
   *
   * @description
   * Sets the control to its pristine state.
   *
   * This method can be called to remove the 'ng-dirty' class and set the control to its pristine
   * state (ng-pristine class).
   */
  this.$setPristine = function () {
    this.$dirty = false;
    this.$pristine = true;
    $animate.removeClass($element, DIRTY_CLASS);
    $animate.addClass($element, PRISTINE_CLASS);
  };

  /**
   * @ngdoc method
   * @name ngModel.NgModelController#$setViewValue
   *
   * @description
   * Update the view value.
   *
   * This method should be called when the view value changes, typically from within a DOM event handler.
   * For example {@link ng.directive:input input} and
   * {@link ng.directive:select select} directives call it.
   *
   * It will update the $viewValue, then pass this value through each of the functions in `$parsers`,
   * which includes any validators. The value that comes out of this `$parsers` pipeline, be applied to
   * `$modelValue` and the **expression** specified in the `ng-model` attribute.
   *
   * Lastly, all the registered change listeners, in the `$viewChangeListeners` list, are called.
   *
   * Note that calling this function does not trigger a `$digest`.
   *
   * @param {string} value Value from the view.
   */
  this.$setViewValue = function(value) {
    this.$viewValue = value;

    // change to dirty
    if (this.$pristine) {
      this.$dirty = true;
      this.$pristine = false;
      $animate.removeClass($element, PRISTINE_CLASS);
      $animate.addClass($element, DIRTY_CLASS);
      parentForm.$setDirty();
    }

    forEach(this.$parsers, function(fn) {
      value = fn(value);
    });

    if (this.$modelValue !== value) {
      this.$modelValue = value;
      ngModelSet($scope, value);
      forEach(this.$viewChangeListeners, function(listener) {
        try {
          listener();
        } catch(e) {
          $exceptionHandler(e);
        }
      });
    }
  };

  // model -> value
  var ctrl = this;

  $scope.$watch(function ngModelWatch() {
    var value = ngModelGet($scope);

    // if scope model value and ngModel value are out of sync
    if (ctrl.$modelValue !== value) {

      var formatters = ctrl.$formatters,
          idx = formatters.length;

      ctrl.$modelValue = value;
      while(idx--) {
        value = formatters[idx](value);
      }

      if (ctrl.$viewValue !== value) {
        ctrl.$viewValue = value;
        ctrl.$render();
      }
    }

    return value;
  });
}];


/**
 * @ngdoc directive
 * @name ngModel
 *
 * @element input
 *
 * @description
 * The `ngModel` directive binds an `input`,`select`, `textarea` (or custom form control) to a
 * property on the scope using {@link ngModel.NgModelController NgModelController},
 * which is created and exposed by this directive.
 *
 * `ngModel` is responsible for:
 *
 * - Binding the view into the model, which other directives such as `input`, `textarea` or `select`
 *   require.
 * - Providing validation behavior (i.e. required, number, email, url).
 * - Keeping the state of the control (valid/invalid, dirty/pristine, validation errors).
 * - Setting related css classes on the element (`ng-valid`, `ng-invalid`, `ng-dirty`, `ng-pristine`) including animations.
 * - Registering the control with its parent {@link ng.directive:form form}.
 *
 * Note: `ngModel` will try to bind to the property given by evaluating the expression on the
 * current scope. If the property doesn't already exist on this scope, it will be created
 * implicitly and added to the scope.
 *
 * For best practices on using `ngModel`, see:
 *
 *  - [https://github.com/angular/angular.js/wiki/Understanding-Scopes]
 *
 * For basic examples, how to use `ngModel`, see:
 *
 *  - {@link ng.directive:input input}
 *    - {@link input[text] text}
 *    - {@link input[checkbox] checkbox}
 *    - {@link input[radio] radio}
 *    - {@link input[number] number}
 *    - {@link input[email] email}
 *    - {@link input[url] url}
 *  - {@link ng.directive:select select}
 *  - {@link ng.directive:textarea textarea}
 *
 * # CSS classes
 * The following CSS classes are added and removed on the associated input/select/textarea element
 * depending on the validity of the model.
 *
 *  - `ng-valid` is set if the model is valid.
 *  - `ng-invalid` is set if the model is invalid.
 *  - `ng-pristine` is set if the model is pristine.
 *  - `ng-dirty` is set if the model is dirty.
 *
 * Keep in mind that ngAnimate can detect each of these classes when added and removed.
 *
 * ## Animation Hooks
 *
 * Animations within models are triggered when any of the associated CSS classes are added and removed
 * on the input element which is attached to the model. These classes are: `.ng-pristine`, `.ng-dirty`,
 * `.ng-invalid` and `.ng-valid` as well as any other validations that are performed on the model itself.
 * The animations that are triggered within ngModel are similar to how they work in ngClass and
 * animations can be hooked into using CSS transitions, keyframes as well as JS animations.
 *
 * The following example shows a simple way to utilize CSS transitions to style an input element
 * that has been rendered as invalid after it has been validated:
 *
 * <pre>
 * //be sure to include ngAnimate as a module to hook into more
 * //advanced animations
 * .my-input {
 *   transition:0.5s linear all;
 *   background: white;
 * }
 * .my-input.ng-invalid {
 *   background: red;
 *   color:white;
 * }
 * </pre>
 *
 * @example
 * <example deps="angular-animate.js" animations="true" fixBase="true">
     <file name="index.html">
       <script>
        function Ctrl($scope) {
          $scope.val = '1';
        }
       </script>
       <style>
         .my-input {
           -webkit-transition:all linear 0.5s;
           transition:all linear 0.5s;
           background: transparent;
         }
         .my-input.ng-invalid {
           color:white;
           background: red;
         }
       </style>
       Update input to see transitions when valid/invalid.
       Integer is a valid value.
       <form name="testForm" ng-controller="Ctrl">
         <input ng-model="val" ng-pattern="/^\d+$/" name="anim" class="my-input" />
       </form>
     </file>
 * </example>
 */
var ngModelDirective = function() {
  return {
    require: ['ngModel', '^?form'],
    controller: NgModelController,
    link: function(scope, element, attr, ctrls) {
      // notify others, especially parent forms

      var modelCtrl = ctrls[0],
          formCtrl = ctrls[1] || nullFormCtrl;

      formCtrl.$addControl(modelCtrl);

      scope.$on('$destroy', function() {
        formCtrl.$removeControl(modelCtrl);
      });
    }
  };
};


/**
 * @ngdoc directive
 * @name ngChange
 *
 * @description
 * Evaluate the given expression when the user changes the input.
 * The expression is evaluated immediately, unlike the JavaScript onchange event
 * which only triggers at the end of a change (usually, when the user leaves the
 * form element or presses the return key).
 * The expression is not evaluated when the value change is coming from the model.
 *
 * Note, this directive requires `ngModel` to be present.
 *
 * @element input
 * @param {expression} ngChange {@link guide/expression Expression} to evaluate upon change
 * in input value.
 *
 * @example
 * <example name="ngChange-directive">
 *   <file name="index.html">
 *     <script>
 *       function Controller($scope) {
 *         $scope.counter = 0;
 *         $scope.change = function() {
 *           $scope.counter++;
 *         };
 *       }
 *     </script>
 *     <div ng-controller="Controller">
 *       <input type="checkbox" ng-model="confirmed" ng-change="change()" id="ng-change-example1" />
 *       <input type="checkbox" ng-model="confirmed" id="ng-change-example2" />
 *       <label for="ng-change-example2">Confirmed</label><br />
 *       <tt>debug = {{confirmed}}</tt><br/>
 *       <tt>counter = {{counter}}</tt><br/>
 *     </div>
 *   </file>
 *   <file name="protractor.js" type="protractor">
 *     var counter = element(by.binding('counter'));
 *     var debug = element(by.binding('confirmed'));
 *
 *     it('should evaluate the expression if changing from view', function() {
 *       expect(counter.getText()).toContain('0');
 *
 *       element(by.id('ng-change-example1')).click();
 *
 *       expect(counter.getText()).toContain('1');
 *       expect(debug.getText()).toContain('true');
 *     });
 *
 *     it('should not evaluate the expression if changing from model', function() {
 *       element(by.id('ng-change-example2')).click();

 *       expect(counter.getText()).toContain('0');
 *       expect(debug.getText()).toContain('true');
 *     });
 *   </file>
 * </example>
 */
var ngChangeDirective = valueFn({
  require: 'ngModel',
  link: function(scope, element, attr, ctrl) {
    ctrl.$viewChangeListeners.push(function() {
      scope.$eval(attr.ngChange);
    });
  }
});


var requiredDirective = function() {
  return {
    require: '?ngModel',
    link: function(scope, elm, attr, ctrl) {
      if (!ctrl) return;
      attr.required = true; // force truthy in case we are on non input element

      var validator = function(value) {
        if (attr.required && ctrl.$isEmpty(value)) {
          ctrl.$setValidity('required', false);
          return;
        } else {
          ctrl.$setValidity('required', true);
          return value;
        }
      };

      ctrl.$formatters.push(validator);
      ctrl.$parsers.unshift(validator);

      attr.$observe('required', function() {
        validator(ctrl.$viewValue);
      });
    }
  };
};


/**
 * @ngdoc directive
 * @name ngList
 *
 * @description
 * Text input that converts between a delimited string and an array of strings. The delimiter
 * can be a fixed string (by default a comma) or a regular expression.
 *
 * @element input
 * @param {string=} ngList optional delimiter that should be used to split the value. If
 *   specified in form `/something/` then the value will be converted into a regular expression.
 *
 * @example
    <example name="ngList-directive">
      <file name="index.html">
       <script>
         function Ctrl($scope) {
           $scope.names = ['igor', 'misko', 'vojta'];
         }
       </script>
       <form name="myForm" ng-controller="Ctrl">
         List: <input name="namesInput" ng-model="names" ng-list required>
         <span class="error" ng-show="myForm.namesInput.$error.required">
           Required!</span>
         <br>
         <tt>names = {{names}}</tt><br/>
         <tt>myForm.namesInput.$valid = {{myForm.namesInput.$valid}}</tt><br/>
         <tt>myForm.namesInput.$error = {{myForm.namesInput.$error}}</tt><br/>
         <tt>myForm.$valid = {{myForm.$valid}}</tt><br/>
         <tt>myForm.$error.required = {{!!myForm.$error.required}}</tt><br/>
        </form>
      </file>
      <file name="protractor.js" type="protractor">
        var listInput = element(by.model('names'));
        var names = element(by.binding('{{names}}'));
        var valid = element(by.binding('myForm.namesInput.$valid'));
        var error = element(by.css('span.error'));

        it('should initialize to model', function() {
          expect(names.getText()).toContain('["igor","misko","vojta"]');
          expect(valid.getText()).toContain('true');
          expect(error.getCssValue('display')).toBe('none');
        });

        it('should be invalid if empty', function() {
          listInput.clear();
          listInput.sendKeys('');

          expect(names.getText()).toContain('');
          expect(valid.getText()).toContain('false');
          expect(error.getCssValue('display')).not.toBe('none');        });
      </file>
    </example>
 */
var ngListDirective = function() {
  return {
    require: 'ngModel',
    link: function(scope, element, attr, ctrl) {
      var match = /\/(.*)\//.exec(attr.ngList),
          separator = match && new RegExp(match[1]) || attr.ngList || ',';

      var parse = function(viewValue) {
        // If the viewValue is invalid (say required but empty) it will be `undefined`
        if (isUndefined(viewValue)) return;

        var list = [];

        if (viewValue) {
          forEach(viewValue.split(separator), function(value) {
            if (value) list.push(trim(value));
          });
        }

        return list;
      };

      ctrl.$parsers.push(parse);
      ctrl.$formatters.push(function(value) {
        if (isArray(value)) {
          return value.join(', ');
        }

        return undefined;
      });

      // Override the standard $isEmpty because an empty array means the input is empty.
      ctrl.$isEmpty = function(value) {
        return !value || !value.length;
      };
    }
  };
};


var CONSTANT_VALUE_REGEXP = /^(true|false|\d+)$/;
/**
 * @ngdoc directive
 * @name ngValue
 *
 * @description
 * Binds the given expression to the value of `input[select]` or `input[radio]`, so
 * that when the element is selected, the `ngModel` of that element is set to the
 * bound value.
 *
 * `ngValue` is useful when dynamically generating lists of radio buttons using `ng-repeat`, as
 * shown below.
 *
 * @element input
 * @param {string=} ngValue angular expression, whose value will be bound to the `value` attribute
 *   of the `input` element
 *
 * @example
    <example name="ngValue-directive">
      <file name="index.html">
       <script>
          function Ctrl($scope) {
            $scope.names = ['pizza', 'unicorns', 'robots'];
            $scope.my = { favorite: 'unicorns' };
          }
       </script>
        <form ng-controller="Ctrl">
          <h2>Which is your favorite?</h2>
            <label ng-repeat="name in names" for="{{name}}">
              {{name}}
              <input type="radio"
                     ng-model="my.favorite"
                     ng-value="name"
                     id="{{name}}"
                     name="favorite">
            </label>
          <div>You chose {{my.favorite}}</div>
        </form>
      </file>
      <file name="protractor.js" type="protractor">
        var favorite = element(by.binding('my.favorite'));

        it('should initialize to model', function() {
          expect(favorite.getText()).toContain('unicorns');
        });
        it('should bind the values to the inputs', function() {
          element.all(by.model('my.favorite')).get(0).click();
          expect(favorite.getText()).toContain('pizza');
        });
      </file>
    </example>
 */
var ngValueDirective = function() {
  return {
    priority: 100,
    compile: function(tpl, tplAttr) {
      if (CONSTANT_VALUE_REGEXP.test(tplAttr.ngValue)) {
        return function ngValueConstantLink(scope, elm, attr) {
          attr.$set('value', scope.$eval(attr.ngValue));
        };
      } else {
        return function ngValueLink(scope, elm, attr) {
          scope.$watch(attr.ngValue, function valueWatchAction(value) {
            attr.$set('value', value);
          });
        };
      }
    }
  };
};