.directive('angularMask', function () {
    return {
        restrict: 'A',
        link: function ($scope, el, attrs) {
            var format = attrs.angularMask;

            function replaceAt(s, index, character) {
                return s.substr(0, index) + character + s.substr(index+character.length);
            }

            function clearByMask(val) {
                var v = val || '';
                for(var i = 0; i < Math.min(format.length, val.length); i++) {
                    if (format[i] != '_' || !v[i].match(/\d/)) {
                        v = replaceAt(v, i, ' ');
                    }
                }

                return v.replace(/\s/g, '');
            }

            function mask(o) {
                var value = clearByMask(o.value);
                var newValue = '';
                for (var valueIndex = 0, formatIndex = 0; formatIndex < format.length;) {
                    if (format[formatIndex] != '_') {
                        newValue += format[formatIndex];
                    } else {
                        if (value[valueIndex] != undefined) {
                            newValue += value[valueIndex];
                            valueIndex++;
                        } else {
                            break;
                        }
                    }
                    formatIndex++;
                }
                o.value = newValue;
            }

            el.bind('keyup keydown', function (e) {
                var keyList = [8, 37, 39, 46];
                if (keyList.indexOf(e.keyCode) == -1) {
                    mask(this);
                }
            });
        }
    };
});