(function () {
    "use strict";
    angular.module('shared')
        .directive('tabsKeydown', ['$state', function ($state) {
            return {
                restrict: 'A',
                link: function (scope, element, attrs) {

                    var keyboardKeys = {
                        tab: 9,
                        space: 32,
                        left: 37,
                        right: 39
                    };

                    element.on('keydown', function (event) {
                        switch (event.keyCode) {
                            case keyboardKeys.left:
                            case keyboardKeys.right:
                                handleArrowsKeydown(event);
                                break;
                            case keyboardKeys.space:
                                handleSpaceKeyDown(event);
                                break;
                            default:
                                return;
                        }
                    });

                    var handleSpaceKeyDown = function (event) {
                        if (attrs.role === 'tab') {
                            event.preventDefault();
                            $state.go(attrs.uiSref);
                        }
                    };

                    var handleArrowsKeydown = function (event) {
                        if (attrs.role === 'tab') {
                            var parentElement = element.parent();
                            var focusableElements = getTabElements();
                            var firstFocusableElement = focusableElements[0];
                            var lastFocusableElement = focusableElements[focusableElements.length - 1];
                            event.preventDefault();
                            if (event.keyCode === keyboardKeys.left) {
                                focusCorrectTab(element[0], firstFocusableElement, lastFocusableElement, parentElement.prev());
                            } else {
                                focusCorrectTab(element[0], lastFocusableElement, firstFocusableElement, parentElement.next());
                            }
                        }
                    };

                    var getTabElements = function () {
                        return angular.element('.navTabs').find('button');
                    };

                    var isSameElement = function(element1, element2) {
                        return element1 === element2 || element1.isEqualNode(element2);
                    };

                    var focusCorrectTab = function (currentElement, compareElement, oppositeEndTab, nextInSequenceTab) {
                        if (isSameElement(currentElement, compareElement)) {
                            oppositeEndTab.focus();
                        } else {
                            nextInSequenceTab[0].firstElementChild.focus();
                        }
                    };
                }
            };
        }]);
})();