angularjs：这段示例代码逻辑上有点看不懂

Question

directive('tabs', function() {
return {
            restrict: 'E',
            transclude: true,
            scope: {},
            controller: ["$scope", function($scope) {//为什么是数组呢："$scope"该怎么理解呢
                var panes = $scope.panes = [];                
                $scope.select = function(pane) {
                    angular.forEach(panes, function(pane) {
                        pane.selected = false;
                    });
                    pane.selected = true;
                }

                this.addPane = function(pane) {//这里的this该怎么解释，为什么能直接this.addPane呢
                    if(panes.length == 0) $scope.select(pane);
                    panes.push(pane);
                }
            }],
            template: '<div class="tabbable">' +                '<ul class="nav nav-tabs">' +                '<li ng-repeat="pane in panes" ng-class="{active:pane.selected}">' +                '<a href="" ng-click="select(pane)">{{pane.title}}</a>' +//ng-click="select(pane)"这里面的参数pane是从哪里来的呢，难道是ng-repeat里面可以直接定义，这里面可以直接传？
                '</li>' +                '</ul>' +                '<div class="tab-content" ng-transclude></div>' +                '</div>',
            replace: true
        };
    }).
    directive('pane', function() {        return {            require: '^tabs',//
            restrict: 'E',
            transclude: true,
            scope: {
                title: '@'
            },
            link: function(scope, element, attrs, tabsCtrl) {
                
                tabsCtrl.addPane(scope);//这里为什么传scope参数呢
            },
            template: '<div class="tab-pane" ng-class="{active: selected}" ng-transclude>' +//ng-class="{active: selected}"怎么理解呢
                '</div>',
            replace: true
        };
    })