/* 
 jQuery UI Sortable plugin wrapper

 @param [ui-sortable] {object} Options to pass to $.fn.sortable() merged onto ui.config
 */
angular.module('ui.sortable', [])
  .value('uiSortableConfig',{})
  .directive('uiSortable', [
    'uiSortableConfig', '$timeout', '$log',
function(uiSortableConfig, $timeout, $log) {
    return {
        require: '?ngModel',
        link: function(scope, element, attrs, ngModel) {
            var savedNodes;

            function combineCallbacks(first,second){
                if(second && (typeof second === 'function')) {
                    return function(e, ui) {
                        first(e, ui);
                        second(e, ui);
                    };
                }
                return first;
            }

            function hasSortingHelper (element, ui) {
                var helperOption = element.sortable('option','helper');
                return helperOption === 'clone' || (typeof helperOption === 'function' && ui.item.sortable.isCustomHelperUsed());
            }

            var opts = {};

            var callbacks = {
                receive: null,
                remove:null,
                start:null,
                stop:null,
                update:null
            };

            var wrappers = {
                helper: null
            };

            angular.extend(opts, uiSortableConfig, scope.$eval(attrs.uiSortable));

            if (!angular.element.fn || !angular.element.fn.jquery) {
                $log.error('ui.sortable: jQuery should be included before AngularJS!');
                return;
            }

            if (ngModel) {

                // When we add or remove elements, we need the sortable to 'refresh'
                // so it can find the new/removed elements.
                scope.$watch(attrs.ngModel+'.length', function() {
                    // Timeout to let ng-repeat modify the DOM
                    $timeout(function() {
                        // ensure that the jquery-ui-sortable widget instance
                        // is still bound to the directive's element
                        if (!!element.data('ui-sortable')) {
                            element.sortable('refresh');
                        }
                    });
                });

                callbacks.start = function(e, ui) {
                    // Save the starting position of dragged item
                    ui.item.sortable = {
                        index: ui.item.index(),
                        cancel: function () {
                            ui.item.sortable._isCanceled = true;
                        },
                        isCanceled: function () {
                            return ui.item.sortable._isCanceled;
                        },
                        isCustomHelperUsed: function () {
                            return !!ui.item.sortable._isCustomHelperUsed;
                        },
                        _isCanceled: false,
                        _isCustomHelperUsed: ui.item.sortable._isCustomHelperUsed
                    };
                };

                callbacks.activate = function(/*e, ui*/) {
                    // We need to make a copy of the current element's contents so
                    // we can restore it after sortable has messed it up.
                    // This is inside activate (instead of start) in order to save
                    // both lists when dragging between connected lists.
                    savedNodes = element.contents();

                    // If this list has a placeholder (the connected lists won't),
                    // don't inlcude it in saved nodes.
                    var placeholder = element.sortable('option','placeholder');

                    // placeholder.element will be a function if the placeholder, has
                    // been created (placeholder will be an object).  If it hasn't
                    // been created, either placeholder will be false if no
                    // placeholder class was given or placeholder.element will be
                    // undefined if a class was given (placeholder will be a string)
                    if (placeholder && placeholder.element && typeof placeholder.element === 'function') {
                        var phElement = placeholder.element();
                        // workaround for jquery ui 1.9.x,
                        // not returning jquery collection
                        phElement = angular.element(phElement);

                        // exact match with the placeholder's class attribute to handle
                        // the case that multiple connected sortables exist and
                        // the placehoilder option equals the class of sortable items
                        var excludes = element.find('[class="' + phElement.attr('class') + '"]');

                        savedNodes = savedNodes.not(excludes);
                    }
                };

                callbacks.update = function(e, ui) {
                    // Save current drop position but only if this is not a second
                    // update that happens when moving between lists because then
                    // the value will be overwritten with the old value
                    if(!ui.item.sortable.received) {
                        ui.item.sortable.dropindex = ui.item.index();
                        ui.item.sortable.droptarget = ui.item.parent();

                        // Cancel the sort (let ng-repeat do the sort for us)
                        // Don't cancel if this is the received list because it has
                        // already been canceled in the other list, and trying to cancel
                        // here will mess up the DOM.
                        element.sortable('cancel');
                    }

                    // Put the nodes back exactly the way they started (this is very
                    // important because ng-repeat uses comment elements to delineate
                    // the start and stop of repeat sections and sortable doesn't
                    // respect their order (even if we cancel, the order of the
                    // comments are still messed up).
                    if (hasSortingHelper(element, ui) && !ui.item.sortable.received &&
                        element.sortable( 'option', 'appendTo' ) === 'parent') {
                        // restore all the savedNodes except .ui-sortable-helper element
                        // (which is placed last). That way it will be garbage collected.
                        savedNodes = savedNodes.not(savedNodes.last());
                    }
                    savedNodes.appendTo(element);

                    // If this is the target connected list then
                    // it's safe to clear the restored nodes since:
                    // update is currently running and
                    // stop is not called for the target list.
                    if(ui.item.sortable.received) {
                        savedNodes = null;
                    }

                    // If received is true (an item was dropped in from another list)
                    // then we add the new item to this list otherwise wait until the
                    // stop event where we will know if it was a sort or item was
                    // moved here from another list
                    if(ui.item.sortable.received && !ui.item.sortable.isCanceled()) {
                        scope.$apply(function () {
                            ngModel.$modelValue.splice(ui.item.sortable.dropindex, 0,
                                                       ui.item.sortable.moved);
                        });
                    }
                };

                callbacks.stop = function(e, ui) {
                    // If the received flag hasn't be set on the item, this is a
                    // normal sort, if dropindex is set, the item was moved, so move
                    // the items in the list.
                    if(!ui.item.sortable.received &&
                       ('dropindex' in ui.item.sortable) &&
                       !ui.item.sortable.isCanceled()) {

                        scope.$apply(function () {
                            ngModel.$modelValue.splice(
                              ui.item.sortable.dropindex, 0,
                              ngModel.$modelValue.splice(ui.item.sortable.index, 1)[0]);
                        });
                    } else {
                        // if the item was not moved, then restore the elements
                        // so that the ngRepeat's comment are correct.
                        if ((!('dropindex' in ui.item.sortable) || ui.item.sortable.isCanceled()) &&
                            !hasSortingHelper(element, ui)) {
                            savedNodes.appendTo(element);
                        }
                    }

                    // It's now safe to clear the savedNodes
                    // since stop is the last callback.
                    savedNodes = null;
                };

                callbacks.receive = function(e, ui) {
                    // An item was dropped here from another list, set a flag on the
                    // item.
                    ui.item.sortable.received = true;
                };

                callbacks.remove = function(e, ui) {
                    // Workaround for a problem observed in nested connected lists.
                    // There should be an 'update' event before 'remove' when moving
                    // elements. If the event did not fire, cancel sorting.
                    if (!('dropindex' in ui.item.sortable)) {
                        element.sortable('cancel');
                        ui.item.sortable.cancel();
                    }

                    // Remove the item from this list's model and copy data into item,
                    // so the next list can retrive it
                    if (!ui.item.sortable.isCanceled()) {
                        scope.$apply(function () {
                            ui.item.sortable.moved = ngModel.$modelValue.splice(
                              ui.item.sortable.index, 1)[0];
                        });
                    }
                };

                wrappers.helper = function (inner) {
                    if (inner && typeof inner === 'function') {
                        return function (e, item) {
                            var innerResult = inner(e, item);
                            item.sortable._isCustomHelperUsed = item !== innerResult;
                            return innerResult;
                        };
                    }
                    return inner;
                };

                scope.$watch(attrs.uiSortable, function(newVal /*, oldVal*/) {
                    // ensure that the jquery-ui-sortable widget instance
                    // is still bound to the directive's element
                    if (!!element.data('ui-sortable')) {
                        angular.forEach(newVal, function(value, key) {
                            if(callbacks[key]) {
                                if( key === 'stop' ){
                                    // call apply after stop
                                    value = combineCallbacks(
                                      value, function() { scope.$apply(); });
                                }
                                // wrap the callback
                                value = combineCallbacks(callbacks[key], value);
                            } else if (wrappers[key]) {
                                value = wrappers[key](value);
                            }
                  
                            element.sortable('option', key, value);
                        });
                    }
                }, true);

                angular.forEach(callbacks, function(value, key) {
                    opts[key] = combineCallbacks(value, opts[key]);
                });

            } else {
                $log.info('ui.sortable: ngModel not provided!', element);
            }

            // Create sortable
            element.sortable(opts);
        }
    };
}
]);