import ngModule from '../module';


export function directive($parse) {
    return {
        restrict: 'A',
        link: function($scope, $element, $attrs) {
            const element = $element[0];
            const onDropEvent = $parse($attrs.onDrop);
            const isDroppable = $attrs.vnDroppable === 'true';

            if (!isDroppable) return;

            /**
             * Captures current dragging element
             */
            element.addEventListener('dragstart', () => {
                this.dragged = element;
            });

            /**
             * Enter droppable area event
             */
            element.addEventListener('dragenter', event => {
                element.style.backgroundColor = 'yellow';

                event.stopImmediatePropagation();
                event.preventDefault();
            }, false);


            /**
             * Exit droppable area event
             */
            element.addEventListener('dragleave', event => {
                element.style.backgroundColor = 'transparent';

                event.stopImmediatePropagation();
                event.preventDefault();
            });

            /**
             * Prevent dragover for allowing
             * dispatch drop event
             */
            element.addEventListener('dragover', event => {
                event.stopPropagation();
                event.preventDefault();
            });

            /**
             * Fires when a drop events
             */
            element.addEventListener('drop', event => {
                const draggedParent = this.dragged.parentNode;
                const targetChild = element.querySelector('ul');


                element.style.transition = 'background 2s';
                element.style.backgroundColor = 'transparent';

                if (this.dragged === element)
                    return event.preventDefault();


                if (targetChild) {
                    const targetNodes = targetChild.querySelectorAll('li');
                    const before = targetNodes[targetNodes.length - 1];

                    targetChild.insertBefore(this.dragged, before);
                } else
                    draggedParent.removeChild(this.dragged);

                onDropEvent($scope, {
                    dragged: {
                        element: this.dragged,
                        scope: angular.element(this.dragged).scope()
                    },
                    dropped: {
                        element: element,
                        scope: angular.element(element).scope()
                    }
                });

                event.stopImmediatePropagation();
            });
        }
    };
}

directive.$inject = ['$parse'];

ngModule.directive('vnDroppable', directive);