// Website: https://github.com/agavazov/dragsort/

(function ($) {
    $.fn.dragsort = function (options) {
        if (options === 'destroy') {
            $(this).trigger('dragsort-uninit');
            return;
        }

        var opts = $.extend({}, $.fn.dragsort.defaults, options);
        var lists = [];
        var list = null, lastPos = null;

        this.each(function (i, cont) {
            // if list container is table, the browser automatically wraps rows in tbody if not specified so change list container to tbody so that children returns rows as user expected
            if ($(cont).is('table') && $(cont).children().length === 1 && $(cont).children().is('tbody')) {
                cont = $(cont).children().get(0);
            }

            var newList = {
                draggedItem: null,
                placeHolderItem: null,
                pos: null,
                offset: null,
                offsetLimit: null,
                scroll: null,
                container: cont,

                init: function () {
                    // set options to default values if not set
                    opts.tagName = $(this.container).children().length === 0 ? 'li' : $(this.container).children().get(0).tagName.toLowerCase();
                    if (!opts.itemSelector) {
                        opts.itemSelector = opts.tagName;
                    }
                    if (!opts.dragSelector) {
                        opts.dragSelector = opts.tagName;
                    }
                    if (!opts.placeHolderTemplate) {
                        opts.placeHolderTemplate = '<' + opts.tagName + '>&nbsp;</' + opts.tagName + '>';
                    }

                    // listidx allows reference back to correct list variable instance
                    $(this.container).attr('data-listidx', i).bind('mousedown touchstart', this.grabItem).bind('dragsort-uninit', this.uninit);
                    this.styleDragHandlers(true);
                },

                uninit: function () {
                    var list = lists[$(this).attr('data-listidx')];
                    $(list.container).unbind('mousedown touchstart', list.grabItem).unbind('dragsort-uninit');
                    list.styleDragHandlers(false);
                },

                getItems: function () {
                    return $(this.container).children(opts.itemSelector);
                },

                styleDragHandlers: function (cursor) {
                    this.getItems().map(function () {
                        return $(this).is(opts.dragSelector) ? this : $(this).find(opts.dragSelector).get();
                    }).css('cursor', cursor ? opts.cursor : 'default');
                },

                grabItem: function (e) {
                    var list = lists[$(this).attr('data-listidx')];
                    var item = $(e.target).closest('[data-listidx] > ' + opts.tagName).get(0);
                    var insideMoveableItem = list.getItems().filter(function () {
                        return this == item;
                    }).length > 0;

                    // if not left click or if clicked on excluded element (e.g. text box) or not a moveable list item return
                    if ((e.which !== 1 && e.which !== 0) || $(e.target).is(opts.dragSelectorExclude) || $(e.target).closest(opts.dragSelectorExclude).length > 0 || !insideMoveableItem) {
                        return;
                    }

                    // prevents selection, stops issue on Fx where dragging hyperlink doesn't work and on IE where it triggers mousemove even though mouse hasn't moved,
                    // does also stop being able to click text boxes hence dragging on text boxes by default is disabled in dragSelectorExclude
                    e.preventDefault();

                    // change cursor to move while dragging
                    var dragHandle = e.target;
                    while (!$(dragHandle).is(opts.dragSelector)) {
                        if (dragHandle == this) {
                            return;
                        }
                        dragHandle = dragHandle.parentNode;
                    }
                    $(dragHandle).attr('data-cursor', $(dragHandle).css('cursor'));
                    $(dragHandle).css('cursor', 'pointer');

                    // on mousedown wait for movement of mouse before triggering dragsort script (dragStart) to allow clicking of hyperlinks to work
                    var listElem = this;
                    var trigger = function () {
                        list.dragStart.call(listElem, e);
                        $(list.container).unbind('mousemove touchmove', trigger);
                    };
                    $(list.container).bind('mousemove touchmove', trigger).bind('mouseup touchend', function () {
                        $(list.container).unbind('mousemove touchmove', trigger);
                        $(dragHandle).css('cursor', $(dragHandle).attr('data-cursor'));
                    });
                },

                dragStart: function (e) {
                    if (list != null && list.draggedItem != null) {
                        list.dropItem();
                    }

                    // hack for touching devices
                    if (e.changedTouches && e.changedTouches[0]) {
                        e.pageX = e.changedTouches[0].pageX;
                        e.pageY = e.changedTouches[0].pageY;
                    }

                    list = lists[$(this).attr('data-listidx')];
                    list.draggedItem = $(e.target).closest('[data-listidx] > ' + opts.tagName)

                    // record current position so on dragend we know if the dragged item changed position or not, not using getItems to allow dragsort to restore dragged item to original location in relation to fixed items
                    list.draggedItem.attr('data-origpos', $(this).attr('data-listidx') + '-' + $(list.container).children().index(list.draggedItem));

                    // calculate mouse offset relative to draggedItem
                    var mt = parseInt(list.draggedItem.css('marginTop'));
                    var ml = parseInt(list.draggedItem.css('marginLeft'));
                    list.offset = list.draggedItem.offset();
                    list.offset.top = e.pageY - list.offset.top + (isNaN(mt) ? 0 : mt) - 1;
                    list.offset.left = e.pageX - list.offset.left + (isNaN(ml) ? 0 : ml) - 1;

                    // calculate box the dragged item can't be dragged outside of
                    if (!opts.dragBetween) {
                        var containerHeight = $(list.container).outerHeight() == 0 ? Math.max(1, Math.round(0.5 + list.getItems().length * list.draggedItem.outerWidth() / $(list.container).outerWidth())) * list.draggedItem.outerHeight() : $(list.container).outerHeight();
                        list.offsetLimit = $(list.container).offset();
                        list.offsetLimit.right = list.offsetLimit.left + $(list.container).outerWidth() - list.draggedItem.outerWidth();
                        list.offsetLimit.bottom = list.offsetLimit.top + containerHeight - list.draggedItem.outerHeight();
                    }

                    // create placeholder item
                    var h = list.draggedItem.height();
                    var w = list.draggedItem.width();
                    if (opts.tagName === 'tr') {
                        list.draggedItem.children().each(function () {
                            $(this).width($(this).width());
                        });
                        list.placeHolderItem = list.draggedItem.clone().attr('data-placeholder', true);
                        list.draggedItem.after(list.placeHolderItem);
                        list.placeHolderItem.children().each(function () {
                            $(this).css({
                                borderWidth: 0,
                                width: $(this).width() + 1,
                                height: $(this).height() + 1
                            }).html('&nbsp;');
                        });
                    } else {
                        list.draggedItem.after(opts.placeHolderTemplate);
                        list.placeHolderItem = list.draggedItem.next().css({
                            height: h,
                            width: w
                        }).attr('data-placeholder', true);
                    }

                    if (opts.tagName === 'td') {
                        var listTable = list.draggedItem.closest('table').get(0);
                        $('<table id="' + listTable.id + '" style="border-width: 0px;" class="dragSortItem ' + listTable.className + '"><tr></tr></table>').appendTo('body').children().append(list.draggedItem);
                    }

                    // style draggedItem while dragging
                    var orig = list.draggedItem.attr('style');
                    list.draggedItem.attr('data-origstyle', orig ? orig : '');
                    list.draggedItem.css({position: 'absolute', opacity: 1, 'box-shadow': '0 0 20px rgba(39, 46, 79, .3)', 'z-index': 999, height: h, width: w});

                    // auto-scroll setup
                    list.scroll = {
                        moveX: 0,
                        moveY: 0,
                        maxX: $(document).width() - $(window).width(),
                        maxY: $(document).height() - $(window).height()
                    };
                    list.scroll.scrollY = window.setInterval(function () {
                        if (opts.scrollContainer != window) {
                            $(opts.scrollContainer).scrollTop($(opts.scrollContainer).scrollTop() + list.scroll.moveY);
                            return;
                        }
                        var t = $(opts.scrollContainer).scrollTop();
                        if (list.scroll.moveY > 0 && t < list.scroll.maxY || list.scroll.moveY < 0 && t > 0) {
                            $(opts.scrollContainer).scrollTop(t + list.scroll.moveY);
                            list.draggedItem.css('top', list.draggedItem.offset().top + list.scroll.moveY + 1);
                        }
                    }, 10);
                    list.scroll.scrollX = window.setInterval(function () {
                        if (opts.scrollContainer != window) {
                            $(opts.scrollContainer).scrollLeft($(opts.scrollContainer).scrollLeft() + list.scroll.moveX);
                            return;
                        }
                        var l = $(opts.scrollContainer).scrollLeft();
                        if (list.scroll.moveX > 0 && l < list.scroll.maxX || list.scroll.moveX < 0 && l > 0) {
                            $(opts.scrollContainer).scrollLeft(l + list.scroll.moveX);
                            list.draggedItem.css('left', list.draggedItem.offset().left + list.scroll.moveX + 1);
                        }
                    }, 10);

                    // misc
                    $(lists).each(function (i, l) {
                        l.createDropTargets();
                        l.buildPositionTable();
                    });
                    list.setPos(e.pageX, e.pageY);
                    $(document).bind('mousemove touchmove', list.swapItems);
                    $(document).bind('mouseup touchend', list.dropItem);
                    if (opts.scrollContainer != window) {
                        $(window).bind('wheel', list.wheel);
                    }
                },

                // set position of draggedItem
                setPos: function (x, y) {
                    // remove mouse offset so mouse cursor remains in same place on draggedItem instead of top left corner
                    var top = y - this.offset.top;
                    var left = x - this.offset.left;

                    // limit top, left to within box draggedItem can't be dragged outside of
                    if (!opts.dragBetween) {
                        top = Math.min(this.offsetLimit.bottom, Math.max(top, this.offsetLimit.top));
                        left = Math.min(this.offsetLimit.right, Math.max(left, this.offsetLimit.left));
                    }

                    // adjust top & left calculations to parent offset
                    var parent = this.draggedItem.offsetParent().not('body').offset(); //offsetParent returns body even when it's static, if not static offset is only factoring margin
                    if (parent != null) {
                        top -= parent.top;
                        left -= parent.left;
                    }

                    // set x or y auto-scroll amount
                    if (opts.scrollContainer == window) {
                        y -= $(window).scrollTop();
                        x -= $(window).scrollLeft();
                        y = Math.max(0, y - $(window).height() + 5) + Math.min(0, y - 5);
                        x = Math.max(0, x - $(window).width() + 5) + Math.min(0, x - 5);
                    } else {
                        var cont = $(opts.scrollContainer);
                        var offset = cont.offset();
                        y = Math.max(0, y - cont.height() - offset.top) + Math.min(0, y - offset.top);
                        x = Math.max(0, x - cont.width() - offset.left) + Math.min(0, x - offset.left);
                    }

                    list.scroll.moveX = x === 0 ? 0 : x * opts.scrollSpeed / Math.abs(x);
                    list.scroll.moveY = y === 0 ? 0 : y * opts.scrollSpeed / Math.abs(y);

                    // move draggedItem to new mouse cursor location
                    this.draggedItem.css({top: top, left: left});
                },

                // if scroll container is a div allow mouse wheel to scroll div instead of window when mouse is hovering over
                wheel: function (e) {
                    if (list && opts.scrollContainer != window) {
                        var cont = $(opts.scrollContainer);
                        var offset = cont.offset();
                        e = e.originalEvent;
                        if (e.clientX > offset.left && e.clientX < offset.left + cont.width() && e.clientY > offset.top && e.clientY < offset.top + cont.height()) {
                            var deltaY = (e.deltaMode === 0 ? 1 : 10) * e.deltaY;
                            cont.scrollTop(cont.scrollTop() + deltaY);
                            e.preventDefault();
                        }
                    }
                },

                // build a table recording all the positions of the moveable list items
                buildPositionTable: function () {
                    var pos = [];
                    this.getItems().not([list.draggedItem[0], list.placeHolderItem[0]]).each(function (i) {
                        var loc = $(this).offset();
                        loc.right = loc.left + $(this).outerWidth();
                        loc.bottom = loc.top + $(this).outerHeight();
                        loc.elm = this;
                        pos[i] = loc;
                    });
                    this.pos = pos;
                },

                dropItem: function () {
                    if (list.draggedItem == null) {
                        return;
                    }

                    // list.draggedItem.attr('style', '') doesn't work on IE8 and jQuery 1.5 or lower
                    // list.draggedItem.removeAttr('style') doesn't work on chrome and jQuery 1.6 (works jQuery 1.5 or lower)
                    var orig = list.draggedItem.attr('data-origstyle');
                    list.draggedItem.attr('style', orig);
                    if (orig == '') {
                        list.draggedItem.removeAttr('style');
                    }
                    list.draggedItem.removeAttr('data-origstyle');

                    list.styleDragHandlers(true);

                    list.placeHolderItem.before(list.draggedItem);
                    list.placeHolderItem.remove();

                    $('[data-droptarget], .dragSortItem').remove();

                    window.clearInterval(list.scroll.scrollY);
                    window.clearInterval(list.scroll.scrollX);

                    // if position changed call dragEnd
                    if (list.draggedItem.attr('data-origpos') != $(lists).index(list) + '-' + $(list.container).children().index(list.draggedItem))
                        if (opts.dragEnd.apply(list.draggedItem) == false) { //if dragEnd returns false revert order
                            var pos = list.draggedItem.attr('data-origpos').split('-');
                            var nextItem = $(lists[pos[0]].container).children().not(list.draggedItem).eq(pos[1]);
                            if (nextItem.length > 0) {
                                nextItem.before(list.draggedItem);
                            } else if (pos[1] == 0) {//was the only item in list
                                $(lists[pos[0]].container).prepend(list.draggedItem);
                            } else {//was the last item in list
                                $(lists[pos[0]].container).append(list.draggedItem);
                            }
                        }
                    list.draggedItem.removeAttr('data-origpos');

                    list.draggedItem = null;
                    $(document).unbind('mousemove touchmove', list.swapItems);
                    $(document).unbind('mouseup touchend', list.dropItem);
                    if (opts.scrollContainer != window) {
                        $(window).unbind('wheel', list.wheel);
                    }
                    return false;
                },

                // swap the draggedItem (represented visually by placeholder) with the list item the it has been dragged on top of
                swapItems: function (e) {
                    if (list.draggedItem == null) {
                        return false;
                    }

                    // hack for touching devices
                    if (e.changedTouches && e.changedTouches[0]) {
                        e.pageX = e.changedTouches[0].pageX;
                        e.pageY = e.changedTouches[0].pageY;
                    }

                    // move draggedItem to mouse location
                    list.setPos(e.pageX, e.pageY);

                    // retrieve list and item position mouse cursor is over
                    var ei = list.findPos(e.pageX, e.pageY);
                    var nlist = list;
                    for (var i = 0; ei == -1 && opts.dragBetween && i < lists.length; i++) {
                        ei = lists[i].findPos(e.pageX, e.pageY);
                        nlist = lists[i];
                    }

                    // if not over another moveable list item return
                    if (ei == -1) {
                        return false;
                    }

                    // save fixed items locations
                    var children = function () {
                        return $(nlist.container).children().not(nlist.draggedItem);
                    };
                    var fixed = children().not(opts.itemSelector).each(function (i) {
                        this.idx = children().index(this);
                    });

                    // if moving draggedItem up or left place placeHolder before list item the dragged item is hovering over otherwise place it after
                    if (lastPos == null || lastPos.top > list.draggedItem.offset().top || lastPos.left > list.draggedItem.offset().left) {
                        $(nlist.pos[ei].elm).before(list.placeHolderItem);
                    } else {
                        $(nlist.pos[ei].elm).after(list.placeHolderItem);
                    }

                    // restore fixed items location
                    fixed.each(function () {
                        var elm = children().eq(this.idx).get(0);
                        if (this != elm && children().index(this) < this.idx) {
                            $(this).insertAfter(elm);
                        } else if (this != elm) {
                            $(this).insertBefore(elm);
                        }
                    });

                    // misc
                    $(lists).each(function (i, l) {
                        l.createDropTargets();
                        l.buildPositionTable();
                    });
                    lastPos = list.draggedItem.offset();

                    return false;
                },

                // returns the index of the list item the mouse is over
                findPos: function (x, y) {
                    for (var i = 0; i < this.pos.length; i++) {
                        if (this.pos[i].left < x && this.pos[i].right > x && this.pos[i].top < y && this.pos[i].bottom > y) {
                            return i;
                        }
                    }
                    return -1;
                },

                // create drop targets which are placeholders at the end of other lists to allow dragging straight to the last position
                createDropTargets: function () {
                    if (!opts.dragBetween) {
                        return;
                    }

                    $(lists).each(function () {
                        var ph = $(this.container).find('[data-placeholder]');
                        var dt = $(this.container).find('[data-droptarget]');
                        if (ph.length > 0 && dt.length > 0) {
                            dt.remove();
                        } else if (ph.length === 0 && dt.length === 0) {
                            if (opts.tagName === 'td') {
                                $(opts.placeHolderTemplate).attr('data-droptarget', true).appendTo(this.container);
                            } else {
                                // list.placeHolderItem.clone().removeAttr('data-placeholder') crashes in IE7 and jquery 1.5.1 (doesn't in jquery 1.4.2 or IE8)
                                $(this.container).append(list.placeHolderItem.removeAttr('data-placeholder').clone().attr('data-droptarget', true));
                            }

                            list.placeHolderItem.attr('data-placeholder', true);
                        }
                    });
                },
            };

            newList.init();
            lists.push(newList);
        });

        return this;
    };

    $.fn.dragsort.defaults = {
        itemSelector: '',
        dragSelector: '',
        dragSelectorExclude: 'input, textarea',
        dragEnd: function () {
        },
        dragBetween: false,
        placeHolderTemplate: '',
        scrollContainer: window,
        scrollSpeed: 5,
        cursor: 'pointer'
    };
})(jQuery);
