jQuery.tableDnD = {
    currentTable : null,
    dragObject: null,
    mouseOffset: null,
    oldY: 0,
    build: function(options) {
        this.each(function() {
            this.tableDnDConfig = jQuery.extend({
                onDragStyle: null,
                onDropStyle: null,
				onDragClass: "tDnD_whileDrag",
                onDrop: null,
                onDragStart: null,
                scrollAmount: 5,
				serializeRegexp: /[^\-]*$/, 
				serializeParamName: null, 
                dragHandle: null 
            }, options || {});
            jQuery.tableDnD.makeDraggable(this);
        });
        jQuery(document)
            .bind('mousemove', jQuery.tableDnD.mousemove)
            .bind('mouseup', jQuery.tableDnD.mouseup);
        return this;
    },
    makeDraggable: function(table) {
        var config = table.tableDnDConfig;
		if (table.tableDnDConfig.dragHandle) {
			var cells = jQuery("td."+table.tableDnDConfig.dragHandle, table);
			cells.each(function() {
                jQuery(this).mousedown(function(ev) {
                    jQuery.tableDnD.dragObject = this.parentNode;
                    jQuery.tableDnD.currentTable = table;
                    jQuery.tableDnD.mouseOffset = jQuery.tableDnD.getMouseOffset(this, ev);
                    if (config.onDragStart) {
                        config.onDragStart(table, this);
                    }
                    return false;
                });
			})
		} else {
	        var rows = jQuery("tr", table); 
	        rows.each(function() {
				var row = jQuery(this);
				if (! row.hasClass("nodrag")) {
	                row.mousedown(function(ev) {
	                    if (ev.target.tagName == "TD") {
	                        jQuery.tableDnD.dragObject = this;
	                        jQuery.tableDnD.currentTable = table;
	                        jQuery.tableDnD.mouseOffset = jQuery.tableDnD.getMouseOffset(this, ev);
	                        if (config.onDragStart) {
	                            config.onDragStart(table, this);
	                        }
	                        return false;
	                    }
	                }).css("cursor", "move");
				}
			});
		}
	},
	updateTables: function() {
		this.each(function() {
			if (this.tableDnDConfig) {
				jQuery.tableDnD.makeDraggable(this);
			}
		})
	},
    mouseCoords: function(ev){
        if(ev.pageX || ev.pageY){
            return {x:ev.pageX, y:ev.pageY};
        }
        return {
            x:ev.clientX + document.body.scrollLeft - document.body.clientLeft,
            y:ev.clientY + document.body.scrollTop  - document.body.clientTop
        };
    },
    getMouseOffset: function(target, ev) {
        ev = ev || window.event;
        var docPos    = this.getPosition(target);
        var mousePos  = this.mouseCoords(ev);
        return {x:mousePos.x - docPos.x, y:mousePos.y - docPos.y};
    },
    getPosition: function(e){
        var left = 0;
        var top  = 0;
        if (e.offsetHeight == 0) {
            e = e.firstChild;
        }
        while (e.offsetParent){
            left += e.offsetLeft;
            top  += e.offsetTop;
            e     = e.offsetParent;
        }
        left += e.offsetLeft;
        top  += e.offsetTop;
        return {x:left, y:top};
    },
    mousemove: function(ev) {
        if (jQuery.tableDnD.dragObject == null) {
            return;
        }
        var dragObj = jQuery(jQuery.tableDnD.dragObject);
        var config = jQuery.tableDnD.currentTable.tableDnDConfig;
        var mousePos = jQuery.tableDnD.mouseCoords(ev);
        var y = mousePos.y - jQuery.tableDnD.mouseOffset.y;
	    var yOffset = window.pageYOffset;
	 	if (document.all) {
	        if (typeof document.compatMode != 'undefined' &&
	             document.compatMode != 'BackCompat') {
	           yOffset = document.documentElement.scrollTop;
	        }
	        else if (typeof document.body != 'undefined') {
	           yOffset=document.body.scrollTop;
	        }
	    }
		if (mousePos.y-yOffset < config.scrollAmount) {
	    	window.scrollBy(0, -config.scrollAmount);
	    } else {
            var windowHeight = window.innerHeight ? window.innerHeight
                    : document.documentElement.clientHeight ? document.documentElement.clientHeight : document.body.clientHeight;
            if (windowHeight-(mousePos.y-yOffset) < config.scrollAmount) {
                window.scrollBy(0, config.scrollAmount);
            }
        }
        if (y != jQuery.tableDnD.oldY) {
            var movingDown = y > jQuery.tableDnD.oldY;
            jQuery.tableDnD.oldY = y;
			if (config.onDragClass) {
				dragObj.addClass(config.onDragClass);
			} else {
	            dragObj.css(config.onDragStyle);
			}
            var currentRow = jQuery.tableDnD.findDropTargetRow(dragObj, y);
            if (currentRow) {
                if (movingDown && jQuery.tableDnD.dragObject != currentRow) {
                    jQuery.tableDnD.dragObject.parentNode.insertBefore(jQuery.tableDnD.dragObject, currentRow.nextSibling);
                } else if (! movingDown && jQuery.tableDnD.dragObject != currentRow) {
                    jQuery.tableDnD.dragObject.parentNode.insertBefore(jQuery.tableDnD.dragObject, currentRow);
                }
            }
        }
        return false;
    },
    findDropTargetRow: function(draggedRow, y) {
        var rows = jQuery.tableDnD.currentTable.rows;
        for (var i=0; i<rows.length; i++) {
            var row = rows[i];
            var rowY    = this.getPosition(row).y;
            var rowHeight = parseInt(row.offsetHeight)/2;
            if (row.offsetHeight == 0) {
                rowY = this.getPosition(row.firstChild).y;
                rowHeight = parseInt(row.firstChild.offsetHeight)/2;
            }
            if ((y > rowY - rowHeight) && (y < (rowY + rowHeight))) {
				if (row == draggedRow) {return null;}
                var config = jQuery.tableDnD.currentTable.tableDnDConfig;
                if (config.onAllowDrop) {
                    if (config.onAllowDrop(draggedRow, row)) {
                        return row;
                    } else {
                        return null;
                    }
                } else {
                    var nodrop = jQuery(row).hasClass("nodrop");
                    if (! nodrop) {
                        return row;
                    } else {
                        return null;
                    }
                }
                return row;
            }
        }
        return null;
    },
    mouseup: function(e) {
        if (jQuery.tableDnD.currentTable && jQuery.tableDnD.dragObject) {
            var droppedRow = jQuery.tableDnD.dragObject;
            var config = jQuery.tableDnD.currentTable.tableDnDConfig;
			if (config.onDragClass) {
	            jQuery(droppedRow).removeClass(config.onDragClass);
			} else {
	            jQuery(droppedRow).css(config.onDropStyle);
			}
            jQuery.tableDnD.dragObject   = null;
            if (config.onDrop) {
                config.onDrop(jQuery.tableDnD.currentTable, droppedRow);
            }
            jQuery.tableDnD.currentTable = null; 
        }
    },
    serialize: function() {
        if (jQuery.tableDnD.currentTable) {
            return jQuery.tableDnD.serializeTable(jQuery.tableDnD.currentTable);
        } else {
            return "Error: No Table id set, you need to set an id on your table and every row";
        }
    },
	serializeTable: function(table) {
        var result = "";
        var tableId = table.id;
        var rows = table.rows;
        for (var i=0; i<rows.length; i++) {
            if (result.length > 0) result += "&";
            var rowId = rows[i].id;
            if (rowId && rowId && table.tableDnDConfig && table.tableDnDConfig.serializeRegexp) {
                rowId = rowId.match(table.tableDnDConfig.serializeRegexp)[0];
            }
            result += tableId + '[]=' + rowId;
        }
        return result;
	},
	serializeTables: function() {
        var result = "";
        this.each(function() {
			result += jQuery.tableDnD.serializeTable(this);
		});
        return result;
    }
}

jQuery.fn.extend(
	{
		tableDnD : jQuery.tableDnD.build,
		tableDnDUpdate : jQuery.tableDnD.updateTables,
		tableDnDSerialize: jQuery.tableDnD.serializeTables
	}
);