/**
 * http://www.isocra.com/2008/02/table-drag-and-drop-jquery-plugin/
 * Licensed like jQuery, see http://docs.jquery.com/License.
 *
 * Configuration options:
 *
 * onDragStyle
 *     This is the style that is assigned to the row during drag. There are limitations to the styles that can be
 *     associated with a row (such as you can't assign a border--well you can, but it won't be
 *     displayed). (So instead consider using onDragClass.) The CSS style to apply is specified as
 *     a map (as used in the jQuery css(...) function).
 * onDropStyle
 *     This is the style that is assigned to the row when it is dropped. As for onDragStyle, there are limitations
 *     to what you can do. Also this replaces the original style, so again consider using onDragClass which
 *     is simply added and then removed on drop.
 * onDragClass
 *     This class is added for the duration of the drag and then removed when the row is dropped. It is more
 *     flexible than using onDragStyle since it can be inherited by the row cells and other content. The default
 *     is class is tDnD_whileDrag. So to use the default, simply customise this CSS class in your
 *     stylesheet.
 * onDrop
 *     Pass a function that will be called when the row is dropped. The function takes 2 parameters: the table
 *     and the row that was dropped. You can work out the new order of the rows by using
 *     table.rows.
 * onDragStart
 *     Pass a function that will be called when the user starts dragging. The function takes 2 parameters: the
 *     table and the row which the user has started to drag.
 * onAllowDrop
 *     Pass a function that will be called as a row is over another row. If the function returns true, allow
 *     dropping on that row, otherwise not. The function takes 2 parameters: the dragged row and the row under
 *     the cursor. It returns a boolean: true allows the drop, false doesn't allow it.
 * scrollAmount
 *     This is the number of pixels to scroll if the user moves the mouse cursor to the top or bottom of the
 *     window. The page should automatically scroll up or down as appropriate (tested in IE6, IE7, Safari, FF2,
 *     FF3 beta
 * dragHandle
 *     This is the name of a class that you assign to one or more cells in each row that is draggable. If you
 *     specify this class, then you are responsible for setting cursor: move in the CSS and only these cells
 *     will have the drag behaviour. If you do not specify a dragHandle, then you get the old behaviour where
 *     the whole row is draggable.
 *
 * Other ways to control behaviour:
 *
 * Add class="nodrop" to any rows for which you don't want to allow dropping, and class="nodrag" to any rows
 * that you don't want to be draggable.
 *
 * Inside the onDrop method you can also call $.tableDnD.serialize() this returns a string of the form
 * <tableID>[]=<rowID1>&<tableID>[]=<rowID2> so that you can send this back to the server. The table must have
 * an ID as must all the rows.
 *
 * Other methods:
 *
 * $("...").tableDnDUpdate()
 * Will update all the matching tables, that is it will reapply the mousedown method to the rows (or handle cells).
 * This is useful if you have updated the table rows using Ajax and you want to make the table draggable again.
 * The table maintains the original configuration (so you don't have to specify it again).
 *
 * $("...").tableDnDSerialize()
 * Will serialize and return the serialized string as above, but for each of the matching tables--so it can be
 * called from anywhere and isn't dependent on the currentTable being set up correctly before calling
 *
 * Known problems:
 * - Auto-scoll has some problems with IE7  (it scrolls even when it shouldn't), work-around: set scrollAmount to 0
 */
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;
        /** Safari fix -- thanks to Luis Chato for this! */
        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) {
	        // Windows version
	        //yOffset=document.body.scrollTop;
	        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) {
                    try {
						jQuery.tableDnD.dragObject.parentNode.insertBefore(jQuery.tableDnD.dragObject, currentRow.nextSibling);
					} catch(e) {}
                } else if (! movingDown && jQuery.tableDnD.dragObject != currentRow) {
                    try {
						jQuery.tableDnD.dragObject.parentNode.insertBefore(jQuery.tableDnD.dragObject, currentRow);
					} catch(e) {}
                }
            }
        }

        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
});