/*!
 * Ext JS Library 3.2.0
 * Copyright(c) 2006-2010 Ext JS, Inc.
 * licensing@extjs.com
 * http://www.extjs.com/license
 */
/**
 * @class Ext.ux.ToolbarReorderer
 * @extends Ext.ux.Reorderer
 * Plugin which can be attached to any Ext.Toolbar instance. Provides ability to reorder toolbar items
 * with drag and drop. Example:
 * <pre>
 * new Ext.Toolbar({
 *     plugins: [
 *         new Ext.ux.ToolbarReorderer({
 *             defaultReorderable: true
 *         })
 *     ],
 *     items: [
 *       {text: 'Button 1', reorderable: false},
 *       {text: 'Button 2'},
 *       {text: 'Button 3'}
 *     ]
 * });
 * </pre>
 * In the example above, buttons 2 and 3 will be reorderable via drag and drop. An event named 'reordered'
 * is added to the Toolbar, and is fired whenever a reorder has been completed.
 */
Ext.ux.ToolbarReorderer = Ext.extend(Ext.ux.Reorderer, {
    /**
     * Initializes the plugin, decorates the toolbar with additional functionality
     */
    init: function(toolbar) {
        /**
         * This is used to store the correct x value of each button in the array. We need to use this
         * instead of the button's reported x co-ordinate because the buttons are animated when they move -
         * if another onDrag is fired while the button is still moving, the comparison x value will be incorrect
         */
        this.buttonXCache = {};
        
        toolbar.on({
            scope: this,
            add  : function(toolbar, item) {
                this.createIfReorderable(item);
            }
        });
        
        //super sets a reference to the toolbar in this.target
        Ext.ux.ToolbarReorderer.superclass.init.apply(this, arguments);
    },
        
    /**
     * Sets up the given Toolbar item as a draggable
     * @param {Mixed} button The item to make draggable (usually an Ext.Button instance)
     */
    createItemDD: function(button) {
        if (button.dd != undefined) return;
        
        var el   = button.getEl(),
            id   = el.id,
            tbar = this.target,
            me   = this;
        
        button.dd = new Ext.dd.DD(el, undefined, {
            isTarget: false
        });
        
        //if a button has a menu, it is disabled while dragging with this function
        var menuDisabler = function() {
            return false;
        };
        
        Ext.apply(button.dd, {
            b4StartDrag: function() {       
                this.startPosition = el.getXY();
                
                //bump up the z index of the button being dragged but keep a reference to the original
                this.startZIndex = el.getStyle('zIndex');
                el.setStyle('zIndex', 10000);
                
                button.suspendEvents();
                if (button.menu) {
                    button.menu.on('beforeshow', menuDisabler, me);
                }
            },
            
            startDrag: function() {
                this.constrainTo(tbar.getEl());
                this.setYConstraint(0, 0, 0);
            },
            
            onDrag: function(e) {
                //calculate the button's index within the toolbar and its current midpoint
                var buttonX  = el.getXY()[0],
                    deltaX   = buttonX - this.startPosition[0],
                    items    = tbar.items.items,
                    oldIndex = items.indexOf(button),
                    newIndex;
                
                //find which item in the toolbar the midpoint is currently over
                for (var index = 0; index < items.length; index++) {
                    var item = items[index];
                    
                    if (item.reorderable && item.id != button.id) {
                        //find the midpoint of the button
                        var box        = item.getEl().getBox(),
                            midpoint   = (me.buttonXCache[item.id] || box.x) + (box.width / 2),
                            movedLeft  = oldIndex > index && deltaX < 0 && buttonX < midpoint,
                            movedRight = oldIndex < index && deltaX > 0 && (buttonX + el.getWidth()) > midpoint;
                        
                        if (movedLeft || movedRight) {
                            me[movedLeft ? 'onMovedLeft' : 'onMovedRight'](button, index, oldIndex);
                            break;
                        }                        
                    }
                }
            },
            
            /**
             * After the drag has been completed, make sure the button being dragged makes it back to
             * the correct location and resets its z index
             */
            endDrag: function() {
                //we need to update the cache here for cases where the button was dragged but its
                //position in the toolbar did not change
                me.updateButtonXCache();
                
                el.moveTo(me.buttonXCache[button.id], el.getY(), {
                    duration: me.animationDuration,
                    scope   : this,
                    callback: function() {
                        button.resumeEvents();
                        if (button.menu) {
                            button.menu.un('beforeshow', menuDisabler, me);
                        }
                        
                        tbar.fireEvent('reordered', button, tbar);
                    }
                });
                
                el.setStyle('zIndex', this.startZIndex);
            }
        });
    },
    
    onMovedLeft: function(item, newIndex, oldIndex) {
        var tbar  = this.target,
            items = tbar.items.items;
        
        if (newIndex != undefined && newIndex != oldIndex) {
            //move the button currently under drag to its new location
            tbar.remove(item, false);
            tbar.insert(newIndex, item);
            
            //set the correct x location of each item in the toolbar
            this.updateButtonXCache();
            for (var index = 0; index < items.length; index++) {
                var obj  = items[index],
                    newX = this.buttonXCache[obj.id];
                
                if (item == obj) {
                    item.dd.startPosition[0] = newX;
                } else {
                    var el = obj.getEl();
                    
                    el.moveTo(newX, el.getY(), {duration: this.animationDuration});
                }
            }
        }
    },
    
    onMovedRight: function(item, newIndex, oldIndex) {
        this.onMovedLeft.apply(this, arguments);
    },
    
    /**
     * @private
     * Updates the internal cache of button X locations. 
     */
    updateButtonXCache: function() {
        var tbar   = this.target,
            items  = tbar.items,
            totalX = tbar.getEl().getBox(true).x;
            
        items.each(function(item) {
            this.buttonXCache[item.id] = totalX;
            totalX += item.getEl().getWidth();
        }, this);
    }
});
