/**
 * @class YAHOO.ext.BasicLayoutRegion
 * @extends YAHOO.ext.util.Observable
 * This class represents a lightweight region in a layout manager. This region does not move dom nodes
 * and does not have a titlebar, tabs or any other features. All it does is size and position 
 * panels. To create a BasicLayoutRegion, add lightweight:true or basic:true to your regions config.
 */
YAHOO.ext.BasicLayoutRegion = function(mgr, config, pos, skipConfig){
    this.mgr = mgr;
    this.position  = pos;
    this.events = {
        /**
         * @event beforeremove
         * Fires before a panel is removed (or closed). To cancel the removal set "e.cancel = true" on the event argument.
         * @param {YAHOO.ext.LayoutRegion} this
         * @param {YAHOO.ext.ContentPanel} panel The panel
         * @param {Object} e The cancel event object
         */
        'beforeremove' : true,
        /**
         * @event invalidated
         * Fires when the layout for this region is changed.
         * @param {YAHOO.ext.LayoutRegion} this
         */
        'invalidated' : true,
        /**
         * @event visibilitychange
         * Fires when this region is shown or hidden 
         * @param {YAHOO.ext.LayoutRegion} this
         * @param {Boolean} visibility true or false
         */
        'visibilitychange' : true,
        /**
         * @event paneladded
         * Fires when a panel is added. 
         * @param {YAHOO.ext.LayoutRegion} this
         * @param {YAHOO.ext.ContentPanel} panel The panel
         */
        'paneladded' : true,
        /**
         * @event panelremoved
         * Fires when a panel is removed. 
         * @param {YAHOO.ext.LayoutRegion} this
         * @param {YAHOO.ext.ContentPanel} panel The panel
         */
        'panelremoved' : true,
        /**
         * @event collapsed
         * Fires when this region is collapsed. 
         * @param {YAHOO.ext.LayoutRegion} this
         */
        'collapsed' : true,
        /**
         * @event expanded
         * Fires when this region is expanded. 
         * @param {YAHOO.ext.LayoutRegion} this
         */
        'expanded' : true,
        /**
         * @event panelactivated
         * Fires when a panel is activated. 
         * @param {YAHOO.ext.LayoutRegion} this
         * @param {YAHOO.ext.ContentPanel} panel The activated panel
         */
        'panelactivated' : true,
        /**
         * @event resized
         * Fires when the user resizes this region. 
         * @param {YAHOO.ext.LayoutRegion} this
         * @param {Number} newSize The new size (width for east/west, height for north/south)
         */
        'resized' : true
    };
    /** A collection of panels in this region. @type YAHOO.ext.util.MixedCollection */
    this.panels = new YAHOO.ext.util.MixedCollection();
    this.panels.getKey = this.getPanelId.createDelegate(this);
    this.box = null;
    this.activePanel = null;
    if(skipConfig !== true){
        this.applyConfig(config);
    }
};

YAHOO.extendX(YAHOO.ext.BasicLayoutRegion, YAHOO.ext.util.Observable, {
    getPanelId : function(p){
        return p.getId();
    },
    
    applyConfig : function(config){
        this.margins = config.margins || this.margins || {top: 0, left: 0, right:0, bottom: 0};
        this.config = config;
    },
    
    /**
     * Resizes the region to the specified size. For vertical regions (west, east) this adjusts 
     * the width, for horizontal (north, south) the height.
     * @param {Number} newSize The new width or height
     */
    resizeTo : function(newSize){
        if(this.activePanel){
            var el = this.activePanel.getEl();
            switch(this.position){
                case 'east':
                case 'west':
                    el.setWidth(newSize);
                    this.fireEvent('resized', this, newSize);
                break;
                case 'north':
                case 'south':
                    el.setHeight(newSize);
                    this.fireEvent('resized', this, newSize);
                break;                
            }
        }
    },
    
    getBox : function(){
        return this.activePanel ? this.activePanel.getEl().getBox(false, true) : null;
    },
    
    getMargins : function(){
        return this.margins;
    },
    
    updateBox : function(box){
        this.box = box;
        var el = this.activePanel.getEl();
        el.dom.style.left = box.x + 'px';
        el.dom.style.top = box.y + 'px';
        el.setSize(box.width, box.height);
    },
    
    /**
     * Returns the container element for this region.
     * @return {YAHOO.ext.Element}
     */
    getEl : function(){
        return this.activePanel;
    },
    
    /**
     * Returns true if this region is currently visible.
     * @return {Boolean}
     */
    isVisible : function(){
        return this.activePanel ? true : false;
    },
    
    setActivePanel : function(panel){
        panel = this.getPanel(panel);
        if(this.activePanel && this.activePanel != panel){
            this.activePanel.setActiveState(false);
            this.activePanel.getEl().setStyle({left:-10000,right:-10000});
        }
        this.activePanel = panel;
        panel.setActiveState(true);
        if(this.box){
            panel.setSize(this.box.width, this.box.height);
        }
        this.fireEvent('panelactivated', this, panel);
        this.fireEvent('invalidated');
    },
    
    /**
     * Show the specified panel.
     * @param {Number/String/ContentPanel} panelId The panels index, id or the panel itself
     * @return {YAHOO.ext.ContentPanel} The shown panel or null
     */
    showPanel : function(panel){
        if(panel = this.getPanel(panel)){
            this.setActivePanel(panel);
        }
        return panel;
    },
    
    /**
     * Get the active panel for this region.
     * @return {YAHOO.ext.ContentPanel} The active panel or null
     */
    getActivePanel : function(){
        return this.activePanel;
    },
    
    /**
     * Add the passed ContentPanel(s)
     * @param {ContentPanel...} panel The ContentPanel(s) to add (you can pass more than one)
     * @return {YAHOO.ext.ContentPanel} The panel added (if only one was added)
     */
    add : function(panel){
        if(arguments.length > 1){
            for(var i = 0, len = arguments.length; i < len; i++) {
            	this.add(arguments[i]);
            }
            return null;
        }
        if(this.hasPanel(panel)){
            this.showPanel(panel);
            return panel;
        }
        panel.setRegion(this);
        this.panels.add(panel);
        panel.getEl().setStyle('position', 'absolute');
        if(!panel.background){
            this.setActivePanel(panel);
            if(this.config.initialSize && this.panels.getCount()==1){
                this.resizeTo(this.config.initialSize);
            }
        }
        this.fireEvent('paneladded', this, panel);
        return panel;
    },
    
    /**
     * Returns true if the panel is in this region.
     * @param {Number/String/ContentPanel} panel The panels index, id or the panel itself
     * @return {Boolean}
     */
    hasPanel : function(panel){
        if(typeof panel == 'object'){ // must be panel obj
            panel = panel.getId();
        }
        return this.getPanel(panel) ? true : false;
    },
    
    /**
     * Removes the specified panel. If preservePanel is not true (either here or in the config), the panel is destroyed.
     * @param {Number/String/ContentPanel} panel The panels index, id or the panel itself
     * @param {Boolean} preservePanel Overrides the config preservePanel option
     * @return {YAHOO.ext.ContentPanel} The panel that was removed
     */
    remove : function(panel, preservePanel){
        panel = this.getPanel(panel);
        if(!panel){
            return null;
        }
        var e = {};
        this.fireEvent('beforeremove', this, panel, e);
        if(e.cancel === true){
            return null;
        }
        var panelId = panel.getId();
        this.panels.removeKey(panelId);
        return panel;
    },
    
    /**
     * Returns the panel specified or null if it's not in this region.
     * @param {Number/String/ContentPanel} panel The panels index, id or the panel itself
     * @return {YAHOO.ext.ContentPanel}
     */
    getPanel : function(id){
        if(typeof id == 'object'){ // must be panel obj
            return id;
        }
        return this.panels.get(id);
    },
    
    /**
     * Returns this regions position (north/south/east/west/center).
     * @return {String} 
     */
    getPosition: function(){
        return this.position;    
    }
});