/**
 * @class Ext.ListView.Sorter
 * @extends Ext.util.Observable
 * 
Supporting Class for Ext.ListView.
 * @constructor
 * @param {Object} config
 */
Ext.ListView.Sorter = Ext.extend(Ext.util.Observable, {
    
/**
     * @cfg {Array} sortClasses
     * The CSS classes applied to a header when it is sorted. (defaults to ["sort-asc", "sort-desc"])
     */
    sortClasses : ["sort-asc", "sort-desc"],

    constructor: function(config){
        Ext.apply(this, config);
        Ext.ListView.Sorter.superclass.constructor.call(this);
    },

    init : function(listView){
        this.view = listView;
        listView.on('render', this.initEvents, this);
    },

    initEvents : function(view){
        view.mon(view.innerHd, 'click', this.onHdClick, this);
        view.innerHd.setStyle('cursor', 'pointer');
        view.mon(view.store, 'datachanged', this.updateSortState, this);
        this.updateSortState.defer(10, this, [view.store]);
    },

    updateSortState : function(store){
        var state = store.getSortState();
        if(!state){
            return;
        }
        this.sortState = state;
        var cs = this.view.columns, sortColumn = -1;
        for(var i = 0, len = cs.length; i < len; i++){
            if(cs[i].dataIndex == state.field){
                sortColumn = i;
                break;
            }
        }
        if(sortColumn != -1){
            var sortDir = state.direction;
            this.updateSortIcon(sortColumn, sortDir);
        }
    },

    updateSortIcon : function(col, dir){
        var sc = this.sortClasses;
        var hds = this.view.innerHd.select('em').removeClass(sc);
        hds.item(col).addClass(sc[dir == "DESC" ? 1 : 0]);
    },

    onHdClick : function(e){
        var hd = e.getTarget('em', 3);
        if(hd && !this.view.disableHeaders){
            var index = this.view.findHeaderIndex(hd);
            this.view.store.sort(this.view.columns[index].dataIndex);
        }
    }
});