Ext.grid.RowExpander = function(config){
    Ext.apply(this, config);

    this.addEvents({
        beforeexpand : true,
        expand: true,
        beforecollapse: true,
        collapse: true
    });

    Ext.grid.RowExpander.superclass.constructor.call(this);

    if(this.tpl){
        if(typeof this.tpl == 'string'){
            this.tpl = new Ext.Template(this.tpl);
        }
        this.tpl.compile();
    }

    this.state = {};
    this.bodyContent = {};
};

Ext.extend(Ext.grid.RowExpander, Ext.util.Observable, {
    header: "",
    width: 20,
    sortable: false,
    fixed:true,
    menuDisabled:true,
    dataIndex: '',
    id: 'expander',
    lazyRender : true,
    enableCaching: true,

    getRowClass : function(record, rowIndex, p, ds){
        p.cols = p.cols-1;
        var content = this.bodyContent[record.id];
        if(!content && !this.lazyRender){
            content = this.getBodyContent(record, rowIndex);

        return this.state[record.id] ? 'x-grid3-row-expanded' : 'x-grid3-row-collapsed';
    },

    init : function(grid){
        this.grid = grid;

        var view = grid.getView();
        view.getRowClass = this.getRowClass.createDelegate(this);

        view.enableRowBody = true;

        grid.on('render', function(){
            view.mainBody.on('mousedown', this.onMouseDown, this);
        }, this);
    },

    getBodyContent : function(record, index){
        if(!this.enableCaching){
            return this.tpl.apply(record.data);
        }
        var content = this.bodyContent[record.id];
        if(!content){
            content = this.tpl.apply(record.data);
            this.bodyContent[record.id] = content;
        }
        return content;
    },

    onMouseDown : function(e, t){
        if(t.className == 'x-grid3-row-expander'){
            e.stopEvent();
            var row = e.getTarget('.x-grid3-row');
            this.toggleRow(row);
        }
    },

    renderer : function(v, p, record){
        p.cellAttr = 'rowspan="2"';
        return '<div class="x-grid3-row-expander">&#160;</div>';
    },

    beforeExpand : function(record, body, rowIndex){
        if(this.fireEvent('beforeexpand', this, record, body, rowIndex) !== false){
            if(this.tpl && this.lazyRender){
                body.innerHTML = this.getBodyContent(record, rowIndex);
            }
            return true;
        }else{
            return false;
        }
    },

    toggleRow : function(row){
        if(typeof row == 'number'){
            row = this.grid.view.getRow(row);
        }
        this[Ext.fly(row).hasClass('x-grid3-row-collapsed') ? 'expandRow' : 'collapseRow'](row);
    },

    expandRow : function(row){
        if(typeof row == 'number'){
            row = this.grid.view.getRow(row);
        }
        var record = this.grid.store.getAt(row.rowIndex);
        var body = Ext.DomQuery.selectNode('tr:nth(2) div.x-grid3-row-body', row);
        if(this.beforeExpand(record, body, row.rowIndex)){
            this.state[record.id] = true;
            Ext.fly(row).replaceClass('x-grid3-row-collapsed', 'x-grid3-row-expanded');
            this.fireEvent('expand', this, record, body, row.rowIndex);
        }
    },

    collapseRow : function(row){
        if(typeof row == 'number'){
            row = this.grid.view.getRow(row);
        }
        var record = this.grid.store.getAt(row.rowIndex);
        var body = Ext.fly(row).child('tr:nth(1) div.x-grid3-row-body', true);
        if(this.fireEvent('beforecollapse', this, record, body, row.rowIndex) !== false){
            this.state[record.id] = false;
            Ext.fly(row).replaceClass('x-grid3-row-expanded', 'x-grid3-row-collapsed');
            this.fireEvent('collapse', this, record, body, row.rowIndex);
        }
    }
});
        }
        if(content){
            p.body = content;
        }
