/**
 * A Header subclass which renders a checkbox in each column cell which toggles the truthiness of the associated data field on click.
 *
 * Example usage:
 * 
 *    // create the grid
 *    var grid = Ext.create('Ext.grid.Panel', {
 *        ...
 *        columns: [{
 *           text: 'Foo',
 *           ...
 *        },{
 *           xtype: 'checkcolumn',
 *           text: 'Indoor?',
 *           dataIndex: 'indoor',
 *           width: 55
 *        }]
 *        ...
 *    });
 *
 * In addition to toggling a Boolean value within the record data, this
 * class adds or removes a css class <tt>'x-grid-checked'</tt> on the td
 * based on whether or not it is checked to alter the background image used
 * for a column.
 */
Ext.define('Ext.ux.CheckColumn', {
    extend: 'Ext.grid.column.Column',
    alias: 'widget.checkcolumn',

    /**
     * @cfg {Boolean} [stopSelection=true]
     * Prevent grid selection upon mousedown.
     */
    stopSelection: true,

    tdCls: Ext.baseCSSPrefix + 'grid-cell-checkcolumn',

    constructor: function() {
        this.addEvents(
            /**
             * @event beforecheckchange
             * Fires when before checked state of a row changes.
             * The change may be vetoed by returning `false` from a listener.
             * @param {Ext.ux.CheckColumn} this CheckColumn
             * @param {Number} rowIndex The row index
             * @param {Boolean} checked True if the box is to be checked
             */
            'beforecheckchange',
            /**
             * @event checkchange
             * Fires when the checked state of a row changes
             * @param {Ext.ux.CheckColumn} this CheckColumn
             * @param {Number} rowIndex The row index
             * @param {Boolean} checked True if the box is now checked
             */
            'checkchange'
        );
        this.callParent(arguments);
    },

    /**
     * @private
     * Process and refire events routed from the GridView's processEvent method.
     */
    processEvent: function(type, view, cell, recordIndex, cellIndex, e, record, row) {
        var me = this,
            key = type === 'keydown' && e.getKey(),
            mousedown = type == 'mousedown';

        if (mousedown || (key == e.ENTER || key == e.SPACE)) {
            var dataIndex = me.dataIndex,
                checked = !record.get(dataIndex);

            // Allow apps to hook beforecheckchange
            if (me.fireEvent('beforecheckchange', me, recordIndex, checked) !== false) {
                record.set(dataIndex, checked);
                me.fireEvent('checkchange', me, recordIndex, checked);

                // Mousedown on the now nonexistent cell causes the view to blur, so stop it continuing.
                if (mousedown) {
                    e.stopEvent();
                }

                // Selection will not proceed after this because of the DOM update caused by the record modification
                // Invoke the SelectionModel unless configured not to do so
                if (!me.stopSelection) {
                    view.selModel.selectByPosition({
                        row: recordIndex,
                        column: cellIndex
                    });
                }

                // Prevent the view from propagating the event to the selection model - we have done that job.
                return false;
            } else {
                // Prevent the view from propagating the event to the selection model if configured to do so.
                return !me.stopSelection;
            }
        } else {
            return me.callParent(arguments);
        }
    },

    // Note: class names are not placed on the prototype bc renderer scope
    // is not in the header.
    renderer : function(value){
        var cssPrefix = Ext.baseCSSPrefix,
            cls = [cssPrefix + 'grid-checkheader'];

        if (value) {
            cls.push(cssPrefix + 'grid-checkheader-checked');
        }
        return '<div class="' + cls.join(' ') + '">&#160;</div>';
    }
});
