/**
 * Paging Memory Proxy, allows to use paging grid with in memory dataset
 */
Ext.define('Ext.ux.data.PagingMemoryProxy', {
    extend: 'Ext.data.proxy.Memory',
    alias: 'proxy.pagingmemory',
    alternateClassName: 'Ext.data.PagingMemoryProxy',

    read : function(operation, callback, scope){
        var reader = this.getReader(),
            result = reader.read(this.data),
            sorters, filters, sorterFn, records;

        scope = scope || this;
        // filtering
        filters = operation.filters;
        if (filters.length > 0) {
            //at this point we have an array of  Ext.util.Filter objects to filter with,
            //so here we construct a function that combines these filters by ANDing them together
            records = [];

            Ext.each(result.records, function(record) {
                var isMatch = true,
                    length = filters.length,
                    i;

                for (i = 0; i < length; i++) {
                    var filter = filters[i],
                        fn     = filter.filterFn,
                        scope  = filter.scope;

                    isMatch = isMatch && fn.call(scope, record);
                }
                if (isMatch) {
                    records.push(record);
                }
            }, this);

            result.records = records;
            result.totalRecords = result.total = records.length;
        }
        
        // sorting
        sorters = operation.sorters;
        if (sorters.length > 0) {
            //construct an amalgamated sorter function which combines all of the Sorters passed
            sorterFn = function(r1, r2) {
                var result = sorters[0].sort(r1, r2),
                    length = sorters.length,
                    i;
                
                    //if we have more than one sorter, OR any additional sorter functions together
                    for (i = 1; i < length; i++) {
                        result = result || sorters[i].sort.call(this, r1, r2);
                    }                
               
                return result;
            };
    
            result.records.sort(sorterFn);
        }
        
        // paging (use undefined cause start can also be 0 (thus false))
        if (operation.start !== undefined && operation.limit !== undefined) {
            result.records = result.records.slice(operation.start, operation.start + operation.limit);
            result.count = result.records.length;
        }

        Ext.apply(operation, {
            resultSet: result
        });
        
        operation.setCompleted();
        operation.setSuccessful();

        Ext.Function.defer(function () {
            Ext.callback(callback, scope, [operation]);
        }, 10);
    }
});
