import { DeepMap } from './deepMap';
export type GroupKeyType<T extends any = any> = T;
export type GroupBy<DataType, KeyType> = {
    field: keyof DataType;
    toKey?: (value: any, data: DataType) => GroupKeyType<KeyType>;
};
export type GroupParams<DataType, KeyType> = {
    groupBy: GroupBy<DataType, KeyType>[];
    defaultToKey?: (value: any, item: DataType) => GroupKeyType<KeyType>;
    reducers?: Record<string, DataSourceAggregationReducer<DataType, any>>;
};
export type DataSourceAggregationReducer<T, AggregationResultType> = {
    name?: string;
    field?: keyof T;
    initialValue?: AggregationResultType;
    getter?: (data: T) => any;
    reducer: string | ((accumulator: any, value: any, data: T) => AggregationResultType | any);
    done?: (accumulatedValue: AggregationResultType | any, array: T[]) => AggregationResultType;
};
export type DataGroupResult<DataType, KeyType extends any> = {
    deepMap: DeepMap<GroupKeyType<KeyType>, DeepMapGroupValueType<DataType, KeyType>>;
    groupParams: GroupParams<DataType, KeyType>;
    initialData: DataType[];
    reducerResults?: Record<string, any>;
};
export type DeepMapGroupValueType<DataType, KeyType> = {
    items: DataType[];
    commonData?: Partial<DataType>;
    reducerResults: Record<string, any>;
};
export type AggregationReducerResult<AggregationResultType extends any = any> = {
    value: AggregationResultType;
    id: string;
};
export declare function group<DataType, KeyType = any>(groupParams: GroupParams<DataType, KeyType>, data: DataType[]): DataGroupResult<DataType, KeyType>;