// (C) 2007-2019 GoodData Corporation
import { flatten } from "lodash";

export function cartesianProduct(arr: any[][]): any[][] {
    return arr.reduce(
        (result, b) => {
            return flatten(
                result.map(x => {
                    return b.map(y => x.concat([y]));
                }),
            );
        },
        [[]],
    );
}

export function rotatedCartesianProduct(arr: any[][]): any[][] {
    const cartesian = cartesianProduct(arr);
    const result = new Array(arr.length).fill(0).map(_ => []);

    cartesian.forEach(combination => {
        combination.forEach((header, idx) => {
            result[idx].push(header);
        });
    });

    return result;
}