aureooms/js-rational

const _cmp = ({jz, lt0, cmp, neg, divmod}) => {
    const compare_positive_fractions = (a, b, c, d) => {
        if (jz(b)) {
            if (jz(d)) return 0;
            return 1;
        }

        if (jz(d)) return -1;
        const [q1, r1] = divmod(a, b);
        const [q2, r2] = divmod(c, d);
        return cmp(q1, q2) || compare_positive_fractions(d, r2, b, r1);
    };

    return (a, b, c, d) => {
        if (lt0(b)) {
            b = neg(b);
            a = neg(a);
        }

        if (lt0(d)) {
            d = neg(d);
            c = neg(c);
        }

        if (lt0(a)) {
            if (lt0(c)) return compare_positive_fractions(neg(c), d, neg(a), b);
            return -1;
        }

        if (lt0(c)) return 1;
        return compare_positive_fractions(a, b, c, d);
    };
};

export default _cmp;