function declension(num: number, words: string[]): string {
    const cases = [2, 0, 1, 1, 1, 2];
    return words[num % 100 > 4 && num % 100 < 20 ? 2 : cases[num % 10 < 5 ? num % 10 : 5]];
}

export function updateFriendAndReferralCounts(
    referralsLength: number,
    referralsCount: number,
): { friendsWord: string; referralWord: string } {
    const friendWord = declension(referralsLength, ['Друг', 'Друга', 'Друзей']);
    const referralWord = declension(referralsCount, ['Реферал', 'Реферала', 'Рефералов']);

    return {
        friendsWord: `${referralsLength} ${friendWord}`,
        referralWord: `${referralsCount} ${referralWord}`,
    };
}