plurals

ru-plurals.ts

const { abs } = Math;
const { isNaN } = Number;
const NBSP = " ";

export function plural(one: string, two?: Maybe<string>, five?: Maybe<string>) {
  return (quantiry: Maybe<number>) =>
    pluralize(absInt(number), [one, two ?? one, five ?? two ?? one]);
}

function nbspJoin<T = number | string>(...arr: T[]): string {
  return arr.join(NBSP);
}

function absInt(number: number): undefined | number {
  const int = abs(parseInt(number, 10));
  return isNaN(int) ? undefined : int;
}

function pluralize(int: number, ...declensions: string[]): string {
  return declensions[
    int % 100 > 4 && int % 100 < 20
      ? 2
      : [2, 0, 1, 1, 1, 2][int % 10 < 5 ? int % 10 : 5]
  ];
}

export function format(
  formatter: <T = any>(quantiry: number, unit: string) => T
) {
  return (one: string, two?: string, five?: string) => (number: number) =>
    formatter(number, plural(one, two, five)(number));
}

const defaultFormat = format(nbspJoin);

export default defaultFormat;