import { type ClassValue, clsx } from "clsx";
import { twMerge } from "tailwind-merge";

export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs));
}

const IRREGULAR: Record<string, string> = {
  person: "people",
  child: "children",
  man: "men",
  woman: "women",
};

const NO_PLURAL = new Set([
  "kg",
  "g",
  "mg",
  "mcg",
  "l",
  "ml",
  "cl",
  "dl",
  "m",
  "cm",
  "mm",
  "km",
  "tick",
  "hertz",
  "hz",
]);

export function pluralize(amount: number, unit: string): string {
  if (amount === 1) return unit;
  const lower = unit.toLowerCase();
  if (NO_PLURAL.has(lower) || unit.endsWith("s")) return unit;
  if (IRREGULAR[lower]) return IRREGULAR[lower];
  if (/[^aeiou]y$/i.test(unit)) return unit.slice(0, -1) + "ies";
  if (/[sxz]$/i.test(unit) || /(sh|ch)$/i.test(unit)) return unit + "es";
  return unit + "s";
}