import { format as dfFormat } from "date-fns";
import { de } from "date-fns/locale";

export const eur = new Intl.NumberFormat("de-DE", {
  style: "currency",
  currency: "EUR",
});

export const pct = new Intl.NumberFormat("de-DE", {
  style: "percent",
  minimumFractionDigits: 1,
  maximumFractionDigits: 1,
});

export function formatDate(date: Date | string | undefined): string {
  if (!date) return "–";
  const d = typeof date === "string" ? new Date(date) : date;
  return dfFormat(d, "dd.MM.yyyy", { locale: de });
}

export function formatMonth(monthKey: string | undefined): string {
  if (!monthKey) return "–";
  const [year, month] = monthKey.split("-");
  return `${month}.${year}`;
}

export function formatAmount(amount: number): string {
  if (amount === 0) return eur.format(0);
  return eur.format(amount);
}

export function formatEurCompact(value: number): string {
  const abs = Math.abs(value);
  const sign = value < 0 ? "-" : "";
  const suffix = (n: number, digits = 1) =>
    `${sign}${n.toFixed(digits).replace(".", ",")}`;
  if (abs >= 1_000_000) return `${suffix(abs / 1_000_000)} Mio. €`;
  if (abs >= 10_000) return `${suffix(abs / 1000)}k €`;
  if (abs >= 1000) return `${suffix(abs / 1000, 2)}k €`;
  return eur.format(value);
}

export function amountClass(amount: number): string {
  if (amount < 0) return "text-red-600 dark:text-red-400";
  if (amount > 0) return "text-emerald-600 dark:text-emerald-400";
  return "";
}

export function dashIfZero(value: number, formatter: (n: number) => string = (n) => String(n)): string {
  if (value === 0) return "–";
  return formatter(value);
}