import { EMPTY } from "./placeholder";

/**
 * Format a numeric (or numeric-string) amount as a localized currency string.
 *
 * Returns the canonical {@link EMPTY} placeholder for null/undefined/NaN
 * inputs so callers can pass raw schema values (which often arrive as decimal
 * strings) without pre-coercing.
 */
export function formatCurrency(
  value: string | number | null | undefined,
  currency = "USD",
  maxDecimals?: number,
): string {
  if (value == null) return EMPTY;
  const n = typeof value === "number" ? value : Number(value);
  if (!Number.isFinite(n)) return EMPTY;

  const opts: Intl.NumberFormatOptions = { style: "currency", currency };
  if (maxDecimals !== undefined) {
    opts.maximumFractionDigits = maxDecimals;
  }
  try {
    return new Intl.NumberFormat("en-US", opts).format(n);
  } catch {
    return n.toLocaleString("en-US", {
      minimumFractionDigits: 2,
      maximumFractionDigits: maxDecimals ?? 2,
    });
  }
}