export type RoomAreaParseResult =
  | { ok: true; value: number | null }
  | { ok: false; error: string };

/** Parses an optional German decimal without rounding the stored value. */
export function parseRoomAreaInput(text: string): RoomAreaParseResult {
  const normalized = text.trim();
  if (!normalized) return { ok: true, value: null };
  if (!/^(?:\d+(?:,\d*)?|,\d+)$/.test(normalized)) {
    return {
      ok: false,
      error: "Bitte eine nicht negative Zahl mit Komma eingeben.",
    };
  }
  const value = Number(normalized.replace(",", "."));
  return Number.isFinite(value) && value >= 0
    ? { ok: true, value }
    : { ok: false, error: "Die Fläche muss mindestens 0 m² betragen." };
}

export function formatRoomArea(areaM2: number): string {
  return areaM2.toLocaleString("de-DE", {
    minimumFractionDigits: 2,
    maximumFractionDigits: 2,
  });
}

export function formatOptionalRoomAreaInput(areaM2: number | null | undefined): string {
  return areaM2 === null || areaM2 === undefined ? "" : formatRoomArea(areaM2);
}