const FA_DIGITS = ["۰", "۱", "۲", "۳", "۴", "۵", "۶", "۷", "۸", "۹"];

export function toFaDigits(input: string | number): string {
  return String(input).replace(/\d/g, (d) => FA_DIGITS[Number(d)]);
}

// Prices come from the API in Toman.
export function formatPrice(value: number | null | undefined): string {
  if (value === null || value === undefined) return "";
  return toFaDigits(value.toLocaleString("en-US"));
}

export function discountPercent(price: number, oldPrice: number): number {
  if (!oldPrice || oldPrice <= price) return 0;
  return Math.round(((oldPrice - price) / oldPrice) * 100);
}

// Per AI_PROMPT.md "Shopping cart" step 3: a variant's stockQuantity of
// `null` means unlimited stock (in stock), not zero/out of stock — never
// treat it as falsy.
export function isInStock(stockQuantity: number | null | undefined): boolean {
  return stockQuantity === null || (stockQuantity ?? 0) > 0;
}

// The static-image-slot API documents aspectRatio as "16:9", but CSS's
// aspect-ratio property needs a slash ("16/9"), not a colon.
export function toCssAspectRatio(value: string | number | null | undefined): string | undefined {
  if (value === null || value === undefined || value === "") return undefined;
  return String(value).replace(":", "/");
}