/**
 * Formats an integer amount in cents to German Euro representation.
 * Example: 249 -> "2,49 €"
 */
export function formatCurrency(cents: number | null | undefined): string {
  if (cents === null || cents === undefined || isNaN(cents)) {
    return '0,00 €';
  }
  return new Intl.NumberFormat('de-DE', {
    style: 'currency',
    currency: 'EUR',
  }).format(cents / 100);
}

/**
 * Calculates stock value in cents.
 * For integer/package units: quantity * packagePriceCents
 * For partial packages: (quantity / packageSize) * packagePriceCents
 */
export function calculateStockValueCents(
  quantity: number,
  packageSize: number,
  packagePriceCents: number | null | undefined
): number {
  if (!packagePriceCents || packagePriceCents <= 0 || quantity <= 0) {
    return 0;
  }
  if (packageSize <= 0) {
    return Math.round(quantity * packagePriceCents);
  }
  const fraction = quantity / packageSize;
  return Math.round(fraction * packagePriceCents);
}

/**
 * Calculates base price (Grundpreis) per 1kg, 1l, 100g, or 1 Stück.
 */
export function calculateBasePrice(
  priceCents: number,
  packageSize: number,
  packageUnit: string
): { basePriceCents: number; basePriceUnit: string } {
  if (packageSize <= 0) {
    return { basePriceCents: priceCents, basePriceUnit: packageUnit };
  }

  const unitLower = packageUnit.toLowerCase().trim();

  if (unitLower === 'g' || unitLower === 'gramm') {
    // Standard base price per 1 kg (1000 g)
    const basePriceCents = Math.round((priceCents / packageSize) * 1000);
    return { basePriceCents, basePriceUnit: '1 kg' };
  }

  if (unitLower === 'ml' || unitLower === 'milliliter') {
    // Standard base price per 1 l (1000 ml)
    const basePriceCents = Math.round((priceCents / packageSize) * 1000);
    return { basePriceCents, basePriceUnit: '1 l' };
  }

  if (unitLower === 'kg' || unitLower === 'kilogramm') {
    const basePriceCents = Math.round(priceCents / packageSize);
    return { basePriceCents, basePriceUnit: '1 kg' };
  }

  if (unitLower === 'l' || unitLower === 'liter') {
    const basePriceCents = Math.round(priceCents / packageSize);
    return { basePriceCents, basePriceUnit: '1 l' };
  }

  const basePriceCents = Math.round(priceCents / packageSize);
  return { basePriceCents, basePriceUnit: `1 ${packageUnit}` };
}