import type { Bill, BillItem, ComputedBill, ComputedBillItem } from "../types";

export function findById<T extends { id: string }>(
  items: T[],
  id: string,
): T | undefined {
  return items.find((item) => item.id === id);
}

export function computeItem(item: BillItem): ComputedBillItem {
  return {
    ...item,
    finalPrice: item.unitPrice * item.quantity,
  };
}

export function computeBill(bill: Bill): ComputedBill {
  const computedItems = bill.items.map(computeItem);

  const subtotal = computedItems.reduce(
    (sum, item) => sum + item.finalPrice,
    0,
  );

  const taxAmount = (subtotal * bill.taxPercent) / 100;
  const total = subtotal + taxAmount;

  return {
    ...bill,
    items: computedItems,
    subtotal,
    taxAmount,
    total,
  };
}

export function formatCurrency(amount: number, currency: string): string {
  return new Intl.NumberFormat("en-IN", {
    style: "currency",
    currency,
    minimumFractionDigits: 2,
  }).format(amount);
}

export function generateId(): string {
  return Math.random().toString(36).slice(2, 9);
}