export const BILL_NOT_FOUND =
  "Bill not found yet. If you just received the SMS, wait a moment and refresh.";

export type BillLine = {
  description: string;
  qty: number | string | null;
  unitPrice: number;
  lineTotal: number;
};

export type BillView = {
  shopName: string;
  address: string;
  phone: string;
  number: string;
  createdAt: string;
  customerName: string;
  customerPhone: string;
  vehicleReg: string;
  vehicleModel: string;
  lines: BillLine[];
  total: number;
  paymentMethod: string;
};

function isRecord(value: unknown): value is Record<string, unknown> {
  return !!value && typeof value === "object" && !Array.isArray(value);
}

function asString(value: unknown): string {
  return typeof value === "string" ? value : "";
}

function asNumber(value: unknown): number {
  return typeof value === "number" && Number.isFinite(value) ? value : 0;
}

export function parseBill(raw: string): BillView | null {
  let data: unknown;
  try {
    data = JSON.parse(raw);
  } catch {
    return null;
  }
  if (!isRecord(data)) return null;
  const lines = Array.isArray(data.lines) ? data.lines.filter(isRecord) : [];
  return {
    shopName: asString(data.shopName),
    address: asString(data.address),
    phone: asString(data.phone),
    number: asString(data.number),
    createdAt: asString(data.createdAt),
    customerName: asString(data.customerName),
    customerPhone: asString(data.customerPhone),
    vehicleReg: asString(data.vehicleReg),
    vehicleModel: asString(data.vehicleModel),
    lines: lines.map((line) => ({
      description: asString(line.description),
      qty: typeof line.qty === "number" || typeof line.qty === "string" ? line.qty : null,
      unitPrice: asNumber(line.unitPrice),
      lineTotal: asNumber(line.lineTotal),
    })),
    total: asNumber(data.total),
    paymentMethod: asString(data.paymentMethod),
  };
}

export function formatBillDate(iso: string): string {
  if (!iso) return "";
  const date = new Date(iso);
  if (Number.isNaN(date.getTime())) return "";
  return date.toLocaleString("en-LK", { timeZone: "Asia/Colombo" });
}