import db from "../../db.server";
import type { ShopSettings } from "@prisma/client";

/**
 * Returns the canonical remittance reference for an order — i.e. the
 * exact string that should appear:
 *   - on the printed invoice PDF (`invoice.number`),
 *   - in the GiroCode QR payload,
 *   - and in the customer-facing payment instructions on the
 *     thank-you / customer-account pages.
 *
 * Banking systems treat each unique reference string as a separate
 * payment, so all three surfaces MUST use this single source of truth.
 *
 * Resolution order:
 *   1. The latest non-cancelled `Invoice` row for the order — guaranteed
 *      to match what's printed on the PDF.
 *   2. Predicted default-mode number (`${prefix}${orderNumber}`). Safe
 *      for the default `order_number` numbering mode and a sensible
 *      best-guess for `prefix_sequential` before the invoice has been
 *      generated (the customer just sees the order number with the
 *      shop's invoice prefix instead of the bare Shopify "#1004").
 */
export async function resolveOrderRemittance(args: {
  shopDomain: string;
  orderGid: string;
  orderNumber: number | null | undefined;
  settings: Pick<ShopSettings, "invoicePrefix">;
}): Promise<string> {
  const invoice = await db.invoice.findFirst({
    where: {
      shopDomain: args.shopDomain,
      orderId: args.orderGid,
      kind: "invoice",
      cancelledAt: null,
    },
    orderBy: [{ version: "desc" }, { createdAt: "desc" }],
    select: { invoiceNumber: true },
  });
  if (invoice?.invoiceNumber) return invoice.invoiceNumber;

  const prefix = args.settings.invoicePrefix || "";
  if (args.orderNumber != null) return `${prefix}${args.orderNumber}`;
  // Last-ditch: derive numeric tail from the GID.
  const tail = args.orderGid.split("/").pop() ?? "";
  return `${prefix}${tail}`;
}