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

/**
 * Allocates an invoice number for the given order, using the shop's
 * configured numbering mode. For `prefix_sequential`, allocation is atomic
 * across concurrent requests via Prisma's interactive transaction (with the
 * counter row acting as the lock).
 */
export async function allocateInvoiceNumber(
  settings: ShopSettings,
  orderNumber: number,
): Promise<string> {
  const prefix = settings.invoicePrefix || "";

  if (settings.numberingMode === "prefix_sequential") {
    const next = await db.$transaction(async (tx) => {
      const counter = await tx.invoiceCounter.upsert({
        where: { shopDomain: settings.shopDomain },
        create: {
          shopDomain: settings.shopDomain,
          lastValue: settings.invoiceSeed,
        },
        update: {},
      });
      const newValue = counter.lastValue + 1;
      await tx.invoiceCounter.update({
        where: { shopDomain: settings.shopDomain },
        data: { lastValue: newValue },
      });
      return newValue;
    });
    return `${prefix}${next}`;
  }

  // Default: reuse the Shopify order number with the configured prefix.
  return `${prefix}${orderNumber}`;
}