import { NextResponse } from "next/server";
import { addShippingMethod } from "@/lib/medusa";
import { parseBody, isNonEmptyString, isValidMedusaId, badRequest, checkCsrf } from "@/lib/apiUtils";

// POST /api/checkout/shipping-method — add a shipping method to the cart
export async function POST(request: Request) {
  const csrfError = await checkCsrf();
  if (csrfError) return csrfError;

  const body = await parseBody<{ cartId?: unknown; optionId?: unknown }>(request);
  if (!body) return badRequest("Invalid request body");

  const { cartId, optionId } = body;

  if (!isNonEmptyString(cartId) || !isNonEmptyString(optionId)) {
    return badRequest("Missing cartId or optionId");
  }
  if (!isValidMedusaId(cartId) || !isValidMedusaId(optionId)) {
    return badRequest("Invalid ID format");
  }

  try {
    const cart = await addShippingMethod(cartId, optionId);
    return NextResponse.json(cart);
  } catch (e) {
    console.error("[checkout:shipping-method]", (e as Error).message);
    return NextResponse.json({ error: "Failed to set shipping method" }, { status: 500 });
  }
}