fix race condition issue

server/services/refund.service.ts

@@ -1,43 +1,10 @@
 import { randomBytes } from "crypto";
 import { Prisma } from "@/app/generated/prisma/client";
-import { prisma } from "@/lib/prisma";
 import { refundRepo } from "@/server/repositories/refund.repo";
 import { calculateRefundAmount, daysUntilDeparture } from "@/lib/refund-policy";
 import { isTripDepartureDayPast } from "@/lib/trip-dates";
 import { payoutService } from "@/server/services/payout.service";
-
-const SERIAL_TX_ATTEMPTS = 6;
-
-function isSerializationConflict(err: unknown): boolean {
-  return (
-    typeof err === "object" &&
-    err !== null &&
-    "code" in err &&
-    (err as { code: string }).code === "P2034"
-  );
-}
-
-async function runSerializable<T>(fn: (tx: Prisma.TransactionClient) => Promise<T>): Promise<T> {
-  let lastErr: unknown;
-  for (let attempt = 0; attempt < SERIAL_TX_ATTEMPTS; attempt++) {
-    try {
-      return await prisma.$transaction(fn, {
-        isolationLevel: Prisma.TransactionIsolationLevel.Serializable,
-        maxWait: 5000,
-        timeout: 15000,
-      });
-    } catch (e) {
-      lastErr = e;
-      if (isSerializationConflict(e) && attempt < SERIAL_TX_ATTEMPTS - 1) {
-        continue;
-      }
-      throw e;
-    }
-  }
-  throw lastErr instanceof Error
-    ? lastErr
-    : new Error("Gagal memproses refund. Coba lagi sebentar.");
-}
+import { runSerializable } from "@/lib/serializable-tx";
 
 function newIdempotencyKey(): string {
   return `refund_${randomBytes(16).toString("hex")}`;
@@ -358,6 +325,14 @@ export const refundService = {
       if (booking.userId !== input.userId) {
         throw new Error("Booking ini bukan milikmu");
       }
+      if (
+        booking.trip.status === "CLOSED" ||
+        booking.trip.status === "COMPLETED"
+      ) {
+        throw new Error(
+          "Trip sudah dibatalkan/selesai — pembatalan mandiri ditutup. Hubungi admin untuk proses refund."
+        );
+      }
       if (booking.status !== "PAID") {
         throw new Error(
           "Hanya booking PAID yang bisa cancel dengan refund. Booking yang belum lunas bisa cancel dari tombol 'Batal Ikut'."