Education is theBridgeto your future.

// Nyeras Capstone: High-Concurrency Checkout Pipeline
import { db } from "@/lib/db";
import { revalidateTag } from "next/cache";

export async function processOrder({ userId, cartItems, idempotencyKey }: OrderPayload) {
  return await db.$transaction(async (tx) => {
    // 1. Pessimistic lock on inventory to prevent overselling
    const inventory = await tx.product.findMany({
      where: { id: { in: cartItems.map(i => i.id) } },
      select: { id: true, stock: true }
    });
    
    // 2. Validate real-time stock availability
    for (const item of cartItems) {
      const match = inventory.find(p => p.id === item.id);
      if (!match || match.stock < item.quantity) {
        throw new Error(`Insufficient stock for product ${item.id}`);
      }
      await tx.product.update({
        where: { id: item.id },
        data: { stock: { decrement: item.quantity } }
      });
    }

    // 3. Commit idempotent order record & trigger background webhook
    const order = await tx.order.create({
      data: { userId, idempotencyKey, status: "CONFIRMED", items: cartItems }
    });

    revalidateTag(`orders_${userId}`);
    return { success: true, orderId: order.id };
  });
}