import { NextResponse } from "next/server";
import { getStripe } from "@/lib/stripe";
import { prisma } from "@/lib/prisma";

export async function POST(req) {
  try {
    if (!process.env.STRIPE_SECRET_KEY) {
      return NextResponse.json({ error: "Stripe is not configured" }, { status: 503 });
    }
    const stripe = getStripe();
    const body = await req.text();
    const signature = req.headers.get("stripe-signature");

    let event;
    try {
      event = stripe.webhooks.constructEvent(body, signature, process.env.STRIPE_WEBHOOK_SECRET);
    } catch (err) {
      console.error(`[WEBHOOK_ERROR] Signature verification failed:`, err.message);
      return NextResponse.json({ error: `Webhook Error: ${err.message}` }, { status: 400 });
    }

    if (event.type === "checkout.session.completed") {
      const session = event.data.object;
      const userId = session.metadata?.userId;
      const creditsToAdd = parseInt(session.metadata?.credits || "0", 10);
      if (userId && creditsToAdd > 0) {
        await prisma.user.update({
          where: { id: userId },
          data: { credits: { increment: creditsToAdd } },
        });
        console.log(`[WEBHOOK_SUCCESS] Added ${creditsToAdd} credits to user ${userId}`);
      }
    }
    return NextResponse.json({ received: true });
  } catch (error) {
    console.error("[STRIPE_WEBHOOK_FATAL_ERROR]", error);
    return NextResponse.json({ error: "Internal Server Error" }, { status: 500 });
  }
}