import { headers } from "next/headers";
import { NextRequest, NextResponse } from "next/server";
import { getPrisma } from "../../../../lib/db";
import { loadSystemConfig } from "../../../../lib/system-config";
import { getStripe } from "../../../../lib/stripe";
import { sendEmail } from "../../../../lib/email";
import { createWebinarCalendarEvent } from "../../../../lib/calendar";

export const runtime = "nodejs";

export async function POST(req: NextRequest) {
  const prisma = await getPrisma();
  const stripe = await getStripe();
  const cfg = await loadSystemConfig();

  const secret = cfg.stripe?.webhookSecret || process.env.STRIPE_WEBHOOK_SECRET;

  if (!prisma || !stripe || !secret) {
    // must still 200 to avoid retries in misconfigured env
    return NextResponse.json({ ok: true });
  }

  const headersList = await headers();
  const sig = headersList.get("stripe-signature");
  const body = await req.text();

  if (!sig) return NextResponse.json({ ok: true });

  let event: any;
  try {
    event = stripe.webhooks.constructEvent(body, sig, secret);
  } catch {
    return NextResponse.json({ ok: true });
  }

  if (event.type === "checkout.session.completed") {
    const session = event.data.object as any;
    const registrationId = session.metadata?.registrationId as string | undefined;
    const paymentIntent = session.payment_intent as string | undefined;

    if (registrationId) {
      try {
        await prisma.webinarRegistration.update({
          where: { id: registrationId },
          data: { status: "PAID", stripePaymentIntentId: paymentIntent ?? null },
        });

        // Send confirmation email with calendar invite
        const registration = await prisma.webinarRegistration.findUnique({
          where: { id: registrationId },
          include: { user: true, webinar: true },
        });

        if (registration && cfg.email?.enabled) {
          const { icsContent } = await createWebinarCalendarEvent(
            registration.webinar,
            registration.user.email
          );

          const meetingInfo = registration.webinar.meetingInfo as any;
          const meetingLink = meetingInfo?.meetingLink || "TBD";
          const htmlContent = `
            <h2>Webinar Registration Confirmed</h2>
            <p>Hi ${registration.user.firstName},</p>
            <p>Thank you for registering for <strong>${registration.webinar.title}</strong>.</p>
            <p><strong>Date & Time:</strong> ${new Date(registration.webinar.startAt).toLocaleString()}</p>
            <p><strong>Duration:</strong> ${registration.webinar.duration} minutes</p>
            <p><strong>Join Link:</strong> <a href="${meetingLink}">${meetingLink}</a></p>
            <p>A calendar invitation is attached to this email.</p>
            <p>See you there!</p>
          `;

          await sendEmail({
            to: registration.user.email,
            subject: `Registration Confirmed: ${registration.webinar.title}`,
            html: htmlContent,
            attachments: [
              {
                filename: "webinar-invite.ics",
                content: icsContent,
                contentType: "text/calendar",
              },
            ],
          });
        }
      } catch (error) {
        console.error("[WEBHOOK] Error processing payment:", error);
        // ignore
      }
    }
  }

  return NextResponse.json({ ok: true });
}