import { type NextRequest, NextResponse } from "next/server"
import Stripe from "stripe"
import { updatePaymentStatus } from "@/lib/google-sheets"

// Lazy initialization to avoid build-time errors
let stripe: Stripe | null = null

function getStripe() {
  if (!stripe) {
    stripe = new Stripe(process.env.STRIPE_SECRET_KEY!, {
      apiVersion: "2024-12-18.acacia",
    })
  }
  return stripe
}

function getWebhookSecret() {
  return process.env.STRIPE_WEBHOOK_SECRET!
}

export async function POST(request: NextRequest) {
  try {
    const body = await request.text()
    const signature = request.headers.get("stripe-signature")!

    let event: Stripe.Event

    try {
      event = getStripe().webhooks.constructEvent(body, signature, getWebhookSecret())
    } catch (err) {
      console.error("[Webhook] Signature verification failed:", err)
      return NextResponse.json({ error: "Invalid signature" }, { status: 400 })
    }

    // Handle the event
    switch (event.type) {
      case "checkout.session.completed": {
        const session = event.data.object as Stripe.Checkout.Session
        console.log("[Webhook] Payment successful:", session.id)

        // Extract registration data from metadata
        const metadata = session.metadata || {}
        const customerEmail = session.customer_details?.email || ""

        // Update Google Sheet with payment confirmation
        const updated = await updatePaymentStatus({
          name: metadata.name || "",
          email: customerEmail,
          stripeSessionId: session.id,
          paymentStatus: "Paid",
          paymentMethod: session.payment_method_types?.[0] || "unknown",
          amountPaid: session.amount_total
            ? `€${(session.amount_total / 100).toFixed(2)}`
            : "",
          paymentDate: new Date().toISOString(),
        })

        if (updated) {
          console.log(`[Webhook] Google Sheet updated for ${metadata.name}`)
        } else {
          console.error(`[Webhook] Failed to update Google Sheet for ${metadata.name}`)
        }

        // TODO: Send confirmation email

        break
      }
      case "payment_intent.succeeded": {
        const paymentIntent = event.data.object as Stripe.PaymentIntent
        console.log("[Webhook] PaymentIntent successful:", paymentIntent.id)
        break
      }
      case "payment_intent.payment_failed": {
        const paymentIntent = event.data.object as Stripe.PaymentIntent
        console.error("[Webhook] Payment failed:", paymentIntent.id)

        // Optionally update sheet to mark as failed
        const failedMetadata = paymentIntent.metadata || {}
        if (failedMetadata.name) {
          await updatePaymentStatus({
            name: failedMetadata.name,
            stripeSessionId: paymentIntent.id,
            paymentStatus: "Failed",
            paymentDate: new Date().toISOString(),
          })
        }

        break
      }
      default:
        console.log("[Webhook] Unhandled event type:", event.type)
    }

    return NextResponse.json({ received: true })
  } catch (err) {
    console.error("[Webhook] Error:", err)
    return NextResponse.json({ error: "Webhook error" }, { status: 500 })
  }
}