import { serve } from 'https://deno.land/std@0.168.0/http/server.ts';
import { createClient } from 'https://esm.sh/@supabase/supabase-js@2';
import Stripe from 'https://esm.sh/stripe@14?target=deno';

const stripe = new Stripe(Deno.env.get('STRIPE_SECRET_KEY')!, { apiVersion: '2023-10-16' });
const webhookSecret = Deno.env.get('STRIPE_WEBHOOK_SECRET')!;

serve(async (req) => {
  const body = await req.text();
  const sig = req.headers.get('stripe-signature');

  let event: Stripe.Event;
  try {
    event = await stripe.webhooks.constructEventAsync(body, sig!, webhookSecret);
  } catch (err) {
    console.error('Webhook signature failed:', err.message);
    return new Response(`Webhook Error: ${err.message}`, { status: 400 });
  }

  if (event.type === 'checkout.session.completed') {
    const session = event.data.object as Stripe.Checkout.Session;
    const invoice_id = session.metadata?.invoice_id;

    if (invoice_id) {
      const supabase = createClient(
        Deno.env.get('SUPABASE_URL')!,
        Deno.env.get('SUPABASE_SERVICE_ROLE_KEY')!,
      );

      // Retrieve the Stripe processing fee from the balance transaction
      let stripe_fee: number | null = null;
      try {
        const paymentIntentId = session.payment_intent as string;
        if (paymentIntentId) {
          const paymentIntent = await stripe.paymentIntents.retrieve(paymentIntentId, {
            expand: ['latest_charge.balance_transaction'],
          });
          const charge = paymentIntent.latest_charge as Stripe.Charge | null;
          const balanceTx = charge?.balance_transaction as Stripe.BalanceTransaction | null;
          if (balanceTx?.fee != null) {
            stripe_fee = balanceTx.fee / 100;
          }
        }
      } catch (err) {
        console.error('Failed to retrieve Stripe fee:', err.message);
      }

      const updateData: Record<string, unknown> = { status: 'paid' };
      if (stripe_fee !== null) updateData.stripe_fee = stripe_fee;

      await supabase.from('invoices').update(updateData).eq('id', invoice_id);
    }
  }

  return new Response(JSON.stringify({ received: true }), { status: 200 });
});