Add optional donation to registration; fix soldOutLines server crash

The register form now offers a "Donation amount" (suggested amounts,
custom, or none) under the ticket options. The donation is added to the
Yoco checkout as its own line and the webhook records it as a separate
donation payment linked to the registration payment.

Move soldOutLines() out of the "use client" JoinWaitlistButton module
into lib/waitlist.ts so the server-rendered event page can call it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/src/controllers/paymentController.js

@@ -935,7 +935,9 @@ function checkoutLineItems(registration) {
 
 // Internal helper: create a Yoco checkout for a registration and return { checkoutId, redirectUrl, amount }
 // Does NOT check user authorization — callers are responsible for ensuring the user owns the registration.
-async function createRegistrationCheckoutInternal(registrationId, userId, { successUrl, cancelUrl, failureUrl } = {}) {
+// donationAmount (optional) is added on top as its own line; the webhook splits it off into a
+// separate donation payment using the amount carried in the checkout metadata.
+async function createRegistrationCheckoutInternal(registrationId, userId, { successUrl, cancelUrl, failureUrl, donationAmount = 0 } = {}) {
   const registration = await prisma.registration.findUnique({
     where: { id: registrationId },
     include: {
@@ -961,7 +963,8 @@ async function createRegistrationCheckoutInternal(registrationId, userId, { succ
 
   if (remainingAmount <= 0) throw new Error('This registration is already paid in full');
 
-  const amountInCents = Math.round(remainingAmount * 100);
+  const donationInCents = Math.round((Number(donationAmount) || 0) * 100);
+  const amountInCents = Math.round(remainingAmount * 100) + donationInCents;
   const idempotencyKey = `reg_${registrationId}_${amountInCents}_${Date.now()}`;
   const lineItems = checkoutLineItems(registration);
 
@@ -974,11 +977,17 @@ async function createRegistrationCheckoutInternal(registrationId, userId, { succ
     });
   }
   // Paying full remaining — no "Partial Payment" line needed
+  if (donationInCents > 0) {
+    lineItems.push({ displayName: 'Donation', quantity: 1, pricingDetails: { price: donationInCents } });
+  }
 
   const checkoutData = {
     amount: amountInCents,
     currency: 'ZAR',
-    metadata: { registrationId, userId, eventId: registration.eventId, eventTitle: registration.event.title, type: 'registration_payment' },
+    metadata: {
+      registrationId, userId, eventId: registration.eventId, eventTitle: registration.event.title, type: 'registration_payment',
+      ...(donationInCents > 0 ? { donationAmount: (donationInCents / 100).toFixed(2) } : {})
+    },
     successUrl,
     cancelUrl,
     failureUrl,
@@ -999,7 +1008,7 @@ async function createRegistrationCheckoutInternal(registrationId, userId, { succ
   return {
     checkoutId: response.data.id,
     redirectUrl: response.data.redirectUrl,
-    amount: remainingAmount,
+    amount: amountInCents / 100,
     registration: { id: registration.id, eventId: registration.eventId, eventTitle: registration.event.title }
   };
 }
@@ -1009,7 +1018,7 @@ async function createRegistrationCheckoutInternal(registrationId, userId, { succ
 // @access  Private
 const createYocoCheckout = async (req, res) => {
   try {
-    const { registrationId, eventId, amount, successUrl, cancelUrl, failureUrl } = req.body;
+    const { registrationId, eventId, amount, donationAmount, successUrl, cancelUrl, failureUrl } = req.body;
     const userId = req.user.id;
 
     // Validate required parameters for either registration payment or donation
@@ -1096,7 +1105,15 @@ const createYocoCheckout = async (req, res) => {
         return res.status(200).json({ checkoutId: response.data.id, redirectUrl: response.data.redirectUrl, amount: charge, registration: { id: registration.id, eventId: registration.eventId, eventTitle: registration.event.title } });
       }
 
-      const result = await createRegistrationCheckoutInternal(registrationId, userId, { successUrl, cancelUrl, failureUrl });
+      // Optional donation added at registration ("Donation amount" on the register form)
+      let donation = 0;
+      if (donationAmount !== undefined && donationAmount !== null && donationAmount !== '') {
+        donation = Math.round(parseFloat(donationAmount) * 100) / 100;
+        if (!(donation >= 0) || donation > 100000) { res.status(400); throw new Error('Invalid donation amount'); }
+        if (donation > 0 && donation < 15) { res.status(400); throw new Error('Minimum donation is R15'); }
+      }
+
+      const result = await createRegistrationCheckoutInternal(registrationId, userId, { successUrl, cancelUrl, failureUrl, donationAmount: donation });
       return res.status(200).json(result);
     }
 

backend/src/controllers/webhookController.js

@@ -314,11 +314,18 @@ const handlePaymentSucceeded = async (webhookData) => {
       } catch (e) { /* ignore — payment will fail below if still null */ }
     }
 
+    // A registration checkout can carry a donation on top (metadata.donationAmount). It's
+    // recorded as its own donation payment so it never counts towards the registration.
+    const grossAmount = amount / 100; // Convert cents to your currency unit
+    const donationPart = registration?.id
+      ? Math.min(Math.max(Number(metadata?.donationAmount) || 0, 0), grossAmount)
+      : 0;
+
     // Create payment record
     const payment = await prisma.payment.create({
       data: {
         id: uuidv4(), // Generate a UUID for the payment
-        amount: amount / 100, // Convert cents to your currency unit
+        amount: Math.round((grossAmount - donationPart) * 100) / 100,
         method: method.type, // The type of payment from the webhook
         status: status === 'succeeded' ? 'completed' : status,
         externalId: yocoPaymentId,
@@ -358,6 +365,24 @@ const handlePaymentSucceeded = async (webhookData) => {
       }
     });
     
+    let donationPayment = null;
+    if (donationPart > 0) {
+      donationPayment = await prisma.payment.create({
+        data: {
+          id: uuidv4(),
+          amount: donationPart,
+          method: method.type,
+          status: status === 'succeeded' ? 'completed' : status,
+          userId: resolvedUserId,
+          recordedById: resolvedUserId,
+          registrationId: null,
+          eventId: registration.eventId,
+          isDonation: true,
+          originalPaymentId: payment.id,
+        }
+      });
+    }
+
     // If this payment is for a registration, update the registration status
     let updatedRegistration = null;
     let generatedTickets = [];
@@ -392,6 +417,7 @@ const handlePaymentSucceeded = async (webhookData) => {
 
     // Send emails: payment confirmation first, then tickets (guarantees order)
     const _whPaymentId = payment.id;
+    const _whDonationId = donationPayment?.id;
     const _whUserId = registration?.userId;
     const _whRegId = registration?.id;
     const _whTicketsGenerated = generatedTickets.length > 0;
@@ -402,6 +428,14 @@ const handlePaymentSucceeded = async (webhookData) => {
       } catch (e) {
         console.error('Failed to send webhook payment emails:', e);
       }
+      if (_whDonationId) {
+        try {
+          const { sendPaymentEmails } = require('../utils/notifications');
+          await sendPaymentEmails(_whDonationId);
+        } catch (e) {
+          console.error('Failed to send webhook donation emails:', e);
+        }
+      }
       if (_whTicketsGenerated && _whUserId && _whRegId) {
         const mockReq = { user: { id: _whUserId }, body: { registrationId: _whRegId } };
         const mockRes = { status: () => mockRes, json: () => {} };