Generate invoice PDFs attached to order confirmation, and send emails on order status changes

Invoice PDFs (§14 UStG line items, tenant-configurable VAT rate) are now
generated at checkout and attached to the confirmation email, plus
available on demand from the order-detail page. Payload-side, orders now
also email the customer on shipped/cancelled/return_requested/returned,
with Stornorechnung/Gutschrift correction PDFs attached for the latter two
so the original invoice's immutable number stays honest.

app/api/account/orders/[orderNumber]/invoice/route.ts

@@ -0,0 +1,50 @@
+import { NextResponse } from "next/server";
+import { getSessionCustomer, getCustomerOrderDetail } from "../../../../../lib/customerAuth";
+import { generateInvoicePdf } from "../../../../../lib/invoiceData";
+
+// On-demand download for "Rechnung herunterladen" on
+// /konto/bestellungen/[orderNumber] — reuses the exact same render call as
+// the checkout-time attachment (app/lib/orderEmail.ts), so a re-download
+// always matches what was emailed; invoiceNumber itself never changes
+// (assigned once, server-side, at order creation — see Orders.ts).
+export async function GET(request: Request, { params }: { params: Promise<{ orderNumber: string }> }) {
+  const session = await getSessionCustomer();
+  if (!session) return NextResponse.json({ ok: false, reason: "Bitte zuerst einloggen." }, { status: 401 });
+
+  const { orderNumber } = await params;
+  const order = await getCustomerOrderDetail(session.token, session.customer.id, decodeURIComponent(orderNumber));
+  if (!order) return NextResponse.json({ ok: false, reason: "Bestellung nicht gefunden." }, { status: 404 });
+  if (!order.invoiceNumber || !order.invoiceIssuedAt) {
+    return NextResponse.json({ ok: false, reason: "Für diese Bestellung liegt noch keine Rechnung vor." }, { status: 404 });
+  }
+
+  const pdf = await generateInvoicePdf({
+    orderNumber: order.orderNumber,
+    invoiceNumber: order.invoiceNumber,
+    invoiceIssuedAt: order.invoiceIssuedAt,
+    customerFirstName: order.customerFirstName,
+    customerLastName: order.customerLastName,
+    deliveryMethod: order.deliveryMethod,
+    street: order.street,
+    packstationNumber: order.packstationNumber,
+    postNumber: order.postNumber,
+    zip: order.zip,
+    city: order.city,
+    country: order.country,
+    items: order.items,
+    subtotal: order.subtotal,
+    shippingCost: order.shippingCost,
+    discountAmount: order.discountAmount,
+    discountCode: order.discountCode,
+    total: order.total,
+  });
+  if (!pdf) return NextResponse.json({ ok: false, reason: "Rechnung konnte nicht erzeugt werden." }, { status: 500 });
+
+  return new NextResponse(new Uint8Array(pdf), {
+    status: 200,
+    headers: {
+      "Content-Type": "application/pdf",
+      "Content-Disposition": `attachment; filename="Rechnung-${order.invoiceNumber}.pdf"`,
+    },
+  });
+}

app/api/checkout/route.ts

@@ -88,11 +88,12 @@ export async function POST(request: Request) {
 
   // Re-price everything server-side — never trust client-submitted prices.
   const productsBySlug = await fetchProductsBySlug();
-  const items: { productId: number; productName: string; quantity: number; unitPrice: number }[] = [];
+  const items: { productId: number; productName: string; quantity: number; unitPrice: number; imageUrl: string | null }[] = [];
   for (const line of body.cart) {
     const product = productsBySlug.get(line.id);
     if (!product) return NextResponse.json({ ok: false, reason: "Ein Artikel im Warenkorb ist nicht mehr verfügbar." }, { status: 400 });
-    items.push({ productId: product.id, productName: product.name, quantity: line.qty, unitPrice: product.price });
+    const imageUrl = typeof product.image === "object" && product.image ? product.image.url : null;
+    items.push({ productId: product.id, productName: product.name, quantity: line.qty, unitPrice: product.price, imageUrl });
   }
   const subtotal = items.reduce((sum, i) => sum + i.quantity * i.unitPrice, 0);
 
@@ -164,7 +165,18 @@ export async function POST(request: Request) {
     {
       orderNumber: order.orderNumber,
       createdAt: order.createdAt,
-      items: items.map((i) => ({ productName: i.productName, quantity: i.quantity, unitPrice: i.unitPrice })),
+      invoiceNumber: order.invoiceNumber,
+      invoiceIssuedAt: order.invoiceIssuedAt,
+      customerFirstName: body.firstName,
+      customerLastName: body.lastName,
+      deliveryMethod: body.deliveryMethod,
+      street: body.street,
+      packstationNumber: body.packstationNumber,
+      postNumber: body.postNumber,
+      zip: body.zip,
+      city: body.city,
+      country: body.country,
+      items: items.map((i) => ({ productName: i.productName, quantity: i.quantity, unitPrice: i.unitPrice, imageUrl: i.imageUrl })),
       subtotal,
       shippingCost,
       discountAmount,