Added discounts to invoices

src/utils/invoice.ts

@@ -27,16 +27,34 @@ export async function recalculateInvoiceTotals(invoiceId: string) {
   // Note: amounts are in cents
   const subtotal = items.reduce((acc, item) => acc + item.amount, 0);
 
-  const taxRate = invoice.taxRate || 0;
-  const taxAmount = Math.round(subtotal * (taxRate / 100));
+  // Calculate discount
+  const discountType = invoice.discountType || "percentage";
+  const discountValue = invoice.discountValue || 0;
+  let discountAmount = 0;
 
-  const total = subtotal + taxAmount;
+  if (discountType === "percentage") {
+    discountAmount = Math.round(subtotal * (discountValue / 100));
+  } else {
+    // Fixed amount is assumed to be in cents
+    discountAmount = Math.round(discountValue);
+  }
+
+  // Ensure discount doesn't exceed subtotal
+  discountAmount = Math.max(0, Math.min(discountAmount, subtotal));
+
+  const taxableAmount = subtotal - discountAmount;
+
+  const taxRate = invoice.taxRate || 0;
+  const taxAmount = Math.round(taxableAmount * (taxRate / 100));
+
+  const total = taxableAmount + taxAmount;
 
   // Update invoice
   await db
     .update(invoices)
     .set({
       subtotal,
+      discountAmount,
       taxAmount,
       total,
     })