feat: Implement auto-incrementing invoice numbers (#43)

Author: aimensahnoun

src/app/i/[id]/page.tsx

@@ -2,6 +2,7 @@ import { BackgroundWrapper } from "@/components/background-wrapper";
 import { Footer } from "@/components/footer";
 import { Header } from "@/components/header";
 import { InvoiceCreator } from "@/components/invoice-creator";
+import { getInvoiceCount } from "@/lib/invoice";
 import { api } from "@/trpc/server";
 import { ArrowLeft } from "lucide-react";
 import type { Metadata } from "next";
@@ -24,6 +25,8 @@ export default async function InvoiceMePage({
     notFound();
   }
 
+  const invoiceCount = await getInvoiceCount(invoiceMeLink.user.id);
+
   return (
     <BackgroundWrapper
       topGradient={{ from: "purple-100", to: "purple-200" }}
@@ -49,6 +52,7 @@ export default async function InvoiceMePage({
             clientEmail: invoiceMeLink.user.email ?? "",
             userId: invoiceMeLink.user.id,
           }}
+          invoiceCount={invoiceCount}
         />
       </main>
       <Footer />

src/app/invoices/create/page.tsx

@@ -2,6 +2,7 @@ import { BackgroundWrapper } from "@/components/background-wrapper";
 import { Footer } from "@/components/footer";
 import { Header } from "@/components/header";
 import { InvoiceCreator } from "@/components/invoice-creator";
+import { getInvoiceCount } from "@/lib/invoice";
 import { getCurrentSession } from "@/server/auth";
 import { ArrowLeft } from "lucide-react";
 import Link from "next/link";
@@ -14,6 +15,8 @@ export default async function CreateInvoicePage() {
     redirect("/");
   }
 
+  const invoiceCount = await getInvoiceCount(user.id);
+
   return (
     <BackgroundWrapper
       topGradient={{ from: "purple-100", to: "purple-200" }}
@@ -38,6 +41,7 @@ export default async function CreateInvoicePage() {
             email: user.email ?? "",
             name: user.name ?? "",
           }}
+          invoiceCount={invoiceCount}
         />
       </main>
       <Footer />

src/components/invoice-creator.tsx

@@ -3,6 +3,7 @@
 import { InvoiceForm } from "@/components/invoice-form";
 import { InvoicePreview } from "@/components/invoice-preview";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
+import { generateInvoiceNumber } from "@/lib/invoice/client";
 import {
   type InvoiceFormValues,
   invoiceFormSchema,
@@ -23,11 +24,13 @@ interface InvoiceCreatorProps {
     name: string;
     email: string;
   };
+  invoiceCount: string;
 }
 
 export function InvoiceCreator({
   recipientDetails,
   currentUser,
+  invoiceCount,
 }: InvoiceCreatorProps) {
   const router = useRouter();
   const isInvoiceMe = !!recipientDetails?.userId;
@@ -52,7 +55,7 @@ export function InvoiceCreator({
   const form = useForm<InvoiceFormValues>({
     resolver: zodResolver(invoiceFormSchema),
     defaultValues: {
-      invoiceNumber: "",
+      invoiceNumber: generateInvoiceNumber(invoiceCount),
       dueDate: "",
       creatorName: !isInvoiceMe ? (currentUser?.name ?? "") : "",
       creatorEmail: !isInvoiceMe ? (currentUser?.email ?? "") : "",

src/lib/invoice/client.ts

@@ -0,0 +1,14 @@
+export const generateInvoiceNumber = (invoiceCount: string) => {
+  const now = new Date();
+  const userTimeZone = Intl.DateTimeFormat().resolvedOptions().timeZone;
+
+  const formatter = new Intl.DateTimeFormat(undefined, {
+    year: "numeric",
+    month: "2-digit",
+    timeZone: userTimeZone,
+  });
+
+  const [{ value: month }, , { value: year }] = formatter.formatToParts(now);
+
+  return `${year}${month}-${invoiceCount}`;
+};

src/lib/invoice/index.ts

@@ -0,0 +1,27 @@
+import { db } from "@/server/db";
+import { requestTable } from "@/server/db/schema";
+import { and, count, eq, gte } from "drizzle-orm";
+
+export const getInvoiceCount = async (userId: string) => {
+  const invoicesCountThisMonth = await db
+    .select({
+      count: count(),
+    })
+    .from(requestTable)
+    .where(
+      and(
+        eq(requestTable.userId, userId),
+        gte(
+          requestTable.createdAt,
+          new Date(new Date().getFullYear(), new Date().getMonth(), 1),
+        ),
+      ),
+    );
+
+  const invoiceCount = String(invoicesCountThisMonth[0].count + 1).padStart(
+    4,
+    "0",
+  );
+
+  return invoiceCount;
+};