feat: add month / year support for ad page (#310)

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## PR Checklist

- [x] Addresses an existing open issue: fixes
#45
- [x] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/boston-ts-website/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/boston-ts-website/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

<!-- Description of what is changed and how the code change does that.
-->

app/components/AdGrid.tsx

@@ -1,7 +1,12 @@
 import * as styles from "./AdGrid.css";
 import { AdLogo } from "./AdLogo";
 
-export function AdGrid() {
+export interface AdGridProps {
+	month: string;
+	year: number;
+}
+
+export function AdGrid({ month, year }: AdGridProps) {
 	return (
 		<main className={styles.adGrid}>
 			<div className={styles.imageArea}>
@@ -11,7 +16,9 @@ export function AdGrid() {
 				<h1 className={styles.h1}>
 					Boston <span className={styles.together}>TS Club</span>
 				</h1>
-				<p className={styles.p}>June 2024</p>
+				<p className={styles.p}>
+					{month} {year}
+				</p>
 			</div>
 		</main>
 	);

app/routes/ad.tsx

@@ -1,10 +1,31 @@
 import { MetaFunction } from "@remix-run/node";
+import { useSearchParams } from "@remix-run/react";
 
 import { AdGrid } from "~/components/AdGrid";
 import { createMeta } from "~/config";
 
 export const meta: MetaFunction = () => createMeta({ page: "Ad" });
 
+function useYearAndMonth() {
+	const [searchParams] = useSearchParams();
+
+	const currentDate = new Date();
+
+	const month =
+		searchParams.get("month") ??
+		currentDate.toLocaleString("default", { month: "long" });
+
+	const paramYear = searchParams.get("year");
+	const parsedYear = paramYear ? parseInt(paramYear, 10) : null;
+
+	const currentYear = currentDate.getFullYear();
+	const year = !parsedYear || isNaN(parsedYear) ? currentYear : parsedYear;
+
+	return { month, year };
+}
+
 export default function Ad() {
-	return <AdGrid />;
+	const { month, year } = useYearAndMonth();
+
+	return <AdGrid month={month} year={year} />;
 }