web: load the news list on /aktuelt a page at a time

web/src/app/api/v1/news/route.test.ts

@@ -0,0 +1,65 @@
+import { NextRequest } from "next/server";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+const queryMock = vi.fn();
+// mirrors cmsQuery: returns the data, throws on a GraphQL error
+vi.mock("@/app/client", () => ({
+  cmsQuery: async (...args: unknown[]) => {
+    const { data, error } = await queryMock(...args);
+    if (error) throw new Error(error.message);
+    return data;
+  },
+}));
+
+import { GET } from "./route.ts";
+
+const request = (query = "") =>
+  new NextRequest(`http://localhost/api/v1/news${query}`);
+
+const articles = (count: number) =>
+  Array.from({ length: count }, (_, i) => ({ id: String(i), slug: `nyhet-${i}` }));
+
+afterEach(() => {
+  vi.clearAllMocks();
+});
+
+describe("GET /api/v1/news", () => {
+  it("returns a page of articles and the total", async () => {
+    queryMock.mockResolvedValue({ data: { index: {}, news: articles(40) } });
+
+    const res = await GET(request("?offset=17&limit=16"));
+
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body.total).toBe(40);
+    expect(body.news.map((n: { id: string }) => n.id)).toEqual(
+      Array.from({ length: 16 }, (_, i) => String(17 + i))
+    );
+  });
+
+  it("defaults to the first page", async () => {
+    queryMock.mockResolvedValue({ data: { index: {}, news: articles(40) } });
+
+    const body = await (await GET(request())).json();
+
+    expect(body.news).toHaveLength(16);
+    expect(body.news[0].id).toBe("0");
+  });
+
+  it("returns what is left at the end, and nothing past it", async () => {
+    queryMock.mockResolvedValue({ data: { index: {}, news: articles(20) } });
+
+    expect((await (await GET(request("?offset=17"))).json()).news).toHaveLength(3);
+    expect((await (await GET(request("?offset=500"))).json()).news).toEqual([]);
+  });
+
+  it.each(["?offset=-1", "?offset=abc", "?limit=0", "?limit=49", "?limit=1.5"])(
+    "rejects %s",
+    async (query) => {
+      const res = await GET(request(query));
+
+      expect(res.status).toBe(400);
+      expect(queryMock).not.toHaveBeenCalled();
+    }
+  );
+});

web/src/app/api/v1/news/route.ts

@@ -0,0 +1,36 @@
+import { NextRequest, NextResponse } from "next/server";
+import { loadAllNews } from "@/components/news/NewsIndexView";
+import { NEWS_PAGE_SIZE, NewsListItemFragment } from "@/lib/news";
+
+const MAX_LIMIT = 48;
+
+export type NewsPageResponse = {
+  news: NewsListItemFragment[];
+  total: number;
+};
+
+function nonNegativeInt(value: string | null, fallback: number): number | null {
+  if (value === null) return fallback;
+  return /^\d+$/.test(value) ? Number(value) : null;
+}
+
+// GET /api/v1/news?offset=17&limit=16: the next articles for "load more" on
+// /aktuelt, newest first. Reads the same cached list as the page
+export async function GET(req: NextRequest) {
+  const searchParams = req.nextUrl.searchParams;
+  const offset = nonNegativeInt(searchParams.get("offset"), 0);
+  const limit = nonNegativeInt(searchParams.get("limit"), NEWS_PAGE_SIZE);
+
+  if (offset === null || limit === null || limit < 1 || limit > MAX_LIMIT) {
+    return NextResponse.json(
+      { error: `offset must be >= 0 and limit between 1 and ${MAX_LIMIT}` },
+      { status: 400 }
+    );
+  }
+
+  const { news } = await loadAllNews();
+  return NextResponse.json({
+    news: news.slice(offset, offset + limit),
+    total: news.length,
+  } satisfies NewsPageResponse);
+}

web/src/components/news/NewsIndexView.tsx

@@ -1,28 +1,48 @@
 import { cmsQuery } from "@/app/client";
 import { PageHeader } from "@/components/general/PageHeader";
 import { NewsList } from "@/components/news/NewsList";
-import { NewsIndexFragment, NewsListItemFragment, newsQuery } from "@/lib/news";
+import {
+  NEWS_FIRST_PAGE,
+  NewsIndexFragment,
+  NewsListItemFragment,
+  newsQuery,
+} from "@/lib/news";
 
 export type NewsIndexViewProps = {
   index: NewsIndexFragment;
+  // the first page only; NewsList fetches the rest from /api/v1/news
   news: NewsListItemFragment[];
+  total: number;
 };
 
+// All articles, newest first. One cached CMS query serves both the page and
+// the API that pages through the rest
+export async function loadAllNews() {
+  const data = await cmsQuery(newsQuery, {});
+  return {
+    index: data?.index as NewsIndexFragment | undefined,
+    news: (data?.news ?? []) as NewsListItemFragment[],
+  };
+}
+
 export async function loadNewsIndexProps(overrides?: {
   indexOverride?: NewsIndexFragment;
 }): Promise<NewsIndexViewProps> {
-  const data = await cmsQuery(newsQuery, {});
+  const all = await loadAllNews();
-  const index = overrides?.indexOverride ?? (data?.index as NewsIndexFragment | undefined);
+  const index = overrides?.indexOverride ?? all.index;
   if (!index) throw new Error("Failed to load /aktuelt");
-  const news = (data?.news ?? []) as NewsListItemFragment[];
+  return {
-  return { index, news };
+    index,
+    news: all.news.slice(0, NEWS_FIRST_PAGE),
+    total: all.news.length,
+  };
 }
 
-export function NewsIndexView({ index, news }: NewsIndexViewProps) {
+export function NewsIndexView({ index, news, total }: NewsIndexViewProps) {
   return (
     <main className="site-main" id="main">
       <PageHeader heading={index.title} lead={index.lead} align="left" />
-      <NewsList news={news} />
+      <NewsList news={news} total={total} />
     </main>
   );
 }

web/src/components/news/NewsList.tsx

@@ -3,22 +3,51 @@ import { useState } from "react";
 import { SectionHeader } from "../general/SectionHeader";
 import { NewsItem } from "./NewsItem";
 import styles from "./newsList.module.scss";
-import { NewsFragment, NewsListItemFragment } from "@/lib/news";
+import { NEWS_PAGE_SIZE, NewsFragment, NewsListItemFragment } from "@/lib/news";
 import { SectionFooter } from "../general/SectionFooter";
+import type { NewsPageResponse } from "@/app/api/v1/news/route";
+
+type NewsListItem = NewsFragment | NewsListItemFragment;
 
 export const NewsList = ({
   news,
+  total,
   heading,
   featured
 }: {
-  news: (NewsFragment | NewsListItemFragment)[];
+  news: NewsListItem[];
+  // how many articles exist; more than `news` holds means the rest can be
+  // fetched with "load more"
+  total?: number;
   heading?: string;
   featured?: boolean;
 }) => {
-  const [limit, setLimit] = useState(featured ? 4 : 17);
+  const [items, setItems] = useState(news);
-  function increaseLimit() {
+  const [knownTotal, setKnownTotal] = useState(total ?? news.length);
-    setLimit(limit + 16);
+  const [loading, setLoading] = useState(false);
+  const [failed, setFailed] = useState(false);
+
+  async function loadMore() {
+    setLoading(true);
+    setFailed(false);
+    try {
+      const res = await fetch(
+        `/api/v1/news?offset=${items.length}&limit=${NEWS_PAGE_SIZE}`
+      );
+      if (!res.ok) throw new Error(`HTTP ${res.status}`);
+      const page = (await res.json()) as NewsPageResponse;
+      // an article published since the page was rendered shifts the offsets
+      const seen = new Set(items.map((item) => item.id));
+      setItems([...items, ...page.news.filter((item) => !seen.has(item.id))]);
+      setKnownTotal(page.total);
+    } catch {
+      setFailed(true);
+    } finally {
+      setLoading(false);
     }
+  }
+
+  const shown = featured ? items.slice(0, 4) : items;
 
   return (
     <section className={styles.newsWrapper}>
@@ -26,14 +55,18 @@ export const NewsList = ({
         <SectionHeader heading={heading} link="/aktuelt" linkText="Se flere artikler" />
       )}
       <ul className={`${styles.newsList} ${featured && styles.featured}`}>
-        {news.slice(0, limit).map((singleNews) => (
+        {shown.map((singleNews) => (
           <NewsItem key={singleNews.id} news={singleNews} />
         ))}
       </ul>
-      {!featured && limit && news.length > limit && (
+      {!featured && knownTotal > items.length && (
         <div className={styles.showMore}>
-          <button onClick={increaseLimit}>
+          <button onClick={loadMore} disabled={loading} aria-busy={loading}>
-            <span>Last inn flere artikler</span>
+            <span>
+              {failed
+                ? "Noe gikk galt. Prøv igjen"
+                : "Last inn flere artikler"}
+            </span>
           </button>
         </div>
       )}

web/src/lib/news.ts

@@ -49,6 +49,12 @@ const NewsIndexFragmentDefinition = graphql(`
   }
 `);
 
+// How many articles /aktuelt shows at first, and how many each "load more"
+// adds. With around 850 articles, sending them all made the page (and every
+// prefetch of it from the header) several hundred kilobytes
+export const NEWS_FIRST_PAGE = 17;
+export const NEWS_PAGE_SIZE = 16;
+
 export const newsIndexMetadataQuery = graphql(`
   query newsIndexMetadata {
     index: newsIndex {

web/tests/smoke/smoke.test.ts

@@ -167,6 +167,24 @@ describe("events api", () => {
   });
 });
 
+describe("news api", () => {
+  test("pages through the articles for \"load more\" on /aktuelt", async () => {
+    const res = await fetch(app("/api/v1/news?offset=0&limit=5"));
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as {
+      news: Array<{ slug: string }>;
+      total: number;
+    };
+    expect(body.total).toBe(1);
+    expect(body.news.map((n) => n.slug)).toEqual([SLUGS.news]);
+  });
+
+  test("rejects a limit that is too large", async () => {
+    const res = await fetch(app("/api/v1/news?limit=1000"));
+    expect(res.status).toBe(400);
+  });
+});
+
 describe("image optimizer", () => {
   test("optimizes a CMS-hosted image", async () => {
     const src = encodeURIComponent(mock("/media/pig.png"));