feat(route/nber): add topic route via generic_listing API

lib/routes/nber/topic.ts

@@ -0,0 +1,98 @@
+import { load } from 'cheerio';
+
+import type { Route } from '@/types';
+import { config } from '@/config';
+import cache from '@/utils/cache';
+import ofetch from '@/utils/ofetch';
+import { parseDate } from '@/utils/parse-date';
+
+export const route: Route = {
+    name: 'Topic',
+    maintainers: ['fredericky123'],
+    path: '/topic/:fields/:values/:limit?',
+    example: '/nber/topic/itm_topics_term_id/656',
+    parameters: {
+        fields: 'Facet field(s) from the topic page\'s listing API. For a taxonomy topic (`nber.org/taxonomy/term/<id>`) this is `itm_topics_term_id`. For a topic landing page (`nber.org/topics/<slug>`) copy the field segment from the page\'s `generic_listing` request, e.g. `nid,itm_topics_term_id`.',
+        values: 'Facet value(s) matching the fields, e.g. `656`, or `11651,4701` for a multi-facet topic.',
+        limit: 'Number of items to fetch, 50 by default.',
+    },
+    features: {
+        supportScihub: true,
+    },
+    radar: [
+        {
+            source: ['nber.org/taxonomy/term/:id'],
+            target: '/topic/itm_topics_term_id/:id',
+        },
+    ],
+    handler,
+    url: 'nber.org/research/topics',
+    description: `Working papers and other research outputs under an NBER topic.
+
+To find the parameters, open the topic page, then in DevTools › Network filter for \`generic_listing\` and read the path segments of
+\`/api/v1/generic_listing/{fields}/{values}/_/_/search/contentType\`.
+
+| Topic page | Route |
+| ---------- | ----- |
+| nber.org/taxonomy/term/656 | \`/nber/topic/itm_topics_term_id/656\` |
+| nber.org/topics/entrepreneurship | \`/nber/topic/nid,itm_topics_term_id/11651,4701\` |`,
+};
+
+async function handler(ctx) {
+    const { fields, values, limit = '50' } = ctx.req.param();
+    const baseUrl = 'https://www.nber.org';
+
+    const apiUrl = `${baseUrl}/api/v1/generic_listing/${fields}/${values}/_/_/search/contentType?page=1&perPage=${limit}`;
+
+    const results = await cache.tryGet(apiUrl, async () => (await ofetch(apiUrl)).results, config.cache.routeExpire, false);
+
+    const items = await Promise.all(
+        results.map((article) => {
+            const link = `${baseUrl}${article.url}`;
+            const listingAuthors = Array.isArray(article.authors) ? article.authors.map((a) => a.replace(/<[^>]+>/g, '').trim()).join(', ') : undefined;
+
+            return cache.tryGet(link, async () => {
+                let description = article.abstract ?? '';
+                let author = listingAuthors;
+                let doi;
+
+                try {
+                    const $ = load(await ofetch(link));
+                    const fullAbstract = $('.page-header__intro-inner').html();
+                    const pdf = $('meta[name="citation_pdf_url"]').attr('content');
+
+                    if (fullAbstract) {
+                        description = fullAbstract;
+                    }
+                    if (pdf) {
+                        description += `<p><a href="${pdf}">Download PDF</a></p>`;
+                    }
+                    author = author || $('meta[name="dcterms.creator"]').attr('content');
+                    doi = $('meta[name="citation_doi"]').attr('content');
+                } catch {
+                    // Non-paper pages (projects, articles, books) may not expose these
+                    // meta tags; fall back to the data already provided by the listing API.
+                }
+
+                return {
+                    title: article.title,
+                    link,
+                    description,
+                    author,
+                    doi,
+                    category: article.displaytypename,
+                    pubDate: article.displaydate ? parseDate(article.displaydate) : undefined,
+                };
+            });
+        })
+    );
+
+    const lastValue = values.split(',').pop();
+
+    return {
+        title: `NBER - Topic ${values}`,
+        link: `${baseUrl}/taxonomy/term/${lastValue}`,
+        item: items,
+        description: `National Bureau of Economic Research outputs under topic ${values}`,
+    };
+}