feat(frontend): add /api/stations.json and /api/stations/:id/cover

frontend/src/pages/api/stations.json.ts

@@ -0,0 +1,17 @@
+import type { APIRoute } from 'astro';
+import { listStations } from '@lib/stations';
+
+export const prerender = false;
+
+export const GET: APIRoute = async () => {
+  const root = process.env.LIBRARY_ROOT ?? '/library';
+  const stations = await listStations(root);
+  return new Response(JSON.stringify(stations), {
+    status: 200,
+    headers: {
+      'Content-Type': 'application/json; charset=utf-8',
+      'Cache-Control': 'max-age=30, public',
+      'Access-Control-Allow-Origin': '*',
+    },
+  });
+};

frontend/src/pages/api/stations/[id]/cover.ts

@@ -0,0 +1,37 @@
+import type { APIRoute } from 'astro';
+import { access, readFile } from 'node:fs/promises';
+import path from 'node:path';
+
+export const prerender = false;
+
+const ID_RE = /^[a-z0-9-]+$/;
+const CANDIDATES: Array<[string, string]> = [
+  ['cover.jpg', 'image/jpeg'],
+  ['cover.png', 'image/png'],
+  ['cover.webp', 'image/webp'],
+];
+
+export const GET: APIRoute = async ({ params }) => {
+  const id = params.id ?? '';
+  if (!ID_RE.test(id)) {
+    return new Response('not found', { status: 404 });
+  }
+  const root = process.env.LIBRARY_ROOT ?? '/library';
+  for (const [name, mime] of CANDIDATES) {
+    const p = path.join(root, id, name);
+    try {
+      await access(p);
+      const buf = await readFile(p);
+      return new Response(new Uint8Array(buf), {
+        status: 200,
+        headers: {
+          'Content-Type': mime,
+          'Cache-Control': 'max-age=300, public',
+        },
+      });
+    } catch {
+      // try next
+    }
+  }
+  return new Response('not found', { status: 404 });
+};