Separate route and recent imagery acquisition from application assembly

src/layers/recentImagery/source.js

@@ -0,0 +1,32 @@
+import { searchHls } from './catalog.js';
+import { gibsTemplate, wvsSnapshotUrl } from './model.js';
+
+/** NASA-compatible imagery acquisition; transport and URL builders are replaceable. */
+export function createRecentImagerySource({
+  fetchImpl = (...args) => globalThis.fetch(...args),
+  search = searchHls,
+  thumbnailUrl = wvsSnapshotUrl,
+  tileTemplate = gibsTemplate,
+  credit = 'NASA GIBS',
+} = {}) {
+  return {
+    credit,
+    searchHls: (query) => search({ ...query, fetchImpl }),
+    async getThumbnail(candidate, box, { size = 256, signal } = {}) {
+      signal?.throwIfAborted();
+      const response = await fetchImpl(
+        thumbnailUrl({
+          product: candidate.product,
+          day: candidate.day,
+          box,
+          width: size,
+          height: size,
+        }),
+        { signal },
+      );
+      signal?.throwIfAborted();
+      return response;
+    },
+    getTileTemplate: (product, day) => tileTemplate(product, day),
+  };
+}