1 files changed, 72 insertions, 0 deletions
diff --git a/src/content/dependencies/listGroupsByLatestAlbum.js b/src/content/dependencies/listGroupsByLatestAlbum.js
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--- /dev/null
+++ b/src/content/dependencies/listGroupsByLatestAlbum.js
@@ -0,0 +1,72 @@
+import {compareDates, sortChronologically} from '#sort';
+import {filterMultipleArrays, sortMultipleArrays, stitchArrays} from '#sugar';
+
+export default {
+  contentDependencies: [
+    'generateListingPage',
+    'linkAlbum',
+    'linkGroup',
+    'linkGroupGallery',
+  ],
+
+  extraDependencies: ['language', 'wikiData'],
+
+  sprawl({groupData}) {
+    return {groupData};
+  },
+
+  query({groupData}, spec) {
+    const groups = sortChronologically(groupData.slice());
+
+    const albums =
+      groups
+        .map(group =>
+          sortChronologically(
+            group.albums.filter(album => album.date),
+            {latestFirst: true}))
+        .map(albums => albums[0]);
+
+    filterMultipleArrays(groups, albums, (group, album) => album);
+
+    const dates = albums.map(album => album.date);
+
+    // Note: After this sort, the groups/dates arrays are misaligned with
+    // albums. That's OK only because we aren't doing anything further with
+    // the albums array.
+    sortMultipleArrays(groups, dates,
+      (groupA, groupB, dateA, dateB) =>
+        compareDates(dateA, dateB, {latestFirst: true}));
+
+    return {spec, groups, dates};
+  },
+
+  relations(relation, query) {
+    return {
+      page: relation('generateListingPage', query.spec),
+
+      groupLinks:
+        query.groups
+          .map(group => relation('linkGroup', group)),
+    };
+  },
+
+  data(query) {
+    return {
+      dates: query.dates,
+    };
+  },
+
+  generate(data, relations, {language}) {
+    return relations.page.slots({
+      type: 'rows',
+      rows:
+        stitchArrays({
+          groupLink: relations.groupLinks,
+          date: data.dates,
+        }).map(({groupLink, date}) => ({
+            group: groupLink,
+            date: language.formatDate(date),
+          })),
+    });
+  },
+};