1 files changed, 73 insertions, 0 deletions
diff --git a/src/content/dependencies/generateFlashNavAccent.js b/src/content/dependencies/generateFlashNavAccent.js
new file mode 100644
index 0000000..55e056d
--- /dev/null
+++ b/src/content/dependencies/generateFlashNavAccent.js
@@ -0,0 +1,73 @@
+import {atOffset, empty} from '#sugar';
+
+export default {
+  contentDependencies: [
+    'generatePreviousNextLinks',
+    'linkFlash',
+  ],
+
+  extraDependencies: ['html', 'language', 'wikiData'],
+
+  sprawl({flashActData}) {
+    return {flashActData};
+  },
+
+  query(sprawl, flash) {
+    // Don't sort chronologically here. The previous/next buttons should match
+    // the order in the sidebar, by act rather than date.
+    const flashes =
+      sprawl.flashActData
+        .flatMap(act => act.flashes);
+
+    const index =
+      flashes.indexOf(flash);
+
+    const previousFlash =
+      atOffset(flashes, index, -1);
+
+    const nextFlash =
+      atOffset(flashes, index, +1);
+
+    return {previousFlash, nextFlash};
+  },
+
+  relations(relation, query) {
+    const relations = {};
+
+    if (query.previousFlash || query.nextFlash) {
+      relations.previousNextLinks =
+        relation('generatePreviousNextLinks');
+
+      relations.previousFlashLink =
+        (query.previousFlash
+          ? relation('linkFlash', query.previousFlash)
+          : null);
+
+      relations.nextFlashLink =
+        (query.nextFlash
+          ? relation('linkFlash', query.nextFlash)
+          : null);
+    }
+
+    return relations;
+  },
+
+  generate(relations, {html, language}) {
+    const {content: previousNextLinks = []} =
+      relations.previousNextLinks &&
+        relations.previousNextLinks.slots({
+          previousLink: relations.previousFlashLink,
+          nextLink: relations.nextFlashLink,
+        });
+
+    const allLinks = [
+      ...previousNextLinks,
+    ].filter(Boolean);
+
+    if (empty(allLinks)) {
+      return html.blank();
+    }
+
+    return `(${language.formatUnitList(allLinks)})`;
+  },
+};