Sort watch history by most recent view

js/watchHistorySort.js

@@ -0,0 +1,45 @@
+// js/watchHistorySort.js
+
+export function toNumber(value, fallback) {
+  const parsed = Number(value);
+  return Number.isFinite(parsed) ? parsed : fallback;
+}
+
+export function getWatchedAtScore(video) {
+  if (!video || typeof video !== "object") {
+    return Number.NEGATIVE_INFINITY;
+  }
+
+  const watchedAt = toNumber(video?.watchHistory?.watchedAt, Number.NaN);
+  if (Number.isFinite(watchedAt)) {
+    return watchedAt;
+  }
+
+  const createdAtSeconds = toNumber(video?.created_at, Number.NaN);
+  if (Number.isFinite(createdAtSeconds)) {
+    return createdAtSeconds * 1000;
+  }
+
+  return Number.NEGATIVE_INFINITY;
+}
+
+export function compareByWatchedAtDesc(a, b) {
+  const aScore = getWatchedAtScore(a);
+  const bScore = getWatchedAtScore(b);
+
+  if (aScore !== bScore) {
+    return bScore - aScore;
+  }
+
+  const aCreated = toNumber(a?.created_at, Number.NEGATIVE_INFINITY);
+  const bCreated = toNumber(b?.created_at, Number.NEGATIVE_INFINITY);
+
+  if (aCreated !== bCreated) {
+    return bCreated - aCreated;
+  }
+
+  const aId = typeof a?.id === "string" ? a.id : "";
+  const bId = typeof b?.id === "string" ? b.id : "";
+
+  return aId.localeCompare(bId);
+}