From 80344e3c5f99584ec72edc5a7343465dbdf480a4 Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Tue, 21 May 2024 18:15:17 -0500
Subject: [PATCH] Fix trends cache

---
 src/app.ts                    |  8 ++---
 src/controllers/api/trends.ts | 68 +++++++++++++++++++----------------
 2 files changed, 40 insertions(+), 36 deletions(-)

diff --git a/src/app.ts b/src/app.ts
index be2ce840..9b82bee2 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -194,12 +194,8 @@ app.get('/api/v2/search', searchController);
 
 app.get('/api/pleroma/frontend_configurations', frontendConfigController);
 
-app.get(
-  '/api/v1/trends/tags',
-  cacheMiddleware({ cacheName: 'web', expires: Time.minutes(15) }),
-  trendingTagsController,
-);
-app.get('/api/v1/trends', cacheMiddleware({ cacheName: 'web', expires: Time.minutes(15) }), trendingTagsController);
+app.get('/api/v1/trends/tags', trendingTagsController);
+app.get('/api/v1/trends', trendingTagsController);
 
 app.get('/api/v1/suggestions', suggestionsV1Controller);
 app.get('/api/v2/suggestions', suggestionsV2Controller);
diff --git a/src/controllers/api/trends.ts b/src/controllers/api/trends.ts
index 1a47d8cd..64b3019a 100644
--- a/src/controllers/api/trends.ts
+++ b/src/controllers/api/trends.ts
@@ -10,10 +10,20 @@ await TrendsWorker.open('data/trends.sqlite3');
 
 const limitSchema = z.coerce.number().catch(10).transform((value) => Math.min(Math.max(value, 0), 20));
 
+let cache = getTrends();
+
+Deno.cron('update trends cache', { minute: { every: 15 } }, async () => {
+  const trends = await getTrends();
+  cache = Promise.resolve(trends);
+});
+
 const trendingTagsController: AppController = async (c) => {
   const limit = limitSchema.parse(c.req.query('limit'));
-  if (limit < 1) return c.json([]);
+  const trends = await cache;
+  return c.json(trends.slice(0, limit));
+};
 
+async function getTrends() {
   const now = new Date();
   const yesterday = new Date(now.getTime() - Time.days(1));
   const lastWeek = new Date(now.getTime() - Time.days(7));
@@ -22,36 +32,34 @@ const trendingTagsController: AppController = async (c) => {
   const tags = await TrendsWorker.getTrendingTags({
     since: yesterday,
     until: now,
-    limit,
+    limit: 20,
   });
 
-  return c.json(
-    await Promise.all(tags.map(async ({ tag, uses, accounts }) => ({
-      name: tag,
-      url: Conf.local(`/tags/${tag}`),
-      history: [
-        // Use the full 24h query for the current day. Then use `offset: 1` to adjust for this below.
-        // This result is more accurate than what Mastodon returns.
-        {
-          day: String(Math.floor(stripTime(now).getTime() / 1000)),
-          accounts: String(accounts),
-          uses: String(uses),
-        },
-        ...(await TrendsWorker.getTagHistory({
-          tag,
-          since: lastWeek,
-          until: now,
-          limit: 6,
-          offset: 1,
-        })).map((history) => ({
-          // For some reason, Mastodon wants these to be strings... oh well.
-          day: String(Math.floor(history.day.getTime() / 1000)),
-          accounts: String(history.accounts),
-          uses: String(history.uses),
-        })),
-      ],
-    }))),
-  );
-};
+  return Promise.all(tags.map(async ({ tag, uses, accounts }) => ({
+    name: tag,
+    url: Conf.local(`/tags/${tag}`),
+    history: [
+      // Use the full 24h query for the current day. Then use `offset: 1` to adjust for this below.
+      // This result is more accurate than what Mastodon returns.
+      {
+        day: String(Math.floor(stripTime(now).getTime() / 1000)),
+        accounts: String(accounts),
+        uses: String(uses),
+      },
+      ...(await TrendsWorker.getTagHistory({
+        tag,
+        since: lastWeek,
+        until: now,
+        limit: 6,
+        offset: 1,
+      })).map((history) => ({
+        // For some reason, Mastodon wants these to be strings... oh well.
+        day: String(Math.floor(history.day.getTime() / 1000)),
+        accounts: String(history.accounts),
+        uses: String(history.uses),
+      })),
+    ],
+  })));
+}
 
 export { trendingTagsController };