Added updated query for topics to update based on recent posts in communities

src/services/miiverse-api/routes/topics.js

@@ -1,6 +1,8 @@
 const express = require('express');
 const router = express.Router();
 const database = require('../../../database');
+const {POST} = require('../../../models/post');
+const {COMMUNITY} = require('../../../models/communities');
 const comPostGen = require('../../../util/xmlResponseGenerator');
 let memoize = require("memoizee");
 memoized = memoize(comPostGen.topics, { async: true, maxAge: 1000 * 60 * 60 });
@@ -12,14 +14,45 @@ router.get('/', async function (req, res) {
         discovery = await database.getEndPoint(user.server_access_level);
     else
         discovery = await database.getEndPoint('prod');
-    if(!discovery.topics)
-        return res.sendStatus(404);
-    let communities = await database.getMostPopularCommunities(10);
-    if(communities === null)
-        return res.sendStatus(404);
+    if(!discovery.topics) return res.sendStatus(404);
+
+    let communities = await calculateMostPopularCommunities(24, 10);
+    if(communities === null) return res.sendStatus(404);
+
     let response = await memoized(communities);
     res.contentType("application/xml");
         res.send(response);
 });
 
+async function calculateMostPopularCommunities(hours, limit) {
+    const now = new Date();
+    const last24Hours = new Date(now.getTime() - hours * 60 * 60 * 1000);
+
+    const posts = await POST.find({ created_at: { $gte: last24Hours },  message_to_pid: null }).lean();
+
+    const communityIds = {};
+    for (const post of posts) {
+        const communityId = post.community_id;
+        communityIds[communityId] = (communityIds[communityId] || 0) + 1;
+    }
+    const communities = Object.entries(communityIds)
+        .sort((a, b) => b[1] - a[1])
+        .map((entry) => entry[0]);
+    if(communities.size < limit)
+        return calculateMostPopularCommunities(hours + hours, limit);
+
+    let response = await COMMUNITY.aggregate([
+        { $match: { community_id: { $in: communities }, parent: null } },
+        {$addFields: {
+                index: { $indexOfArray: [ communities, "$community_id" ] }
+            }},
+        { $sort: { index: 1 } },
+        { $limit : limit },
+        { $project: { index: 0, _id: 0 } }
+    ]);
+    if(response.length < limit)
+        return calculateMostPopularCommunities(hours + hours, limit);
+    else return response;
+}
+
 module.exports = router;