full

utils/commentEngagement.js

@@ -0,0 +1,34 @@
+const CommentLikeModel = require('../models/CommentLikeModel')
+
+async function attachCommentLikeFields(comments, viewerId) {
+  if (!comments?.length) return comments
+
+  const ids = comments.map((c) => c._id)
+  const [likeAgg, userLikes] = await Promise.all([
+    CommentLikeModel.aggregate([
+      { $match: { commentId: { $in: ids } } },
+      { $group: { _id: '$commentId', count: { $sum: 1 } } },
+    ]),
+    viewerId
+      ? CommentLikeModel.find({
+          userId: viewerId,
+          commentId: { $in: ids },
+        })
+          .select('commentId')
+          .lean()
+      : [],
+  ])
+
+  const countMap = Object.fromEntries(
+    likeAgg.map((row) => [String(row._id), row.count])
+  )
+  const likedSet = new Set(userLikes.map((l) => String(l.commentId)))
+
+  return comments.map((c) => ({
+    ...c,
+    likesCount: countMap[String(c._id)] || 0,
+    is_liked: likedSet.has(String(c._id)),
+  }))
+}
+
+module.exports = { attachCommentLikeFields }