gistfile1.txt

 fun startListenToComments(postId: String, result: (List<CommentItem>) -> Unit) {
        val collection = FirebaseFirestore.getInstance().collection("posts").document(postId)
            .collection("comments")
        commentListener = collection.orderBy("date", Query.Direction.DESCENDING)
            .addSnapshotListener(MetadataChanges.INCLUDE) { data, firebaseFirestoreExceptioor ->
                if (data != null) {
                    val comments = data.toObjects(CommentItem::class.java)
                    result(comments)
                }
            }
    }

    fun stopCommentListening() {
        commentListener?.remove()
        commentListener = null
    }