From 52136030be49d91619a19779d3837abd983337c0 Mon Sep 17 00:00:00 2001
From: Philipp Heckel <pheckel@datto.com>
Date: Mon, 15 Nov 2021 07:56:58 -0500
Subject: [PATCH] Subscribe to more than one topic

---
 server/server.go | 77 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 50 insertions(+), 27 deletions(-)

diff --git a/server/server.go b/server/server.go
index 1cb185cb..71ab024c 100644
--- a/server/server.go
+++ b/server/server.go
@@ -78,9 +78,9 @@ const (
 
 var (
 	topicRegex = regexp.MustCompile(`^/[-_A-Za-z0-9]{1,64}$`) // Regex must match JS & Android app!
-	jsonRegex  = regexp.MustCompile(`^/[-_A-Za-z0-9]{1,64}/json$`)
-	sseRegex   = regexp.MustCompile(`^/[-_A-Za-z0-9]{1,64}/sse$`)
-	rawRegex   = regexp.MustCompile(`^/[-_A-Za-z0-9]{1,64}/raw$`)
+	jsonRegex  = regexp.MustCompile(`^/[-_A-Za-z0-9]{1,64}(,[-_A-Za-z0-9]{1,64})*/json$`)
+	sseRegex   = regexp.MustCompile(`^/[-_A-Za-z0-9]{1,64}(,[-_A-Za-z0-9]{1,64})*/sse$`)
+	rawRegex   = regexp.MustCompile(`^/[-_A-Za-z0-9]{1,64}(,[-_A-Za-z0-9]{1,64})*/raw$`)
 
 	staticRegex = regexp.MustCompile(`^/static/.+`)
 
@@ -223,7 +223,7 @@ func (s *Server) handleStatic(w http.ResponseWriter, r *http.Request) error {
 }
 
 func (s *Server) handlePublish(w http.ResponseWriter, r *http.Request, v *visitor) error {
-	t, err := s.topic(r.URL.Path[1:])
+	t, err := s.topicFromID(r.URL.Path[1:])
 	if err != nil {
 		return err
 	}
@@ -289,7 +289,9 @@ func (s *Server) handleSubscribe(w http.ResponseWriter, r *http.Request, v *visi
 		return errHTTPTooManyRequests
 	}
 	defer v.RemoveSubscription()
-	t, err := s.topic(strings.TrimSuffix(r.URL.Path[1:], "/"+format)) // Hack
+	topicsStr := strings.TrimSuffix(r.URL.Path[1:], "/"+format) // Hack
+	topicIDs := strings.Split(topicsStr, ",")
+	topics, err := s.topicsFromIDs(topicIDs...)
 	if err != nil {
 		return err
 	}
@@ -314,14 +316,21 @@ func (s *Server) handleSubscribe(w http.ResponseWriter, r *http.Request, v *visi
 	w.Header().Set("Access-Control-Allow-Origin", "*")            // CORS, allow cross-origin requests
 	w.Header().Set("Content-Type", contentType+"; charset=utf-8") // Android/Volley client needs charset!
 	if poll {
-		return s.sendOldMessages(t, since, sub)
+		return s.sendOldMessages(topics, since, sub)
 	}
-	subscriberID := t.Subscribe(sub)
-	defer t.Unsubscribe(subscriberID)
-	if err := sub(newOpenMessage(t.id)); err != nil { // Send out open message
+	subscriberIDs := make([]int, 0)
+	for _, t := range topics {
+		subscriberIDs = append(subscriberIDs, t.Subscribe(sub))
+	}
+	defer func() {
+		for i, subscriberID := range subscriberIDs {
+			topics[i].Unsubscribe(subscriberID) // Order!
+		}
+	}()
+	if err := sub(newOpenMessage(topicsStr)); err != nil { // Send out open message
 		return err
 	}
-	if err := s.sendOldMessages(t, since, sub); err != nil {
+	if err := s.sendOldMessages(topics, since, sub); err != nil {
 		return err
 	}
 	for {
@@ -330,25 +339,27 @@ func (s *Server) handleSubscribe(w http.ResponseWriter, r *http.Request, v *visi
 			return nil
 		case <-time.After(s.config.KeepaliveInterval):
 			v.Keepalive()
-			if err := sub(newKeepaliveMessage(t.id)); err != nil { // Send keepalive message
+			if err := sub(newKeepaliveMessage(topicsStr)); err != nil { // Send keepalive message
 				return err
 			}
 		}
 	}
 }
 
-func (s *Server) sendOldMessages(t *topic, since sinceTime, sub subscriber) error {
+func (s *Server) sendOldMessages(topics []*topic, since sinceTime, sub subscriber) error {
 	if since.IsNone() {
 		return nil
 	}
-	messages, err := s.cache.Messages(t.id, since)
-	if err != nil {
-		return err
-	}
-	for _, m := range messages {
-		if err := sub(m); err != nil {
+	for _, t := range topics {
+		messages, err := s.cache.Messages(t.id, since)
+		if err != nil {
 			return err
 		}
+		for _, m := range messages {
+			if err := sub(m); err != nil {
+				return err
+			}
+		}
 	}
 	return nil
 }
@@ -382,19 +393,31 @@ func (s *Server) handleOptions(w http.ResponseWriter, r *http.Request) error {
 	return nil
 }
 
-func (s *Server) topic(id string) (*topic, error) {
+func (s *Server) topicFromID(id string) (*topic, error) {
+	topics, err := s.topicsFromIDs(id)
+	if err != nil {
+		return nil, err
+	}
+	return topics[0], nil
+}
+
+func (s *Server) topicsFromIDs(ids... string) ([]*topic, error) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
-	if _, ok := s.topics[id]; !ok {
-		if len(s.topics) >= s.config.GlobalTopicLimit {
-			return nil, errHTTPTooManyRequests
-		}
-		s.topics[id] = newTopic(id, time.Now())
-		if s.firebase != nil {
-			s.topics[id].Subscribe(s.firebase)
+	topics := make([]*topic, 0)
+	for  _, id := range ids {
+		if _, ok := s.topics[id]; !ok {
+			if len(s.topics) >= s.config.GlobalTopicLimit {
+				return nil, errHTTPTooManyRequests
+			}
+			s.topics[id] = newTopic(id, time.Now())
+			if s.firebase != nil {
+				s.topics[id].Subscribe(s.firebase)
+			}
 		}
+		topics = append(topics, s.topics[id])
 	}
-	return s.topics[id], nil
+	return topics, nil
 }
 
 func (s *Server) updateStatsAndExpire() {