From cddab32419bf67af8ac7acad1d1e006d56b611ba Mon Sep 17 00:00:00 2001
From: Simon Thoby <git@nightmared.fr>
Date: Sun, 9 Apr 2023 14:27:11 +0200
Subject: [PATCH] matrix: revert to the classical syncer when the application
 sevrice is no longer working

---
 bridge/matrix/handlers.go | 58 ++++++++++++++++++++++++++++++---------
 bridge/matrix/matrix.go   |  5 ++--
 2 files changed, 48 insertions(+), 15 deletions(-)

diff --git a/bridge/matrix/handlers.go b/bridge/matrix/handlers.go
index 78ed8470..f2bb6e47 100644
--- a/bridge/matrix/handlers.go
+++ b/bridge/matrix/handlers.go
@@ -77,7 +77,6 @@ func (b *Bmatrix) ignoreBridgingEvents(ev *event.Event) bool {
 	return false
 }
 
-//nolint:funlen
 func (b *Bmatrix) handleEvent(origin EventOrigin, ev *event.Event) {
 	if ev.Type == event.EphemeralEventReceipt {
 		// we do not support read receipts across servers, considering that
@@ -99,8 +98,8 @@ func (b *Bmatrix) handleEvent(origin EventOrigin, ev *event.Event) {
 	// This needs to be defined before rejecting bridging events, as we rely on this to cache
 	// avatar URLs sent with appService (otherwise we would upload one avatar per message sent
 	// across the bridge!).
-	// As such, beware! Moving this below the b.ignoreBridgingEvents condiiton would appear to
-	// work, but it would also lead to a high file upload rate, until being eventually
+	// As such, beware! Moving this below the b.ignoreBridgingEvents condition would appear to
+	// work, but it would also lead to a high file upload rate, until the bridge becomes eventually
 	// rate-limited by the homeserver
 	if ev.Type == event.StateMember {
 		b.handleMemberChange(ev)
@@ -108,25 +107,57 @@ func (b *Bmatrix) handleEvent(origin EventOrigin, ev *event.Event) {
 		return
 	}
 
-	// if we receive messages both via the classical matrix syncer and appserver, prefer appservice and throw away this duplicate event
-	if channel.appService && origin != originAppService {
-		b.Log.Debugf("Dropping event, should receive it via appservice: %s", ev.ID)
-
-		return
-	}
-
 	if b.ignoreBridgingEvents(ev) {
 		return
 	}
 
-	// if we receive appservice events for this room, there is no need to check them with the classical syncer
-	if !channel.appService && origin == originAppService {
+	// try again later in case the appservice is not working
+	if origin == originClassicSyncer && channel.appService {
+		go b.processMessageIfAppServiceIsNotWorking(ev)
+
+		return
+	} else if origin == originAppService {
+		// if we receive appservice events for this room, there is no need to check them with the classical syncer
 		channel.appService = true
+		channel.lastMessageAppService = time.Now()
 		b.Lock()
 		b.RoomMap[ev.RoomID] = channel
 		b.Unlock()
 	}
 
+	b.handleAcceptedEvent(ev, channel, origin == originAppService)
+}
+
+func (b *Bmatrix) processMessageIfAppServiceIsNotWorking(ev *event.Event) {
+	// sleep some time and check whether we received the event via the appService
+	time.Sleep(15 * time.Second)
+
+	b.RLock()
+	channel, ok := b.RoomMap[ev.RoomID]
+	b.RUnlock()
+	if !ok {
+		b.Log.Debugf("Room %s no longer exit, aborting the retry operation", ev.RoomID)
+
+		return
+	}
+
+	// we receive no appservice message in the latest 30 seconds -> appService must be failing for now, disable it
+	if time.Since(channel.lastMessageAppService) > 30*time.Second {
+		b.Log.Warnf("The AppService no longer receive the events in room %s, reverting to the classical syncer", ev.RoomID)
+
+		channel.appService = false
+		b.Lock()
+		b.RoomMap[ev.RoomID] = channel
+		b.Unlock()
+
+		b.handleAcceptedEvent(ev, channel, false)
+	} else {
+		// if we receive messages both via the classical matrix syncer and appserver, prefer appservice and throw away this duplicate event
+		b.Log.Debugf("Dropping event, should receive it via appservice: %s", ev.ID)
+	}
+}
+
+func (b *Bmatrix) handleAcceptedEvent(ev *event.Event, channel RoomInfo, appservice bool) {
 	if ev.Type == event.EphemeralEventTyping {
 		typing := ev.Content.AsTyping()
 		if len(typing.UserIDs) > 0 {
@@ -141,7 +172,7 @@ func (b *Bmatrix) handleEvent(origin EventOrigin, ev *event.Event) {
 		return
 	}
 
-	b.Log.Debugf("== Receiving event: %#v (appService=%t)", ev, origin == originAppService)
+	b.Log.Debugf("== Receiving event: %#v (appService=%t)", ev, appservice)
 
 	defer (func(ev *event.Event) {
 		// not crucial, so no ratelimit check here
@@ -343,6 +374,7 @@ func (b *Bmatrix) handleUploadFiles(msg *config.Message, channel id.RoomID) (str
 }
 
 // handleUploadFile handles native upload of a file.
+//
 //nolint:funlen
 func (b *Bmatrix) handleUploadFile(msg *config.Message, channel id.RoomID, fi *config.FileInfo) {
 	content := bytes.NewReader(*fi.Data)
diff --git a/bridge/matrix/matrix.go b/bridge/matrix/matrix.go
index 0011c45f..c5ba43e7 100644
--- a/bridge/matrix/matrix.go
+++ b/bridge/matrix/matrix.go
@@ -29,8 +29,9 @@ const (
 )
 
 type RoomInfo struct {
-	name       string
-	appService bool
+	name                  string
+	appService            bool
+	lastMessageAppService time.Time
 }
 
 type Bmatrix struct {