From 31f9c0dfee0d51dd592652d8b068c604ca28299d Mon Sep 17 00:00:00 2001
From: Simon-Pierre <simvivier@status.im>
Date: Wed, 27 May 2026 10:13:48 -0400
Subject: [PATCH] pubsub topic instead of content topic

---
 apps/chat2disco/chat2disco.nim | 72 ++++++++++++++++++++++++----------
 1 file changed, 51 insertions(+), 21 deletions(-)

diff --git a/apps/chat2disco/chat2disco.nim b/apps/chat2disco/chat2disco.nim
index cb5260802..837b3c1cd 100644
--- a/apps/chat2disco/chat2disco.nim
+++ b/apps/chat2disco/chat2disco.nim
@@ -65,6 +65,7 @@ const Help = """
 type
   ChatRoom = object
     serviceId*: string
+    pubsubTopic*: string
     contentTopic*: string
     discovered*: seq[RemotePeerInfo]
 
@@ -77,6 +78,7 @@ type
     prompt: bool
     rooms: Table[string, ChatRoom]
     currentRoom: string
+    relayHandler: WakuRelayHandler
 
   PrivateKey* = crypto.PrivateKey
   Topic* = waku_core.PubsubTopic
@@ -181,7 +183,7 @@ proc publish(c: Chat, line: string) =
   )
 
   try:
-    (waitFor c.node.publish(some(DefaultPubsubTopic), message)).isOkOr:
+    (waitFor c.node.publish(some(room.pubsubTopic), message)).isOkOr:
       error "failed to publish message", error = error
   except CatchableError:
     error "caught error publishing message: ", error = getCurrentExceptionMsg()
@@ -189,6 +191,7 @@ proc publish(c: Chat, line: string) =
 proc createRoom(c: Chat, roomName: string) {.async.} =
   let serviceIdStr = "/waku/chat-room/" & roomName & "/1.0.0"
   let contentTopic = "/chat2disco/1/" & roomName & "/proto"
+  let pubsubTopic = "/chat2disco/room/" & roomName
 
   let serviceInfo = ServiceInfo(id: serviceIdStr, data: @[])
 
@@ -204,15 +207,32 @@ proc createRoom(c: Chat, roomName: string) {.async.} =
       echo "Connected to discovered peers"
 
     c.rooms[roomName] = ChatRoom(
-      serviceId: serviceIdStr, contentTopic: contentTopic, discovered: peers
+      serviceId: serviceIdStr, pubsubTopic: pubsubTopic,
+      contentTopic: contentTopic, discovered: peers
     )
   else:
     echo "Warning: Kademlia not available. Room created locally only."
-    c.rooms[roomName] =
-      ChatRoom(serviceId: serviceIdStr, contentTopic: contentTopic, discovered: @[])
+    c.rooms[roomName] = ChatRoom(
+      serviceId: serviceIdStr, pubsubTopic: pubsubTopic,
+      contentTopic: contentTopic, discovered: @[]
+    )
+
+  # Unsubscribe from previous room's pubsub topic
+  if c.currentRoom.len > 0 and c.currentRoom in c.rooms:
+    let oldTopic = c.rooms[c.currentRoom].pubsubTopic
+    c.node.unsubscribe((kind: PubsubUnsub, topic: oldTopic)).isOkOr:
+      error "failed to unsubscribe from previous room", topic = oldTopic, error = error
 
   c.currentRoom = roomName
-  echo &"Created/joined room '{roomName}'. Content topic: {contentTopic}"
+
+  # Subscribe to this room's pubsub topic
+  c.node.subscribe(
+    (kind: PubsubSub, topic: pubsubTopic), c.relayHandler
+  ).isOkOr:
+    error "failed to subscribe to room pubsub topic",
+      topic = pubsubTopic, error = error
+
+  echo &"Created/joined room '{roomName}'. Pubsub topic: {pubsubTopic}"
 
 # TODO Implement
 proc writeAndPrint(c: Chat) {.async.} =
@@ -230,7 +250,21 @@ proc writeAndPrint(c: Chat) {.async.} =
         continue
 
       if roomName in c.rooms:
+        # Unsubscribe from current room, subscribe to target room
+        if c.currentRoom.len > 0 and c.currentRoom != roomName and c.currentRoom in c.rooms:
+          let oldTopic = c.rooms[c.currentRoom].pubsubTopic
+          c.node.unsubscribe((kind: PubsubUnsub, topic: oldTopic)).isOkOr:
+            error "failed to unsubscribe from room", topic = oldTopic, error = error
+
         c.currentRoom = roomName
+
+        let newTopic = c.rooms[roomName].pubsubTopic
+        c.node.subscribe(
+          (kind: PubsubSub, topic: newTopic), c.relayHandler
+        ).isOkOr:
+          error "failed to subscribe to room pubsub topic",
+            topic = newTopic, error = error
+
         echo &"Switched to room '{roomName}'"
       else:
         await c.createRoom(roomName)
@@ -241,7 +275,7 @@ proc writeAndPrint(c: Chat) {.async.} =
         echo "Joined rooms:"
         for name, room in c.rooms:
           let marker = if name == c.currentRoom: " *" else: ""
-          echo &"  {name} ({room.discovered.len} peers){marker}"
+          echo &"  {name} (pubsub: {room.pubsubTopic}, {room.discovered.len} peers){marker}"
     elif line.startsWith("/nick"):
       c.nick = await readNick(c.transp)
       echo "You are now known as " & c.nick
@@ -394,20 +428,12 @@ proc processInput(rfd: AsyncFD, rng: crypto.Rng) {.async.} =
     prompt: false,
   )
 
-  let roomName = await readRoom(transp)
-  if roomName.len > 0:
-    await chat.createRoom(roomName)
-
-  let peerInfo = node.switch.peerInfo
-  let listenStr = $peerInfo.addrs[0] & "/p2p/" & $peerInfo.peerId
-  echo &"Listening on\n {listenStr}"
-
-  # Subscribe to relay topic
+  # Define relay handler for pubsub-topic-based routing
   if conf.relay:
     proc handler(topic: PubsubTopic, msg: WakuMessage): Future[void] {.async, gcsafe.} =
       var matched = false
       for roomName, room in chat.rooms:
-        if msg.contentTopic == room.contentTopic:
+        if topic == room.pubsubTopic:
           let chatLine = getChatLine(msg.payload)
           let prefix =
             if chat.rooms.len > 1:
@@ -431,11 +457,15 @@ proc processInput(rfd: AsyncFD, rng: crypto.Rng) {.async.} =
         chat.prompt = false
         showChatPrompt(chat)
 
-    node.subscribe(
-      (kind: PubsubSub, topic: DefaultPubsubTopic), WakuRelayHandler(handler)
-    ).isOkOr:
-      error "failed to subscribe to pubsub topic",
-        topic = DefaultPubsubTopic, error = error
+    chat.relayHandler = WakuRelayHandler(handler)
+
+  let roomName = await readRoom(transp)
+  if roomName.len > 0:
+    await chat.createRoom(roomName)
+
+  let peerInfo = node.switch.peerInfo
+  let listenStr = $peerInfo.addrs[0] & "/p2p/" & $peerInfo.peerId
+  echo &"Listening on\n {listenStr}"
 
   if conf.metricsLogging:
     startMetricsLog()