From 5a899abaab3ae737ef4b995c4c63262a12ca03a9 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Mon, 29 Mar 2021 16:55:57 +0200
Subject: [PATCH] Simplify network.offlineClients

Replace it with a list of all clients (online or offline).
---
 downstream.go |  9 +++++++--
 upstream.go   | 18 ++++--------------
 user.go       | 45 ++++++++++++++-------------------------------
 3 files changed, 25 insertions(+), 47 deletions(-)

diff --git a/downstream.go b/downstream.go
index 32ffd6f..347d042 100644
--- a/downstream.go
+++ b/downstream.go
@@ -990,9 +990,14 @@ func (dc *downstreamConn) welcome() error {
 	dc.forEachNetwork(func(net *network) {
 		// Only send history if we're the first connected client with that name
 		// for the network
-		if _, ok := net.offlineClients[dc.clientName]; ok {
+		firstClient := true
+		dc.user.forEachDownstream(func(c *downstreamConn) {
+			if c != dc && c.clientName == dc.clientName && c.network == dc.network {
+				firstClient = false
+			}
+		})
+		if firstClient {
 			dc.sendNetworkBacklog(net)
-			delete(net.offlineClients, dc.clientName)
 		}
 
 		// Fast-forward history to last message
diff --git a/upstream.go b/upstream.go
index 616151e..422b82d 100644
--- a/upstream.go
+++ b/upstream.go
@@ -1740,14 +1740,12 @@ func (uc *upstreamConn) appendLog(entity string, msg *irc.Message) (msgID string
 		return ""
 	}
 
-	detached := false
-	if ch := uc.network.channels.Value(entity); ch != nil {
-		detached = ch.Detached
-	}
-
 	delivered := uc.network.delivered.Value(entity)
 	entityCM := uc.network.casemap(entity)
 	if delivered == nil {
+		// This is the first message we receive from this target. Save the last
+		// message ID in delivery receipts, so that we can send the new message
+		// in the backlog if an offline client reconnects.
 		lastID, err := uc.user.msgStore.LastMsgID(uc.network, entityCM, time.Now())
 		if err != nil {
 			uc.logger.Printf("failed to log message: failed to get last message ID: %v", err)
@@ -1757,17 +1755,9 @@ func (uc *upstreamConn) appendLog(entity string, msg *irc.Message) (msgID string
 		delivered = make(deliveredClientMap)
 		uc.network.delivered.SetValue(entity, delivered)
 
-		for clientName, _ := range uc.network.offlineClients {
+		for clientName, _ := range uc.network.clients {
 			delivered[clientName] = lastID
 		}
-
-		if detached {
-			// If the channel is detached, online clients act as offline
-			// clients too
-			uc.forEachDownstream(func(dc *downstreamConn) {
-				delivered[dc.clientName] = lastID
-			})
-		}
 	}
 
 	msgID, err := uc.user.msgStore.Append(uc.network, entityCM, msg)
diff --git a/user.go b/user.go
index 9dcc260..fe5f504 100644
--- a/user.go
+++ b/user.go
@@ -62,12 +62,12 @@ type network struct {
 	user    *user
 	stopped chan struct{}
 
-	conn           *upstreamConn
-	channels       channelCasemapMap
-	delivered      deliveredCasemapMap
-	offlineClients map[string]struct{} // indexed by client name
-	lastError      error
-	casemap        casemapping
+	conn      *upstreamConn
+	channels  channelCasemapMap
+	delivered deliveredCasemapMap
+	clients   map[string]struct{} // indexed by client name
+	lastError error
+	casemap   casemapping
 }
 
 func newNetwork(user *user, record *Network, channels []Channel) *network {
@@ -78,13 +78,13 @@ func newNetwork(user *user, record *Network, channels []Channel) *network {
 	}
 
 	return &network{
-		Network:        *record,
-		user:           user,
-		stopped:        make(chan struct{}),
-		channels:       m,
-		delivered:      deliveredCasemapMap{newCasemapMap(0)},
-		offlineClients: make(map[string]struct{}),
-		casemap:        casemapRFC1459,
+		Network:   *record,
+		user:      user,
+		stopped:   make(chan struct{}),
+		channels:  m,
+		delivered: deliveredCasemapMap{newCasemapMap(0)},
+		clients:   make(map[string]struct{}),
+		casemap:   casemapRFC1459,
 	}
 }
 
@@ -196,8 +196,6 @@ func (net *network) detach(ch *Channel) {
 	}
 
 	net.forEachDownstream(func(dc *downstreamConn) {
-		net.offlineClients[dc.clientName] = struct{}{}
-
 		dc.SendMessage(&irc.Message{
 			Prefix:  dc.prefix(),
 			Command: "PART",
@@ -448,6 +446,7 @@ func (u *user) run() {
 			u.downstreamConns = append(u.downstreamConns, dc)
 
 			dc.forEachNetwork(func(network *network) {
+				network.clients[dc.clientName] = struct{}{}
 				if network.lastError != nil {
 					sendServiceNOTICE(dc, fmt.Sprintf("disconnected from %s: %v", network.GetName(), network.lastError))
 				}
@@ -466,22 +465,6 @@ func (u *user) run() {
 				}
 			}
 
-			// Save history if we're the last client with this name
-			skipHistory := make(map[*network]bool)
-			u.forEachDownstream(func(conn *downstreamConn) {
-				if dc.clientName == conn.clientName {
-					skipHistory[conn.network] = true
-				}
-			})
-
-			dc.forEachNetwork(func(net *network) {
-				if skipHistory[net] || skipHistory[nil] {
-					return
-				}
-
-				net.offlineClients[dc.clientName] = struct{}{}
-			})
-
 			u.forEachUpstream(func(uc *upstreamConn) {
 				uc.updateAway()
 			})