From 5a19ff00aca5d979bf9ca45a2b0d6e85acdc9fc3 Mon Sep 17 00:00:00 2001
From: Sadie Powell <sadie@witchery.services>
Date: Mon, 11 Jan 2021 10:07:11 +0000
Subject: [PATCH] Add a user mode which allows disabling receiving channel
 history.

Closes #1830.
---
 docs/conf/modules.conf.example | 26 +++++++++++++++++++-------
 src/modules/m_chanhistory.cpp  | 28 ++++++++++++++++++++++------
 2 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/docs/conf/modules.conf.example b/docs/conf/modules.conf.example
index 4fab166d2..1faec808c 100644
--- a/docs/conf/modules.conf.example
+++ b/docs/conf/modules.conf.example
@@ -450,13 +450,25 @@
 # the current topic of conversation is when joining the channel.
 #<module name="chanhistory">
 #
-# Set the maximum number of lines allowed to be stored per channel below.
-# This is the hard limit for 'X'.
-# If prefixmsg is set to yes, joining users without batch support will get
-# a NOTICE before playback telling them about the following lines being
-# the pre-join history.
-# If bots is set to yes, it will also send to users marked with +B
-#<chanhistory maxlines="50" prefixmsg="yes" bots="yes">
+#-#-#-#-#-#-#-#-#-#-#- CHANHISTORY CONFIGURATION -#-#-#-#-#-#-#-#-#-#-#
+#                                                                     #
+# bots - Whether to send channel history to bots. Defaults to yes.    #
+#                                                                     #
+# enableumode - Whether to enable the +N user mode which allows users #
+#               to opt-out of receiving channel history. Defaults to  #
+#               no.                                                   #
+#                                                                     #
+# maxlines - The maximum number of lines of chat history to send to a #
+#            joining users. Defaults to 50.                           #
+#                                                                     #
+# prefixmsg - Whether to send an explanatory message to clients that  #
+#             don't support the chathistory batch type. Defaults to   #
+#             yes.                                                    #
+#                                                                     #
+#<chanhistory bots="yes"
+#             enableumode="yes"
+#             maxlines="50"
+#             prefixmsg="yes">
 
 #-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
 # Channel logging module: Used to send snotice output to channels, to
diff --git a/src/modules/m_chanhistory.cpp b/src/modules/m_chanhistory.cpp
index f689b292c..4bd230a7c 100644
--- a/src/modules/m_chanhistory.cpp
+++ b/src/modules/m_chanhistory.cpp
@@ -124,12 +124,24 @@ class HistoryMode : public ParamMode<HistoryMode, SimpleExtItem<HistoryList> >
 	}
 };
 
+class NoHistoryMode : public SimpleUserModeHandler
+{
+public:
+	NoHistoryMode(Module* Creator)
+		: SimpleUserModeHandler(Creator, "nohistory", 'N')
+	{
+		if (!ServerInstance->Config->ConfValue("chanhistory")->getBool("enableumode"))
+			DisableAutoRegister();
+	}
+};
+
 class ModuleChanHistory
 	: public Module
 	, public ServerProtocol::BroadcastEventListener
 {
  private:
-	HistoryMode m;
+	HistoryMode historymode;
+	NoHistoryMode nohistorymode;
 	bool prefixmsg;
 	UserModeReference botmode;
 	bool dobots;
@@ -183,7 +195,8 @@ class ModuleChanHistory
  public:
 	ModuleChanHistory()
 		: ServerProtocol::BroadcastEventListener(this)
-		, m(this)
+		, historymode(this)
+		, nohistorymode(this)
 		, botmode(this, "bot")
 		, batchcap(this)
 		, batchmanager(this)
@@ -196,14 +209,14 @@ class ModuleChanHistory
 	void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 	{
 		ConfigTag* tag = ServerInstance->Config->ConfValue("chanhistory");
-		m.maxlines = tag->getUInt("maxlines", 50, 1);
+		historymode.maxlines = tag->getUInt("maxlines", 50, 1);
 		prefixmsg = tag->getBool("prefixmsg", tag->getBool("notice", true));
 		dobots = tag->getBool("bots", true);
 	}
 
 	ModResult OnBroadcastMessage(Channel* channel, const Server* server) CXX11_OVERRIDE
 	{
-		return channel->IsModeSet(m) ? MOD_RES_ALLOW : MOD_RES_PASSTHRU;
+		return channel->IsModeSet(historymode) ? MOD_RES_ALLOW : MOD_RES_PASSTHRU;
 	}
 
 	void OnUserPostMessage(User* user, const MessageTarget& target, const MessageDetails& details) CXX11_OVERRIDE
@@ -212,7 +225,7 @@ class ModuleChanHistory
 		if ((target.type == MessageTarget::TYPE_CHANNEL) && (target.status == 0) && (!details.IsCTCP(ctcpname) || irc::equals(ctcpname, "ACTION")))
 		{
 			Channel* c = target.Get<Channel>();
-			HistoryList* list = m.ext.get(c);
+			HistoryList* list = historymode.ext.get(c);
 			if (list)
 			{
 				list->lines.push_back(HistoryItem(user, details));
@@ -231,7 +244,10 @@ class ModuleChanHistory
 		if (memb->user->IsModeSet(botmode) && !dobots)
 			return;
 
-		HistoryList* list = m.ext.get(memb->chan);
+		if (memb->user->IsModeSet(nohistorymode))
+			return;
+
+		HistoryList* list = historymode.ext.get(memb->chan);
 		if (!list)
 			return;
 
-- 
2.39.2