From 4b1e6b04c4c61d83de1517fefdcc4c67dbe5f90d Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Sun, 25 Oct 2020 22:16:19 -0400
Subject: [PATCH] add UNINVITE command (#1171)

---
 irc/channel.go  | 16 ++++++++++++++++
 irc/client.go   |  6 ++++++
 irc/commands.go |  4 ++++
 irc/handlers.go |  9 ++++++++-
 irc/help.go     |  5 +++++
 5 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/irc/channel.go b/irc/channel.go
index 7304654d..59a80a04 100644
--- a/irc/channel.go
+++ b/irc/channel.go
@@ -1524,6 +1524,22 @@ func (channel *Channel) Invite(invitee *Client, inviter *Client, rb *ResponseBuf
 	}
 }
 
+// Uninvite rescinds a channel invitation, if the inviter can do so.
+func (channel *Channel) Uninvite(invitee *Client, inviter *Client, rb *ResponseBuffer) {
+	if !channel.flags.HasMode(modes.InviteOnly) {
+		rb.Add(nil, channel.server.name, "FAIL", "UNINVITE", "NOT_INVITE_ONLY", channel.Name(), inviter.t("Channel is not invite-only"))
+		return
+	}
+
+	if !channel.ClientIsAtLeast(inviter, modes.ChannelOperator) {
+		rb.Add(nil, channel.server.name, "FAIL", "UNINVITE", "NOT_PRIVED", channel.Name(), inviter.t("You're not a channel operator"))
+		return
+	}
+
+	invitee.Uninvite(channel.NameCasefolded())
+	rb.Add(nil, channel.server.name, "UNINVITE", invitee.Nick(), channel.Name())
+}
+
 // returns who the client can "see" in the channel, respecting the auditorium mode
 func (channel *Channel) auditoriumFriends(client *Client) (friends []*Client) {
 	channel.stateMutex.RLock()
diff --git a/irc/client.go b/irc/client.go
index 018918a5..693d14b8 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -1787,6 +1787,12 @@ func (client *Client) Invite(casefoldedChannel string, channelCreatedAt time.Tim
 	return
 }
 
+func (client *Client) Uninvite(casefoldedChannel string) {
+	client.stateMutex.Lock()
+	defer client.stateMutex.Unlock()
+	delete(client.invitedTo, casefoldedChannel)
+}
+
 // Checks that the client was invited to join a given channel
 func (client *Client) CheckInvited(casefoldedChannel string, createdTime time.Time) (invited bool) {
 	config := client.server.Config()
diff --git a/irc/commands.go b/irc/commands.go
index c1ec6f41..cb81fd2f 100644
--- a/irc/commands.go
+++ b/irc/commands.go
@@ -324,6 +324,10 @@ func init() {
 			minParams: 1,
 			oper:      true,
 		},
+		"UNINVITE": {
+			handler:   inviteHandler,
+			minParams: 2,
+		},
 		"UNKLINE": {
 			handler:   unKLineHandler,
 			minParams: 1,
diff --git a/irc/handlers.go b/irc/handlers.go
index 78f34b81..241bbefe 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -1113,7 +1113,9 @@ func infoHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 }
 
 // INVITE <nickname> <channel>
+// UNINVITE <nickname> <channel>
 func inviteHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) bool {
+	invite := msg.Command == "INVITE"
 	nickname := msg.Params[0]
 	channelName := msg.Params[1]
 
@@ -1129,7 +1131,12 @@ func inviteHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Re
 		return false
 	}
 
-	channel.Invite(target, client, rb)
+	if invite {
+		channel.Invite(target, client, rb)
+	} else {
+		channel.Uninvite(target, client, rb)
+	}
+
 	return false
 }
 
diff --git a/irc/help.go b/irc/help.go
index c867c31d..5fbd130b 100644
--- a/irc/help.go
+++ b/irc/help.go
@@ -541,6 +541,11 @@ For example:
 
 Used in connection registration, sets your username and realname to the given
 values (though your username may also be looked up with Ident).`,
+	},
+	"uninvite": {
+		text: `UNINVITE <nickname> <channel>
+
+UNINVITE rescinds a channel invitation sent for an invite-only channel.`,
 	},
 	"users": {
 		text: `USERS [parameters]