From 360a4d4a96dfcbecc6c257394f081ef9a4f767a6 Mon Sep 17 00:00:00 2001
From: Forest Belton <65484+forestbelton@users.noreply.github.com>
Date: Tue, 22 Jun 2021 17:31:38 -0400
Subject: [PATCH] Broadcast message when client updates their nickname

---
 paircd/channel.py      | 10 ++++++++++
 paircd/handler/nick.py | 27 +++++++++++++++++----------
 paircd/reply.py        |  2 ++
 paircd/server.py       |  8 ++++++++
 4 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/paircd/channel.py b/paircd/channel.py
index c573f0b..679b9c2 100644
--- a/paircd/channel.py
+++ b/paircd/channel.py
@@ -34,3 +34,13 @@ class Channel:
 
     def get_user_modes_by_nick(self, nick: str) -> Set[str]:
         return self.modes_by_nick[nick]
+
+    def rename_client(self, name: str, new_name: str) -> None:
+        if name not in self.clients_by_nick:
+            raise KeyError(f"No client on channel with nick {name}")
+        if new_name in self.clients_by_nick:
+            raise KeyError(f"Client already exists with nick {new_name}")
+        self.clients_by_nick[new_name] = self.clients_by_nick[name]
+        del self.clients_by_nick[name]
+        self.modes_by_nick[new_name] = self.modes_by_nick[name]
+        del self.modes_by_nick[name]
diff --git a/paircd/handler/nick.py b/paircd/handler/nick.py
index 46620f6..cd0352d 100644
--- a/paircd/handler/nick.py
+++ b/paircd/handler/nick.py
@@ -1,7 +1,7 @@
 from paircd.client import Client
 from paircd.command_handler import CommandHandler
 from paircd.message import Message
-from paircd.reply import ERR_NICKNAMEINUSE
+from paircd.reply import ERR_NICKNAMEINUSE, ERR_NONICKNAMEGIVEN, NICK
 from paircd.server import Server
 
 
@@ -11,6 +11,10 @@ class NickHandler(CommandHandler):
 
     async def handle(self, server: Server, client: Client, msg: Message) -> None:
         nickname = msg.args[0]
+        if nickname == "":
+            target = client.nickname if client.nickname else nickname
+            client.write_message(ERR_NONICKNAMEGIVEN(target))
+            return
 
         existing_client = server.get_client_by_name(nickname)
         if existing_client is not None:
@@ -19,19 +23,22 @@ class NickHandler(CommandHandler):
                 client.write_message(ERR_NICKNAMEINUSE(target, nickname))
             return
 
-        # Remove stale references if they exist
-        if client.nickname:
-            server.remove_client_by_name(client.nickname)
-            for channel_name in client.channels:
-                channel = server.get_channel_by_name(channel_name)
-                channel.remove_client_by_nick(client.nickname)
+        rename = client.nickname != ""
+        old_nick = client.nickname
+        old_id = client.id()
 
         client.nickname = nickname
+        if rename:
+            server.rename_client(old_nick, nickname)
+        else:
+            server.add_client(client)
 
-        # Add references for client
-        server.add_client(client)
         for channel_name in client.channels:
             channel = server.get_channel_by_name(channel_name)
-            channel.remove_client_by_nick(client.nickname)
+            if rename:
+                channel.rename_client(old_nick, nickname)
+                channel.write_message(NICK(nickname, prefix=old_id))
+            else:
+                raise RuntimeError("shouldn't be in any channels without a nick")
 
         client.register()
diff --git a/paircd/reply.py b/paircd/reply.py
index 07050a2..77bdd2b 100644
--- a/paircd/reply.py
+++ b/paircd/reply.py
@@ -26,6 +26,7 @@ def reply_fn(cmd: Union[int, str], tmpl: str) -> Callable:
 # Commands
 JOIN = cmd_fn("JOIN", "{0}")
 MODE = cmd_fn("MODE", "{0} {1}")
+NICK = cmd_fn("NICK", "{0}")
 PONG = cmd_fn("PONG", ":{0}")
 PRIVMSG = cmd_fn("PRIVMSG", "{0} :{1}")
 
@@ -35,6 +36,7 @@ ERR_NOSUCHSERVER = reply_fn(402, "{0} :No such server")
 ERR_NOSUCHCHANNEL = reply_fn(403, "{0} :No such channel")
 ERR_CANNOTSENDTOCHAN = reply_fn(404, "{0} :Cannot send to channel")
 ERR_TOOMANYCHANNELS = reply_fn(405, "{0} :You have joined too many channels")
+ERR_NONICKNAMEGIVEN = reply_fn(431, ":No nickname given")
 ERR_NICKNAMEINUSE = reply_fn(433, "{0} :Nickname is already in use")
 ERR_NOTEXTTOSEND = reply_fn(412, ":No text to send")
 ERR_NOTREGISTERED = reply_fn(451, ":You have not registered")
diff --git a/paircd/server.py b/paircd/server.py
index db491d1..f20b97f 100644
--- a/paircd/server.py
+++ b/paircd/server.py
@@ -25,3 +25,11 @@ class Server:
 
     def remove_client_by_name(self, name: str) -> None:
         del self.clients_by_nick[name]
+
+    def rename_client(self, name: str, new_name: str) -> None:
+        if name not in self.clients_by_nick:
+            raise KeyError(f"No client on server with nick {name}")
+        if new_name in self.clients_by_nick:
+            raise KeyError(f"Client already exists with nick {new_name}")
+        self.clients_by_nick[new_name] = self.clients_by_nick[name]
+        del self.clients_by_nick[name]