Implemented use of alternative nickname.

IRCClient/IRCBase.cpp

@@ -637,8 +637,11 @@ const std::string& IRCBase::getNickname() const
 
 void IRCBase::setNickname(const std::string& nickname)
 {
-	if (mp->isConnected)
-		mp->write(Command::IRC::NICK, nickname);
+	if (mp->isConnected) {
+        if (!isOnline())
+            mp->nickname = nickname;
+        mp->write(Command::IRC::NICK, nickname);
+    }
 	else
 		mp->nickname = nickname;
 }

IdealIRC/IRC.cpp

@@ -586,6 +586,17 @@ void IRC::onMsgNumeric(const IRCPrefix& /*sender*/, const std::string& num, cons
         }
     }
 
+    if (num == Numeric::ERR_NICKNAMEINUSE && !isOnline()) {
+        auto& conf = ConfigMgr::instance();
+        auto altNick = conf.connection("AltNickname");
+        if (!altNick.isEmpty() && altNick.toStdString() != getNickname()) {
+            setNickname(altNick.toStdString());
+        }
+        else {
+            getStatus().getInputBox().setText("/NICK ");
+        }
+    }
+
     /* Script event */
     {
         ScriptArray pval;