Prevent user from entering incorrect characters in Live Notifications channels list (#3715)

Co-authored-by: Sidd <iProdigy@users.noreply.github.com>
Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/util/Twitch.cpp

@@ -5,6 +5,12 @@
 
 namespace chatterino {
 
+namespace {
+
+    const auto TWITCH_USER_LOGIN_PATTERN = R"(^[a-z0-9]\w{0,24}$)";
+
+}  // namespace
+
 void openTwitchUsercard(QString channel, QString username)
 {
     QDesktopServices::openUrl("https://www.twitch.tv/popout/" + channel +
@@ -35,4 +41,20 @@ void stripChannelName(QString &channelName)
     }
 }
 
+QRegularExpression twitchUserNameRegexp()
+{
+    static QRegularExpression re(
+        TWITCH_USER_LOGIN_PATTERN,
+        QRegularExpression::PatternOption::CaseInsensitiveOption);
+
+    return re;
+}
+
+QRegularExpression twitchUserLoginRegexp()
+{
+    static QRegularExpression re(TWITCH_USER_LOGIN_PATTERN);
+
+    return re;
+}
+
 }  // namespace chatterino

src/util/Twitch.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <QRegularExpression>
 #include <QString>
 
 namespace chatterino {
@@ -12,4 +13,16 @@ void stripUserName(QString &userName);
 // stripChannelName removes any @ prefix or , suffix to make it more suitable for command use
 void stripChannelName(QString &channelName);
 
+// Matches a strict Twitch user login.
+// May contain lowercase a-z, 0-9, and underscores
+// Must contain between 1 and 25 characters
+// Must not start with an underscore
+QRegularExpression twitchUserLoginRegexp();
+
+// Matches a loose Twitch user login name.
+// May contain lowercase and uppercase a-z, 0-9, and underscores
+// Must contain between 1 and 25 characters
+// Must not start with an underscore
+QRegularExpression twitchUserNameRegexp();
+
 }  // namespace chatterino