UI: Enable first-party YouTube Chat features in OBS

Unlock the full feature set of the YouTube Chat dock in OBS by removing
custom scripting/CSS logic. Enable the signed-in experience for live
streaming content creators (sharing login credentials with the YouTube
Control panel dock, see
#10747).

This will allow OBS users to utilize features _already_ supported in the
YouTube Chat plugin, such as

* creating polls
* managing Q&A sessions
* a rich emoji set in the input panel
* emoji fountains
* moderation tools

and many more. These features are available to users who are logged-in
to YouTube Chat and/or the YouTube Control panel.

UI/auth-youtube.cpp

@@ -26,6 +26,7 @@
 
 #ifdef BROWSER_AVAILABLE
 #include "window-dock-browser.hpp"
+#include <QTimerEvent>
 #endif
 
 using namespace json11;
@@ -130,14 +131,6 @@ bool YoutubeAuth::LoadInternal()
 	return implicit ? !token.empty() : !refresh_token.empty();
 }
 
-#ifdef BROWSER_AVAILABLE
-static const char *ytchat_script = "\
-const obsCSS = document.createElement('style');\
-obsCSS.innerHTML = \"#panel-pages.yt-live-chat-renderer {display: none;}\
-yt-live-chat-viewer-engagement-message-renderer {display: none;}\";\
-document.querySelector('head').appendChild(obsCSS);";
-#endif
-
 void YoutubeAuth::LoadUI()
 {
 	if (uiLoaded)
@@ -163,7 +156,6 @@ void YoutubeAuth::LoadUI()
 
 	browser = cef->create_widget(chat, YOUTUBE_CHAT_PLACEHOLDER_URL,
 				     panel_cookies);
-	browser->setStartupScript(ytchat_script);
 
 	chat->SetWidget(browser);
 	main->AddDockWidget(chat, Qt::RightDockWidgetArea);
@@ -350,6 +342,28 @@ std::shared_ptr<Auth> YoutubeAuth::Login(QWidget *owner,
 }
 
 #ifdef BROWSER_AVAILABLE
+void YoutubeChatDock::timerEvent(QTimerEvent *event)
+{
+	if (event->timerId() != awaitLoginTimer)
+		return;
+
+	QPointer<YoutubeChatDock> this_ = this;
+	auto cb = [this_](bool found) {
+		bool previouslyLoggedIn = this_->isLoggedIn;
+		this_->isLoggedIn = found;
+		if (found ^ previouslyLoggedIn) {
+			// There was a change in login state.
+			QMetaObject::invokeMethod(this_, "EnableChatInput",
+						  Qt::QueuedConnection,
+						  Q_ARG(bool, !found));
+		}
+	};
+	if (panel_cookies) {
+		panel_cookies->CheckForCookie("https://www.youtube.com", "SID",
+					      cb);
+	}
+}
+
 void YoutubeChatDock::SetWidget(QCefWidget *widget_)
 {
 	lineEdit = new LineEditAutoResize();
@@ -422,9 +436,10 @@ void YoutubeChatDock::ShowErrorMessage(const QString &error)
 			     QTStr("YouTube.Chat.Error.Text").arg(error));
 }
 
-void YoutubeChatDock::EnableChatInput()
+void YoutubeChatDock::EnableChatInput(bool visible)
 {
-	lineEdit->setVisible(true);
-	sendButton->setVisible(true);
+	bool setVisible = visible && !isLoggedIn;
+	lineEdit->setVisible(setVisible);
+	sendButton->setVisible(setVisible);
 }
 #endif

UI/auth-youtube.hpp

@@ -11,24 +11,35 @@
 #include "window-dock-browser.hpp"
 #include "lineedit-autoresize.hpp"
 #include <QHBoxLayout>
+#include <QTimerEvent>
+
 class YoutubeChatDock : public BrowserDock {
 	Q_OBJECT
 
 private:
 	std::string apiChatId;
+	int awaitLoginTimer;
+	bool isLoggedIn;
 	LineEditAutoResize *lineEdit;
 	QPushButton *sendButton;
 	QHBoxLayout *chatLayout;
 
+protected:
+	void timerEvent(QTimerEvent *event);
+
 public:
-	inline YoutubeChatDock(const QString &title) : BrowserDock(title) {}
+	inline YoutubeChatDock(const QString &title) : BrowserDock(title)
+	{
+		// Check youtube.com login status periodically
+		awaitLoginTimer = startTimer(1000);
+	}
 	void SetWidget(QCefWidget *widget_);
 	void SetApiChatId(const std::string &id);
 
 private slots:
 	void SendChatMessage();
 	void ShowErrorMessage(const QString &error);
-	void EnableChatInput();
+	void EnableChatInput(bool visible = true);
 };
 #endif