--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/gui/dark_theme.cc	Mon Oct 23 12:07:27 2023 -0400
@@ -0,0 +1,100 @@
+#include "core/config.h"
+#include "core/session.h"
+#include <QApplication>
+#include <QFile>
+#include <QTextStream>
+#ifdef MACOSX
+#	include "sys/osx/dark_theme.h"
+#else
+#	include "sys/win32/dark_theme.h"
+#endif
+
+namespace DarkTheme {
+
+bool IsInDarkMode() {
+	if (session.config.theme != Themes::OS)
+		return (session.config.theme == Themes::DARK);
+#ifdef MACOSX
+	if (osx::DarkThemeAvailable()) {
+		if (osx::IsInDarkTheme()) {
+			return true;
+		} else {
+			return false;
+		}
+	}
+#elif defined(WIN32)
+	if (win32::DarkThemeAvailable()) {
+		if (win32::IsInDarkTheme()) {
+			return true;
+		} else {
+			return false;
+		}
+	}
+#endif
+	return (session.config.theme == Themes::DARK);
+}
+
+/* this function is private, and should stay that way */
+void SetStyleSheet(enum Themes theme) {
+	switch (theme) {
+		case Themes::DARK: {
+			QFile f(":qdarkstyle/dark/darkstyle.qss");
+			if (!f.exists())
+				return; // fail
+			f.open(QFile::ReadOnly | QFile::Text);
+			QTextStream ts(&f);
+			qApp->setStyleSheet(ts.readAll());
+			break;
+		}
+		default: qApp->setStyleSheet(""); break;
+	}
+}
+
+void SetToDarkTheme() {
+	/* macOS >= 10.14 has its own global dark theme,
+	   use it :) */
+#if MACOSX
+	if (osx::DarkThemeAvailable())
+		osx::SetToDarkTheme();
+	else
+#endif
+		SetStyleSheet(Themes::DARK);
+}
+
+void SetToLightTheme() {
+#if MACOSX
+	if (osx::DarkThemeAvailable())
+		osx::SetToLightTheme();
+	else
+#endif
+		SetStyleSheet(Themes::LIGHT);
+}
+
+enum Themes GetCurrentOSTheme() {
+#if MACOSX
+	if (osx::DarkThemeAvailable())
+		return osx::IsInDarkTheme() ? Themes::DARK : Themes::LIGHT;
+#elif defined(WIN32)
+	if (win32::DarkThemeAvailable())
+		return win32::IsInDarkTheme() ? Themes::DARK : Themes::LIGHT;
+#endif
+	/* Currently OS detection only supports Windows and macOS.
+	   Please don't be shy if you're willing to port it to other OSes
+	   (or desktop environments, or window managers) */
+	return Themes::LIGHT;
+}
+
+void SetTheme(enum Themes theme) {
+	switch (theme) {
+		case Themes::LIGHT: SetToLightTheme(); break;
+		case Themes::DARK: SetToDarkTheme(); break;
+		case Themes::OS:
+			if (GetCurrentOSTheme() == Themes::LIGHT)
+				SetToLightTheme();
+			else
+				SetToDarkTheme();
+			break;
+	}
+}
+
+} // namespace DarkTheme