Allow setting theme color theme from the menu bar

This functions essentially the same as the language selector. The language selector now also checks the currently set option on launch, and both the language and theme selectors spawn a popup prompting the user to restart NUSGet after selecting a new value.

NUSGet.py

@@ -32,7 +32,7 @@ from qt.py.ui_MainMenu import Ui_MainWindow
 from modules.config import *
 from modules.core import *
 from modules.language import *
-from modules.theme import is_dark_theme
+from modules.theme import *
 from modules.tree import NUSGetTreeModel, TIDFilterProxyModel
 from modules.download_batch import run_nus_download_batch
 from modules.download_wii import run_nus_download_wii
@@ -135,9 +135,38 @@ class MainWindow(QMainWindow, Ui_MainWindow):
         # languages at once makes no sense.
         language_group = QActionGroup(self)
         language_group.setExclusive(True)
+        current_language = ""
+        try:
+            current_language = config_data["language"]
+        except KeyError:
+            pass
         for action in self.ui.menu_options_language.actions():
             language_group.addAction(action)
-        language_group.triggered.connect(lambda lang=action: set_language(config_data, lang.text()))
+            if current_language != "":
+                if LANGS[current_language] == action.text():
+                    action.setChecked(True)
+        # There is no language set, so check the system language option.
+        if current_language == "":
+            self.ui.action_language_system.setChecked(True)
+        language_group.triggered.connect(lambda lang=action: self.change_language(lang.text()))
+        # Another QActionGroup used for the theme selector.
+        theme_group = QActionGroup(self)
+        theme_group.setExclusive(True)
+        for action in self.ui.menu_options_theme.actions():
+            theme_group.addAction(action)
+        self.ui.action_theme_system.triggered.connect(lambda: self.change_theme("system"))
+        self.ui.action_theme_light.triggered.connect(lambda: self.change_theme("light"))
+        self.ui.action_theme_dark.triggered.connect(lambda: self.change_theme("dark"))
+        try:
+            match config_data["theme"]:
+                case "light":
+                    self.ui.action_theme_light.setChecked(True)
+                case "dark":
+                    self.ui.action_theme_dark.setChecked(True)
+                case _:
+                    self.ui.action_theme_system.setChecked(True)
+        except KeyError:
+            pass
         # ---------
         # Help Menu
         # ---------
@@ -146,7 +175,7 @@ class MainWindow(QMainWindow, Ui_MainWindow):
         self.ui.action_about.triggered.connect(self.about_nusget)
         self.ui.action_about_qt.triggered.connect(lambda: QMessageBox.aboutQt(self))
         # Save some light/dark theme values for later, including the appropriately colored info icon.
-        if is_dark_theme():
+        if is_dark_theme(config_data):
             bg_color = "#2b2b2b"
             icon = QIcon(os.path.join(os.path.dirname(__file__), "resources", "information_white.svg"))
         else:
@@ -622,6 +651,26 @@ class MainWindow(QMainWindow, Ui_MainWindow):
         about_box = AboutNUSGet([nusget_version, version("libWiiPy"), version("libTWLPy")])
         about_box.exec()
 
+    def change_language(self, new_lang):
+        set_language(config_data, new_lang)
+        msg_box = QMessageBox()
+        msg_box.setIcon(QMessageBox.Icon.Warning)
+        msg_box.setStandardButtons(QMessageBox.StandardButton.Ok)
+        msg_box.setDefaultButton(QMessageBox.StandardButton.Ok)
+        msg_box.setWindowTitle(app.translate("MainWindow", "Restart Required"))
+        msg_box.setText(app.translate("MainWindow", "NUSGet must be restarted for the new language to take effect."))
+        msg_box.exec()
+
+    def change_theme(self, new_theme):
+        set_theme(config_data, new_theme)
+        msg_box = QMessageBox()
+        msg_box.setIcon(QMessageBox.Icon.Warning)
+        msg_box.setStandardButtons(QMessageBox.StandardButton.Ok)
+        msg_box.setDefaultButton(QMessageBox.StandardButton.Ok)
+        msg_box.setWindowTitle(app.translate("MainWindow", "Restart Required"))
+        msg_box.setText(app.translate("MainWindow", "NUSGet must be restarted for the new theme to take effect."))
+        msg_box.exec()
+
 
 if __name__ == "__main__":
     app = QApplication(sys.argv)
@@ -684,7 +733,7 @@ if __name__ == "__main__":
     # NUSGet look nice and pretty.
     app.setStyle("fusion")
     theme_sheet = "style_dark.qss"
-    if is_dark_theme():
+    if is_dark_theme(config_data):
         theme_sheet = "style_dark.qss"
     else:
         theme_sheet = "style_light.qss"