mod: adjustments

src/main.rs

@@ -7,6 +7,7 @@ use std::rc::Rc;
 
 use gtk4::gio;
 use gtk4::glib;
+use gtk4::glib::ToVariant;
 use gtk4::pango::EllipsizeMode;
 use gtk4::prelude::*;
 use gtk4::{
@@ -17,6 +18,8 @@ use gtk4::{
 
 const APP_ID: &str = "com.wyattjmiller.snespatcher";
 const APP_NAME: &str = "SNES Patcher";
+const THEME_SYSTEM: &str = "system";
+const THEME_DARK: &str = "dark";
 
 #[derive(Clone)]
 struct SelectionState {
@@ -71,7 +74,7 @@ fn build_ui(app: &Application) {
 
     let introduction = GtkBox::new(Orientation::Vertical, 8);
     let heading = Label::new(Some("Patch a Super Nintendo ROM"));
-    heading.add_css_class("title");
+    heading.add_css_class("intro-title");
     heading.set_justify(Justification::Center);
     heading.set_wrap(true);
 
@@ -192,6 +195,8 @@ fn build_header_bar(
     header_bar.pack_start(rom_info_button);
     header_bar.pack_end(&menu_button);
 
+    add_theme_action(app);
+
     let about = gio::SimpleAction::new("about", None);
     about.connect_activate(glib::clone!(@weak window => move |_, _| {
         let dialog = AboutDialog::builder()
@@ -219,6 +224,61 @@ fn build_header_bar(
     header_bar
 }
 
+fn add_theme_action(app: &Application) {
+    let preference = load_theme_preference();
+    let settings = gtk4::Settings::default().expect("Could not access GTK settings");
+    apply_theme_preference(&settings, &preference);
+
+    let theme = gio::SimpleAction::new_stateful(
+        "theme",
+        Some(glib::VariantTy::STRING),
+        &preference.to_variant(),
+    );
+    theme.connect_activate(move |action, parameter| {
+        let Some(preference) = parameter.and_then(|value| value.get::<String>()) else {
+            return;
+        };
+        if preference != THEME_SYSTEM && preference != THEME_DARK {
+            return;
+        }
+
+        apply_theme_preference(&settings, &preference);
+        action.set_state(&preference.to_variant());
+        save_theme_preference(&preference);
+    });
+    app.add_action(&theme);
+}
+
+fn apply_theme_preference(settings: &gtk4::Settings, preference: &str) {
+    settings.set_gtk_application_prefer_dark_theme(preference == THEME_DARK);
+}
+
+fn theme_preference_path() -> PathBuf {
+    glib::user_config_dir().join(APP_ID).join("theme")
+}
+
+fn load_theme_preference() -> String {
+    match std::fs::read_to_string(theme_preference_path()) {
+        Ok(preference) if preference.trim() == THEME_DARK => THEME_DARK.to_string(),
+        _ => THEME_SYSTEM.to_string(),
+    }
+}
+
+fn save_theme_preference(preference: &str) {
+    let path = theme_preference_path();
+    let Some(parent) = path.parent() else {
+        return;
+    };
+
+    if let Err(error) = std::fs::create_dir_all(parent) {
+        eprintln!("Could not create the preferences directory: {error}");
+        return;
+    }
+    if let Err(error) = std::fs::write(path, preference) {
+        eprintln!("Could not save the theme preference: {error}");
+    }
+}
+
 fn selection_row(title: &str, placeholder: &str, icon_name: &str) -> SelectionRow {
     let icon = Image::from_icon_name(icon_name);
     icon.set_pixel_size(24);