fix(#366): preserve users custom theme while also properly switching default themes

nmrs-gui/src/lib.rs

@@ -9,7 +9,6 @@ use gtk::Application;
 use gtk::prelude::*;
 
 use crate::file_lock::acquire_app_lock;
-use crate::style::load_css;
 use crate::ui::build_ui;
 
 #[derive(Parser, Debug)]
@@ -44,7 +43,7 @@ pub fn run() -> anyhow::Result<()> {
     };
 
     app.connect_activate(|app| {
-        load_css();
+        crate::style::init(include_str!("style.css"));
         build_ui(app);
     });
 

nmrs-gui/src/style.rs

@@ -1,55 +1,96 @@
 use gtk::gdk::Display;
 use gtk::gio::File;
-use gtk::{CssProvider, STYLE_PROVIDER_PRIORITY_APPLICATION, STYLE_PROVIDER_PRIORITY_USER};
+use gtk::{CssProvider, STYLE_PROVIDER_PRIORITY_USER};
+use std::cell::RefCell;
 use std::fs;
 use std::io::Write;
+use std::path::PathBuf;
 
-/// Load and apply the user's custom ~/.config/nmrs/style.css.
-/// If the file does not exist it is created with the bundled defaults.
-/// This must be called after any theme provider is registered so that
-/// same-priority (STYLE_PROVIDER_PRIORITY_USER) rules resolve in favour of
-/// the user's stylesheet.
-pub fn load_user_css() {
-    let path = dirs::config_dir()
-        .unwrap_or_default()
-        .join("nmrs/style.css");
+thread_local! {
+    static PROVIDER: RefCell<CssProvider> = RefCell::new(CssProvider::new());
+}
 
-    let display = Display::default().expect("No display found");
+fn config_dir() -> PathBuf {
+    dirs::config_dir().unwrap_or_default().join("nmrs")
+}
 
-    if path.exists() {
-        let provider = CssProvider::new();
-        let file = File::for_path(&path);
+fn style_path() -> PathBuf {
+    config_dir().join("style.css")
+}
 
-        provider.load_from_file(&file);
+fn custom_backup_path() -> PathBuf {
+    config_dir().join("style.custom.css")
+}
+
+/// Register a single persistent CSS provider and load `~/.config/nmrs/style.css`.
+/// If it doesn't exist, seeds it with the bundled default.
+pub fn init(default_css: &str) {
+    let display = Display::default().expect("No display found");
 
+    PROVIDER.with(|p| {
         gtk::style_context_add_provider_for_display(
             &display,
-            &provider,
+            &*p.borrow(),
             STYLE_PROVIDER_PRIORITY_USER,
         );
-    } else {
-        if let Some(parent) = path.parent() {
-            fs::create_dir_all(parent).ok();
-        }
-
-        let default = include_str!("style.css");
-        let mut f = fs::File::create(&path).expect("Failed to create CSS file");
-        f.write_all(default.as_bytes())
-            .expect("Failed to write default CSS");
+    });
+
+    ensure_dir();
+    if !style_path().exists() {
+        write_file(&style_path(), default_css);
+    }
+    reload();
+}
+
+/// Switch to a named theme: if the user was on "Custom", back up their
+/// `style.css` to `style.custom.css` first. Then overwrite `style.css`
+/// with the theme content and reload.
+pub fn switch_to_theme(css: &str) {
+    let current = crate::theme_config::load_theme().unwrap_or_default();
+    if current == "custom" {
+        backup_custom();
+    }
+    write_file(&style_path(), css);
+    reload();
+}
+
+/// Switch to "Custom": restore `style.custom.css` back to `style.css`
+/// if a backup exists, then reload.
+pub fn switch_to_custom() {
+    let backup = custom_backup_path();
+    if backup.exists()
+        && let Ok(contents) = fs::read_to_string(&backup)
+    {
+        write_file(&style_path(), &contents);
     }
+    reload();
 }
 
-pub fn load_css() {
-    let provider = CssProvider::new();
+/// Reload `~/.config/nmrs/style.css` into the persistent provider.
+pub fn reload() {
+    let path = style_path();
+    if path.exists() {
+        let file = File::for_path(&path);
+        PROVIDER.with(|p| {
+            p.borrow().load_from_file(&file);
+        });
+    }
+}
 
-    let css = include_str!("style.css");
-    provider.load_from_data(css);
+fn backup_custom() {
+    let src = style_path();
+    if src.exists() {
+        fs::copy(&src, custom_backup_path()).ok();
+    }
+}
 
-    let display = Display::default().expect("No display found");
+fn write_file(path: &PathBuf, contents: &str) {
+    ensure_dir();
+    let mut f = fs::File::create(path).expect("Failed to write CSS file");
+    f.write_all(contents.as_bytes())
+        .expect("Failed to write CSS file");
+}
 
-    gtk::style_context_add_provider_for_display(
-        &display,
-        &provider,
-        STYLE_PROVIDER_PRIORITY_APPLICATION,
-    );
+fn ensure_dir() {
+    fs::create_dir_all(config_dir()).ok();
 }

nmrs-gui/src/ui/mod.rs

@@ -8,16 +8,14 @@ pub mod wired_page;
 
 use gtk::prelude::*;
 use gtk::{
-    Application, ApplicationWindow, Box as GtkBox, Label, Orientation,
-    STYLE_PROVIDER_PRIORITY_USER, ScrolledWindow, Spinner, Stack, pango::EllipsizeMode,
+    Application, ApplicationWindow, Box as GtkBox, Label, Orientation, ScrolledWindow, Spinner,
+    Stack, pango::EllipsizeMode,
 };
 use std::cell::Cell;
 use std::rc::Rc;
 use std::sync::Arc;
 use tokio::sync::Notify;
 
-use crate::ui::header::THEMES;
-
 type Callback = Rc<dyn Fn()>;
 type CallbackCell = Rc<std::cell::RefCell<Option<Callback>>>;
 
@@ -34,26 +32,7 @@ pub fn build_ui(app: &Application) {
     let win = ApplicationWindow::new(app);
     win.set_title(Some(""));
     win.set_default_size(100, 600);
-
-    if let Some(key) = crate::theme_config::load_theme()
-        && let Some(theme) = THEMES.iter().find(|t| t.key == key.as_str())
-    {
-        let provider = gtk::CssProvider::new();
-        provider.load_from_data(theme.css);
-
-        let display = gtk::prelude::RootExt::display(&win);
-        gtk::style_context_add_provider_for_display(
-            &display,
-            &provider,
-            STYLE_PROVIDER_PRIORITY_USER,
-        );
-
-        win.add_css_class("dark-theme");
-    }
-
-    // User's custom style.css must be registered after the theme so that it
-    // takes precedence when both run at STYLE_PROVIDER_PRIORITY_USER.
-    crate::style::load_user_css();
+    win.add_css_class("dark-theme");
 
     let vbox = GtkBox::new(Orientation::Vertical, 0);
     let status = Label::new(None);

nmrs-gui/src/ui/settings_page.rs

@@ -1,7 +1,9 @@
 use gtk::prelude::*;
-use gtk::{Align, Box, Button, Label, Orientation, STYLE_PROVIDER_PRIORITY_USER};
+use gtk::{Align, Box, Button, Label, Orientation};
 
-use crate::ui::header::{THEMES, ThemeDef};
+use crate::ui::header::THEMES;
+
+const CUSTOM_INDEX: u32 = 0;
 
 pub struct SettingsPage {
     root: gtk::Box,
@@ -33,43 +35,61 @@ impl SettingsPage {
         title.set_halign(Align::Start);
         root.append(&title);
 
-        Self::build_theme_section(&root, window);
+        Self::build_theme_section(&root);
         Self::build_light_dark_section(&root, window);
 
         Self { root }
     }
 
-    fn build_theme_section(root: &gtk::Box, window: &gtk::ApplicationWindow) {
+    fn build_theme_section(root: &gtk::Box) {
         let section = Box::new(Orientation::Vertical, 6);
 
         let label = Label::new(Some("Theme"));
         label.add_css_class("info-label");
         label.set_halign(Align::Start);
         section.append(&label);
 
-        let names: Vec<&str> = THEMES.iter().map(|t| t.name).collect();
+        let hint = Label::new(Some(
+            "Your overrides in ~/.config/nmrs/style.css are preserved",
+        ));
+        hint.add_css_class("info-value");
+        hint.set_halign(Align::Start);
+        hint.set_opacity(0.6);
+        section.append(&hint);
+
+        let mut names: Vec<&str> = vec!["Custom"];
+        names.extend(THEMES.iter().map(|t| t.name));
         let dropdown = gtk::DropDown::from_strings(&names);
         dropdown.set_halign(Align::Start);
         dropdown.set_hexpand(false);
 
-        if let Some(saved) = crate::theme_config::load_theme()
-            && let Some(idx) = THEMES.iter().position(|t| t.key == saved.as_str())
-        {
-            dropdown.set_selected(idx as u32);
+        if let Some(saved) = crate::theme_config::load_theme() {
+            if let Some(idx) = THEMES.iter().position(|t| t.key == saved.as_str()) {
+                dropdown.set_selected(idx as u32 + 1);
+            } else {
+                dropdown.set_selected(CUSTOM_INDEX);
+            }
+        } else {
+            dropdown.set_selected(CUSTOM_INDEX);
         }
 
-        let window_weak = window.downgrade();
         dropdown.connect_selected_notify(move |dd| {
-            let idx = dd.selected() as usize;
-            if idx >= THEMES.len() {
+            let idx = dd.selected();
+
+            if idx == CUSTOM_INDEX {
+                crate::style::switch_to_custom();
+                crate::theme_config::save_theme("custom");
                 return;
             }
 
-            let theme = &THEMES[idx];
-
-            if let Some(window) = window_weak.upgrade() {
-                Self::apply_theme(theme, &window);
+            let theme_idx = (idx - 1) as usize;
+            if theme_idx >= THEMES.len() {
+                return;
             }
+
+            let theme = &THEMES[theme_idx];
+            crate::style::switch_to_theme(theme.css);
+            crate::theme_config::save_theme(theme.key);
         });
 
         section.append(&dropdown);
@@ -101,7 +121,6 @@ impl SettingsPage {
                     window.add_css_class("light-theme");
                     btn.add_css_class("appearance-active");
                     dark_btn_clone.remove_css_class("appearance-active");
-                    crate::theme_config::save_theme("dark");
                 }
             });
         }
@@ -115,7 +134,6 @@ impl SettingsPage {
                     window.add_css_class("dark-theme");
                     btn.add_css_class("appearance-active");
                     light_btn_clone.remove_css_class("appearance-active");
-                    crate::theme_config::save_theme("light");
                 }
             });
         }
@@ -132,22 +150,6 @@ impl SettingsPage {
         root.append(&section);
     }
 
-    fn apply_theme(theme: &ThemeDef, window: &gtk::ApplicationWindow) {
-        let provider = gtk::CssProvider::new();
-        provider.load_from_data(theme.css);
-
-        let display = gtk::prelude::RootExt::display(window);
-
-        gtk::style_context_add_provider_for_display(
-            &display,
-            &provider,
-            STYLE_PROVIDER_PRIORITY_USER,
-        );
-
-        crate::theme_config::save_theme(theme.key);
-        crate::style::load_user_css();
-    }
-
     pub fn widget(&self) -> &gtk::Box {
         &self.root
     }

nmrs-gui/tests/style_test.rs

@@ -5,5 +5,5 @@ fn style_css_loads() {
     }
 
     gtk::init().unwrap();
-    nmrs_gui::style::load_css();
+    nmrs_gui::style::init(include_str!("../src/style.css"));
 }