feat: integrate ThemeToggle component and fix module visibility errors

frontend/src/components/hooks/use_theme_mode.rs

@@ -0,0 +1,108 @@
+use leptos::prelude::*;
+use web_sys::Storage;
+
+#[derive(Debug, Clone, Copy)]
+pub struct ThemeMode {
+    state: RwSignal<bool>,
+}
+
+const LOCALSTORAGE_KEY: &str = "darkmode";
+
+/// Hook to access the dark mode context
+///
+/// Returns the ThemeMode instance from context for easy access
+pub fn use_theme_mode() -> ThemeMode {
+    expect_context::<ThemeMode>()
+}
+
+/* ========================================================== */
+/*                     ✨ FUNCTIONS ✨                        */
+/* ========================================================== */
+
+impl ThemeMode {
+    #[must_use]
+    /// Initializes a new ThemeMode instance.
+    pub fn init() -> Self {
+        let theme_mode = Self { state: RwSignal::new(false) };
+
+        provide_context(theme_mode);
+
+        // Use Effect to handle browser-only initialization
+        Effect::new(move |_| {
+            let initial = Self::get_storage_state().unwrap_or(Self::prefers_dark_mode());
+            theme_mode.state.set(initial);
+        });
+
+        theme_mode
+    }
+
+    pub fn toggle(&self) {
+        self.state.update(|state| {
+            *state = !*state;
+            Self::set_storage_state(*state);
+        });
+    }
+
+    pub fn set_dark(&self) {
+        self.set(true);
+    }
+
+    pub fn set_light(&self) {
+        self.set(false);
+    }
+
+    /// - `dark`: Set to `true` for dark mode, and `false` for light mode.
+    pub fn set(&self, dark: bool) {
+        self.state.set(dark);
+        Self::set_storage_state(dark);
+    }
+
+    #[must_use]
+    pub fn get(&self) -> bool {
+        self.state.get()
+    }
+
+    #[must_use]
+    pub fn is_dark(&self) -> bool {
+        self.state.get()
+    }
+
+    #[must_use]
+    pub fn is_light(&self) -> bool {
+        !self.state.get()
+    }
+
+    /* ========================================================== */
+    /*                     ✨ FUNCTIONS ✨                        */
+    /* ========================================================== */
+
+    /// Retrieves the local storage object, if available.
+    fn get_storage() -> Option<Storage> {
+        window().local_storage().ok().flatten()
+    }
+
+    /// Retrieves the dark mode state from local storage, if available.
+    fn get_storage_state() -> Option<bool> {
+        Self::get_storage()
+            .and_then(|storage| storage.get(LOCALSTORAGE_KEY).ok())
+            .flatten()
+            .and_then(|entry| entry.parse::<bool>().ok())
+    }
+
+    /// Checks whether the user's system prefers dark mode based on media queries.
+    fn prefers_dark_mode() -> bool {
+        window()
+            .match_media("(prefers-color-scheme: dark)")
+            .ok()
+            .flatten()
+            .map(|media| media.matches())
+            .unwrap_or_default()
+    }
+
+    /// Stores the dark mode state in local storage.
+    fn set_storage_state(state: bool) {
+        if let Some(storage) = Self::get_storage() {
+            storage.set(LOCALSTORAGE_KEY, state.to_string().as_str()).ok();
+        }
+    }
+}