🚀 feat: determining the initial theme is encapsulated in a separate function

src/hooks/useTheme.ts

@@ -3,11 +3,13 @@ import { useState, useEffect } from 'react';
 type Theme = 'light' | 'dark';
 
 export function useTheme() {
-  const [theme, setTheme] = useState<Theme>(() => {
-    const savedTheme = localStorage.getItem('theme');
+  const getInitialTheme = (): Theme => {
+    const savedTheme = localStorage.getItem('theme') as Theme;
     if (savedTheme === 'dark' || savedTheme === 'light') return savedTheme;
     return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
-  });
+  };
+
+  const [theme, setTheme] = useState<Theme>(getInitialTheme);
 
   useEffect(() => {
     const root = window.document.documentElement;
@@ -17,8 +19,22 @@ export function useTheme() {
   }, [theme]);
 
   const toggleTheme = () => {
-    setTheme(prev => prev === 'light' ? 'dark' : 'light');
+    setTheme(prevTheme => (prevTheme === 'light' ? 'dark' : 'light'));
   };
 
+  useEffect(() => {
+    const handleMediaChange = (event: MediaQueryListEvent) => {
+      setTheme(event.matches ? 'dark' : 'light');
+    };
+
+    const mediaQueryList = window.matchMedia('(prefers-color-scheme: dark)');
+    mediaQueryList.addEventListener('change', handleMediaChange);
+
+    // Cleanup listener on unmount
+    return () => {
+      mediaQueryList.removeEventListener('change', handleMediaChange);
+    };
+  }, []);
+
   return { theme, toggleTheme };
 }