useTheme.ts

import { useState, useEffect } from 'react';

export type Theme = 'light' | 'dark';

export const useTheme = () => {
  const [theme, setTheme] = useState<Theme>(() => {
    const savedTheme = localStorage.getItem('theme') as Theme | null;
    if (savedTheme) return savedTheme;

    return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
  });

  useEffect(() => {
    const root = window.document.documentElement;
    if (theme === 'dark') {
      root.classList.add('dark');
    } else {
      root.classList.remove('dark');
    }
    localStorage.setItem('theme', theme);
  }, [theme]);

  const toggleTheme = () => {
    setTheme((prev) => (prev === 'light' ? 'dark' : 'light'));
  };

  return { theme, toggleTheme };
};