// hooks/theme.ts
import { useState, useEffect, useCallback } from 'react';

type Theme = 'light' | 'dark';

const STORAGE_KEY = 'theme';

export function useTheme() {
  const [theme, setTheme] = useState<Theme>(() => {
    const stored = typeof window !== 'undefined' ? localStorage.getItem(STORAGE_KEY) : null;
    if (stored === 'light' || stored === 'dark') {
      return stored;
    }
    
    if (typeof window !== 'undefined' && window.matchMedia('(prefers-color-scheme: dark)').matches) {
      return 'dark';
    }
    return 'light';
  });

  useEffect(() => {
    const root = document.documentElement;
    root.setAttribute('data-theme', theme);
    root.classList.toggle('dark', theme === 'dark');
    localStorage.setItem(STORAGE_KEY, theme);
  }, [theme]);

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

  return { theme, toggleTheme };
}