src/hooks/useTheme.js

import { useEffect, useState } from 'react';

const STORAGE_KEY = 'uaide-theme';

function getInitialTheme() {
  if (typeof window === 'undefined') return 'dark';
  const stored = window.localStorage.getItem(STORAGE_KEY);
  if (stored === 'light' || stored === 'dark') return stored;
  return 'dark';
}

export function useTheme() {
  const [theme, setTheme] = useState(getInitialTheme);

  useEffect(() => {
    document.documentElement.setAttribute('data-theme', theme);
    window.localStorage.setItem(STORAGE_KEY, theme);
  }, [theme]);

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

  return { theme, toggleTheme, setTheme };
}