paint-ui/components/editor/theme-toggle.tsx

'use client';

import { useEffect, useState } from 'react';
import { Moon, Sun } from 'lucide-react';

export function ThemeToggle() {
  const [theme, setTheme] = useState<'light' | 'dark'>('light');
  const [mounted, setMounted] = useState(false);

  useEffect(() => {
    setMounted(true);
    const savedTheme = localStorage.getItem('theme');
    const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
    const currentTheme = savedTheme === 'dark' || (!savedTheme && prefersDark) ? 'dark' : 'light';
    setTheme(currentTheme);
  }, []);

  const toggleTheme = () => {
    const newTheme = theme === 'light' ? 'dark' : 'light';
    setTheme(newTheme);
    localStorage.setItem('theme', newTheme);

    if (newTheme === 'dark') {
      document.documentElement.classList.add('dark');
    } else {
      document.documentElement.classList.remove('dark');
    }
  };

  // Prevent hydration mismatch
  if (!mounted) {
    return (
      <button
        className="rounded-md p-2 text-muted-foreground"
        disabled
      >
        <Sun className="h-4 w-4" />
      </button>
    );
  }

  return (
    <button
      onClick={toggleTheme}
      className="rounded-md p-2 hover:bg-accent transition-colors"
      title={`Switch to ${theme === 'light' ? 'dark' : 'light'} mode`}
    >
      {theme === 'light' ? (
        <Moon className="h-4 w-4" />
      ) : (
        <Sun className="h-4 w-4" />
      )}
    </button>
  );
}