import { createContext, useContext, useEffect, useState } from 'react';

const ThemeContext = createContext();

function readThemeFromStorage() {
  if (typeof window === 'undefined') return 'light';
  return localStorage.getItem('theme') || 'light';
}

export function ThemeProvider({ children }) {
  const [theme, setTheme] = useState(readThemeFromStorage);

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

  const toggleTheme = () => {
    const newTheme = theme === 'light' ? 'dark' : 'light';
    setTheme(newTheme);
    localStorage.setItem('theme', newTheme);
    document.documentElement.setAttribute('data-theme', newTheme);
  };

  return (
    <ThemeContext.Provider value={{ theme, toggleTheme }}>
      {children}
    </ThemeContext.Provider>
  );
}

export function useTheme() {
  const context = useContext(ThemeContext);
  if (context === undefined) {
    throw new Error('useTheme must be used within a ThemeProvider');
  }
  return context;
}