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

const ThemeContext = createContext();

export function ThemeProvider({ children }) {
  const [theme, setTheme] = useState(() => {
    return localStorage.getItem('diffweave_theme') || 'dark';
  });

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

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

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

export const useTheme = () => {
  const context = useContext(ThemeContext);
  if (!context) {
    return { theme: 'dark', setTheme: () => {}, toggleTheme: () => {} };
  }
  return context;
};