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

type Theme = 'light' | 'dark';

interface ThemeContextType {
  theme: Theme;
  toggleTheme: () => void;
}

const ThemeContext = createContext<ThemeContextType | undefined>(undefined);

export const ThemeProvider: React.FC<{ children: ReactNode }> = ({ children }) => {
  const [theme, setTheme] = useState<Theme>(() => {
    const storedTheme = localStorage.getItem('theme');
    if (storedTheme) {
      return storedTheme as Theme;
    }
    return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
  });

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

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

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

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