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

type Theme = 'light' | 'dark';

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

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

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

interface ThemeProviderProps {
  children: ReactNode;
}

export const ThemeProvider: React.FC<ThemeProviderProps> = ({ children }) => {
  const [theme, setThemeState] = useState<Theme>('light');

  useEffect(() => {
    // Check for saved theme preference
    const savedTheme = localStorage.getItem('enamel_theme') as Theme;
    if (savedTheme) {
      setThemeState(savedTheme);
      applyTheme(savedTheme);
    } else {
      // Check system preference
      const systemTheme = window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
      setThemeState(systemTheme);
      applyTheme(systemTheme);
    }

    // Listen for system theme changes
    const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)');
    const handleChange = (e: MediaQueryListEvent) => {
      if (!localStorage.getItem('enamel_theme')) {
        const newTheme = e.matches ? 'dark' : 'light';
        setThemeState(newTheme);
        applyTheme(newTheme);
      }
    };

    mediaQuery.addEventListener('change', handleChange);
    return () => mediaQuery.removeEventListener('change', handleChange);
  }, []);

  const applyTheme = (newTheme: Theme) => {
    const root = document.documentElement;
    if (newTheme === 'dark') {
      root.classList.add('dark');
    } else {
      root.classList.remove('dark');
    }
  };

  const setTheme = (newTheme: Theme) => {
    setThemeState(newTheme);
    localStorage.setItem('enamel_theme', newTheme);
    applyTheme(newTheme);
  };

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

  const value: ThemeContextType = {
    theme,
    toggleTheme,
    setTheme
  };

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