'use client';

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

type Theme = 'light' | 'dark' | 'system';

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

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

export function ThemeProvider({ children }: { children: ReactNode }) {
  const [theme, setTheme] = useState<Theme>('system');

  useEffect(() => {
    // Get the theme preference from localStorage if available
    const storedTheme = localStorage.getItem('theme') as Theme | null;
    if (storedTheme) {
      setTheme(storedTheme);
    }
  }, []);

  useEffect(() => {
    const root = window.document.documentElement;
    
    // Remove all theme classes
    root.classList.remove('light', 'dark');
    
    // Add the appropriate class based on theme
    if (theme === 'system') {
      const systemTheme = window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
      root.classList.add(systemTheme);
    } else {
      root.classList.add(theme);
    }
    
    // Store the preference
    localStorage.setItem('theme', theme);
  }, [theme]);

  return (
    <ThemeContext.Provider value={{ theme, setTheme }}>
      {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;
}