'use client';

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

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

interface ThemeContextType {
  theme: Theme;
  setTheme: (theme: Theme) => void;
  actualTheme: 'light' | 'dark';
}

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

export function ThemeProvider({ children }: { children: React.ReactNode }) {
  const [theme, setTheme] = useState<Theme>('system');
  const [actualTheme, setActualTheme] = useState<'light' | 'dark'>('dark');

  useEffect(() => {
    // Load saved theme
    const saved = localStorage.getItem('theme') as Theme;
    if (saved) {
      setTheme(saved);
    }
  }, []);

  useEffect(() => {
    const applyTheme = () => {
      if (theme === 'system') {
        const systemPrefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
        setActualTheme(systemPrefersDark ? 'dark' : 'light');
        document.documentElement.classList.toggle('dark', systemPrefersDark);
      } else {
        setActualTheme(theme);
        document.documentElement.classList.toggle('dark', theme === 'dark');
      }
    };

    applyTheme();
    localStorage.setItem('theme', theme);

    // Listen for system theme changes
    const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)');
    mediaQuery.addEventListener('change', applyTheme);
    return () => mediaQuery.removeEventListener('change', applyTheme);
  }, [theme]);

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

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