'use client';

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

type Theme = 'light' | 'dark';

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

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

export function ThemeProvider({ children }: { children: React.ReactNode }) {
  const [theme, setThemeState] = useState<Theme>('light');
  const [mounted, setMounted] = useState(false);

  useEffect(() => {
    const savedTheme = localStorage.getItem('edutrack-theme') as Theme | null;
    if (savedTheme === 'light' || savedTheme === 'dark') {
      setThemeState(savedTheme);
    } else {
      const systemTheme = window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
      setThemeState(systemTheme);
    }
    setMounted(true);
  }, []);

  useEffect(() => {
    if (!mounted) return;
    
    const root = window.document.documentElement;
    if (theme === 'dark') {
      root.classList.add('dark');
    } else {
      root.classList.remove('dark');
    }
    localStorage.setItem('edutrack-theme', theme);
  }, [theme, mounted]);

  const setTheme = (newTheme: Theme) => {
    setThemeState(newTheme);
  };

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

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

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