'use client';

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

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

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

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

export function ThemeProvider({ children }: { children: ReactNode }) {
  const [theme, setThemeState] = useState<Theme>('system');
  const [resolvedTheme, setResolvedTheme] = useState<'light' | 'dark'>('light');
  const [mounted, setMounted] = useState(false);

  useEffect(() => {
    setMounted(true);
    const stored = localStorage.getItem('theme') as Theme | null;
    if (stored) {
      setThemeState(stored);
    }
  }, []);

  useEffect(() => {
    if (!mounted) return;

    const root = document.documentElement;
    const systemTheme = window.matchMedia('(prefers-color-scheme: dark)').matches
      ? 'dark'
      : 'light';
    const effectiveTheme = theme === 'system' ? systemTheme : theme;

    // Add transition disable class
    root.classList.add('disable-transitions');

    // Update theme
    if (effectiveTheme === 'dark') {
      root.classList.add('dark');
    } else {
      root.classList.remove('dark');
    }

    setResolvedTheme(effectiveTheme);

    // Re-enable transitions after a frame
    requestAnimationFrame(() => {
      root.classList.remove('disable-transitions');
    });
  }, [theme, mounted]);

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

  if (!mounted) {
    return <>{children}</>;
  }

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

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