import { createContext, useContext, useMemo, useState } from 'react';

const ThemeContext = createContext(null);

export function ThemeProvider({ children }) {
  const [theme, setTheme] = useState('light');
  const value = useMemo(
    () => ({
      theme,
      toggle: () => setTheme((t) => (t === 'light' ? 'dark' : 'light')),
    }),
    [theme]
  );
  return (
    <ThemeContext.Provider value={value}>
      <div className={`app theme-${theme}`}>{children}</div>
    </ThemeContext.Provider>
  );
}

export function useTheme() {
  const ctx = useContext(ThemeContext);
  if (!ctx) throw new Error('useTheme вызывают вне ThemeProvider');
  return ctx;
}