dataflow-rs 2.1.5

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

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

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

const ThemeContext = createContext<ThemeContextValue | null>(null);

function getSystemTheme(): 'light' | 'dark' {
  if (typeof window !== 'undefined') {
    return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
  }
  return 'light';
}

interface ThemeProviderProps {
  children: ReactNode;
  defaultTheme?: Theme;
}

export function ThemeProvider({ children, defaultTheme = 'system' }: ThemeProviderProps) {
  const [theme, setTheme] = useState<Theme>(defaultTheme);
  const [resolvedTheme, setResolvedTheme] = useState<'light' | 'dark'>(
    defaultTheme === 'system' ? getSystemTheme() : defaultTheme
  );

  // Sync theme when defaultTheme prop changes
  useEffect(() => {
    setTheme(defaultTheme);
  }, [defaultTheme]);

  useEffect(() => {
    if (theme === 'system') {
      const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)');
      const handleChange = () => setResolvedTheme(mediaQuery.matches ? 'dark' : 'light');
      handleChange();
      mediaQuery.addEventListener('change', handleChange);
      return () => mediaQuery.removeEventListener('change', handleChange);
    } else {
      setResolvedTheme(theme);
    }
  }, [theme]);

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

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