State Management

Explanation

import { createContext, useContext, useState, type ReactNode } from "react";

type Theme = "light" | "dark";

const ThemeContext = createContext<{
  theme: Theme;
  toggle: () => void;
} | null>(null);

export function ThemeProvider({ children }: { children: ReactNode }) {
  const [theme, setTheme] = useState<Theme>("light");
  const toggle = () => setTheme((t) => (t === "light" ? "dark" : "light"));
  return (
    <ThemeContext.Provider value={{ theme, toggle }}>
      {children}
    </ThemeContext.Provider>
  );
}

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