client/src/hooks/useThemeMode.js

import { useState, useEffect } from "react";

export const useThemeMode = () => {
  const [mode, setMode] = useState(() => {
    const savedMode = localStorage.getItem("theme-mode");
    return savedMode || "light";
  });

  useEffect(() => {
    localStorage.setItem("theme-mode", mode);
  }, [mode]);

  const toggleTheme = () => {
    setMode((prevMode) => (prevMode === "light" ? "dark" : "light"));
  };

  return { mode, toggleTheme };
};