hawkband-nextjs/components/light_dark.js

import React, { useState,useEffect  } from 'react';
import { createTheme } from '@material-ui/core/styles';
import { ThemeProvider } from '@material-ui/styles';

const ToggleButton = styled.button`
  --toggle-width: 80px;
  --toggle-height: 38px;
  --toggle-padding: 4px;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-around;
  font-size: 1.5rem;
  line-height: 1;
  width: var(--toggle-width);
  height: var(--toggle-height);
  padding: var(--toggle-padding);
  border: 0;
  border-radius: calc(var(--toggle-width) / 2);
  cursor: pointer;
  background: var(--color-bg-toggle);
  transition: background 0.25s ease-in-out, box-shadow 0.25s ease-in-out;
  &:focus {
    outline-offset: 5px;
  }
  &:focus:not(:focus-visible) {
    outline: none;
  }
  &:hover {
    box-shadow: 0 0 5px 2px var(--color-bg-toggle);
  },
`;

const ToggleThumb = styled.span`
  position: absolute;
  top: var(--toggle-padding);
  left: var(--toggle-padding);
  width: calc(var(--toggle-height) - (var(--toggle-padding) * 2));
  height: calc(var(--toggle-height) - (var(--toggle-padding) * 2));
  border-radius: 50%;
  background: white;
  transition: transform 0.25s ease-in-out;
  transform: ${(p) =>
    p.activeTheme === "dark"
      ? "translate3d(calc(var(--toggle-width) - var(--toggle-height)), 0, 0)"
      : "none"};
`;
const light = createTheme({
  palette: {
    mode: 'light',
  },
});

const dark = createTheme({
  palette: {
    mode: 'dark',
  },
});
function activeTheme(themeMode){
  return themeMode === 'light'? light : dark;
}
export const toggleTheme = () => { 
      const [activeTheme, setTheme] = useState("light");
      const altheme = activeTheme === "light" ? "dark" : "light";
    useEffect(() => {
      const savedTheme = window.localStorage.getItem("theme");
      savedTheme && setActiveTheme(savedTheme);
    }, []);
    useEffect(() => {
      document.body.dataset.theme = activeTheme;
      window.localStorage.setItem("theme", activeTheme);
    }, [activeTheme]);

    return (
      <ToggleButton
        aria-label={`Change to ${altheme} mode`}
        title={`Change to ${altheme} mode`}
        type="button"
        onClick={() => setActiveTheme(altheme)}
      >
        <ToggleThumb activeTheme={activeTheme} />
        <span>🌙</span>
      <span>☀️</span>
      </ToggleButton>
    );
  };