bot-whatsapp/packages/docs/src/components/core/ToggleTheme.tsx

import { component$, useStore, useClientEffect$ } from '@builder.io/qwik'

import { IconSun } from '~/components/icons/IconSun'
import { IconMoon } from '../icons/IconMoon'

interface ItemProps {
    iconClass?: string
}

export default component$((props: ItemProps) => {
    const { iconClass } = props
    const store = useStore({
        theme: (typeof window !== 'undefined' && window?.localStorage?.theme) || undefined,
    })

    useClientEffect$(() => {
        store.theme =
            window.localStorage.theme === 'dark' ||
            (!('theme' in window.localStorage) && window.matchMedia('(prefers-color-scheme: dark)').matches)
                ? 'dark'
                : 'light'
    })

    return (
        <button
            type="button"
            class="text-gray-500 dark:text-gray-400 hover:bg-gray-100 dark:hover:bg-gray-700 focus:outline-none focus:ring-4 focus:ring-gray-200 dark:focus:ring-gray-700 rounded-lg text-sm p-2.5 inline-flex items-center"
            aria-label="Toggle between Dark and Light mode"
            onClick$={() => {
                switch (store.theme) {
                    case 'dark':
                        document.documentElement.classList.remove('dark')
                        store.theme = window.localStorage.theme = 'light'
                        break
                    default:
                        document.documentElement.classList.add('dark')
                        store.theme = window.localStorage.theme = 'dark'
                        break
                }
            }}
        >
            {store.theme == 'dark' ? <IconMoon class={iconClass} /> : <IconSun class={iconClass} />}
        </button>
    )
})