const scrollButtons = `
    <a href="#up" id="scroll-up" class="btn btn-primary btn-sm" role="button" aria-pressed="true" style="display: sticky; position: fixed; bottom: 3rem; right: 1rem;">
        <span class="ing-caret ing-rotate-180 ing-fw"></span>
    </a>

    <a href="#down" id="scroll-down" class="btn btn-primary btn-sm" role="button" aria-pressed="true" style="display: sticky; position: fixed; bottom: 1rem; right: 1rem;">
        <span class="ing-caret ing-fw"></span>
    </a>
`

document.body.insertAdjacentHTML('beforeend', scrollButtons);

const scroll_up = document.querySelector('#scroll-up');
const scroll_down = document.querySelector('#scroll-down');

scroll_up.style.transition = scroll_down.style.transition = 'display 1.5s ease-in-out';
scroll_up.style.display = scroll_down.style.display = 'none';

scroll_up.addEventListener('click', () =>
    window.scrollTo({ top: 0, behavior: 'smooth' }))


scroll_down.addEventListener('click', () =>
    window.scrollTo({ top: document.body.scrollHeight, behavior: 'smooth' }))

const check = () => {
    scroll_down.style.display = (window.scrollY + window.innerHeight) > document.body.scrollHeight * .8 ? 'none' : 'block'
    scroll_up.style.display = (window.scrollY) < document.body.scrollHeight * .2 ? 'none' : 'block'
}

['scroll', 'resize'].forEach(e => window.addEventListener(e, check))