function isTabbable(el) {
    const tag = el.tagName.toLowerCase();
    if (el.getAttribute('tabindex') === '-1') {
        return false;
    }
    if (el.hasAttribute('disabled')) {
        return false;
    }
    if (el.hasAttribute('aria-disabled') && el.getAttribute('aria-disabled') !== 'false') {
        return false;
    }
    if (el.hasAttribute('tabindex')) {
        return true;
    }
    if (el.hasAttribute('contenteditable') && el.getAttribute('contenteditable') !== 'false') {
        return true;
    }
    if ((tag === 'audio' || tag === 'video') && el.hasAttribute('controls')) {
        return true;
    }
    if (tag === 'input' && el.getAttribute('type') === 'radio' && !el.hasAttribute('checked')) {
        return false;
    }
    if (!el.offsetParent) {
        return false;
    }
    if (window.getComputedStyle(el).visibility === 'hidden') {
        return false;
    }
    return ['button', 'input', 'select', 'textarea', 'a', 'audio', 'video', 'summary'].includes(tag);
}
export function getTabbableElements(root) {
    const tabbableElements = [];
    if (root instanceof HTMLElement) {
        if (isTabbable(root)) {
            tabbableElements.push(root);
        }
        if (root.shadowRoot && root.shadowRoot.mode === 'open') {
            getTabbableElements(root.shadowRoot).map(el => tabbableElements.push(el));
        }
        if (root instanceof HTMLSlotElement) {
            root.assignedElements().map((slottedEl) => {
                getTabbableElements(slottedEl).map(el => tabbableElements.push(el));
            });
        }
    }
    [...root.querySelectorAll('*')].map((el) => {
        getTabbableElements(el).map(el => tabbableElements.push(el));
    });
    return tabbableElements;
}
export function getNearestTabbableElement(el) {
    const tabbableElements = getTabbableElements(el);
    return tabbableElements.length ? tabbableElements[0] : null;
}