(function () {
    const CLASS_OPEN_MENU = 'cst-header-navigation--open';
    const CLASS_OVERFLOW_HIDDEN_BODY = 'body--oh';

    const SELECTORS = {
        BUTTON: '.cst-header-navigation__toggle-button',
        CONTAINER: '.cst-header-navigation'
    };

    function initNavigation() {
        const btn = document.querySelector(SELECTORS.BUTTON);
        const container = document.querySelector(SELECTORS.CONTAINER);

        if (!btn || !container) return;

        const toggleMenu = () => {
            const body = document.body;

            container.classList.toggle(CLASS_OPEN_MENU);
            body.classList.toggle(CLASS_OVERFLOW_HIDDEN_BODY);
        };

        btn.addEventListener('click', toggleMenu);
    }

    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', initNavigation);
    } else {
        initNavigation();
    }
})();