const HanyuuOAuth2Header = function(element = '.js-oauth2-header', simpleElement = '.js-oauth2-header-simple') {
    if(typeof element === 'string')
        element = document.querySelector(element);
    if(!(element instanceof HTMLElement))
        throw 'element must be a valid query selector or an instance of HTMLElement';

    if(typeof simpleElement === 'string')
        simpleElement = element.querySelector(simpleElement);

    const simpleElementIcon = simpleElement?.querySelector('.js-oauth2-header-simple-icon');
    const simpleElementText = simpleElement?.querySelector('.js-oauth2-header-simple-text');

    const hasSimpleElement = simpleElement instanceof HTMLElement;
    const setSimpleVisible = state => {
        if(hasSimpleElement)
            simpleElement.classList.toggle('hidden', !state);
    };
    const setSimpleData = (icon, text) => {
        if(hasSimpleElement) {
            for(const className of simpleElementIcon.classList)
                if(className.startsWith('oauth2-simplehead-icon--'))
                    simpleElementIcon.classList.remove(className);

            simpleElementIcon.classList.add(`oauth2-simplehead-icon--${icon}`);
            simpleElementText.textContent = text;
        }
    };

    const removeElement = (forceSimple = true) => {
        while(element.childElementCount > 1)
            element.lastElementChild.remove();

        if(typeof forceSimple === 'boolean')
            setSimpleVisible(forceSimple);
    };

    return {
        get element() { return element; },

        get simpleVisible() { return hasSimpleElement && !simpleElement.classList.contains('hidden'); },
        set simpleVisible(state) { setSimpleVisible(state); },

        setSimpleData: setSimpleData,

        setElement: elementInfo => {
            removeElement(false);

            if(elementInfo instanceof Element)
                element.appendChild(elementInfo);
            else if('element' in elementInfo)
                element.appendChild(elementInfo.element);
            else
                throw 'elementInfo must be an instance of Element or contain an object with an element property';
        },
        removeElement: removeElement,
    };
};