const cookie_control_banner = function(url, callback){
    var banner = document.querySelector('.cookie-control_banner');
    if (!banner) {
		finish('no banner');
        return;
	}

    var saveButton = banner.querySelector('.cookie-control_banner_accept');
    if (!saveButton) {
		finish('no save button');
        return;
	}

    saveButton.addEventListener('click', function(evt) { return acceptCookies(evt, 'all'); });

	var requiredButton = banner.querySelector('.cookie-control_banner_required');
    if (requiredButton) {
    	requiredButton.addEventListener('click', function(evt) { return acceptCookies(evt, 'required');});
	}

	var submit_url = url ? url : '/slade/about/cookies/';

    function acceptCookies(evt, which) {
        evt.currentTarget.classList.add('cookie-control_banner_button-processing')
        var r = new XMLHttpRequest();
        r.open("POST", submit_url, true);
        r.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        r.onreadystatechange = statechange;
        r.setRequestHeader('Accept', 'application/json');
        r.send('allow=' + which);
        evt.preventDefault();
        return false;
    }

    function statechange(evt) {
        if (evt.target.status == 200) {
            success(evt.target.responseText);
        } else if (evt.target.status == 404 || evt.target.status == 500) {
            fail();
        }
    }

    function success(message) {
        banner.classList.add('cookie-control_banner-hidden');
		finish('success');
    }

    function fail() {
        saveButton.classList.remove('cookie-control_banner_button-processing');
		finish('fail');
    }

	function finish(message) 
	{
		if (typeof callback === 'function') {
			callback({message: message});
		}
	}
};