function log(msg) {
    // if (LOG) {
    //     document.getElementById('div').innerHTML += msg + '<br>'
    // }
    console.log(msg);
}


function openFullscreen(elem) {
    if (elem.requestFullscreen) {
        elem.requestFullscreen();
    } else if (elem.mozRequestFullScreen) { /* Firefox */
        elem.mozRequestFullScreen();
    } else if (elem.webkitRequestFullscreen) { /* Chrome, Safari and Opera */
        elem.webkitRequestFullscreen();
    } else if (elem.msRequestFullscreen) { /* IE/Edge */
        elem.msRequestFullscreen();
    }
}

function closeFullscreen() {
    if (document.exitFullscreen) {
        document.exitFullscreen();
    } else if (document.mozCancelFullScreen) { /* Firefox */
        document.mozCancelFullScreen();
    } else if (document.webkitExitFullscreen) { /* Chrome, Safari and Opera */
        document.webkitExitFullscreen();
    } else if (document.msExitFullscreen) { /* IE/Edge */
        document.msExitFullscreen();
    }
}


function getOS() {
    // linux? ios?
    var OSName = "unknown";
    if (navigator.appVersion.indexOf("Win") != -1) OSName = "win";
    else if (navigator.appVersion.indexOf("Mac") != -1) OSName = "mac";
    else if (navigator.userAgent.indexOf("Android") != -1) OSName = "android";
    return OSName;
}

function getBrowser() {
    var browserName = "unknown";
    if (navigator.userAgent.indexOf("Firefox") != -1) browserName = "firefox";
    if (navigator.userAgent.indexOf("Chrome") != -1) browserName = "chrome";
    if (navigator.userAgent.indexOf("Edge") != -1) browserName = "edge";
    if (navigator.userAgent.indexOf("Version/") != -1) browserName = "safari";
    if (navigator.userAgent.indexOf("UCBrowser") != -1) browserName = "uc";
    return browserName;
}

function isPortrait() {
    // ios / mobile app
    switch (window.orientation) {
        case 0:
        case 180:
            return true;
            break;
    }

    // desktop
    orient = screen.msOrientation || screen.mozOrientation || (screen.orientation || {}).type;
    if (orient == "portrait-primary") {
        return true;
    }

    return false;
}