/*
 * Copyright (C) 2018 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

function enterFullscreen() {

    let callback = arguments[0];
    if (!document.webkitFullscreenEnabled) {
        callback(false);
        return;
    }

    if (document.webkitIsFullScreen) {
        callback(true);
        return;
    }

    let fullscreenChangeListener, fullscreenErrorListener;
    fullscreenChangeListener = (e) => {
        // Some other element went fullscreen, we didn't request it.
        if (e.target !== document.documentElement)
            return;

        if (!document.webkitIsFullScreen)
            return;

        document.removeEventListener("webkitfullscreenerror", fullscreenChangeListener);
        document.documentElement.removeEventListener("webkitfullscreenchange", fullscreenErrorListener);
        callback(true);
    };
    fullscreenErrorListener = (e) => {
        // Some other element caused an error, we didn't request it.
        if (e.target !== document.documentElement)
            return;

        document.removeEventListener("webkitfullscreenchange", fullscreenChangeListener);
        document.documentElement.removeEventListener("webkitfullscreenerror", fullscreenErrorListener);
        callback(document.webkitIsFullscreen);
    };

    // The document fires change events, but the fullscreen element fires error events.
    document.addEventListener("webkitfullscreenchange", fullscreenChangeListener);
    document.documentElement.addEventListener("webkitfullscreenerror", fullscreenErrorListener);
    document.documentElement.webkitRequestFullscreen();
}