<!DOCTYPE html>
<html>
    <head>
        <style>
            .horizontalGallery {
                width: 300px;
                height: 300px;
                overflow-y: hidden;
                overflow-x: auto;
                margin: 2px;
            }
            .verticalGallery {
                width: 300px;
                height: 300px;
                display: inline-block;
                overflow-x: hidden;
                overflow-y: auto;
                margin: 2px;
            }
        </style>
        <script src="../../../resources/js-test-pre.js"></script>
        <script>
        window.jsTestIsAsync = true;

        var iframeScrollPositionBeforeGlide;
        var divScrollPositionBeforeSnap;

        function locationInWindowCoordinates(element)
        {
            var position = {};
            position.x = element.offsetLeft;
            position.y = element.offsetTop;

            while (element.offsetParent) {
                position.x = position.x + element.offsetParent.offsetLeft;
                position.y = position.y + element.offsetParent.offsetTop;
                if (element == document.getElementsByTagName("body")[0])
                    break;

                element = element.offsetParent;
            }

            return position;
        }

        function checkForScrollSnap(targetLabel)
        {
            var iframeTarget = document.getElementById(targetLabel);

            var actualPosition = iframeTarget.scrollTop;
            if (targetLabel == 'horizontalTarget')
                actualPosition = iframeTarget.scrollLeft;

            // The div should have snapped back to the previous position
            if (actualPosition != divScrollPositionBeforeSnap)
                testFailed("div did not snap back to proper location for " + targetLabel +". Expected " + divScrollPositionBeforeSnap + ", but got " + actualPosition);
            else
                testPassed("div honored snap points.");

            if (targetLabel == 'horizontalTarget')
                setTimeout(() => { scrollGlideTest('verticalTarget') }, 0);
            else   
                finishJSTest();
        }

        function scrollSnapTest(targetLabel)
        {
            debug("Testing scroll-snap snap for " + targetLabel + ":");
            var iframeTarget = document.getElementById(targetLabel);
 
            var dx = 0;
            var dy = 0;
            if (targetLabel == 'horizontalTarget') {
                divScrollPositionBeforeSnap = iframeTarget.scrollLeft;
                dx = -1;
            } else {
                divScrollPositionBeforeSnap = iframeTarget.scrollTop;
                dy = -1;
            }

            var windowPosition = locationInWindowCoordinates(iframeTarget);

            var startPosX = windowPosition.x + 0.5 * iframeTarget.clientWidth;
            var startPosY = windowPosition.y + 0.5 * iframeTarget.clientHeight;
            eventSender.monitorWheelEvents();
            eventSender.mouseMoveTo(startPosX, startPosY); // Make sure we are just outside the iFrame
            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'began', 'none');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 0, 'ended', 'none');
            eventSender.callAfterScrollingCompletes(() => { return checkForScrollSnap(targetLabel); });
        }

        function checkForScrollGlide(targetLabel)
        {
            var iframeTarget = document.getElementById(targetLabel);
            var iframeScrollingElement = window.frames[targetLabel].contentDocument.scrollingElement;

            var actualPosition = iframeScrollingElement.scrollTop;
            var expectedPosition = iframeTarget.clientHeight;
            if (targetLabel == 'horizontalTarget') {
                actualPosition = iframeScrollingElement.scrollLeft;
                expectedPosition = iframeTarget.clientWidth;
            }

            // The div should have scrolled (glided) to the next snap point.
            if (actualPosition == expectedPosition)
                testPassed("div scrolled to next window.");
            else
                testFailed("div did not honor snap points. Expected " + expectedPosition + ", but got " + actualPosition);

            setTimeout(() => { scrollSnapTest(targetLabel) }, 0);
        }

        function scrollGlideTest(targetLabel)
        {
            debug("Testing scroll-snap glide for " + targetLabel + ":");
            var iframeTarget = document.getElementById(targetLabel);
            var iframeScrollingElement = window.frames[targetLabel].contentDocument.scrollingElement;
 
            var dx = 0;
            var dy = 0;
            if (targetLabel == 'horizontalTarget') {
                iframeScrollPositionBeforeGlide = iframeScrollingElement.scrollLeft;
                dx = -1;
            } else {
                iframeScrollPositionBeforeGlide = iframeScrollingElement.scrollTop;
                dy = -1;
            }

            var windowPosition = locationInWindowCoordinates(iframeTarget);

            var startPosX = windowPosition.x + 0.5 * iframeTarget.clientWidth;
            var startPosY = windowPosition.y + 0.5 * iframeTarget.clientHeight;
            eventSender.monitorWheelEvents();
            eventSender.mouseMoveTo(startPosX, startPosY);
            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'began', 'none');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 0, 'ended', 'none');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'none', 'begin');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'none', 'continue');
            eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 0, 'none', 'end');
            eventSender.callAfterScrollingCompletes(() => { return checkForScrollGlide(targetLabel) });
        }

        function onLoad()
        {
            if (window.eventSender) {
                internals.setPlatformMomentumScrollingPredictionEnabled(false);
                setTimeout(function() { scrollGlideTest('horizontalTarget') }, 0);
            }
        }
        </script>
    </head>
    <body onload="onLoad();">
        <div style="position: relative; width: 300px;">
            <div>Tests that the scroll-snap feature works properly in iframes.</div>
            <iframe id="horizontalTarget" class="horizontalGallery" src="resources/horizontal-mainframe.html" style="height: 300px; width: 300px"></iframe>
            <iframe id="verticalTarget" class="verticalGallery" src="resources/vertical-mainframe.html"  style="height: 300px; width: 300px"></iframe>
            <div id="console"></div>
        </div>
    <script src="../../../resources/js-test-post.js"></script>
    </body>
</html>