<!DOCTYPE html>
<meta name="viewport" content="width=device-width,initial-scale=1">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="./resources/intersection-observer-test-utils.js"></script>

<style>
    pre,
    #log {
        position: absolute;
        top: 0;
        left: 200px;
    }

    .spacer {
        height: calc(100vh + 100px);
    }

    #target {
        width: 100px;
        height: 100px;
        background-color: green;
    }
</style>

<div class="spacer"></div>
<div id="target"></div>
<div class="spacer"></div>

<script>
    var vw = document.documentElement.clientWidth;
    var vh = document.documentElement.clientHeight;

    var entries = [];
    var target;

    runTestCycle(function () {
        target = document.getElementById("target");
        assert_true(!!target, "target exists");
        var observer = new IntersectionObserver(function (changes) {
            entries = entries.concat(changes)
        }, {root: document});
        observer.observe(target);
        entries = entries.concat(observer.takeRecords());
        assert_equals(entries.length, 0, "No initial notifications.");
        runTestCycle(step0, "First rAF.");
    }, "IntersectionObserver in a single document using document as root.");

    function step0() {
        document.scrollingElement.scrollTop = 300;
        runTestCycle(step1, "document.scrollingElement.scrollTop = 300");
        checkLastEntry(entries, 0, [8, 108, vh + 108, vh + 208, 0, 0, 0, 0, 0, vw, 0, vh, false]);
    }

    function step1() {
        document.scrollingElement.scrollTop = 0;
        checkLastEntry(entries, 1, [8, 108, vh - 192, vh - 92, 8, 108, vh - 192, vh - 92, 0, vw, 0, vh, true]);
    }
</script>