<!DOCTYPE html>
<html id="top">
<meta charset="utf-8">
<title>View timeline nested subject</title>
<link rel="help" href="https://drafts.csswg.org/scroll-animations-1/#viewtimeline-interface">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/web-animations/testcommon.js"></script>
<script src="/scroll-animations/scroll-timelines/testcommon.js"></script>
<script src="/scroll-animations/view-timelines/testcommon.js"></script>
<style type="text/css">
  #container {
    overflow-y: scroll;
    height:  300px;
    width: 300px;
  }
  .big-spacer {
    height:  800px;
  }
  .small-spacer {
    height:  100px;
  }
  #block {
    background-color:  #ddd;
  }
  #target {
    background-color:  green;
    height:  100px;
    width:  100px;
  }
</style>
<body>
  <div id="container">
    <div class="big-spacer"></div>
    <div id="block">
      <div class="small-spacer"></div>
      <div id="target"></div>
    </div>
    <div class="big-spacer"></div>
  </div>
</body>
<script type="text/javascript">
  promise_test(async t => {
    container.scrollTop = 0;
    await waitForNextFrame();

    const anim = CreateViewTimelineOpacityAnimation(t, target);
    const timeline = anim.timeline;
    await anim.ready;

    // start offset = 800 + 100 - 300 = 600
    // end offset = 800 + 100 + 100 = 1000
    // scroll limit = L = 800 + 200 + 800 - 300 = 1500
    // progress = P =  (current - start) / (end - start)
    // P(0) = -600 / 400 = -1.5
    // P(L) = 900 / 400 = 2.5

    // Initially before start-offset and animation effect is in the before
    // phase.
    assert_percents_equal(timeline.currentTime, -150,
                          "Timeline's currentTime at container start boundary");
    assert_percents_equal(anim.currentTime, -150,
                          "Animation's currentTime at container start boundary");
    assert_equals(getComputedStyle(target).opacity, "1",
                  'Effect is inactive in the before phase');


    // Advance to the start offset, which triggers entry to the active phase.
    container.scrollTop = 600;
    await waitForNextFrame();
    assert_percents_equal(timeline.currentTime, 0,
                          "Timeline's current time at start offset");
    assert_percents_equal(anim.currentTime, 0,
                          "Animation's current time at start offset");
    assert_equals(getComputedStyle(target).opacity, '0.3',
                  'Effect at the start of the active phase');

    // Advance to the midpoint of the animation.
    container.scrollTop = 800;
    await waitForNextFrame();
    assert_percents_equal(timeline.currentTime, 50,
                          "Timeline's currentTime at midpoint");
    assert_percents_equal(anim.currentTime, 50,
                          "Animation's currentTime at midpoint");
    assert_equals(getComputedStyle(target).opacity,'0.5',
                  'Effect at the midpoint of the active range');

    // Advance to the end of the animation.
    container.scrollTop = 1000;
    await waitForNextFrame();
    assert_percents_equal(timeline.currentTime, 100,
                          "Timeline's currentTime at end offset");
    assert_percents_equal(anim.currentTime, 100,
                          "Animation's currentTime at end offset");
    assert_equals(getComputedStyle(target).opacity, '1',
                  'Effect is in the after phase at effect end time');

    // Advance to the scroll limit.
    container.scrollTop = 1600;
    await waitForNextFrame();
    assert_percents_equal(timeline.currentTime, 225,
                          "Timeline's currentTime at scroll limit");
    // Hold time set when the animation finishes, which clamps the value of
    // the animation's currentTime.
    assert_percents_equal(anim.currentTime, 100,
                          "Animation's currentTime at scroll limit");
    // In the after phase, so the effect should not be applied.
    assert_equals(getComputedStyle(target).opacity, '1',
                  'After phase at scroll limit');
  }, 'View timeline with subject that is not a direct descendant of the ' +
     'scroll container');
</script>
</html>
