<!DOCTYPE html>
<title>Tests anchor-scroll resolving name conflicts</title>
<link rel="help" href="https://drafts.csswg.org/css-anchor-position-1/#scroll">
<link rel="author" href="mailto:xiaochengh@chromium.org">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="support/test-common.js"></script>

<style>
body {
  margin: 0;
}

.scroller {
  width: 100px;
  height: 100px;
  overflow-y: scroll;
}

.nonpos-cb {
  transform: scale(1);
}

.abspos-cb {
  position: absolute;
}

.anchor {
  background: orange;
  anchor-name: --a1;
  position: absolute;
  width: 50px;
  height: 50px;
  top: 50px;
}

.spacer {
  height: 200px;
}

.target {
  background: lime;
  position: absolute;
  width: 50px;
  height: 50px;
  top: anchor(--a1 top);
  left: anchor(--a1 right);
  anchor-scroll: --a1;
}
</style>

<div class="abspos-cb" style="width: 300px; height: 400px">
  <div class="scroller nonpos-cb" id="scroller1">
    <div class="anchor" id="anchor1"></div>
    <div class="spacer"></div>
  </div>
  <div class="target" id="target1"></div>

  <div class="scroller abspos-cb" style="top: 125px" id="scroller2">
    <div class="anchor" id="anchor2"></div>
    <div class="spacer"></div>
  </div>
  <div class="target" id="target2"></div>

  <div class="scroller abspos-cb" style="top: 250px" id="scroller3">
    <div class="anchor" id="anchor3"></div>
    <div class="spacer"></div>
  </div>
  <div class="target" id="target3"></div>
</div>

<script>
promise_test(async () => {
  scroller1.scrollTop = 10;
  await waitUntilNextAnimationFrame();
  await waitUntilNextAnimationFrame();

  assert_equals(target1.getBoundingClientRect().top, anchor1.getBoundingClientRect().top);
  assert_equals(target1.getBoundingClientRect().top, 40);
}, 'target1 should scroll with anchor1');

promise_test(async () => {
  scroller2.scrollTop = 20;
  await waitUntilNextAnimationFrame();
  await waitUntilNextAnimationFrame();

  assert_equals(target2.getBoundingClientRect().top, anchor2.getBoundingClientRect().top);
  assert_equals(target2.getBoundingClientRect().top, 155);
}, 'target2 should scroll with anchor2');

promise_test(async () => {
  scroller3.scrollTop = 30;
  await waitUntilNextAnimationFrame();
  await waitUntilNextAnimationFrame();

  assert_equals(target3.getBoundingClientRect().top, anchor3.getBoundingClientRect().top);
  assert_equals(target3.getBoundingClientRect().top, 270);
}, 'target3 should scroll with anchor3');
</script>
