<!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>
body {
  margin: 0;
}
pre, #log {
  position: absolute;
  top: 0;
  left: 200px;
}
.spacer {
  height: calc(100vh + 100px);
}
#target {
  width: 100px;
  height: 100px;
  visibility: hidden;
}
</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 = [];

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

function step0() {
  document.scrollingElement.scrollTop = 300;
  runTestCycle(step1, "document.scrollingElement.scrollTop = 300");
  // The numbers in brackets are target client rect; intersection rect;
  // and root bounds.
  checkLastEntry(entries, 0, [0, 100, vh + 100, vh + 200, 0, 0, 0, 0, 0, vw, 0, vh, false]);
}

function step1() {
  document.scrollingElement.scrollTop = 0;
  checkLastEntry(entries, 1, [0, 100, vh - 200, vh - 100, 0, 100, vh - 200, vh - 100, 0, vw, 0, vh, true]);
}
</script>