<!doctype html>
<title>Same document navigation to text fragment directives</title>
<meta charset=utf-8>
<link rel="help" href="https://wicg.github.io/ScrollToTextFragment/">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
  function reset() {
    location.hash = '';
    window.scrollTo(0, 0);
  }

  function isInViewport(element) {
    const viewportRect = {
      left: visualViewport.offsetLeft,
      top: visualViewport.offsetTop,
      right: visualViewport.offsetLeft + visualViewport.width,
      bottom: visualViewport.offsetTop + visualViewport.height
    };

    const elementRect = element.getBoundingClientRect();
    const elementCenter = {
      x: elementRect.left + elementRect.width / 2,
      y: elementRect.top + elementRect.height / 2
    };

    return elementCenter.x > viewportRect.left &&
           elementCenter.x < viewportRect.right &&
           elementCenter.y > viewportRect.top &&
           elementCenter.y < viewportRect.bottom;
  }

  function runTests() {
    // Ensure a simple text directive works correctly when navigated to the
    // same document using `location.hash`.
    promise_test(async t => {
      assert_implements(document.fragmentDirective, 'Text directive not implemented');
      reset();

      location.hash = ':~:text=line%20of%20text';
      await t.step_wait(() => window.scrollY > 0, "Wait for scroll");
      assert_true(isInViewport(document.getElementById('text')), 'Scrolled to text');
    }, 'Basic text directive navigation');

    // Test that we correctly fallback to the element id when we have a text
    // directive that doesn't match any text in the page.
    promise_test(async t => {
      assert_implements(document.fragmentDirective, 'Text directive not implemented');
      reset();

      location.hash = 'elementid:~:text=textDoesntExist';
      await t.step_wait(() => window.scrollY > 0, "Wait for scroll");
      assert_true(isInViewport(document.getElementById('elementid')), 'Scrolled to `elementid`');
    }, 'Basic element id fallback');

    // Test that we correctly fallback to the element id when we have a text
    // directive that's malformed and won't be parsed.
    promise_test(async t => {
      assert_implements(document.fragmentDirective, 'Text directive not implemented');
      reset();

      location.hash = 'elementid:~:text=,,,,,';
      await t.step_wait(() => window.scrollY > 0, "Wait for scroll");
      assert_true(isInViewport(document.getElementById('elementid')), 'Scrolled to `elementid`');
    }, 'Malformed text directive element id fallback');
  }
</script>
<style>
  div {
    margin: 200vh 0 200vh 0;
  }
</style>
<body onload="runTests()">
  <div id="text">
    This is a line of text.
  </div>
  <div id="elementid">
    This div has an id: 'elementid'.
  </div>
</body>
