<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/webxr_util.js"></script>
<script src="resources/webxr_test_constants_single_view.js"></script>

<script>
let testName = "XRViewport attributes are valid even when there is only one view";

let fakeDeviceInitParams = TRACKED_IMMERSIVE_SINGLE_VIEWDEVICE;

let testFunction = function(session, fakeDeviceController, t, sessionObjects) {
  return session.requestReferenceSpace('local')
    .then((referenceSpace) => new Promise((resolve) =>{
      let webglLayer = sessionObjects.glLayer;
      function onFrame(time, xrFrame) {
        let pose = xrFrame.getViewerPose(referenceSpace);
        assert_not_equals(pose, null);
        assert_not_equals(pose.views, null);
        assert_equals(pose.views.length, 1);

        let leftView = pose.views[0];

        let leftViewport = webglLayer.getViewport(leftView);

        t.step(() => {
          // Ensure the views report the expected viewports into the WebGL layer.
          assert_true(leftViewport instanceof XRViewport);

          assert_not_equals(leftViewport, null);

          // Exact viewport values don't matter, but they must pass several tests:

          // Viewports have non-zero widths and heights.
          assert_greater_than(leftViewport.width, 0);
          assert_greater_than(leftViewport.height, 0);

          // Viewports are located within the framebuffer.
          assert_greater_than_equal(leftViewport.x, 0);
          assert_greater_than_equal(leftViewport.y, 0);
          assert_greater_than_equal(leftViewport.x, 0);
          assert_greater_than_equal(leftViewport.y, 0);

          assert_less_than_equal(
            leftViewport.x + leftViewport.width, webglLayer.framebufferWidth);
          assert_less_than_equal(
            leftViewport.y + leftViewport.height, webglLayer.framebufferHeight);
        });

        resolve();
      }
      session.requestAnimationFrame(onFrame);
  }));
};

xr_session_promise_test(
  testName, testFunction, fakeDeviceInitParams, 'immersive-vr');

</script>