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'use strict';

['audio', 'video'].forEach((kind) => {
  // Make sure "ontrack" fires if a prevuously rolled back track is added back.
  promise_test(async t => {
    const constraints = {};
    constraints[kind] = true;
    const stream = await navigator.mediaDevices.getUserMedia(constraints);
    const [track] = stream.getTracks();
    t.add_cleanup(() => track.stop());

    const pc1 = new RTCPeerConnection();
    t.add_cleanup(() => pc1.close());
    const pc2 = new RTCPeerConnection();
    t.add_cleanup(() => pc2.close());

    pc1.addTrack(track, stream);
    pc2.addTrack(track, stream);
    const [pc1Transceiver] = pc1.getTransceivers();
    const [pc2Transceiver] = pc2.getTransceivers();

    let remoteStreamViaOnTrackPromise = getRemoteStreamViaOnTrackPromise(pc2);

    // Apply remote offer, but don't complete the entire exchange.
    await pc1.setLocalDescription();
    await pc2.setRemoteDescription(pc1.localDescription);
    // The addTrack-transceiver gets associated, no need for a second
    // transceiver.
    assert_equals(pc2.getTransceivers().length, 1);
    const remoteStream = await remoteStreamViaOnTrackPromise;
    assert_equals(remoteStream.id, stream.id);

    const onRemoveTrackPromise = new Promise(r => {
      remoteStream.onremovetrack = () => { r(); };
    });

    // Cause track removal due to rollback.
    await pc2.setRemoteDescription({type:'rollback'});
    // The track was removed.
    await onRemoveTrackPromise;

    // Sanity check that ontrack still fires if we add it back again by applying
    // the same remote offer.
    remoteStreamViaOnTrackPromise = getRemoteStreamViaOnTrackPromise(pc2);
    await pc2.setRemoteDescription(pc1.localDescription);
    const revivedRemoteStream = await remoteStreamViaOnTrackPromise;
    // This test only expects IDs to be the same. The same stream object should
    // also be used, but this should be covered by separate tests.
    // TODO(https://crbug.com/1321738): Add MediaStream identity tests.
    assert_equals(remoteStream.id, revivedRemoteStream.id);
    // No cheating, the same transciever should be used as before.
    assert_equals(pc2.getTransceivers().length, 1);
  }, `[${kind}] Track with stream: removal due to disassociation in rollback and then add it back again`);

  // This is the same test as above, but this time without any remote streams.
  // This test could fail if [[FiredDirection]] was not reset in a rollback but
  // the above version of the test might still pass due to the track being
  // re-added to its stream.
  promise_test(async t => {
    const constraints = {};
    constraints[kind] = true;
    const stream = await navigator.mediaDevices.getUserMedia(constraints);
    const [track] = stream.getTracks();
    t.add_cleanup(() => track.stop());

    const pc1 = new RTCPeerConnection();
    t.add_cleanup(() => pc1.close());
    const pc2 = new RTCPeerConnection();
    t.add_cleanup(() => pc2.close());

    pc1.addTrack(track);
    pc2.addTrack(track);
    const [pc1Transceiver] = pc1.getTransceivers();
    const [pc2Transceiver] = pc2.getTransceivers();

    let remoteTrackPromise = getTrackViaOnTrackPromise(pc2);

    // Apply remote offer, but don't complete the entire exchange.
    await pc1.setLocalDescription();
    await pc2.setRemoteDescription(pc1.localDescription);
    // The addTrack-transceiver gets associated, no need for a second
    // transceiver.
    assert_equals(pc2.getTransceivers().length, 1);
    const remoteTrack = await remoteTrackPromise;
    assert_not_equals(remoteTrack, null);

    // Cause track removal due to rollback.
    await pc2.setRemoteDescription({type:'rollback'});
    // There's nothing equivalent to stream.onremovetrack when you don't have a
    // stream, but the track should become muted (if it isn't already).
    if (!remoteTrack.muted) {
      await new Promise(r => remoteTrack.onmute = () => { r(); });
    }
    assert_equals(remoteTrack.muted, true);

    // Sanity check that ontrack still fires if we add it back again by applying
    // the same remote offer.
    remoteTrackPromise = getTrackViaOnTrackPromise(pc2);
    await pc2.setRemoteDescription(pc1.localDescription);
    const revivedRemoteTrack = await remoteTrackPromise;
    // We can be sure the same track is used, because the same transceiver is
    // used (and transciever.receiver.track has same lifetime as transceiver).
    assert_equals(pc2.getTransceivers().length, 1);
    assert_equals(remoteTrack, revivedRemoteTrack);
  }, `[${kind}] Track without stream: removal due to disassociation in rollback and then add it back`);

  // Make sure "ontrack" can fire in a rollback (undo making it inactive).
  promise_test(async t => {
    const constraints = {};
    constraints[kind] = true;
    const stream = await navigator.mediaDevices.getUserMedia(constraints);
    const [track] = stream.getTracks();
    t.add_cleanup(() => track.stop());

    const pc1 = new RTCPeerConnection();
    t.add_cleanup(() => pc1.close());
    const pc2 = new RTCPeerConnection();
    t.add_cleanup(() => pc2.close());

    pc1.addTrack(track, stream);
    const [pc1Transceiver] = pc1.getTransceivers();

    let remoteStreamViaOnTrackPromise = getRemoteStreamViaOnTrackPromise(pc2);

    // Complete O/A exchange such that the transceiver gets associated.
    await pc1.setLocalDescription();
    await pc2.setRemoteDescription(pc1.localDescription);
    await pc2.setLocalDescription();
    await pc1.setRemoteDescription(pc2.localDescription);
    const [pc2Transceiver] = pc2.getTransceivers();
    assert_equals(pc2Transceiver.direction, 'recvonly');
    assert_equals(pc2Transceiver.currentDirection, 'recvonly');

    const remoteStream = await remoteStreamViaOnTrackPromise;
    assert_equals(remoteStream.id, stream.id);
    const onRemoveTrackPromise = new Promise(r => {
      remoteStream.onremovetrack = () => { r(); };
    });

    // Cause track removal.
    pc1Transceiver.direction = 'inactive';
    await pc1.setLocalDescription();
    await pc2.setRemoteDescription(pc1.localDescription);
    // The track was removed.
    await onRemoveTrackPromise;

    // Rolling back the offer revives the track, causing ontrack to fire again.
    remoteStreamViaOnTrackPromise = getRemoteStreamViaOnTrackPromise(pc2);
    await pc2.setRemoteDescription({type:'rollback'});
    const revivedRemoteStream = await remoteStreamViaOnTrackPromise;
    // This test only expects IDs to be the same. The same stream object should
    // also be used, but this should be covered by separate tests.
    // TODO(https://crbug.com/1321738): Add MediaStream identity tests.
    assert_equals(remoteStream.id, revivedRemoteStream.id);
  }, `[${kind}] Track with stream: removal due to direction changing and then add back using rollback`);

  // Same test as above but without remote streams.
  promise_test(async t => {
    const constraints = {};
    constraints[kind] = true;
    const stream = await navigator.mediaDevices.getUserMedia(constraints);
    const [track] = stream.getTracks();
    t.add_cleanup(() => track.stop());

    const pc1 = new RTCPeerConnection();
    t.add_cleanup(() => pc1.close());
    const pc2 = new RTCPeerConnection();
    t.add_cleanup(() => pc2.close());

    pc1.addTrack(track);
    const [pc1Transceiver] = pc1.getTransceivers();

    let remoteTrackPromise = getTrackViaOnTrackPromise(pc2);

    // Complete O/A exchange such that the transceiver gets associated.
    await pc1.setLocalDescription();
    await pc2.setRemoteDescription(pc1.localDescription);
    await pc2.setLocalDescription();
    await pc1.setRemoteDescription(pc2.localDescription);
    const [pc2Transceiver] = pc2.getTransceivers();
    assert_equals(pc2Transceiver.direction, 'recvonly');
    assert_equals(pc2Transceiver.currentDirection, 'recvonly');

    const remoteTrack = await remoteTrackPromise;

    // Cause track removal.
    pc1Transceiver.direction = 'inactive';
    await pc1.setLocalDescription();
    await pc2.setRemoteDescription(pc1.localDescription);
    // There's nothing equivalent to stream.onremovetrack when you don't have a
    // stream, but the track should become muted (if it isn't already).
    if (!remoteTrack.muted) {
      await new Promise(r => remoteTrack.onmute = () => { r(); });
    }
    assert_equals(remoteTrack.muted, true);

    // Rolling back the offer revives the track, causing ontrack to fire again.
    remoteTrackPromise = getTrackViaOnTrackPromise(pc2);
    await pc2.setRemoteDescription({type:'rollback'});
    const revivedRemoteTrack = await remoteTrackPromise;
    // We can be sure the same track is used, because the same transceiver is
    // used (and transciever.receiver.track has same lifetime as transceiver).
    assert_equals(pc2.getTransceivers().length, 1);
    assert_equals(remoteTrack, revivedRemoteTrack);
  }, `[${kind}] Track without stream: removal due to direction changing and then add back using rollback`);
});

function getTrackViaOnTrackPromise(pc) {
  return new Promise(r => {
    pc.ontrack = e => {
      pc.ontrack = null;
      r(e.track);
    };
  });
}

function getRemoteStreamViaOnTrackPromise(pc) {
  return new Promise(r => {
    pc.ontrack = e => {
      pc.ontrack = null;
      r(e.streams[0]);
    };
  });
}

</script>