<!doctype html>
<meta charset=utf-8>
<title>RTCPeerConnection.prototype.setRemoteDescription rollback</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="RTCPeerConnection-helper.js"></script>
<script>
  'use strict';

  // Test is based on the following editor draft:
  // https://w3c.github.io/webrtc-pc/archives/20170605/webrtc.html

  // The following helper functions are called from RTCPeerConnection-helper.js:
  //   assert_session_desc_similar
  //   generateAudioReceiveOnlyOffer
  //   generateDataChannelOffer

  /*
    4.3.2.  Interface Definition
      [Constructor(optional RTCConfiguration configuration)]
      interface RTCPeerConnection : EventTarget {
        Promise<void>                      setLocalDescription(
            RTCSessionDescriptionInit description);

        readonly attribute RTCSessionDescription? localDescription;
        readonly attribute RTCSessionDescription? currentLocalDescription;
        readonly attribute RTCSessionDescription? pendingLocalDescription;

        Promise<void>                      setRemoteDescription(
            RTCSessionDescriptionInit description);

        readonly attribute RTCSessionDescription? remoteDescription;
        readonly attribute RTCSessionDescription? currentRemoteDescription;
        readonly attribute RTCSessionDescription? pendingRemoteDescription;
        ...
      };

    4.6.2.  RTCSessionDescription Class
      dictionary RTCSessionDescriptionInit {
        required RTCSdpType type;
                 DOMString  sdp = "";
      };

    4.6.1.  RTCSdpType
      enum RTCSdpType {
        "offer",
        "pranswer",
        "answer",
        "rollback"
      };
   */

  /*
    4.3.1.6.  Set the RTCSessionSessionDescription
      2.2.3.  Otherwise, if description is set as a remote description, then run one
              of the following steps:
        - If description is of type "rollback", then this is a rollback.
          Set connection.pendingRemoteDescription to null and signaling state to stable.
   */
  promise_test(t => {
    const pc = new RTCPeerConnection();
    t.add_cleanup(() => pc.close());

    const states = [];
    pc.addEventListener('signalingstatechange', () => states.push(pc.signalingState));

    return generateDataChannelOffer(pc)
    .then(offer => pc.setRemoteDescription(offer))
    .then(() => {
      assert_equals(pc.signalingState, 'have-remote-offer');
      assert_not_equals(pc.remoteDescription, null);
      assert_not_equals(pc.pendingRemoteDescription, null);
      assert_equals(pc.currentRemoteDescription, null);

      return pc.setRemoteDescription({ type: 'rollback' });
    })
    .then(() => {
      assert_equals(pc.signalingState, 'stable');
      assert_equals(pc.remoteDescription, null);
      assert_equals(pc.pendingRemoteDescription, null);
      assert_equals(pc.currentRemoteDescription, null);

      assert_array_equals(states, ['have-remote-offer', 'stable']);
    });
  }, 'setRemoteDescription(rollback) in have-remote-offer state should revert to stable state');

  /*
    4.3.1.6.  Set the RTCSessionSessionDescription
      2.3.  If the description's type is invalid for the current signaling state of
            connection, then reject p with a newly created InvalidStateError and abort
            these steps.

    [jsep]
      4.1.8.2.  Rollback
        - Rollback can only be used to cancel proposed changes;
          there is no support for rolling back from a stable state to a
          previous stable state
   */
  promise_test(t => {
    const pc = new RTCPeerConnection();
    t.add_cleanup(() => pc.close());
    return promise_rejects(t, 'InvalidStateError',
      pc.setRemoteDescription({ type: 'rollback' }));
  }, `setRemoteDescription(rollback) from stable state should reject with InvalidStateError`);

  promise_test(t => {
    const pc = new RTCPeerConnection();
    t.add_cleanup(() => pc.close());
    return generateAudioReceiveOnlyOffer(pc)
    .then(offer => pc.setRemoteDescription(offer))
    .then(() => pc.setRemoteDescription({
      type: 'rollback',
      sdp: '!<Invalid SDP Content>;'
    }));
  }, `setRemoteDescription(rollback) should ignore invalid sdp content and succeed`);

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

    // We don't use this right away
    const offer1 = await pc1.createOffer({offerToReceiveAudio: true});

    // Create offer from pc2, apply and rollback on pc1
    const offer2 = await pc2.createOffer({offerToReceiveAudio: true});
    await pc1.setRemoteDescription(offer2);
    await pc1.setRemoteDescription({type: "rollback"});

    // Then try applying pc1's old offer
    await pc1.setLocalDescription(offer1);
  }, `local offer created before setRemoteDescription(remote offer) then rollback should still be usable`);

</script>