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<title>RTCPeerConnection Simulcast Answer</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
'use strict';

const offer_sdp = `v=0
o=- 3840232462471583827 2 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE 0
a=msid-semantic: WMS
m=video 9 UDP/TLS/RTP/SAVPF 96
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:Li6+
a=ice-pwd:3C05CTZBRQVmGCAq7hVasHlT
a=ice-options:trickle
a=fingerprint:sha-256 5B:D3:8E:66:0E:7D:D3:F3:8E:E6:80:28:19:FC:55:AD:58:5D:B9:3D:A8:DE:45:4A:E7:87:02:F8:3C:0B:3B:B3
a=setup:actpass
a=mid:0
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id
a=recvonly
a=rtcp-mux
a=rtpmap:96 VP8/90000
a=rtcp-fb:96 goog-remb
a=rtcp-fb:96 transport-cc
a=rtcp-fb:96 ccm fir
a=rid:foo recv
a=rid:bar recv
a=rid:baz recv
a=simulcast:recv foo;bar;baz
`;
// Tests for the construction of answers with simulcast according to:
// draft-ietf-mmusic-sdp-simulcast-13
// draft-ietf-mmusic-rid-15
promise_test(async t => {
  const pc = new RTCPeerConnection();
  t.add_cleanup(() => pc.close());
  const expected_rids = ['foo', 'bar', 'baz'];

  await pc.setRemoteDescription({type: 'offer', sdp: offer_sdp});
  const transceiver = pc.getTransceivers()[0];
  // The created transceiver should be in "recvonly" state. Allow it to send.
  transceiver.direction = 'sendonly';
  const answer = await pc.createAnswer();
  const answer_lines = answer.sdp.split('\r\n');
  // Check for a RID line for each layer.
  for (const rid of expected_rids) {
    const result = answer_lines.find(line => line.startsWith(`a=rid:${rid}`));
    assert_not_equals(result, undefined, `RID attribute for '${rid}' missing.`);
  }

  // Check for simulcast attribute with send direction and all RIDs.
  const result = answer_lines.find(
      line => line.startsWith(`a=simulcast:send ${expected_rids.join(';')}`));
  assert_not_equals(result, undefined, 'Could not find simulcast attribute.');
}, 'createAnswer() with multiple send encodings should create simulcast answer');

promise_test(async t => {
  const pc = new RTCPeerConnection();
  t.add_cleanup(() => pc.close());
  const expected_rids = ['foo', 'bar', 'baz'];

  // Try to disable the `bar` encoding in a=simulcast by prefixing it with the
  // `~` character.
  await pc.setRemoteDescription({type: 'offer', sdp: offer_sdp.replace(/(a=simulcast:.*)bar/, '$1~bar')});
  const transceiver = pc.getTransceivers()[0];
  transceiver.direction = 'sendonly';
  await pc.setLocalDescription();

  const parameters = pc.getSenders()[0].getParameters();
  const barEncoding = parameters.encodings.find(encoding => encoding.rid === 'bar');
  assert_not_equals(barEncoding, undefined);
  assert_not_equals(barEncoding.active, false);
}, 'Using the ~rid SDP syntax in a remote offer does not control the local encodings active flag');

promise_test(async t => {
  const pc = new RTCPeerConnection();
  t.add_cleanup(() => pc.close());
  const expected_rids = ['foo', 'bar', 'baz'];

  await pc.setRemoteDescription({type: 'offer', sdp: offer_sdp});
  const transceiver = pc.getTransceivers()[0];
  transceiver.direction = 'sendonly';
  await pc.setLocalDescription();

  // Disabling the encoding should not change the rid to ~rid.
  const parameters = pc.getSenders()[0].getParameters();
  parameters.encodings.forEach(e => e.active = false);
  await pc.getSenders()[0].setParameters(parameters);
  const offer = await pc.createOffer();

  const offer_lines = offer.sdp.split('\r\n');
  const result = offer_lines.find(
      line => line.startsWith(`a=simulcast:send ${expected_rids.join(';')}`));
  assert_not_equals(result, undefined, 'Could not find simulcast attribute.');
}, 'Disabling encodings locally does not change the SDP');
</script>
