[Exposed=(Window,Worker), SecureContext]
interface WebTransportDatagramDuplexStream {
  readonly attribute ReadableStream readable;
  readonly attribute WritableStream writable;

  readonly attribute unsigned long maxDatagramSize;
  attribute unrestricted double? incomingMaxAge;
  attribute unrestricted double? outgoingMaxAge;
  attribute unrestricted double incomingHighWaterMark;
  attribute unrestricted double outgoingHighWaterMark;
};

[Exposed=(Window,Worker), SecureContext]
interface WebTransport {
  constructor(USVString url, optional WebTransportOptions options = {});

  Promise<WebTransportConnectionStats> getStats();
  readonly attribute Promise<undefined> ready;
  readonly attribute WebTransportReliabilityMode reliability;
  readonly attribute WebTransportCongestionControl congestionControl;
  readonly attribute Promise<WebTransportCloseInfo> closed;
  readonly attribute Promise<undefined> draining;
  undefined close(optional WebTransportCloseInfo closeInfo = {});

  readonly attribute WebTransportDatagramDuplexStream datagrams;

  Promise<WebTransportBidirectionalStream> createBidirectionalStream(
      optional WebTransportSendStreamOptions options = {});
  /* a ReadableStream of WebTransportBidirectionalStream objects */
  readonly attribute ReadableStream incomingBidirectionalStreams;

  Promise<WebTransportSendStream> createUnidirectionalStream(
      optional WebTransportSendStreamOptions options = {});
  /* a ReadableStream of WebTransportReceiveStream objects */
  readonly attribute ReadableStream incomingUnidirectionalStreams;
  WebTransportSendGroup createSendGroup();

  static readonly attribute boolean supportsReliableOnly;
};

enum WebTransportReliabilityMode {
  "pending",
  "reliable-only",
  "supports-unreliable",
};

dictionary WebTransportHash {
  DOMString algorithm;
  BufferSource value;
};

dictionary WebTransportOptions {
  boolean allowPooling = false;
  boolean requireUnreliable = false;
  sequence<WebTransportHash> serverCertificateHashes;
  WebTransportCongestionControl congestionControl = "default";
};

enum WebTransportCongestionControl {
  "default",
  "throughput",
  "low-latency",
};

dictionary WebTransportCloseInfo {
  unsigned long closeCode = 0;
  USVString reason = "";
};

dictionary WebTransportSendStreamOptions {
  WebTransportSendGroup? sendGroup = null;
  long long sendOrder = 0;
  boolean waitUntilAvailable = false;
};

dictionary WebTransportConnectionStats {
  unsigned long long bytesSent;
  unsigned long long packetsSent;
  unsigned long long bytesLost;
  unsigned long long packetsLost;
  unsigned long long bytesReceived;
  unsigned long long packetsReceived;
  DOMHighResTimeStamp smoothedRtt;
  DOMHighResTimeStamp rttVariation;
  DOMHighResTimeStamp minRtt;
  WebTransportDatagramStats datagrams;
  unsigned long long? estimatedSendRate;
};

dictionary WebTransportDatagramStats {
  unsigned long long expiredOutgoing;
  unsigned long long droppedIncoming;
  unsigned long long lostOutgoing;
};

[Exposed=(Window,Worker), SecureContext, Transferable]
interface WebTransportSendStream : WritableStream {
  attribute WebTransportSendGroup? sendGroup;
  attribute long long sendOrder;
  Promise<WebTransportSendStreamStats> getStats();
};

dictionary WebTransportSendStreamStats {
  unsigned long long bytesWritten;
  unsigned long long bytesSent;
  unsigned long long bytesAcknowledged;
};

[Exposed=(Window,Worker), SecureContext]
interface WebTransportSendGroup {
  Promise<WebTransportSendStreamStats> getStats();
};

[Exposed=(Window,Worker), SecureContext, Transferable]
interface WebTransportReceiveStream : ReadableStream {
  Promise<WebTransportReceiveStreamStats> getStats();
};

dictionary WebTransportReceiveStreamStats {
  unsigned long long bytesReceived;
  unsigned long long bytesRead;
};

[Exposed=(Window,Worker), SecureContext]
interface WebTransportBidirectionalStream {
  readonly attribute WebTransportReceiveStream readable;
  readonly attribute WebTransportSendStream writable;
};

[Exposed=(Window,Worker), Serializable, SecureContext]
interface WebTransportError : DOMException {
  constructor(optional DOMString message = "", optional WebTransportErrorOptions options = {});

  readonly attribute WebTransportErrorSource source;
  readonly attribute unsigned long? streamErrorCode;
};

dictionary WebTransportErrorOptions {
  WebTransportErrorSource source = "stream";
  [Clamp] unsigned long? streamErrorCode = null;
};

enum WebTransportErrorSource {
  "stream",
  "session",
};