/*
 *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "p2p/base/datagram_dtls_adaptor.h"

#include <algorithm>
#include <memory>
#include <utility>

#include "absl/memory/memory.h"
#include "absl/strings/string_view.h"
#include "api/rtc_error.h"
#include "logging/rtc_event_log/events/rtc_event_dtls_transport_state.h"
#include "logging/rtc_event_log/events/rtc_event_dtls_writable_state.h"
#include "logging/rtc_event_log/rtc_event_log.h"
#include "p2p/base/dtls_transport_internal.h"
#include "p2p/base/packet_transport_internal.h"
#include "rtc_base/buffer.h"
#include "rtc_base/checks.h"
#include "rtc_base/dscp.h"
#include "rtc_base/flags.h"
#include "rtc_base/logging.h"
#include "rtc_base/message_queue.h"
#include "rtc_base/rtc_certificate.h"
#include "rtc_base/ssl_stream_adapter.h"
#include "rtc_base/stream.h"
#include "rtc_base/thread.h"

#ifdef BYPASS_DATAGRAM_DTLS_TEST_ONLY
// Send unencrypted packets directly to ICE, bypassing datagtram
// transport. Use in tests only.
constexpr bool kBypassDatagramDtlsTestOnly = true;
#else
constexpr bool kBypassDatagramDtlsTestOnly = false;
#endif

namespace cricket {

DatagramDtlsAdaptor::DatagramDtlsAdaptor(
    IceTransportInternal* ice_transport,
    webrtc::DatagramTransportInterface* datagram_transport,
    const webrtc::CryptoOptions& crypto_options,
    webrtc::RtcEventLog* event_log)
    : crypto_options_(crypto_options),
      ice_transport_(ice_transport),
      datagram_transport_(datagram_transport),
      event_log_(event_log) {
  RTC_DCHECK(ice_transport_);
  RTC_DCHECK(datagram_transport_);
  ConnectToIceTransport();
}

void DatagramDtlsAdaptor::ConnectToIceTransport() {
  ice_transport_->SignalWritableState.connect(
      this, &DatagramDtlsAdaptor::OnWritableState);
  ice_transport_->SignalReadyToSend.connect(
      this, &DatagramDtlsAdaptor::OnReadyToSend);
  ice_transport_->SignalReceivingState.connect(
      this, &DatagramDtlsAdaptor::OnReceivingState);

  // Datagram transport does not propagate network route change.
  ice_transport_->SignalNetworkRouteChanged.connect(
      this, &DatagramDtlsAdaptor::OnNetworkRouteChanged);

  if (kBypassDatagramDtlsTestOnly) {
    // In bypass mode we have to subscribe to ICE read and sent events.
    // Test only case to use ICE directly instead of data transport.
    ice_transport_->SignalReadPacket.connect(
        this, &DatagramDtlsAdaptor::OnReadPacket);

    ice_transport_->SignalSentPacket.connect(
        this, &DatagramDtlsAdaptor::OnSentPacket);
  } else {
    // Subscribe to Data Transport read packets.
    datagram_transport_->SetDatagramSink(this);
    datagram_transport_->SetTransportStateCallback(this);
  }
}

DatagramDtlsAdaptor::~DatagramDtlsAdaptor() {
  // Unsubscribe from Datagram Transport dinks.
  datagram_transport_->SetDatagramSink(nullptr);
  datagram_transport_->SetTransportStateCallback(nullptr);
}

const webrtc::CryptoOptions& DatagramDtlsAdaptor::crypto_options() const {
  return crypto_options_;
}

int DatagramDtlsAdaptor::SendPacket(const char* data,
                                    size_t len,
                                    const rtc::PacketOptions& options,
                                    int flags) {
  // TODO(sukhanov): Handle options and flags.
  if (kBypassDatagramDtlsTestOnly) {
    // In bypass mode sent directly to ICE.
    return ice_transport_->SendPacket(data, len, options);
  }

  // Send datagram with id equal to options.packet_id, so we get it back
  // in DatagramDtlsAdaptor::OnDatagramSent() and propagate notification
  // up.
  webrtc::RTCError error = datagram_transport_->SendDatagram(
      rtc::MakeArrayView(reinterpret_cast<const uint8_t*>(data), len),
      /*datagram_id=*/options.packet_id);

  return (error.ok() ? len : -1);
}

void DatagramDtlsAdaptor::OnReadPacket(rtc::PacketTransportInternal* transport,
                                       const char* data,
                                       size_t size,
                                       const int64_t& packet_time_us,
                                       int flags) {
  // Only used in bypass mode.
  RTC_DCHECK(kBypassDatagramDtlsTestOnly);

  RTC_DCHECK_RUN_ON(&thread_checker_);
  RTC_DCHECK_EQ(transport, ice_transport_);
  RTC_DCHECK(flags == 0);

  PropagateReadPacket(
      rtc::MakeArrayView(reinterpret_cast<const uint8_t*>(data), size),
      packet_time_us);
}

void DatagramDtlsAdaptor::OnDatagramReceived(
    rtc::ArrayView<const uint8_t> data) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  RTC_DCHECK(!kBypassDatagramDtlsTestOnly);

  // TODO(sukhanov): I am not filling out time, but on my video quality
  // test in WebRTC the time was not set either and higher layers of the stack
  // overwrite -1 with current current rtc time. Leaveing comment for now to
  // make sure it works as expected.
  int64_t packet_time_us = -1;

  PropagateReadPacket(data, packet_time_us);
}

void DatagramDtlsAdaptor::OnDatagramSent(webrtc::DatagramId datagram_id) {
  // When we called DatagramTransportInterface::SendDatagram, we passed
  // packet_id as datagram_id, so we simply need to set it in sent_packet
  // and propagate notification up the stack.

  // Also see how DatagramDtlsAdaptor::OnSentPacket handles OnSentPacket
  // notification from ICE in bypass mode.
  rtc::SentPacket sent_packet(/*packet_id=*/datagram_id, rtc::TimeMillis());

  PropagateOnSentNotification(sent_packet);
}

void DatagramDtlsAdaptor::OnSentPacket(rtc::PacketTransportInternal* transport,
                                       const rtc::SentPacket& sent_packet) {
  // Only used in bypass mode.
  RTC_DCHECK(kBypassDatagramDtlsTestOnly);
  RTC_DCHECK_RUN_ON(&thread_checker_);

  PropagateOnSentNotification(sent_packet);
}

void DatagramDtlsAdaptor::PropagateOnSentNotification(
    const rtc::SentPacket& sent_packet) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  SignalSentPacket(this, sent_packet);
}

void DatagramDtlsAdaptor::PropagateReadPacket(
    rtc::ArrayView<const uint8_t> data,
    const int64_t& packet_time_us) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  SignalReadPacket(this, reinterpret_cast<const char*>(data.data()),
                   data.size(), packet_time_us, /*flags=*/0);
}

int DatagramDtlsAdaptor::component() const {
  return kDatagramDtlsAdaptorComponent;
}
bool DatagramDtlsAdaptor::IsDtlsActive() const {
  return false;
}
bool DatagramDtlsAdaptor::GetDtlsRole(rtc::SSLRole* role) const {
  return false;
}
bool DatagramDtlsAdaptor::SetDtlsRole(rtc::SSLRole role) {
  return false;
}
bool DatagramDtlsAdaptor::GetSrtpCryptoSuite(int* cipher) {
  return false;
}
bool DatagramDtlsAdaptor::GetSslCipherSuite(int* cipher) {
  return false;
}

rtc::scoped_refptr<rtc::RTCCertificate>
DatagramDtlsAdaptor::GetLocalCertificate() const {
  return nullptr;
}

bool DatagramDtlsAdaptor::SetLocalCertificate(
    const rtc::scoped_refptr<rtc::RTCCertificate>& certificate) {
  return false;
}

std::unique_ptr<rtc::SSLCertChain> DatagramDtlsAdaptor::GetRemoteSSLCertChain()
    const {
  return nullptr;
}

bool DatagramDtlsAdaptor::ExportKeyingMaterial(const std::string& label,
                                               const uint8_t* context,
                                               size_t context_len,
                                               bool use_context,
                                               uint8_t* result,
                                               size_t result_len) {
  return false;
}

bool DatagramDtlsAdaptor::SetRemoteFingerprint(const std::string& digest_alg,
                                               const uint8_t* digest,
                                               size_t digest_len) {
  // TODO(sukhanov): We probably should not called with fingerptints in
  // datagram scenario, but we may need to change code up the stack before
  // we can return false or DCHECK.
  return true;
}

bool DatagramDtlsAdaptor::SetSslMaxProtocolVersion(
    rtc::SSLProtocolVersion version) {
  // TODO(sukhanov): We may be able to return false and/or DCHECK that we
  // are not called if datagram transport is used, but we need to change
  // integration before we can do it.
  return true;
}

IceTransportInternal* DatagramDtlsAdaptor::ice_transport() {
  return ice_transport_;
}

// Similar implementaton as in p2p/base/dtls_transport.cc.
void DatagramDtlsAdaptor::OnReadyToSend(
    rtc::PacketTransportInternal* transport) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  if (writable()) {
    SignalReadyToSend(this);
  }
}

void DatagramDtlsAdaptor::OnWritableState(
    rtc::PacketTransportInternal* transport) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  RTC_DCHECK(transport == ice_transport_);
  RTC_LOG(LS_VERBOSE) << ": ice_transport writable state changed to "
                      << ice_transport_->writable();

  if (kBypassDatagramDtlsTestOnly) {
    // Note: SignalWritableState fired by set_writable.
    set_writable(ice_transport_->writable());
    return;
  }

  switch (dtls_state()) {
    case DTLS_TRANSPORT_NEW:
      break;
    case DTLS_TRANSPORT_CONNECTED:
      // Note: SignalWritableState fired by set_writable.
      // Do we also need set_receiving(ice_transport_->receiving()) here now, in
      // case we lose that signal before "DTLS" connects?
      // DtlsTransport::OnWritableState does not set_receiving in a similar
      // case, so leaving it out for the time being, but it would be good to
      // understand why.
      set_writable(ice_transport_->writable());
      break;
    case DTLS_TRANSPORT_CONNECTING:
      // Do nothing.
      break;
    case DTLS_TRANSPORT_FAILED:
    case DTLS_TRANSPORT_CLOSED:
      // Should not happen. Do nothing.
      break;
  }
}

void DatagramDtlsAdaptor::OnStateChanged(webrtc::MediaTransportState state) {
  // Convert MediaTransportState to DTLS state.
  switch (state) {
    case webrtc::MediaTransportState::kPending:
      set_dtls_state(DTLS_TRANSPORT_CONNECTING);
      break;

    case webrtc::MediaTransportState::kWritable:
      // Since we do not set writable state until datagram transport is
      // connected, we need to call set_writable first.
      set_writable(ice_transport_->writable());
      set_dtls_state(DTLS_TRANSPORT_CONNECTED);
      break;

    case webrtc::MediaTransportState::kClosed:
      set_dtls_state(DTLS_TRANSPORT_CLOSED);
      break;
  }
}

DtlsTransportState DatagramDtlsAdaptor::dtls_state() const {
  return dtls_state_;
}

const std::string& DatagramDtlsAdaptor::transport_name() const {
  return ice_transport_->transport_name();
}

bool DatagramDtlsAdaptor::writable() const {
  // NOTE that even if ice is writable, writable_ maybe false, because we
  // propagte writable only after DTLS is connect (this is consistent with
  // implementation in dtls_transport.cc).
  return writable_;
}

bool DatagramDtlsAdaptor::receiving() const {
  return receiving_;
}

int DatagramDtlsAdaptor::SetOption(rtc::Socket::Option opt, int value) {
  return ice_transport_->SetOption(opt, value);
}

int DatagramDtlsAdaptor::GetError() {
  return ice_transport_->GetError();
}

void DatagramDtlsAdaptor::OnNetworkRouteChanged(
    absl::optional<rtc::NetworkRoute> network_route) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  SignalNetworkRouteChanged(network_route);
}

void DatagramDtlsAdaptor::OnReceivingState(
    rtc::PacketTransportInternal* transport) {
  RTC_DCHECK_RUN_ON(&thread_checker_);
  RTC_DCHECK(transport == ice_transport_);
  RTC_LOG(LS_VERBOSE) << "ice_transport receiving state changed to "
                      << ice_transport_->receiving();

  if (kBypassDatagramDtlsTestOnly || dtls_state() == DTLS_TRANSPORT_CONNECTED) {
    // Note: SignalReceivingState fired by set_receiving.
    set_receiving(ice_transport_->receiving());
  }
}

void DatagramDtlsAdaptor::set_receiving(bool receiving) {
  if (receiving_ == receiving) {
    return;
  }
  receiving_ = receiving;
  SignalReceivingState(this);
}

// Similar implementaton as in p2p/base/dtls_transport.cc.
void DatagramDtlsAdaptor::set_writable(bool writable) {
  if (writable_ == writable) {
    return;
  }
  if (event_log_) {
    event_log_->Log(
        absl::make_unique<webrtc::RtcEventDtlsWritableState>(writable));
  }
  RTC_LOG(LS_VERBOSE) << "set_writable to: " << writable;
  writable_ = writable;
  if (writable_) {
    SignalReadyToSend(this);
  }
  SignalWritableState(this);
}

// Similar implementaton as in p2p/base/dtls_transport.cc.
void DatagramDtlsAdaptor::set_dtls_state(DtlsTransportState state) {
  if (dtls_state_ == state) {
    return;
  }
  if (event_log_) {
    event_log_->Log(absl::make_unique<webrtc::RtcEventDtlsTransportState>(
        ConvertDtlsTransportState(state)));
  }
  RTC_LOG(LS_VERBOSE) << "set_dtls_state from:" << dtls_state_ << " to "
                      << state;
  dtls_state_ = state;
  SignalDtlsState(this, state);
}

}  // namespace cricket