// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cast/streaming/receiver_session.h"

#include <utility>

#include "cast/streaming/mock_environment.h"
#include "cast/streaming/receiver.h"
#include "cast/streaming/testing/simple_message_port.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "platform/base/ip_address.h"
#include "platform/test/fake_clock.h"
#include "platform/test/fake_task_runner.h"
#include "util/chrono_helpers.h"

using ::testing::_;
using ::testing::InSequence;
using ::testing::Invoke;
using ::testing::NiceMock;
using ::testing::Return;
using ::testing::StrictMock;

namespace openscreen {
namespace cast {

namespace {

constexpr char kValidOfferMessage[] = R"({
  "type": "OFFER",
  "seqNum": 1337,
  "offer": {
    "castMode": "mirroring",
    "receiverGetStatus": true,
    "supportedStreams": [
      {
        "index": 31337,
        "type": "video_source",
        "codecName": "vp9",
        "rtpProfile": "cast",
        "rtpPayloadType": 127,
        "ssrc": 19088743,
        "maxFrameRate": "60000/1000",
        "timeBase": "1/90000",
        "maxBitRate": 5000000,
        "profile": "main",
        "level": "4",
        "aesKey": "bbf109bf84513b456b13a184453b66ce",
        "aesIvMask": "edaf9e4536e2b66191f560d9c04b2a69",
        "resolutions": [
          {
            "width": 1280,
            "height": 720
          }
        ]
      },
      {
        "index": 31338,
        "type": "video_source",
        "codecName": "vp8",
        "rtpProfile": "cast",
        "rtpPayloadType": 127,
        "ssrc": 19088745,
        "maxFrameRate": "60000/1000",
        "timeBase": "1/90000",
        "maxBitRate": 5000000,
        "profile": "main",
        "level": "4",
        "aesKey": "040d756791711fd3adb939066e6d8690",
        "aesIvMask": "9ff0f022a959150e70a2d05a6c184aed",
        "resolutions": [
          {
            "width": 1280,
            "height": 720
          }
        ]
      },
      {
        "index": 1337,
        "type": "audio_source",
        "codecName": "opus",
        "rtpProfile": "cast",
        "rtpPayloadType": 97,
        "ssrc": 19088747,
        "bitRate": 124000,
        "timeBase": "1/48000",
        "channels": 2,
        "aesKey": "51027e4e2347cbcb49d57ef10177aebc",
        "aesIvMask": "7f12a19be62a36c04ae4116caaeff6d1"
      }
    ]
  }
})";

constexpr char kNoAudioOfferMessage[] = R"({
  "type": "OFFER",
  "seqNum": 1337,
  "offer": {
    "castMode": "mirroring",
    "receiverGetStatus": true,
    "supportedStreams": [
      {
        "index": 31338,
        "type": "video_source",
        "codecName": "vp8",
        "rtpProfile": "cast",
        "rtpPayloadType": 127,
        "ssrc": 19088745,
        "maxFrameRate": "60000/1000",
        "timeBase": "1/90000",
        "maxBitRate": 5000000,
        "profile": "main",
        "level": "4",
        "aesKey": "040d756791711fd3adb939066e6d8690",
        "aesIvMask": "9ff0f022a959150e70a2d05a6c184aed",
        "resolutions": [
          {
            "width": 1280,
            "height": 720
          }
        ]
      }
    ]
  }
})";

constexpr char kInvalidCodecOfferMessage[] = R"({
  "type": "OFFER",
  "seqNum": 1337,
  "offer": {
    "castMode": "mirroring",
    "receiverGetStatus": true,
    "supportedStreams": [
      {
        "index": 31338,
        "type": "video_source",
        "codecName": "vp12",
        "rtpProfile": "cast",
        "rtpPayloadType": 127,
        "ssrc": 19088745,
        "maxFrameRate": "60000/1000",
        "timeBase": "1/90000",
        "maxBitRate": 5000000,
        "profile": "main",
        "level": "4",
        "aesKey": "040d756791711fd3adb939066e6d8690",
        "aesIvMask": "9ff0f022a959150e70a2d05a6c184aed",
        "resolutions": [
          {
            "width": 1280,
            "height": 720
          }
        ]
      }
    ]
  }
})";

constexpr char kNoVideoOfferMessage[] = R"({
  "type": "OFFER",
  "seqNum": 1337,
  "offer": {
    "castMode": "mirroring",
    "receiverGetStatus": true,
    "supportedStreams": [
      {
        "index": 1337,
        "type": "audio_source",
        "codecName": "opus",
        "rtpProfile": "cast",
        "rtpPayloadType": 97,
        "ssrc": 19088747,
        "bitRate": 124000,
        "timeBase": "1/48000",
        "channels": 2,
        "aesKey": "51027e4e2347cbcb49d57ef10177aebc",
        "aesIvMask": "7f12a19be62a36c04ae4116caaeff6d1"
      }
    ]
  }
})";

constexpr char kNoAudioOrVideoOfferMessage[] = R"({
  "type": "OFFER",
  "seqNum": 1337,
  "offer": {
    "castMode": "mirroring",
    "receiverGetStatus": true,
    "supportedStreams": []
  }
})";

constexpr char kInvalidJsonOfferMessage[] = R"({
  "type": "OFFER",
  "seqNum": 1337,
  "offer": {
    "castMode": "mirroring",
    "receiverGetStatus": true,
    "supportedStreams": [
  }
})";

constexpr char kMissingMandatoryFieldOfferMessage[] = R"({
  "type": "OFFER",
  "seqNum": 1337
})";

constexpr char kMissingSeqNumOfferMessage[] = R"({
  "type": "OFFER",
  "offer": {
    "castMode": "mirroring",
    "receiverGetStatus": true,
    "supportedStreams": []
  }
})";

constexpr char kValidJsonInvalidFormatOfferMessage[] = R"({
  "type": "OFFER",
  "seqNum": 1337,
  "offer": {
    "castMode": "mirroring",
    "receiverGetStatus": true,
    "supportedStreams": "anything"
  }
})";

constexpr char kNullJsonOfferMessage[] = R"({
  "type": "OFFER",
  "seqNum": 1337
})";

constexpr char kInvalidSequenceNumberMessage[] = R"({
  "type": "OFFER",
  "seqNum": "not actually a number"
})";

constexpr char kUnknownTypeMessage[] = R"({
  "type": "OFFER_VERSION_2",
  "seqNum": 1337
})";

constexpr char kInvalidTypeMessage[] = R"({
  "type": 39,
  "seqNum": 1337
})";

class FakeClient : public ReceiverSession::Client {
 public:
  MOCK_METHOD(void,
              OnNegotiated,
              (const ReceiverSession*, ReceiverSession::ConfiguredReceivers),
              (override));
  MOCK_METHOD(void,
              OnReceiversDestroying,
              (const ReceiverSession*, ReceiversDestroyingReason),
              (override));
  MOCK_METHOD(void, OnError, (const ReceiverSession*, Error error), (override));
};

void ExpectIsErrorAnswerMessage(const ErrorOr<Json::Value>& message_or_error) {
  EXPECT_TRUE(message_or_error.is_value());
  const Json::Value message = std::move(message_or_error.value());
  EXPECT_TRUE(message["answer"].isNull());
  EXPECT_EQ("error", message["result"].asString());
  EXPECT_EQ(1337, message["seqNum"].asInt());
  EXPECT_EQ("ANSWER", message["type"].asString());

  const Json::Value& error = message["error"];
  EXPECT_TRUE(error.isObject());
  EXPECT_GT(error["code"].asInt(), 0);
}

}  // namespace

class ReceiverSessionTest : public ::testing::Test {
 public:
  ReceiverSessionTest() : clock_(Clock::time_point{}), task_runner_(&clock_) {}

  std::unique_ptr<MockEnvironment> MakeEnvironment() {
    auto environment_ = std::make_unique<NiceMock<MockEnvironment>>(
        &FakeClock::now, &task_runner_);
    ON_CALL(*environment_, GetBoundLocalEndpoint())
        .WillByDefault(Return(IPEndpoint{{127, 0, 0, 1}, 12345}));
    environment_->set_socket_state_for_testing(
        Environment::SocketState::kReady);
    return environment_;
  }

  void SetUp() {
    message_port_ = std::make_unique<SimpleMessagePort>("sender-12345");
    environment_ = MakeEnvironment();
    session_ = std::make_unique<ReceiverSession>(
        &client_, environment_.get(), message_port_.get(),
        ReceiverSession::Preferences{});
  }

 protected:
  void AssertGotAnErrorAnswerResponse() {
    const auto& messages = message_port_->posted_messages();
    ASSERT_EQ(1u, messages.size());

    auto message_body = json::Parse(messages[0]);
    ExpectIsErrorAnswerMessage(message_body);
  }

  StrictMock<FakeClient> client_;
  FakeClock clock_;
  std::unique_ptr<MockEnvironment> environment_;
  std::unique_ptr<SimpleMessagePort> message_port_;
  std::unique_ptr<ReceiverSession> session_;
  FakeTaskRunner task_runner_;
};

TEST_F(ReceiverSessionTest, CanNegotiateWithDefaultPreferences) {
  InSequence s;
  EXPECT_CALL(client_, OnNegotiated(session_.get(), _))
      .WillOnce([](const ReceiverSession* session_,
                   ReceiverSession::ConfiguredReceivers cr) {
        EXPECT_TRUE(cr.audio_receiver);
        EXPECT_EQ(cr.audio_receiver->config().sender_ssrc, 19088747u);
        EXPECT_EQ(cr.audio_receiver->config().receiver_ssrc, 19088748u);
        EXPECT_EQ(cr.audio_receiver->config().channels, 2);
        EXPECT_EQ(cr.audio_receiver->config().rtp_timebase, 48000);

        // We should have chosen opus
        EXPECT_EQ(cr.audio_config.codec, AudioCodec::kOpus);

        EXPECT_TRUE(cr.video_receiver);
        EXPECT_EQ(cr.video_receiver->config().sender_ssrc, 19088745u);
        EXPECT_EQ(cr.video_receiver->config().receiver_ssrc, 19088746u);
        EXPECT_EQ(cr.video_receiver->config().channels, 1);
        EXPECT_EQ(cr.video_receiver->config().rtp_timebase, 90000);

        // We should have chosen vp8
        EXPECT_EQ(cr.video_config.codec, VideoCodec::kVp8);
      });
  EXPECT_CALL(client_,
              OnReceiversDestroying(session_.get(),
                                    ReceiverSession::Client::kEndOfSession));

  message_port_->ReceiveMessage(kValidOfferMessage);

  const auto& messages = message_port_->posted_messages();
  ASSERT_EQ(1u, messages.size());

  auto message_body = json::Parse(messages[0]);
  EXPECT_TRUE(message_body.is_value());
  const Json::Value answer = std::move(message_body.value());

  EXPECT_EQ("ANSWER", answer["type"].asString());
  EXPECT_EQ(1337, answer["seqNum"].asInt());
  EXPECT_EQ("ok", answer["result"].asString());

  const Json::Value& answer_body = answer["answer"];
  EXPECT_TRUE(answer_body.isObject());

  // Spot check the answer body fields. We have more in depth testing
  // of answer behavior in answer_messages_unittest, but here we can
  // ensure that the ReceiverSession properly configured the answer.
  EXPECT_EQ(1337, answer_body["sendIndexes"][0].asInt());
  EXPECT_EQ(31338, answer_body["sendIndexes"][1].asInt());
  EXPECT_LT(0, answer_body["udpPort"].asInt());
  EXPECT_GT(65535, answer_body["udpPort"].asInt());

  // Get status should always be false, as we have no plans to implement it.
  EXPECT_EQ(false, answer_body["receiverGetStatus"].asBool());

  // Constraints and display should not be present with no preferences.
  EXPECT_TRUE(answer_body["constraints"].isNull());
  EXPECT_TRUE(answer_body["display"].isNull());
}

TEST_F(ReceiverSessionTest, CanNegotiateWithCustomCodecPreferences) {
  ReceiverSession session(
      &client_, environment_.get(), message_port_.get(),
      ReceiverSession::Preferences{{VideoCodec::kVp9}, {AudioCodec::kOpus}});

  InSequence s;
  EXPECT_CALL(client_, OnNegotiated(&session, _))
      .WillOnce([](const ReceiverSession* session_,
                   ReceiverSession::ConfiguredReceivers cr) {
        EXPECT_TRUE(cr.audio_receiver);
        EXPECT_EQ(cr.audio_receiver->config().sender_ssrc, 19088747u);
        EXPECT_EQ(cr.audio_receiver->config().receiver_ssrc, 19088748u);
        EXPECT_EQ(cr.audio_receiver->config().channels, 2);
        EXPECT_EQ(cr.audio_receiver->config().rtp_timebase, 48000);
        EXPECT_EQ(cr.audio_config.codec, AudioCodec::kOpus);

        EXPECT_TRUE(cr.video_receiver);
        EXPECT_EQ(cr.video_receiver->config().sender_ssrc, 19088743u);
        EXPECT_EQ(cr.video_receiver->config().receiver_ssrc, 19088744u);
        EXPECT_EQ(cr.video_receiver->config().channels, 1);
        EXPECT_EQ(cr.video_receiver->config().rtp_timebase, 90000);
        EXPECT_EQ(cr.video_config.codec, VideoCodec::kVp9);
      });
  EXPECT_CALL(client_, OnReceiversDestroying(
                           &session, ReceiverSession::Client::kEndOfSession));
  message_port_->ReceiveMessage(kValidOfferMessage);
}

TEST_F(ReceiverSessionTest, CanNegotiateWithCustomConstraints) {
  auto constraints = std::make_unique<Constraints>(Constraints{
      AudioConstraints{48001, 2, 32001, 32002, milliseconds(3001)},
      VideoConstraints{3.14159,
                       absl::optional<Dimensions>(
                           Dimensions{320, 240, SimpleFraction{24, 1}}),
                       Dimensions{1920, 1080, SimpleFraction{144, 1}}, 300000,
                       90000000, milliseconds(1000)}});

  auto display = std::make_unique<DisplayDescription>(DisplayDescription{
      absl::optional<Dimensions>(Dimensions{640, 480, SimpleFraction{60, 1}}),
      absl::optional<AspectRatio>(AspectRatio{16, 9}),
      absl::optional<AspectRatioConstraint>(AspectRatioConstraint::kFixed)});

  ReceiverSession session(&client_, environment_.get(), message_port_.get(),
                          ReceiverSession::Preferences{{VideoCodec::kVp9},
                                                       {AudioCodec::kOpus},
                                                       std::move(constraints),
                                                       std::move(display)});

  InSequence s;
  EXPECT_CALL(client_, OnNegotiated(&session, _));
  EXPECT_CALL(client_, OnReceiversDestroying(
                           &session, ReceiverSession::Client::kEndOfSession));
  message_port_->ReceiveMessage(kValidOfferMessage);

  const auto& messages = message_port_->posted_messages();
  ASSERT_EQ(1u, messages.size());

  auto message_body = json::Parse(messages[0]);
  ASSERT_TRUE(message_body.is_value());
  const Json::Value answer = std::move(message_body.value());

  const Json::Value& answer_body = answer["answer"];
  ASSERT_TRUE(answer_body.isObject());

  // Constraints and display should be valid with valid preferences.
  ASSERT_FALSE(answer_body["constraints"].isNull());
  ASSERT_FALSE(answer_body["display"].isNull());

  const Json::Value& display_json = answer_body["display"];
  EXPECT_EQ("16:9", display_json["aspectRatio"].asString());
  EXPECT_EQ("60", display_json["dimensions"]["frameRate"].asString());
  EXPECT_EQ(640, display_json["dimensions"]["width"].asInt());
  EXPECT_EQ(480, display_json["dimensions"]["height"].asInt());
  EXPECT_EQ("sender", display_json["scaling"].asString());

  const Json::Value& constraints_json = answer_body["constraints"];
  ASSERT_TRUE(constraints_json.isObject());

  const Json::Value& audio = constraints_json["audio"];
  ASSERT_TRUE(audio.isObject());
  EXPECT_EQ(32002, audio["maxBitRate"].asInt());
  EXPECT_EQ(2, audio["maxChannels"].asInt());
  EXPECT_EQ(3001, audio["maxDelay"].asInt());
  EXPECT_EQ(48001, audio["maxSampleRate"].asInt());
  EXPECT_EQ(32001, audio["minBitRate"].asInt());

  const Json::Value& video = constraints_json["video"];
  ASSERT_TRUE(video.isObject());
  EXPECT_EQ(90000000, video["maxBitRate"].asInt());
  EXPECT_EQ(1000, video["maxDelay"].asInt());
  EXPECT_EQ("144", video["maxDimensions"]["frameRate"].asString());
  EXPECT_EQ(1920, video["maxDimensions"]["width"].asInt());
  EXPECT_EQ(1080, video["maxDimensions"]["height"].asInt());
  EXPECT_DOUBLE_EQ(3.14159, video["maxPixelsPerSecond"].asDouble());
  EXPECT_EQ(300000, video["minBitRate"].asInt());
  EXPECT_EQ("24", video["minDimensions"]["frameRate"].asString());
  EXPECT_EQ(320, video["minDimensions"]["width"].asInt());
  EXPECT_EQ(240, video["minDimensions"]["height"].asInt());
}

TEST_F(ReceiverSessionTest, HandlesNoValidAudioStream) {
  InSequence s;
  EXPECT_CALL(client_, OnNegotiated(session_.get(), _));
  EXPECT_CALL(client_,
              OnReceiversDestroying(session_.get(),
                                    ReceiverSession::Client::kEndOfSession));

  message_port_->ReceiveMessage(kNoAudioOfferMessage);
  const auto& messages = message_port_->posted_messages();
  EXPECT_EQ(1u, messages.size());

  auto message_body = json::Parse(messages[0]);
  EXPECT_TRUE(message_body.is_value());
  const Json::Value& answer_body = message_body.value()["answer"];
  EXPECT_TRUE(answer_body.isObject());

  // Should still select video stream.
  EXPECT_EQ(1u, answer_body["sendIndexes"].size());
  EXPECT_EQ(31338, answer_body["sendIndexes"][0].asInt());
  EXPECT_EQ(1u, answer_body["ssrcs"].size());
  EXPECT_EQ(19088746, answer_body["ssrcs"][0].asInt());
}

TEST_F(ReceiverSessionTest, HandlesInvalidCodec) {
  // We didn't select any streams, but didn't have any errors either.
  message_port_->ReceiveMessage(kInvalidCodecOfferMessage);
  const auto& messages = message_port_->posted_messages();
  EXPECT_EQ(1u, messages.size());

  auto message_body = json::Parse(messages[0]);
  EXPECT_TRUE(message_body.is_value());

  // We should have failed to produce a valid answer message due to not
  // selecting any stream.
  EXPECT_EQ("error", message_body.value()["result"].asString());
}

TEST_F(ReceiverSessionTest, HandlesNoValidVideoStream) {
  InSequence s;
  EXPECT_CALL(client_, OnNegotiated(session_.get(), _));
  EXPECT_CALL(client_,
              OnReceiversDestroying(session_.get(),
                                    ReceiverSession::Client::kEndOfSession));

  message_port_->ReceiveMessage(kNoVideoOfferMessage);
  const auto& messages = message_port_->posted_messages();
  EXPECT_EQ(1u, messages.size());

  auto message_body = json::Parse(messages[0]);
  EXPECT_TRUE(message_body.is_value());
  const Json::Value& answer_body = message_body.value()["answer"];
  EXPECT_TRUE(answer_body.isObject());

  // Should still select audio stream.
  EXPECT_EQ(1u, answer_body["sendIndexes"].size());
  EXPECT_EQ(1337, answer_body["sendIndexes"][0].asInt());
  EXPECT_EQ(1u, answer_body["ssrcs"].size());
  EXPECT_EQ(19088748, answer_body["ssrcs"][0].asInt());
}

TEST_F(ReceiverSessionTest, HandlesNoValidStreams) {
  // We shouldn't call OnNegotiated if we failed to negotiate any streams.
  message_port_->ReceiveMessage(kNoAudioOrVideoOfferMessage);
  AssertGotAnErrorAnswerResponse();
}

TEST_F(ReceiverSessionTest, HandlesMalformedOffer) {
  // Note that unlike when we simply don't select any streams, when the offer
  // is not valid JSON we actually have no way of knowing it's an offer at all,
  // so we call OnError and do not reply with an Answer.
  EXPECT_CALL(client_, OnError(session_.get(), _));
  message_port_->ReceiveMessage(kInvalidJsonOfferMessage);
}

TEST_F(ReceiverSessionTest, HandlesMissingSeqNumInOffer) {
  // If the OFFER is missing a sequence number it gets rejected before being
  // parsed as an OFFER, since the sender expects all messages to come back
  // with a sequence number.
  message_port_->ReceiveMessage(kMissingSeqNumOfferMessage);
}

TEST_F(ReceiverSessionTest, HandlesOfferMissingMandatoryFields) {
  // If the OFFER is missing mandatory fields, we notify the client as well as
  // reply with an error-case Answer.
  EXPECT_CALL(client_, OnError(session_.get(), _));

  message_port_->ReceiveMessage(kMissingMandatoryFieldOfferMessage);
  AssertGotAnErrorAnswerResponse();
}

TEST_F(ReceiverSessionTest, HandlesImproperlyFormattedOffer) {
  EXPECT_CALL(client_, OnError(session_.get(), _));
  message_port_->ReceiveMessage(kValidJsonInvalidFormatOfferMessage);
  AssertGotAnErrorAnswerResponse();
}

TEST_F(ReceiverSessionTest, HandlesNullOffer) {
  EXPECT_CALL(client_, OnError(session_.get(), _));
  message_port_->ReceiveMessage(kNullJsonOfferMessage);
  AssertGotAnErrorAnswerResponse();
}

TEST_F(ReceiverSessionTest, HandlesInvalidSequenceNumber) {
  // We should just discard messages with an invalid sequence number.
  message_port_->ReceiveMessage(kInvalidSequenceNumberMessage);
}

TEST_F(ReceiverSessionTest, HandlesUnknownTypeMessage) {
  // We should just discard messages with an unknown message type.
  message_port_->ReceiveMessage(kUnknownTypeMessage);
}

TEST_F(ReceiverSessionTest, HandlesInvalidTypeMessage) {
  // We should just discard messages with an invalid message type.
  message_port_->ReceiveMessage(kInvalidTypeMessage);
}

TEST_F(ReceiverSessionTest, DoesNotCrashOnMessagePortError) {
  message_port_->ReceiveError(Error(Error::Code::kUnknownError));
}

TEST_F(ReceiverSessionTest, NotifiesReceiverDestruction) {
  InSequence s;
  EXPECT_CALL(client_, OnNegotiated(session_.get(), _));
  EXPECT_CALL(client_,
              OnReceiversDestroying(session_.get(),
                                    ReceiverSession::Client::kRenegotiated));
  EXPECT_CALL(client_, OnNegotiated(session_.get(), _));
  EXPECT_CALL(client_,
              OnReceiversDestroying(session_.get(),
                                    ReceiverSession::Client::kEndOfSession));

  message_port_->ReceiveMessage(kNoAudioOfferMessage);
  message_port_->ReceiveMessage(kValidOfferMessage);
}

TEST_F(ReceiverSessionTest, HandlesInvalidAnswer) {
  // Simulate an unbound local endpoint.
  EXPECT_CALL(*environment_, GetBoundLocalEndpoint)
      .WillOnce(Return(IPEndpoint{}));

  message_port_->ReceiveMessage(kValidOfferMessage);
  const auto& messages = message_port_->posted_messages();
  ASSERT_EQ(1u, messages.size());

  auto message_body = json::Parse(messages[0]);
  EXPECT_TRUE(message_body.is_value());
  const Json::Value answer = std::move(message_body.value());

  EXPECT_EQ("ANSWER", answer["type"].asString());
  EXPECT_EQ("error", answer["result"].asString());
}

TEST_F(ReceiverSessionTest, DelaysAnswerUntilEnvironmentIsReady) {
  environment_->set_socket_state_for_testing(
      Environment::SocketState::kStarting);

  // We should not have sent an answer yet--the UDP socket is not ready.
  message_port_->ReceiveMessage(kValidOfferMessage);
  ASSERT_TRUE(message_port_->posted_messages().empty());

  // Simulate the environment calling back into us with the socket being ready.
  // state() will not be called again--we just need to get the bind event.
  EXPECT_CALL(*environment_, GetBoundLocalEndpoint())
      .WillOnce(Return(IPEndpoint{{10, 0, 0, 2}, 4567}));
  EXPECT_CALL(client_, OnNegotiated(session_.get(), _));
  EXPECT_CALL(client_,
              OnReceiversDestroying(session_.get(),
                                    ReceiverSession::Client::kEndOfSession));
  session_->OnSocketReady();
  const auto& messages = message_port_->posted_messages();
  ASSERT_EQ(1u, messages.size());

  // We should have set the UDP port based on the ready socket value.
  auto message_body = json::Parse(messages[0]);
  EXPECT_TRUE(message_body.is_value());
  const Json::Value& answer_body = message_body.value()["answer"];
  EXPECT_TRUE(answer_body.isObject());
  EXPECT_EQ(4567, answer_body["udpPort"].asInt());
}

TEST_F(ReceiverSessionTest,
       ReturnsErrorAnswerIfEnvironmentIsAlreadyInvalidated) {
  environment_->set_socket_state_for_testing(
      Environment::SocketState::kInvalid);

  // If the environment is already in a bad state, we can respond immediately.
  message_port_->ReceiveMessage(kValidOfferMessage);
  const auto& messages = message_port_->posted_messages();
  ASSERT_EQ(1u, messages.size());

  auto message_body = json::Parse(messages[0]);
  EXPECT_TRUE(message_body.is_value());
  EXPECT_EQ("ANSWER", message_body.value()["type"].asString());
  EXPECT_EQ("error", message_body.value()["result"].asString());
}

TEST_F(ReceiverSessionTest, ReturnsErrorAnswerIfEnvironmentIsInvalidated) {
  environment_->set_socket_state_for_testing(
      Environment::SocketState::kStarting);

  // We should not have sent an answer yet--the environment is not ready.
  message_port_->ReceiveMessage(kValidOfferMessage);
  ASSERT_TRUE(message_port_->posted_messages().empty());

  // Simulate the environment calling back into us with invalidation.
  EXPECT_CALL(client_, OnError(_, _)).Times(1);
  session_->OnSocketInvalid(Error::Code::kSocketBindFailure);
  const auto& messages = message_port_->posted_messages();
  ASSERT_EQ(1u, messages.size());

  // We should have an error answer.
  auto message_body = json::Parse(messages[0]);
  EXPECT_TRUE(message_body.is_value());
  EXPECT_EQ("ANSWER", message_body.value()["type"].asString());
  EXPECT_EQ("error", message_body.value()["result"].asString());
}

}  // namespace cast
}  // namespace openscreen