/*
 *  Copyright (c) 2012 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 <memory>

#include "testing/gmock/include/gmock/gmock.h"
#include "testing/gtest/include/gtest/gtest.h"

#include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
#include "webrtc/system_wrappers/include/metrics.h"
#include "webrtc/test/histogram.h"
#include "webrtc/video/call_stats.h"

using ::testing::_;
using ::testing::AnyNumber;
using ::testing::Return;

namespace webrtc {

class MockStatsObserver : public CallStatsObserver {
 public:
  MockStatsObserver() {}
  virtual ~MockStatsObserver() {}

  MOCK_METHOD2(OnRttUpdate, void(int64_t, int64_t));
};

class CallStatsTest : public ::testing::Test {
 public:
  CallStatsTest() : fake_clock_(12345) {}

 protected:
  virtual void SetUp() { call_stats_.reset(new CallStats(&fake_clock_)); }
  SimulatedClock fake_clock_;
  std::unique_ptr<CallStats> call_stats_;
};

TEST_F(CallStatsTest, AddAndTriggerCallback) {
  MockStatsObserver stats_observer;
  RtcpRttStats* rtcp_rtt_stats = call_stats_->rtcp_rtt_stats();
  call_stats_->RegisterStatsObserver(&stats_observer);
  fake_clock_.AdvanceTimeMilliseconds(1000);
  EXPECT_EQ(-1, rtcp_rtt_stats->LastProcessedRtt());

  const int64_t kRtt = 25;
  rtcp_rtt_stats->OnRttUpdate(kRtt);
  EXPECT_CALL(stats_observer, OnRttUpdate(kRtt, kRtt)).Times(1);
  call_stats_->Process();
  EXPECT_EQ(kRtt, rtcp_rtt_stats->LastProcessedRtt());

  const int64_t kRttTimeOutMs = 1500 + 10;
  fake_clock_.AdvanceTimeMilliseconds(kRttTimeOutMs);
  EXPECT_CALL(stats_observer, OnRttUpdate(_, _)).Times(0);
  call_stats_->Process();
  EXPECT_EQ(-1, rtcp_rtt_stats->LastProcessedRtt());

  call_stats_->DeregisterStatsObserver(&stats_observer);
}

TEST_F(CallStatsTest, ProcessTime) {
  MockStatsObserver stats_observer;
  call_stats_->RegisterStatsObserver(&stats_observer);
  RtcpRttStats* rtcp_rtt_stats = call_stats_->rtcp_rtt_stats();
  rtcp_rtt_stats->OnRttUpdate(100);

  // Time isn't updated yet.
  EXPECT_CALL(stats_observer, OnRttUpdate(_, _)).Times(0);
  call_stats_->Process();

  // Advance clock and verify we get an update.
  fake_clock_.AdvanceTimeMilliseconds(1000);
  EXPECT_CALL(stats_observer, OnRttUpdate(_, _)).Times(1);
  call_stats_->Process();

  // Advance clock just too little to get an update.
  fake_clock_.AdvanceTimeMilliseconds(999);
  rtcp_rtt_stats->OnRttUpdate(100);
  EXPECT_CALL(stats_observer, OnRttUpdate(_, _)).Times(0);
  call_stats_->Process();

  // Advance enough to trigger a new update.
  fake_clock_.AdvanceTimeMilliseconds(1);
  EXPECT_CALL(stats_observer, OnRttUpdate(_, _)).Times(1);
  call_stats_->Process();

  call_stats_->DeregisterStatsObserver(&stats_observer);
}

// Verify all observers get correct estimates and observers can be added and
// removed.
TEST_F(CallStatsTest, MultipleObservers) {
  MockStatsObserver stats_observer_1;
  call_stats_->RegisterStatsObserver(&stats_observer_1);
  // Add the second observer twice, there should still be only one report to the
  // observer.
  MockStatsObserver stats_observer_2;
  call_stats_->RegisterStatsObserver(&stats_observer_2);
  call_stats_->RegisterStatsObserver(&stats_observer_2);

  RtcpRttStats* rtcp_rtt_stats = call_stats_->rtcp_rtt_stats();
  const int64_t kRtt = 100;
  rtcp_rtt_stats->OnRttUpdate(kRtt);

  // Verify both observers are updated.
  fake_clock_.AdvanceTimeMilliseconds(1000);
  EXPECT_CALL(stats_observer_1, OnRttUpdate(kRtt, kRtt)).Times(1);
  EXPECT_CALL(stats_observer_2, OnRttUpdate(kRtt, kRtt)).Times(1);
  call_stats_->Process();

  // Deregister the second observer and verify update is only sent to the first
  // observer.
  call_stats_->DeregisterStatsObserver(&stats_observer_2);
  rtcp_rtt_stats->OnRttUpdate(kRtt);
  fake_clock_.AdvanceTimeMilliseconds(1000);
  EXPECT_CALL(stats_observer_1, OnRttUpdate(kRtt, kRtt)).Times(1);
  EXPECT_CALL(stats_observer_2, OnRttUpdate(kRtt, kRtt)).Times(0);
  call_stats_->Process();

  // Deregister the first observer.
  call_stats_->DeregisterStatsObserver(&stats_observer_1);
  rtcp_rtt_stats->OnRttUpdate(kRtt);
  fake_clock_.AdvanceTimeMilliseconds(1000);
  EXPECT_CALL(stats_observer_1, OnRttUpdate(kRtt, kRtt)).Times(0);
  EXPECT_CALL(stats_observer_2, OnRttUpdate(kRtt, kRtt)).Times(0);
  call_stats_->Process();
}

// Verify increasing and decreasing rtt triggers callbacks with correct values.
TEST_F(CallStatsTest, ChangeRtt) {
  MockStatsObserver stats_observer;
  call_stats_->RegisterStatsObserver(&stats_observer);
  RtcpRttStats* rtcp_rtt_stats = call_stats_->rtcp_rtt_stats();

  // Advance clock to be ready for an update.
  fake_clock_.AdvanceTimeMilliseconds(1000);

  // Set a first value and verify the callback is triggered.
  const int64_t kFirstRtt = 100;
  rtcp_rtt_stats->OnRttUpdate(kFirstRtt);
  EXPECT_CALL(stats_observer, OnRttUpdate(kFirstRtt, kFirstRtt)).Times(1);
  call_stats_->Process();

  // Increase rtt and verify the new value is reported.
  fake_clock_.AdvanceTimeMilliseconds(1000);
  const int64_t kHighRtt = kFirstRtt + 20;
  const int64_t kAvgRtt1 = 103;
  rtcp_rtt_stats->OnRttUpdate(kHighRtt);
  EXPECT_CALL(stats_observer, OnRttUpdate(kAvgRtt1, kHighRtt)).Times(1);
  call_stats_->Process();

  // Increase time enough for a new update, but not too much to make the
  // rtt invalid. Report a lower rtt and verify the old/high value still is sent
  // in the callback.
  fake_clock_.AdvanceTimeMilliseconds(1000);
  const int64_t kLowRtt = kFirstRtt - 20;
  const int64_t kAvgRtt2 = 102;
  rtcp_rtt_stats->OnRttUpdate(kLowRtt);
  EXPECT_CALL(stats_observer, OnRttUpdate(kAvgRtt2, kHighRtt)).Times(1);
  call_stats_->Process();

  // Advance time to make the high report invalid, the lower rtt should now be
  // in the callback.
  fake_clock_.AdvanceTimeMilliseconds(1000);
  const int64_t kAvgRtt3 = 95;
  EXPECT_CALL(stats_observer, OnRttUpdate(kAvgRtt3, kLowRtt)).Times(1);
  call_stats_->Process();

  call_stats_->DeregisterStatsObserver(&stats_observer);
}

TEST_F(CallStatsTest, LastProcessedRtt) {
  MockStatsObserver stats_observer;
  call_stats_->RegisterStatsObserver(&stats_observer);
  RtcpRttStats* rtcp_rtt_stats = call_stats_->rtcp_rtt_stats();
  fake_clock_.AdvanceTimeMilliseconds(1000);

  // Set a first values and verify that LastProcessedRtt initially returns the
  // average rtt.
  const int64_t kRttLow = 10;
  const int64_t kRttHigh = 30;
  const int64_t kAvgRtt = 20;
  rtcp_rtt_stats->OnRttUpdate(kRttLow);
  rtcp_rtt_stats->OnRttUpdate(kRttHigh);
  EXPECT_CALL(stats_observer, OnRttUpdate(kAvgRtt, kRttHigh)).Times(1);
  call_stats_->Process();
  EXPECT_EQ(kAvgRtt, rtcp_rtt_stats->LastProcessedRtt());

  // Update values and verify LastProcessedRtt.
  fake_clock_.AdvanceTimeMilliseconds(1000);
  rtcp_rtt_stats->OnRttUpdate(kRttLow);
  rtcp_rtt_stats->OnRttUpdate(kRttHigh);
  EXPECT_CALL(stats_observer, OnRttUpdate(kAvgRtt, kRttHigh)).Times(1);
  call_stats_->Process();
  EXPECT_EQ(kAvgRtt, rtcp_rtt_stats->LastProcessedRtt());

  call_stats_->DeregisterStatsObserver(&stats_observer);
}

TEST_F(CallStatsTest, ProducesHistogramMetrics) {
  const int64_t kRtt = 123;
  RtcpRttStats* rtcp_rtt_stats = call_stats_->rtcp_rtt_stats();
  rtcp_rtt_stats->OnRttUpdate(kRtt);
  fake_clock_.AdvanceTimeMilliseconds(metrics::kMinRunTimeInSeconds * 1000);
  rtcp_rtt_stats->OnRttUpdate(kRtt);
  call_stats_->Process();
  call_stats_.reset();

  EXPECT_EQ(1, test::NumHistogramSamples(
                   "WebRTC.Video.AverageRoundTripTimeInMilliseconds"));
  EXPECT_EQ(kRtt, test::LastHistogramSample(
                      "WebRTC.Video.AverageRoundTripTimeInMilliseconds"));
}

}  // namespace webrtc