// Copyright 2015 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 "remoting/protocol/capture_scheduler.h"

#include <stddef.h>

#include <utility>

#include "base/bind.h"
#include "base/memory/ptr_util.h"
#include "base/stl_util.h"
#include "base/test/simple_test_tick_clock.h"
#include "base/test/task_environment.h"
#include "base/timer/mock_timer.h"
#include "remoting/proto/video.pb.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace remoting {
namespace protocol {

static const int kTestInputs[] = { 100, 50, 30, 20, 10, 30, 60, 80 };
static const int kMinumumFrameIntervalMs = 50;

class CaptureSchedulerTest : public testing::Test {
 public:
  CaptureSchedulerTest() : capture_called_(false) {}

  void InitScheduler() {
    scheduler_.reset(new CaptureScheduler(base::BindRepeating(
        &CaptureSchedulerTest::DoCapture, base::Unretained(this))));
    scheduler_->set_minimum_interval(
        base::TimeDelta::FromMilliseconds(kMinumumFrameIntervalMs));
    scheduler_->SetTickClockForTest(&tick_clock_);
    capture_timer_ = new base::MockOneShotTimer();
    scheduler_->SetTimerForTest(base::WrapUnique(capture_timer_));
    scheduler_->Start();
  }

  void DoCapture() {
    capture_called_ = true;
  }

  void CheckCaptureCalled() {
    EXPECT_TRUE(capture_called_);
    capture_called_ = false;
  }

  void SimulateSingleFrameCapture(
      base::TimeDelta capture_delay,
      base::TimeDelta encode_delay,
      base::TimeDelta expected_delay_between_frames) {
    capture_timer_->Fire();
    CheckCaptureCalled();
    tick_clock_.Advance(capture_delay);
    scheduler_->OnCaptureCompleted();

    VideoPacket packet;
    packet.set_encode_time_ms(encode_delay.InMilliseconds());
    scheduler_->OnFrameEncoded(&packet);

    scheduler_->OnFrameSent();

    std::unique_ptr<VideoAck> ack(new VideoAck());
    ack->set_frame_id(packet.frame_id());
    scheduler_->ProcessVideoAck(std::move(ack));

    EXPECT_TRUE(capture_timer_->IsRunning());
    EXPECT_EQ(std::max(base::TimeDelta(),
                       expected_delay_between_frames - capture_delay),
              capture_timer_->GetCurrentDelay());
  }

 protected:
  base::test::SingleThreadTaskEnvironment task_environment_;

  std::unique_ptr<CaptureScheduler> scheduler_;

  base::SimpleTestTickClock tick_clock_;

  // Owned by |scheduler_|.
  base::MockOneShotTimer* capture_timer_;

  bool capture_called_;
};

TEST_F(CaptureSchedulerTest, SingleSampleSameTimes) {
  const int kTestResults[][base::size(kTestInputs)] = {
      {400, 200, 120, 80, 50, 120, 240, 320},  // One core.
      {200, 100, 60, 50, 50, 60, 120, 160},    // Two cores.
      {100, 50, 50, 50, 50, 50, 60, 80},       // Four cores.
      {50, 50, 50, 50, 50, 50, 50, 50}         // Eight cores.
  };

  for (size_t i = 0; i < base::size(kTestResults); ++i) {
    for (size_t j = 0; j < base::size(kTestInputs); ++j) {
      InitScheduler();
      scheduler_->SetNumOfProcessorsForTest(1 << i);

      SimulateSingleFrameCapture(
          base::TimeDelta::FromMilliseconds(kTestInputs[j]),
          base::TimeDelta::FromMilliseconds(kTestInputs[j]),
          base::TimeDelta::FromMilliseconds(kTestResults[i][j]));
    }
  }
}

TEST_F(CaptureSchedulerTest, SingleSampleDifferentTimes) {
  const int kTestResults[][base::size(kTestInputs)] = {
      {360, 220, 120, 60, 60, 120, 220, 360},  // One core.
      {180, 110, 60, 50, 50, 60, 110, 180},    // Two cores.
      {90, 55, 50, 50, 50, 50, 55, 90},        // Four cores.
      {50, 50, 50, 50, 50, 50, 50, 50}         // Eight cores.
  };

  for (size_t i = 0; i < base::size(kTestResults); ++i) {
    for (size_t j = 0; j < base::size(kTestInputs); ++j) {
      InitScheduler();
      scheduler_->SetNumOfProcessorsForTest(1 << i);

      SimulateSingleFrameCapture(
          base::TimeDelta::FromMilliseconds(kTestInputs[j]),
          base::TimeDelta::FromMilliseconds(
              kTestInputs[base::size(kTestInputs) - 1 - j]),
          base::TimeDelta::FromMilliseconds(kTestResults[i][j]));
    }
  }
}

TEST_F(CaptureSchedulerTest, RollingAverageDifferentTimes) {
  const int kTestResults[][base::size(kTestInputs)] = {
      {360, 290, 233, 133, 80, 80, 133, 233},  // One core.
      {180, 145, 116, 66, 50, 50, 66, 116},    // Two cores.
      {90, 72, 58, 50, 50, 50, 50, 58},        // Four cores.
      {50, 50, 50, 50, 50, 50, 50, 50}         // Eight cores.
  };

  for (size_t i = 0; i < base::size(kTestResults); ++i) {
    InitScheduler();
    scheduler_->SetNumOfProcessorsForTest(1 << i);
    for (size_t j = 0; j < base::size(kTestInputs); ++j) {
      SimulateSingleFrameCapture(
          base::TimeDelta::FromMilliseconds(kTestInputs[j]),
          base::TimeDelta::FromMilliseconds(
              kTestInputs[base::size(kTestInputs) - 1 - j]),
          base::TimeDelta::FromMilliseconds(kTestResults[i][j]));
    }
  }
}

// Verify that we never have more than 2 encoding frames.
TEST_F(CaptureSchedulerTest, MaximumEncodingFrames) {
  InitScheduler();

  // Process the first frame to let the scheduler know that receiver supports
  // ACKs.
  SimulateSingleFrameCapture(
      base::TimeDelta(), base::TimeDelta(),
      base::TimeDelta::FromMilliseconds(kMinumumFrameIntervalMs));

  capture_timer_->Fire();
  CheckCaptureCalled();
  scheduler_->OnCaptureCompleted();

  capture_timer_->Fire();
  CheckCaptureCalled();
  scheduler_->OnCaptureCompleted();

  EXPECT_FALSE(capture_timer_->IsRunning());
  VideoPacket packet;
  scheduler_->OnFrameEncoded(&packet);
  EXPECT_TRUE(capture_timer_->IsRunning());
}

// Verify that the scheduler doesn't exceed maximum number of pending frames.
TEST_F(CaptureSchedulerTest, MaximumPendingFrames) {
  InitScheduler();

  // Process the first frame to let the scheduler know that receiver supports
  // ACKs.
  SimulateSingleFrameCapture(
      base::TimeDelta(), base::TimeDelta(),
      base::TimeDelta::FromMilliseconds(kMinumumFrameIntervalMs));

  // Queue some frames until the sender is blocked.
  while (capture_timer_->IsRunning()) {
    capture_timer_->Fire();
    CheckCaptureCalled();
    scheduler_->OnCaptureCompleted();
    VideoPacket packet;
    scheduler_->OnFrameEncoded(&packet);
    scheduler_->OnFrameSent();
  }

  // Next frame should be scheduled, once one of the queued frames is
  // acknowledged.
  EXPECT_FALSE(capture_timer_->IsRunning());
  scheduler_->ProcessVideoAck(base::WrapUnique(new VideoAck()));
  EXPECT_TRUE(capture_timer_->IsRunning());
}

}  // namespace protocol
}  // namespace remoting