// Copyright (c) 2012 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 "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "net/quic/congestion_control/paced_sender.h"
#include "net/quic/quic_protocol.h"
#include "net/quic/test_tools/mock_clock.h"
#include "testing/gmock/include/gmock/gmock.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace net {
namespace test {

const int kHundredKBytesPerS = 100;

class PacedSenderTest : public ::testing::Test {
 protected:
  PacedSenderTest()
      : zero_time_(QuicTime::Delta::Zero()),
        paced_sender_(new PacedSender(
            QuicBandwidth::FromKBytesPerSecond(kHundredKBytesPerS),
            kDefaultMaxPacketSize)) {
  }

  const QuicTime::Delta zero_time_;
  MockClock clock_;
  scoped_ptr<PacedSender> paced_sender_;
};

TEST_F(PacedSenderTest, Basic) {
  paced_sender_->UpdateBandwidthEstimate(clock_.Now(),
      QuicBandwidth::FromKBytesPerSecond(kHundredKBytesPerS * 10));
  EXPECT_TRUE(paced_sender_->TimeUntilSend(clock_.Now(), zero_time_).IsZero());
  paced_sender_->OnPacketSent(clock_.Now(), kDefaultMaxPacketSize);
  EXPECT_TRUE(paced_sender_->TimeUntilSend(clock_.Now(), zero_time_).IsZero());
  paced_sender_->OnPacketSent(clock_.Now(), kDefaultMaxPacketSize);
  EXPECT_EQ(static_cast<int64>(kDefaultMaxPacketSize * 2),
            paced_sender_->TimeUntilSend(
                clock_.Now(), zero_time_).ToMicroseconds());
  clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(24));
  EXPECT_TRUE(paced_sender_->TimeUntilSend(clock_.Now(), zero_time_).IsZero());
}

TEST_F(PacedSenderTest, LowRate) {
  paced_sender_->UpdateBandwidthEstimate(clock_.Now(),
      QuicBandwidth::FromKBytesPerSecond(kHundredKBytesPerS));
  EXPECT_TRUE(paced_sender_->TimeUntilSend(clock_.Now(), zero_time_).IsZero());
  paced_sender_->OnPacketSent(clock_.Now(), kDefaultMaxPacketSize);
  EXPECT_TRUE(paced_sender_->TimeUntilSend(clock_.Now(), zero_time_).IsZero());
  paced_sender_->OnPacketSent(clock_.Now(), kDefaultMaxPacketSize);
  EXPECT_EQ(static_cast<int64>(kDefaultMaxPacketSize * 20),
            paced_sender_->TimeUntilSend(
                clock_.Now(), zero_time_).ToMicroseconds());
  clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(24));
  EXPECT_TRUE(paced_sender_->TimeUntilSend(clock_.Now(), zero_time_).IsZero());
}

TEST_F(PacedSenderTest, HighRate) {
  QuicBandwidth bandwidth_estimate = QuicBandwidth::FromKBytesPerSecond(
      kHundredKBytesPerS * 100);
  paced_sender_->UpdateBandwidthEstimate(clock_.Now(), bandwidth_estimate);
  EXPECT_TRUE(paced_sender_->TimeUntilSend(clock_.Now(), zero_time_).IsZero());
  for (int i = 0; i < 16; ++i) {
    paced_sender_->OnPacketSent(clock_.Now(), kDefaultMaxPacketSize);
    EXPECT_TRUE(paced_sender_->TimeUntilSend(
        clock_.Now(), zero_time_).IsZero());
  }
  paced_sender_->OnPacketSent(clock_.Now(), kDefaultMaxPacketSize);
  EXPECT_EQ(2040, paced_sender_->TimeUntilSend(
      clock_.Now(), zero_time_).ToMicroseconds());
  clock_.AdvanceTime(QuicTime::Delta::FromMicroseconds(20400));
  EXPECT_TRUE(paced_sender_->TimeUntilSend(clock_.Now(), zero_time_).IsZero());
}

}  // namespace test
}  // namespace net