/*
 * Copyright (c) 2015 Natale Patriciello, <natale.patriciello@gmail.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#include "ns3/log.h"
#include "ns3/tcp-congestion-ops.h"
#include "ns3/tcp-hybla.h"
#include "ns3/tcp-socket-base.h"
#include "ns3/test.h"

using namespace ns3;

NS_LOG_COMPONENT_DEFINE("TcpHyblaTestSuite");

/**
 * @ingroup internet-test
 *
 * @brief Testing the congestion avoidance increment on TcpHybla
 */
class TcpHyblaIncrementTest : public TestCase
{
  public:
    /**
     * @brief Constructor.
     * @param cWnd Congestion window.
     * @param ssThresh Slow Start Threshold.
     * @param segmentSize Segment size.
     * @param rtt Round trip time.
     * @param name Test description.
     */
    TcpHyblaIncrementTest(uint32_t cWnd,
                          uint32_t ssThresh,
                          uint32_t segmentSize,
                          const Time& rtt,
                          const std::string& name);

  private:
    void DoRun() override;

    /**
     * @brief Tracks TCP Hybla rho parameter changes.
     * @param oldVal Previous value.
     * @param newVal Actual value.
     */
    void RhoUpdated(double oldVal, double newVal);

    uint32_t m_cWnd;             //!< Congestion window.
    uint32_t m_ssThresh;         //!< Slow Start Threshold.
    uint32_t m_segmentSize;      //!< Segment size.
    Time m_rtt;                  //!< Round trip time.
    double m_rho;                //!< TCP Hybla rho parameter.
    Ptr<TcpSocketState> m_state; //!< TCP socket state.
};

TcpHyblaIncrementTest::TcpHyblaIncrementTest(uint32_t cWnd,
                                             uint32_t ssThresh,
                                             uint32_t segmentSize,
                                             const Time& rtt,
                                             const std::string& name)
    : TestCase(name),
      m_cWnd(cWnd),
      m_ssThresh(ssThresh),
      m_segmentSize(segmentSize),
      m_rtt(rtt),
      m_rho(0)
{
}

void
TcpHyblaIncrementTest::RhoUpdated(double /* oldVal */, double newVal)
{
    m_rho = newVal;
}

void
TcpHyblaIncrementTest::DoRun()
{
    m_state = CreateObject<TcpSocketState>();

    m_state->m_cWnd = m_cWnd;
    m_state->m_ssThresh = m_ssThresh;
    m_state->m_segmentSize = m_segmentSize;
    m_state->m_minRtt = m_rtt;

    Ptr<TcpHybla> cong = CreateObject<TcpHybla>();

    cong->TraceConnectWithoutContext("Rho", MakeCallback(&TcpHyblaIncrementTest::RhoUpdated, this));

    // Each received ACK weight is "coeffA". To see an increase of 1 MSS, we need
    // to ACK at least segCwnd/coeffA ACK.

    TimeValue rRtt;
    cong->GetAttribute("RRTT", rRtt);
    cong->PktsAcked(m_state, 1, m_rtt);

    double calcRho = std::max(m_rtt.GetSeconds() / rRtt.Get().GetSeconds(), 1.0);

    NS_TEST_ASSERT_MSG_NE(m_rho, 0.0, "Rho never updated by implementation");
    NS_TEST_ASSERT_MSG_EQ_TOL(calcRho,
                              m_rho,
                              0.01,
                              "Different rho values between implementation and test");

    cong->IncreaseWindow(m_state, 1);

    if (m_cWnd <= m_ssThresh)
    {
        // We expect an increment of 2^rho - 1, which does not go beyond ssThresh
        double inc = std::pow(2, calcRho) - 1.0;
        uint32_t cWndExpected = m_cWnd + (inc * m_segmentSize);
        NS_TEST_ASSERT_MSG_LT_OR_EQ(m_state->m_cWnd.Get(),
                                    m_state->m_ssThresh.Get(),
                                    "Congestion window has gone too far");
        NS_TEST_ASSERT_MSG_EQ(m_state->m_cWnd.Get(),
                              cWndExpected,
                              "Congestion window different than expected");
    }
    else
    {
        // We expect an increment of rho^2 / cWnd
        uint32_t segCwnd = m_cWnd / m_segmentSize;
        double inc = std::pow(m_rho, 2) / ((double)segCwnd);
        uint32_t cWndExpected = m_cWnd + (inc * m_segmentSize);

        if (inc >= 1.0)
        {
            // LT because implementation does not add value less than MSS.
            NS_TEST_ASSERT_MSG_LT_OR_EQ(m_state->m_cWnd.Get(),
                                        cWndExpected,
                                        "Congestion window different than expected");
        }
    }
}

/**
 * @ingroup internet-test
 *
 * @brief TCP Hybla TestSuite
 */
class TcpHyblaTestSuite : public TestSuite
{
  public:
    TcpHyblaTestSuite()
        : TestSuite("tcp-hybla-test", Type::UNIT)
    {
        AddTestCase(new TcpHyblaIncrementTest(1000,
                                              0xFFFFFFFF,
                                              500,
                                              MilliSeconds(55),
                                              "Rho=1.1, slow start"),
                    TestCase::Duration::QUICK);
        AddTestCase(new TcpHyblaIncrementTest(1000,
                                              0xFFFFFFFF,
                                              500,
                                              MilliSeconds(100),
                                              "Rho=2, slow start"),
                    TestCase::Duration::QUICK);
        AddTestCase(new TcpHyblaIncrementTest(1000,
                                              0xFFFFFFFF,
                                              500,
                                              MilliSeconds(750),
                                              "Rho=30, slow start"),
                    TestCase::Duration::QUICK);
        AddTestCase(new TcpHyblaIncrementTest(1000, 500, 500, Seconds(0.55), "Rho=1.1, cong avoid"),
                    TestCase::Duration::QUICK);
        AddTestCase(new TcpHyblaIncrementTest(1000, 500, 500, Seconds(0.1), "Rho=2, cong avoid"),
                    TestCase::Duration::QUICK);
        AddTestCase(new TcpHyblaIncrementTest(1000, 500, 500, Seconds(0.75), "Rho=30, cong avoid"),
                    TestCase::Duration::QUICK);
    }
};

static TcpHyblaTestSuite g_tcpHyblaTest; //!< Static variable for test initialization
