/*
 * Copyright (c) 2014 University of Washington
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 * Author: Benjamin Cizdziel <ben.cizdziel@gmail.com>
 */

#include "tv-spectrum-transmitter.h"

#include "ns3/antenna-model.h"
#include "ns3/double.h"
#include "ns3/enum.h"
#include "ns3/integer.h"
#include "ns3/isotropic-antenna-model.h"
#include "ns3/log.h"
#include "ns3/pointer.h"
#include "ns3/simulator.h"
#include "ns3/string.h"
#include "ns3/uinteger.h"

#include <cmath>

namespace ns3
{

NS_LOG_COMPONENT_DEFINE("TvSpectrumTransmitter");

NS_OBJECT_ENSURE_REGISTERED(TvSpectrumTransmitter);

TvSpectrumTransmitter::TvSpectrumTransmitter()
    : m_mobility(nullptr),
      m_antenna(CreateObject<IsotropicAntennaModel>()),
      m_netDevice(nullptr),
      m_channel(nullptr),
      m_tvType(TVTYPE_8VSB),
      m_startFrequency(500e6),
      m_channelBandwidth(6e6),
      m_basePsd(20),
      m_txPsd(nullptr),
      m_startingTime(),
      m_transmitDuration(Seconds(0.2)),
      m_active(false)
{
    NS_LOG_FUNCTION(this);
}

TvSpectrumTransmitter::~TvSpectrumTransmitter()
{
    m_mobility = nullptr;
    m_antenna = nullptr;
    m_netDevice = nullptr;
    m_channel = nullptr;
    m_txPsd = nullptr;
    NS_LOG_FUNCTION(this);
}

TypeId
TvSpectrumTransmitter::GetTypeId()
{
    static TypeId tid =
        TypeId("ns3::TvSpectrumTransmitter")
            .SetParent<SpectrumPhy>()
            .SetGroupName("Spectrum")
            .AddConstructor<TvSpectrumTransmitter>()
            .AddAttribute(
                "TvType",
                "The type of TV transmitter/modulation to be used.",
                EnumValue(TvSpectrumTransmitter::TVTYPE_8VSB),
                MakeEnumAccessor<TvSpectrumTransmitter::TvType>(&TvSpectrumTransmitter::m_tvType),
                MakeEnumChecker(TvSpectrumTransmitter::TVTYPE_8VSB,
                                "8vsb",
                                TvSpectrumTransmitter::TVTYPE_COFDM,
                                "cofdm",
                                TvSpectrumTransmitter::TVTYPE_ANALOG,
                                "analog"))
            .AddAttribute("StartFrequency",
                          "The lower end frequency (in Hz) of the TV transmitter's "
                          "signal. Must be greater than or equal to 0.",
                          DoubleValue(500e6),
                          MakeDoubleAccessor(&TvSpectrumTransmitter::m_startFrequency),
                          MakeDoubleChecker<double>(0, std::numeric_limits<double>::max()))
            .AddAttribute("ChannelBandwidth",
                          "The bandwidth (in Hz) of the TV transmitter's signal. Must "
                          "be greater than or equal to 0.",
                          DoubleValue(6e6),
                          MakeDoubleAccessor(&TvSpectrumTransmitter::m_channelBandwidth),
                          MakeDoubleChecker<double>(0, std::numeric_limits<double>::max()))
            .AddAttribute("BasePsd",
                          "The base power spectral density (in dBm/Hz) of the TV "
                          "transmitter's transmitted spectrum. Base PSD is the "
                          "maximum PSD of the spectrum excluding pilots. For analog "
                          "and COFDM transmitters this is the maximum PSD, but for "
                          "8-VSB transmitters this is the maximum PSD of the main "
                          "signal spectrum (flat-top segment) since the pilot "
                          "actually has the maximum PSD overall.",
                          DoubleValue(20),
                          MakeDoubleAccessor(&TvSpectrumTransmitter::m_basePsd),
                          MakeDoubleChecker<double>())
            .AddAttribute("Antenna",
                          "The AntennaModel to be used. Allows classes inherited "
                          "from ns3::AntennaModel. Defaults to ns3::IsotropicAntennaModel.",
                          StringValue("ns3::IsotropicAntennaModel"),
                          MakePointerAccessor(&TvSpectrumTransmitter::m_antenna),
                          MakePointerChecker<AntennaModel>())
            .AddAttribute("StartingTime",
                          "The time point after the simulation begins in which the TV "
                          "transmitter will begin transmitting.",
                          TimeValue(Seconds(0)),
                          MakeTimeAccessor(&TvSpectrumTransmitter::m_startingTime),
                          MakeTimeChecker())
            .AddAttribute("TransmitDuration",
                          "The duration of time that the TV transmitter will transmit for.",
                          TimeValue(Seconds(0.2)),
                          MakeTimeAccessor(&TvSpectrumTransmitter::m_transmitDuration),
                          MakeTimeChecker());
    return tid;
}

void
TvSpectrumTransmitter::SetChannel(Ptr<SpectrumChannel> c)
{
    NS_LOG_FUNCTION(this << c);
    m_channel = c;
}

void
TvSpectrumTransmitter::SetMobility(Ptr<MobilityModel> m)
{
    NS_LOG_FUNCTION(this << m);
    m_mobility = m;
}

void
TvSpectrumTransmitter::SetDevice(Ptr<NetDevice> d)
{
    NS_LOG_FUNCTION(this << d);
    m_netDevice = d;
}

Ptr<MobilityModel>
TvSpectrumTransmitter::GetMobility() const
{
    NS_LOG_FUNCTION(this);
    return m_mobility;
}

Ptr<NetDevice>
TvSpectrumTransmitter::GetDevice() const
{
    NS_LOG_FUNCTION(this);
    return m_netDevice;
}

Ptr<const SpectrumModel>
TvSpectrumTransmitter::GetRxSpectrumModel() const
{
    NS_LOG_FUNCTION(this);
    return nullptr;
}

Ptr<Object>
TvSpectrumTransmitter::GetAntenna() const
{
    NS_LOG_FUNCTION(this);
    return m_antenna;
}

void
TvSpectrumTransmitter::StartRx(Ptr<SpectrumSignalParameters> params)
{
    NS_LOG_FUNCTION(this << params);
}

Ptr<SpectrumChannel>
TvSpectrumTransmitter::GetChannel() const
{
    NS_LOG_FUNCTION(this);
    return m_channel;
}

/// Used as key for map containing created spectrum models
struct TvSpectrumModelId
{
    /**
     * Constructor
     * @param stFreq Start frequency [Hz]
     * @param bwidth Bandwidth [Hz]
     */
    TvSpectrumModelId(double stFreq, double bwidth);
    double startFrequency; //!< Start frequency [Hz]
    double bandwidth;      //!< Bandwidth [Hz]
};

TvSpectrumModelId::TvSpectrumModelId(double stFreq, double bwidth)
    : startFrequency(stFreq),
      bandwidth(bwidth)
{
}

/**
 * Minus-than operator
 * @param a left operand
 * @param b right operand
 * @returns true if the left operand has a lower starting frequency
 *          or a smaller bandwidth (if both have the same starting freq.)
 */
bool
operator<(const TvSpectrumModelId& a, const TvSpectrumModelId& b)
{
    return ((a.startFrequency < b.startFrequency) ||
            ((a.startFrequency == b.startFrequency) && (a.bandwidth < b.bandwidth)));
}

/// Stores created spectrum models
static std::map<TvSpectrumModelId, Ptr<SpectrumModel>> g_tvSpectrumModelMap;

/**
 * 8-VSB PSD approximated from Figure 3 of the following article:
 * Baron, Stanley. "First-Hand:Digital Television: The Digital Terrestrial
 * Television Broadcasting (DTTB) Standard." IEEE Global History Network.
 * <http://www.ieeeghn.org/wiki/index.php/First-Hand:Digital_Television:_The_Digital_Terrestrial_Television_Broadcasting_(DTTB)_Standard>.
 *
 * COFDM PSD approximated from Figure 12 (8k mode) of the following article:
 * Kopp, Carlo. "High Definition Television." High Definition Television. Air
 * Power Australia. <http://www.ausairpower.net/AC-1100.html>.
 *
 * Analog PSD approximated from Figure 4 of the following paper:
 * Stephen Shellhammer, Ahmed Sadek, and Wenyi Zhang. "Technical Challenges for
 * Cognitive Radio in the TV White Space Spectrum." Qualcomm Incorporated.
 */
void
TvSpectrumTransmitter::CreateTvPsd()
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT(m_channelBandwidth != 0);
    Ptr<SpectrumModel> model;
    TvSpectrumModelId key(m_startFrequency, m_channelBandwidth);
    auto iter = g_tvSpectrumModelMap.find(key);
    if (iter != g_tvSpectrumModelMap.end())
    {
        model = iter->second; // set SpectrumModel to previously created one
    }
    else // no previously created SpectrumModel with same frequency and bandwidth
    {
        Bands bands;
        double halfSubBand = 0.5 * (m_channelBandwidth / 100);
        for (double fl = m_startFrequency - halfSubBand;
             fl <= (m_startFrequency - halfSubBand) + m_channelBandwidth;
             fl += m_channelBandwidth / 100)
        {
            BandInfo bi;
            bi.fl = fl;
            bi.fc = fl + halfSubBand;
            bi.fh = fl + (2 * halfSubBand);
            bands.push_back(bi);
        }
        model = Create<SpectrumModel>(bands);
        g_tvSpectrumModelMap.insert(std::pair<TvSpectrumModelId, Ptr<SpectrumModel>>(key, model));
    }
    Ptr<SpectrumValue> psd = Create<SpectrumValue>(model);
    double basePsdWattsHz = pow(10.0, (m_basePsd - 30) / 10.0); // convert dBm to W/Hz
    switch (m_tvType)
    {
    case TVTYPE_8VSB: {
        for (int i = 0; i <= 100; i++)
        {
            switch (i)
            {
            case 0:
            case 100:
                (*psd)[i] = 0.015 * basePsdWattsHz;
                break;
            case 1:
            case 99:
                (*psd)[i] = 0.019 * basePsdWattsHz;
                break;
            case 2:
            case 98:
                (*psd)[i] = 0.034 * basePsdWattsHz;
                break;
            case 3:
            case 97:
                (*psd)[i] = 0.116 * basePsdWattsHz;
                break;
            case 4:
            case 96:
                (*psd)[i] = 0.309 * basePsdWattsHz;
                break;
            case 5:
                (*psd)[i] = (0.502 * basePsdWattsHz) + (21.577 * basePsdWattsHz); // pilot
                break;
            case 6:
            case 94:
                (*psd)[i] = 0.696 * basePsdWattsHz;
                break;
            case 7:
            case 93:
                (*psd)[i] = 0.913 * basePsdWattsHz;
                break;
            case 8:
            case 92:
                (*psd)[i] = 0.978 * basePsdWattsHz;
                break;
            case 9:
            case 91:
                (*psd)[i] = 0.990 * basePsdWattsHz;
                break;
            case 95:
                (*psd)[i] = 0.502 * basePsdWattsHz;
                break;
            default:
                (*psd)[i] = basePsdWattsHz;
                break;
            }
        }
        break;
    }
    case TVTYPE_COFDM: {
        for (int i = 0; i <= 100; i++)
        {
            switch (i)
            {
            case 0:
            case 100:
                (*psd)[i] = 1.52e-4 * basePsdWattsHz;
                break;
            case 1:
            case 99:
                (*psd)[i] = 2.93e-4 * basePsdWattsHz;
                break;
            case 2:
            case 98:
                (*psd)[i] = 8.26e-4 * basePsdWattsHz;
                break;
            case 3:
            case 97:
                (*psd)[i] = 0.0927 * basePsdWattsHz;
                break;
            default:
                (*psd)[i] = basePsdWattsHz;
                break;
            }
        }
        break;
    }
    case TVTYPE_ANALOG: {
        for (int i = 0; i <= 100; i++)
        {
            switch (i)
            {
            case 0:
            case 1:
            case 2:
            case 3:
                (*psd)[i] = 27.07946e-08 * basePsdWattsHz;
                break;
            case 4:
            case 5:
            case 6:
                (*psd)[i] = 2.51189e-07 * basePsdWattsHz;
                break;
            case 7:
            case 8:
            case 9:
                (*psd)[i] = 1e-06 * basePsdWattsHz;
                break;
            case 10:
            case 11:
            case 12:
                (*psd)[i] = 2.39883e-06 * basePsdWattsHz;
                break;
            case 13:
            case 14:
            case 15:
                (*psd)[i] = 5.62341e-06 * basePsdWattsHz;
                break;
            case 16:
            case 17:
            case 18:
                (*psd)[i] = 6.68344e-06 * basePsdWattsHz;
                break;
            case 19:
            case 20:
            case 21:
                (*psd)[i] = 1.25893e-05 * basePsdWattsHz;
                break;
            case 22:
            case 23:
            case 24:
                (*psd)[i] = 3.16228e-05 * basePsdWattsHz;
                break;
            case 25:
                (*psd)[i] = 0.000158489 * basePsdWattsHz;
                break;
            case 26:
                (*psd)[i] = basePsdWattsHz;
                break;
            case 27:
                (*psd)[i] = 7.49894e-05 * basePsdWattsHz;
                break;
            case 28:
            case 29:
            case 30:
                (*psd)[i] = 2.37137e-05 * basePsdWattsHz;
                break;
            case 31:
            case 32:
            case 33:
                (*psd)[i] = 1.14815e-05 * basePsdWattsHz;
                break;
            case 34:
            case 35:
            case 36:
                (*psd)[i] = 7.49894e-06 * basePsdWattsHz;
                break;
            case 37:
            case 38:
            case 39:
                (*psd)[i] = 5.62341e-06 * basePsdWattsHz;
                break;
            case 40:
            case 41:
            case 42:
                (*psd)[i] = 4.21697e-06 * basePsdWattsHz;
                break;
            case 43:
            case 44:
            case 45:
                (*psd)[i] = 3.16228e-06 * basePsdWattsHz;
                break;
            case 46:
            case 47:
            case 48:
                (*psd)[i] = 1.99526e-06 * basePsdWattsHz;
                break;
            case 49:
            case 50:
            case 51:
                (*psd)[i] = 1.25893e-06 * basePsdWattsHz;
                break;
            case 52:
            case 53:
            case 54:
                (*psd)[i] = 8.41395e-07 * basePsdWattsHz;
                break;
            case 55:
            case 56:
            case 57:
                (*psd)[i] = 6.30957e-07 * basePsdWattsHz;
                break;
            case 58:
            case 59:
            case 60:
                (*psd)[i] = 5.88844e-07 * basePsdWattsHz;
                break;
            case 61:
            case 62:
            case 63:
                (*psd)[i] = 5.62341e-07 * basePsdWattsHz;
                break;
            case 64:
            case 65:
            case 66:
                (*psd)[i] = 5.30884e-07 * basePsdWattsHz;
                break;
            case 67:
            case 68:
            case 69:
                (*psd)[i] = 5.01187e-07 * basePsdWattsHz;
                break;
            case 70:
            case 71:
            case 72:
                (*psd)[i] = 5.30884e-07 * basePsdWattsHz;
                break;
            case 73:
            case 74:
            case 75:
                (*psd)[i] = 7.49894e-07 * basePsdWattsHz;
                break;
            case 76:
            case 77:
            case 78:
                (*psd)[i] = 1.77828e-06 * basePsdWattsHz;
                break;
            case 79:
                (*psd)[i] = 5.62341e-06 * basePsdWattsHz;
                break;
            case 80:
                (*psd)[i] = 0.000177828 * basePsdWattsHz;
                break;
            case 81:
                (*psd)[i] = 4.21697e-06 * basePsdWattsHz;
                break;
            case 82:
            case 83:
            case 84:
            case 85:
            case 86:
            case 87:
                (*psd)[i] = 3.16228e-06 * basePsdWattsHz;
                break;
            case 88:
            case 89:
            case 90:
                (*psd)[i] = 4.73151e-06 * basePsdWattsHz;
                break;
            case 91:
            case 92:
            case 93:
                (*psd)[i] = 7.49894e-06 * basePsdWattsHz;
                break;
            case 94:
                (*psd)[i] = 7.49894e-05 * basePsdWattsHz;
                break;
            case 95:
                (*psd)[i] = 0.1 * basePsdWattsHz;
                break;
            case 96:
                (*psd)[i] = 7.49894e-05 * basePsdWattsHz;
                break;
            case 97:
            case 98:
            case 99:
            case 100:
                (*psd)[i] = 1.77828e-06 * basePsdWattsHz;
                break;
            }
        }
        break;
    }
    default: {
        NS_LOG_ERROR("no valid TvType selected");
        break;
    }
    }
    m_txPsd = psd;
}

Ptr<SpectrumValue>
TvSpectrumTransmitter::GetTxPsd() const
{
    NS_LOG_FUNCTION(this);
    return m_txPsd;
}

void
TvSpectrumTransmitter::SetupTx()
{
    NS_LOG_FUNCTION(this);
    NS_ASSERT(m_txPsd);
    Ptr<SpectrumSignalParameters> signal = Create<SpectrumSignalParameters>();
    signal->duration = m_transmitDuration;
    signal->psd = m_txPsd;
    signal->txPhy = GetObject<SpectrumPhy>();
    signal->txAntenna = m_antenna;
    m_channel->StartTx(signal);
}

void
TvSpectrumTransmitter::Start()
{
    NS_LOG_FUNCTION(this);
    if (!m_active)
    {
        NS_LOG_LOGIC("starting TV transmitter");
        m_active = true;
        Simulator::Schedule(m_startingTime, &TvSpectrumTransmitter::SetupTx, this);
    }
}

void
TvSpectrumTransmitter::Stop()
{
    NS_LOG_FUNCTION(this);
    m_active = false;
}

} // namespace ns3
