#include "amuse/SongConverter.hpp"
#include "amuse/SongState.hpp"
#include "amuse/Common.hpp"
#include <cstdlib>
#include <map>

namespace amuse
{

static inline uint8_t clamp7(uint8_t val) { return std::max(0, std::min(127, int(val))); }

enum class Status
{
    NoteOff = 0x80,
    NoteOn = 0x90,
    NotePressure = 0xA0,
    ControlChange = 0xB0,
    ProgramChange = 0xC0,
    ChannelPressure = 0xD0,
    PitchBend = 0xE0,
    SysEx = 0xF0,
    TimecodeQuarterFrame = 0xF1,
    SongPositionPointer = 0xF2,
    SongSelect = 0xF3,
    TuneRequest = 0xF6,
    SysExTerm = 0xF7,
    TimingClock = 0xF8,
    Start = 0xFA,
    Continue = 0xFB,
    Stop = 0xFC,
    ActiveSensing = 0xFE,
    Reset = 0xFF,
};

/* Event tags */
struct NoteEvent
{
};
struct CtrlEvent
{
};
struct ProgEvent
{
};
struct PitchEvent
{
};

/* Intermediate event */
struct Event
{
    enum class Type : uint8_t
    {
        Note,
        Control,
        Program,
        Pitch
    } m_type;

    bool endEvent = false;
    uint8_t channel;
    uint8_t noteOrCtrl;
    uint8_t velOrVal;
    uint8_t program;
    int length;
    int pitchBend;

    Event(NoteEvent, uint8_t chan, uint8_t note, uint8_t vel, int len)
    : m_type(Type::Note), channel(chan), noteOrCtrl(note), velOrVal(vel), length(len)
    {
    }

    Event(CtrlEvent, uint8_t chan, uint8_t note, uint8_t vel, int len)
    : m_type(Type::Control), channel(chan), noteOrCtrl(note), velOrVal(vel), length(len)
    {
    }

    Event(ProgEvent, uint8_t chan, uint8_t prog) : m_type(Type::Program), channel(chan), program(prog) {}

    Event(PitchEvent, uint8_t chan, int pBend) : m_type(Type::Pitch), channel(chan), pitchBend(pBend) {}
};

class MIDIDecoder
{
    int m_tick = 0;
    std::vector<std::multimap<int, Event>> m_results[16];
    std::multimap<int, int> m_tempos;
    std::array<std::multimap<int, Event>::iterator, 128> m_notes[16];
    int m_minLoopStart[16];
    int m_minLoopEnd[16];

    bool isEmptyIterator(int chan, std::multimap<int, Event>::iterator it) const
    {
        for (const auto& res : m_results[chan])
            if (res.end() == it)
                return true;
        return false;
    }

    void _addRegionChange(int chan)
    {
        auto& results = m_results[chan];
        results.reserve(2);
        results.emplace_back();
        if (results.size() == 1)
            for (size_t i = 0; i < 128; ++i)
                m_notes[chan][i] = results.back().end();
    }

    uint8_t m_status = 0;
    bool _readContinuedValue(std::vector<uint8_t>::const_iterator& it, std::vector<uint8_t>::const_iterator end,
                             uint32_t& valOut)
    {
        uint8_t a = *it++;
        valOut = a & 0x7f;

        if (a & 0x80)
        {
            if (it == end)
                return false;
            valOut <<= 7;
            a = *it++;
            valOut |= a & 0x7f;

            if (a & 0x80)
            {
                if (it == end)
                    return false;
                valOut <<= 7;
                a = *it++;
                valOut |= a & 0x7f;
            }
        }

        return true;
    }

public:
    MIDIDecoder()
    {
        std::fill(std::begin(m_minLoopStart), std::end(m_minLoopStart), INT_MAX);
        std::fill(std::begin(m_minLoopEnd), std::end(m_minLoopEnd), INT_MAX);
    }

    std::vector<uint8_t>::const_iterator receiveBytes(std::vector<uint8_t>::const_iterator begin,
                                                      std::vector<uint8_t>::const_iterator end,
                                                      int loopStart[16] = nullptr, int loopEnd[16] = nullptr)
    {
        std::vector<uint8_t>::const_iterator it = begin;
        while (it != end)
        {
            uint32_t deltaTime;
            _readContinuedValue(it, end, deltaTime);
            m_tick += deltaTime;

            uint8_t a = *it++;
            uint8_t b;
            if (a & 0x80)
                m_status = a;
            else
                it--;

            if (m_status == 0xff)
            {
                /* Meta events */
                if (it == end)
                    break;
                a = *it++;

                uint32_t length;
                _readContinuedValue(it, end, length);

                switch (a)
                {
                case 0x51:
                {
                    uint32_t tempo = 0;
                    memcpy(&reinterpret_cast<uint8_t*>(&tempo)[1], &*it, 3);
                    m_tempos.emplace(m_tick, 60000000 / SBig(tempo));
                }
                default:
                    it += length;
                }
            } else
            {
                uint8_t chan = m_status & 0xf;
                auto& results = m_results[chan];

                if (loopEnd && loopEnd[chan] != INT_MAX && m_tick >= loopEnd[chan])
                    break;

                /* Split region at loop start point */
                if (loopStart && loopStart[chan] != INT_MAX && m_tick >= loopStart[chan])
                {
                    _addRegionChange(chan);
                    loopStart[chan] = INT_MAX;
                }
                else if (results.empty())
                {
                    _addRegionChange(chan);
                }

                std::multimap<int, Event>& res = results.back();

                switch (Status(m_status & 0xf0))
                {
                case Status::NoteOff:
                {
                    if (it == end)
                        break;
                    a = *it++;
                    if (it == end)
                        break;
                    b = *it++;

                    uint8_t notenum = clamp7(a);
                    std::multimap<int, Event>::iterator note = m_notes[chan][notenum];
                    if (!isEmptyIterator(chan, note))
                    {
                        note->second.length = m_tick - note->first;
                        m_notes[chan][notenum] = res.end();
                    }
                    break;
                }
                case Status::NoteOn:
                {
                    if (it == end)
                        break;
                    a = *it++;
                    if (it == end)
                        break;
                    b = *it++;

                    uint8_t notenum = clamp7(a);
                    uint8_t vel = clamp7(b);
                    std::multimap<int, Event>::iterator note = m_notes[chan][notenum];
                    if (!isEmptyIterator(chan, note))
                        note->second.length = m_tick - note->first;

                    if (vel != 0)
                        m_notes[chan][notenum] = res.emplace(m_tick, Event{NoteEvent{}, chan, notenum, vel, 0});
                    else
                        m_notes[chan][notenum] = res.end();

                    break;
                }
                case Status::NotePressure:
                {
                    if (it == end)
                        break;
                    a = *it++;
                    if (it == end)
                        break;
                    b = *it++;
                    break;
                }
                case Status::ControlChange:
                {
                    if (it == end)
                        break;
                    a = *it++;
                    if (it == end)
                        break;
                    b = *it++;
                    if (a == 0x66)
                        m_minLoopStart[chan] = std::min(m_tick, m_minLoopStart[chan]);
                    else if (a == 0x67)
                        m_minLoopEnd[chan] = std::min(m_tick, m_minLoopEnd[chan]);
                    else
                        res.emplace(m_tick, Event{CtrlEvent{}, chan, clamp7(a), clamp7(b), 0});
                    break;
                }
                case Status::ProgramChange:
                {
                    if (it == end)
                        break;
                    a = *it++;
                    res.emplace(m_tick, Event{ProgEvent{}, chan, a});
                    break;
                }
                case Status::ChannelPressure:
                {
                    if (it == end)
                        break;
                    a = *it++;
                    break;
                }
                case Status::PitchBend:
                {
                    if (it == end)
                        break;
                    a = *it++;
                    if (it == end)
                        break;
                    b = *it++;
                    res.emplace(m_tick, Event{PitchEvent{}, chan, clamp7(b) * 128 + clamp7(a)});
                    break;
                }
                case Status::SysEx:
                {
                    switch (Status(m_status & 0xff))
                    {
                    case Status::SysEx:
                    {
                        uint32_t len;
                        if (!_readContinuedValue(it, end, len) || end - it < len)
                            break;
                        break;
                    }
                    case Status::TimecodeQuarterFrame:
                    {
                        if (it == end)
                            break;
                        a = *it++;
                        break;
                    }
                    case Status::SongPositionPointer:
                    {
                        if (it == end)
                            break;
                        a = *it++;
                        if (it == end)
                            break;
                        b = *it++;
                        break;
                    }
                    case Status::SongSelect:
                    {
                        if (it == end)
                            break;
                        a = *it++;
                        break;
                    }
                    case Status::TuneRequest:
                    case Status::Start:
                    case Status::Continue:
                    case Status::Stop:
                    case Status::Reset:
                    case Status::SysExTerm:
                    case Status::TimingClock:
                    case Status::ActiveSensing:
                    default:
                        break;
                    }
                    break;
                }
                default:
                    break;
                }
            }
        }

        return it;
    }

    std::vector<std::multimap<int, Event>>& getResults(int chan) { return m_results[chan]; }
    std::multimap<int, int>& getTempos() { return m_tempos; }
    int getMinLoopStart(int chan) const { return m_minLoopStart[chan]; }
    int getMinLoopEnd(int chan) const { return m_minLoopEnd[chan]; }
};

class MIDIEncoder
{
    friend class SongConverter;
    std::vector<uint8_t> m_result;
    uint8_t m_status = 0;

    void _sendMessage(const uint8_t* data, size_t len)
    {
        if (data[0] == m_status)
        {
            for (size_t i = 1; i < len; ++i)
                m_result.push_back(data[i]);
        }
        else
        {
            if (data[0] & 0x80)
                m_status = data[0];
            for (size_t i = 0; i < len; ++i)
                m_result.push_back(data[i]);
        }
    }

    void _sendContinuedValue(uint32_t val)
    {
        uint8_t send[3] = {};
        uint8_t* ptr = nullptr;
        if (val >= 0x4000)
        {
            ptr = &send[0];
            send[0] = 0x80 | ((val / 0x4000) & 0x7f);
            send[1] = 0x80;
            val &= 0x3fff;
        }

        if (val >= 0x80)
        {
            if (!ptr)
                ptr = &send[1];
            send[1] = 0x80 | ((val / 0x80) & 0x7f);
        }

        if (!ptr)
            ptr = &send[2];
        send[2] = val & 0x7f;

        size_t len = 3 - (ptr - send);
        for (size_t i = 0; i < len; ++i)
            m_result.push_back(ptr[i]);
    }

public:
    void noteOff(uint8_t chan, uint8_t key, uint8_t velocity)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::NoteOff) | (chan & 0xf)), uint8_t(key & 0x7f), uint8_t(velocity & 0x7f)};
        _sendMessage(cmd, 3);
    }

    void noteOn(uint8_t chan, uint8_t key, uint8_t velocity)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::NoteOn) | (chan & 0xf)), uint8_t(key & 0x7f), uint8_t(velocity & 0x7f)};
        _sendMessage(cmd, 3);
    }

    void notePressure(uint8_t chan, uint8_t key, uint8_t pressure)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::NotePressure) | (chan & 0xf)), uint8_t(key & 0x7f),
                          uint8_t(pressure & 0x7f)};
        _sendMessage(cmd, 3);
    }

    void controlChange(uint8_t chan, uint8_t control, uint8_t value)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::ControlChange) | (chan & 0xf)), uint8_t(control & 0x7f),
                          uint8_t(value & 0x7f)};
        _sendMessage(cmd, 3);
    }

    void programChange(uint8_t chan, uint8_t program)
    {
        uint8_t cmd[2] = {uint8_t(int(Status::ProgramChange) | (chan & 0xf)), uint8_t(program & 0x7f)};
        _sendMessage(cmd, 2);
    }

    void channelPressure(uint8_t chan, uint8_t pressure)
    {
        uint8_t cmd[2] = {uint8_t(int(Status::ChannelPressure) | (chan & 0xf)), uint8_t(pressure & 0x7f)};
        _sendMessage(cmd, 2);
    }

    void pitchBend(uint8_t chan, int16_t pitch)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::PitchBend) | (chan & 0xf)), uint8_t((pitch % 128) & 0x7f),
                          uint8_t((pitch / 128) & 0x7f)};
        _sendMessage(cmd, 3);
    }

    void allSoundOff(uint8_t chan)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::ControlChange) | (chan & 0xf)), 120, 0};
        _sendMessage(cmd, 3);
    }

    void resetAllControllers(uint8_t chan)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::ControlChange) | (chan & 0xf)), 121, 0};
        _sendMessage(cmd, 3);
    }

    void localControl(uint8_t chan, bool on)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::ControlChange) | (chan & 0xf)), 122, uint8_t(on ? 127 : 0)};
        _sendMessage(cmd, 3);
    }

    void allNotesOff(uint8_t chan)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::ControlChange) | (chan & 0xf)), 123, 0};
        _sendMessage(cmd, 3);
    }

    void omniMode(uint8_t chan, bool on)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::ControlChange) | (chan & 0xf)), uint8_t(on ? 125 : 124), 0};
        _sendMessage(cmd, 3);
    }

    void polyMode(uint8_t chan, bool on)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::ControlChange) | (chan & 0xf)), uint8_t(on ? 127 : 126), 0};
        _sendMessage(cmd, 3);
    }

    void sysex(const void* data, size_t len)
    {
        uint8_t cmd = uint8_t(Status::SysEx);
        _sendMessage(&cmd, 1);
        _sendContinuedValue(len);
        for (size_t i = 0; i < len; ++i)
            m_result.push_back(reinterpret_cast<const uint8_t*>(data)[i]);
        cmd = uint8_t(Status::SysExTerm);
        _sendMessage(&cmd, 1);
    }

    void timeCodeQuarterFrame(uint8_t message, uint8_t value)
    {
        uint8_t cmd[2] = {uint8_t(int(Status::TimecodeQuarterFrame)), uint8_t((message & 0x7 << 4) | (value & 0xf))};
        _sendMessage(cmd, 2);
    }

    void songPositionPointer(uint16_t pointer)
    {
        uint8_t cmd[3] = {uint8_t(int(Status::SongPositionPointer)), uint8_t((pointer % 128) & 0x7f),
                          uint8_t((pointer / 128) & 0x7f)};
        _sendMessage(cmd, 3);
    }

    void songSelect(uint8_t song)
    {
        uint8_t cmd[2] = {uint8_t(int(Status::TimecodeQuarterFrame)), uint8_t(song & 0x7f)};
        _sendMessage(cmd, 2);
    }

    void tuneRequest()
    {
        uint8_t cmd = uint8_t(Status::TuneRequest);
        _sendMessage(&cmd, 1);
    }

    void startSeq()
    {
        uint8_t cmd = uint8_t(Status::Start);
        _sendMessage(&cmd, 1);
    }

    void continueSeq()
    {
        uint8_t cmd = uint8_t(Status::Continue);
        _sendMessage(&cmd, 1);
    }

    void stopSeq()
    {
        uint8_t cmd = uint8_t(Status::Stop);
        _sendMessage(&cmd, 1);
    }

    void reset()
    {
        uint8_t cmd = uint8_t(Status::Reset);
        _sendMessage(&cmd, 1);
    }

    const std::vector<uint8_t>& getResult() const { return m_result; }
    std::vector<uint8_t>& getResult() { return m_result; }
};

static uint16_t DecodeUnsignedValue(const unsigned char*& data)
{
    uint16_t ret;
    if (data[0] & 0x80)
    {
        ret = data[1] | ((data[0] & 0x7f) << 8);
        data += 2;
    }
    else
    {
        ret = data[0];
        data += 1;
    }
    return ret;
}

static void EncodeUnsignedValue(std::vector<uint8_t>& vecOut, uint16_t val)
{
    if (val >= 128)
    {
        vecOut.push_back(0x80 | ((val >> 8) & 0x7f));
        vecOut.push_back(val & 0xff);
    }
    else
    {
        vecOut.push_back(val & 0x7f);
    }
}

static int16_t DecodeSignedValue(const unsigned char*& data)
{
    int16_t ret;
    if (data[0] & 0x80)
    {
        ret = data[1] | ((data[0] & 0x7f) << 8);
        ret |= ((ret << 1) & 0x8000);
        data += 2;
    }
    else
    {
        ret = int8_t(data[0] | ((data[0] << 1) & 0x80));
        data += 1;
    }
    return ret;
}

static void EncodeSignedValue(std::vector<uint8_t>& vecOut, int16_t val)
{
    if (val >= 64 || val < -64)
    {
        vecOut.push_back(0x80 | ((val >> 8) & 0x7f));
        vecOut.push_back(val & 0xff);
    }
    else
    {
        vecOut.push_back(val & 0x7f);
    }
}

static std::pair<uint32_t, int32_t> DecodeDelta(const unsigned char*& data)
{
    std::pair<uint32_t, int32_t> ret = {};
    do {
        if (data[0] == 0x80 && data[1] == 0x00)
            break;
        ret.first += DecodeUnsignedValue(data);
        ret.second = DecodeSignedValue(data);
    } while (ret.second == 0);
    return ret;
}

static void EncodeDelta(std::vector<uint8_t>& vecOut, uint32_t deltaTime, int32_t val)
{
    while (deltaTime > 32767)
    {
        EncodeUnsignedValue(vecOut, 32767);
        EncodeSignedValue(vecOut, 0);
        deltaTime -= 32767;
    }
    EncodeUnsignedValue(vecOut, deltaTime);
    EncodeSignedValue(vecOut, val);
}

static uint32_t DecodeTime(const unsigned char*& data)
{
    uint32_t ret = 0;

    while (true)
    {
        uint16_t thisPart = SBig(*reinterpret_cast<const uint16_t*>(data));
        uint16_t nextPart = *reinterpret_cast<const uint16_t*>(data + 2);
        if (nextPart == 0)
        {
            // Automatically consume no-op command as continued time
            ret += thisPart;
            data += 4;
            continue;
        }

        ret += thisPart;
        data += 2;
        break;
    }

    return ret;
}

static void EncodeTime(std::vector<uint8_t>& vecOut, uint32_t val)
{
    while (val >= 65535)
    {
        // Automatically emit no-op command as continued time
        vecOut.push_back(0xff);
        vecOut.push_back(0xff);
        vecOut.push_back(0);
        vecOut.push_back(0);
        val -= 65535;
    }

    uint16_t lastPart = SBig(uint16_t(val));
    vecOut.push_back(reinterpret_cast<const uint8_t*>(&lastPart)[0]);
    vecOut.push_back(reinterpret_cast<const uint8_t*>(&lastPart)[1]);
}

std::vector<uint8_t> SongConverter::SongToMIDI(const unsigned char* data, int& versionOut, bool& isBig)
{
    std::vector<uint8_t> ret = {'M', 'T', 'h', 'd'};
    uint32_t six32 = SBig(uint32_t(6));
    for (int i = 0; i < 4; ++i)
        ret.push_back(reinterpret_cast<uint8_t*>(&six32)[i]);

    ret.push_back(0);
    ret.push_back(1);

    SongState song;
    if (!song.initialize(data, false))
        return {};
    versionOut = song.m_sngVersion;
    isBig = song.m_bigEndian;

    size_t trkCount = 1;
    for (SongState::Track& trk : song.m_tracks)
        if (trk)
            ++trkCount;

    uint16_t trkCount16 = SBig(uint16_t(trkCount));
    ret.push_back(reinterpret_cast<uint8_t*>(&trkCount16)[0]);
    ret.push_back(reinterpret_cast<uint8_t*>(&trkCount16)[1]);

    uint16_t tickDiv16 = SBig(uint16_t(384));
    ret.push_back(reinterpret_cast<uint8_t*>(&tickDiv16)[0]);
    ret.push_back(reinterpret_cast<uint8_t*>(&tickDiv16)[1]);

    /* Write tempo track */
    {
        MIDIEncoder encoder;

        /* Initial tempo */
        encoder._sendContinuedValue(0);
        encoder.getResult().push_back(0xff);
        encoder.getResult().push_back(0x51);
        encoder.getResult().push_back(3);

        uint32_t tempo24 = SBig(60000000 / (song.m_header.m_initialTempo & 0x7fffffff));
        for (int i = 1; i < 4; ++i)
            encoder.getResult().push_back(reinterpret_cast<uint8_t*>(&tempo24)[i]);

        /* Write out tempo changes */
        int lastTick = 0;
        const SongState::TempoChange* tempoPtr = nullptr;
        if (song.m_header.m_tempoTableOff)
            tempoPtr = reinterpret_cast<const SongState::TempoChange*>(song.m_songData + song.m_header.m_tempoTableOff);
        while (tempoPtr && tempoPtr->m_tick != 0xffffffff)
        {
            SongState::TempoChange change = *tempoPtr;
            if (song.m_bigEndian)
                change.swapBig();

            encoder._sendContinuedValue(change.m_tick - lastTick);
            lastTick = change.m_tick;
            encoder.getResult().push_back(0xff);
            encoder.getResult().push_back(0x51);
            encoder.getResult().push_back(3);

            uint32_t tempo24 = SBig(60000000 / (change.m_tempo & 0x7fffffff));
            for (int i = 1; i < 4; ++i)
                encoder.getResult().push_back(reinterpret_cast<uint8_t*>(&tempo24)[i]);

            ++tempoPtr;
        }

        encoder.getResult().push_back(0);
        encoder.getResult().push_back(0xff);
        encoder.getResult().push_back(0x2f);
        encoder.getResult().push_back(0);

        ret.push_back('M');
        ret.push_back('T');
        ret.push_back('r');
        ret.push_back('k');
        uint32_t trkSz = SBig(uint32_t(encoder.getResult().size()));
        for (int i = 0; i < 4; ++i)
            ret.push_back(reinterpret_cast<uint8_t*>(&trkSz)[i]);
        ret.insert(ret.cend(), encoder.getResult().begin(), encoder.getResult().end());
    }

    bool loopsAdded = false;

    /* Iterate each SNG track into type-1 MIDI track */
    for (SongState::Track& trk : song.m_tracks)
    {
        if (trk)
        {
            MIDIEncoder encoder;
            std::multimap<int, Event> allEvents;

            /* Iterate all regions */
            while (trk.m_nextRegion->indexValid(song.m_bigEndian))
            {
                std::multimap<int, Event> events;
                trk.advanceRegion();
                uint32_t regStart =
                    song.m_bigEndian ? SBig(trk.m_curRegion->m_startTick) : trk.m_curRegion->m_startTick;

                /* Initial program change */
                if (trk.m_curRegion->m_progNum != 0xff)
                    events.emplace(regStart, Event{ProgEvent{}, trk.m_midiChan, trk.m_curRegion->m_progNum});

                /* Update continuous pitch data */
                if (trk.m_pitchWheelData)
                {
                    while (true)
                    {
                        /* Update pitch */
                        trk.m_pitchVal += trk.m_nextPitchDelta;
                        events.emplace(regStart + trk.m_nextPitchTick,
                                       Event{PitchEvent{}, trk.m_midiChan,
                                             clamp(0, trk.m_pitchVal + 0x2000, 0x4000)});
                        if (trk.m_pitchWheelData[0] != 0x80 || trk.m_pitchWheelData[1] != 0x00)
                        {
                            auto delta = DecodeDelta(trk.m_pitchWheelData);
                            trk.m_nextPitchTick += delta.first;
                            trk.m_nextPitchDelta = delta.second;
                        }
                        else
                        {
                            break;
                        }
                    }
                }

                /* Update continuous modulation data */
                if (trk.m_modWheelData)
                {
                    while (true)
                    {
                        /* Update modulation */
                        trk.m_modVal += trk.m_nextModDelta;
                        events.emplace(regStart + trk.m_nextModTick,
                                       Event{CtrlEvent{}, trk.m_midiChan, 1,
                                             uint8_t(clamp(0, trk.m_modVal / 128, 127)), 0});
                        if (trk.m_modWheelData[0] != 0x80 || trk.m_modWheelData[1] != 0x00)
                        {
                            auto delta = DecodeDelta(trk.m_modWheelData);
                            trk.m_nextModTick += delta.first;
                            trk.m_nextModDelta = delta.second;
                        }
                        else
                        {
                            break;
                        }
                    }
                }

                /* Loop through as many commands as we can for this time period */
                if (song.m_sngVersion == 1)
                {
                    /* Revision */
                    while (true)
                    {
                        /* Load next command */
                        if (*reinterpret_cast<const uint16_t*>(trk.m_data) == 0xffff)
                        {
                            /* End of channel */
                            trk.m_data = nullptr;
                            break;
                        }
                        else if (trk.m_data[0] & 0x80 && trk.m_data[1] & 0x80)
                        {
                            /* Control change */
                            uint8_t val = trk.m_data[0] & 0x7f;
                            uint8_t ctrl = trk.m_data[1] & 0x7f;
                            events.emplace(regStart + trk.m_eventWaitCountdown,
                                           Event{CtrlEvent{}, trk.m_midiChan, ctrl, val, 0});
                            trk.m_data += 2;
                        }
                        else if (trk.m_data[0] & 0x80)
                        {
                            /* Program change */
                            uint8_t prog = trk.m_data[0] & 0x7f;
                            events.emplace(regStart + trk.m_eventWaitCountdown,
                                           Event{ProgEvent{}, trk.m_midiChan, prog});
                            trk.m_data += 2;
                        }
                        else
                        {
                            /* Note */
                            uint8_t note = trk.m_data[0] & 0x7f;
                            uint8_t vel = trk.m_data[1] & 0x7f;
                            uint16_t length =
                                (song.m_bigEndian ? SBig(*reinterpret_cast<const uint16_t*>(trk.m_data + 2))
                                                  : *reinterpret_cast<const uint16_t*>(trk.m_data + 2));
                            events.emplace(regStart + trk.m_eventWaitCountdown,
                                           Event{NoteEvent{}, trk.m_midiChan, note, vel, length});
                            trk.m_data += 4;
                        }

                        /* Set next delta-time */
                        trk.m_eventWaitCountdown += int32_t(DecodeTime(trk.m_data));
                    }
                }
                else
                {
                    /* Legacy */
                    while (true)
                    {
                        /* Load next command */
                        if (*reinterpret_cast<const uint16_t*>(&trk.m_data[2]) == 0xffff)
                        {
                            /* End of channel */
                            trk.m_data = nullptr;
                            break;
                        }
                        else
                        {
                            if ((trk.m_data[2] & 0x80) != 0x80)
                            {
                                /* Note */
                                uint16_t length =
                                    (song.m_bigEndian ? SBig(*reinterpret_cast<const uint16_t*>(trk.m_data))
                                                      : *reinterpret_cast<const uint16_t*>(trk.m_data));
                                uint8_t note = trk.m_data[2] & 0x7f;
                                uint8_t vel = trk.m_data[3] & 0x7f;
                                events.emplace(regStart + trk.m_eventWaitCountdown,
                                               Event{NoteEvent{}, trk.m_midiChan, note, vel, length});
                            }
                            else if (trk.m_data[2] & 0x80 && trk.m_data[3] & 0x80)
                            {
                                /* Control change */
                                uint8_t val = trk.m_data[2] & 0x7f;
                                uint8_t ctrl = trk.m_data[3] & 0x7f;
                                events.emplace(regStart + trk.m_eventWaitCountdown,
                                               Event{CtrlEvent{}, trk.m_midiChan, ctrl, val, 0});
                            }
                            else if (trk.m_data[2] & 0x80)
                            {
                                /* Program change */
                                uint8_t prog = trk.m_data[2] & 0x7f;
                                events.emplace(regStart + trk.m_eventWaitCountdown,
                                               Event{ProgEvent{}, trk.m_midiChan, prog});
                            }
                            trk.m_data += 4;
                        }

                        /* Set next delta-time */
                        int32_t absTick = (song.m_bigEndian ? SBig(*reinterpret_cast<const int32_t*>(trk.m_data))
                                                            : *reinterpret_cast<const int32_t*>(trk.m_data));
                        trk.m_eventWaitCountdown += absTick - trk.m_lastN64EventTick;
                        trk.m_lastN64EventTick = absTick;
                        trk.m_data += 4;
                    }
                }

                /* Merge events */
                allEvents.insert(events.begin(), events.end());

                /* Resolve key-off events */
                for (auto& pair : events)
                {
                    if (pair.second.m_type == Event::Type::Note)
                    {
                        auto it = allEvents.emplace(pair.first + pair.second.length, pair.second);
                        it->second.endEvent = true;
                    }
                }
            }

            /* Add loop events */
            if (!loopsAdded && trk.m_nextRegion->indexLoop(song.m_bigEndian) != -1)
            {
                uint32_t loopEnd =
                    song.m_bigEndian ? SBig(trk.m_nextRegion->m_startTick) : trk.m_nextRegion->m_startTick;
                allEvents.emplace(trk.m_loopStartTick, Event{CtrlEvent{}, trk.m_midiChan, 0x66, 0, 0});
                allEvents.emplace(loopEnd, Event{CtrlEvent{}, trk.m_midiChan, 0x67, 0, 0});
                if (!(song.m_header.m_initialTempo & 0x80000000))
                    loopsAdded = true;
            }

            /* Emit MIDI events */
            int lastTime = 0;
            for (auto& pair : allEvents)
            {
                encoder._sendContinuedValue(pair.first - lastTime);
                lastTime = pair.first;

                switch (pair.second.m_type)
                {
                case Event::Type::Control:
                    encoder.controlChange(pair.second.channel, pair.second.noteOrCtrl, pair.second.velOrVal);
                    break;
                case Event::Type::Program:
                    encoder.programChange(trk.m_midiChan, pair.second.program);
                    break;
                case Event::Type::Pitch:
                    encoder.pitchBend(trk.m_midiChan, pair.second.pitchBend);
                    break;
                case Event::Type::Note:
                    if (pair.second.endEvent)
                        encoder.noteOff(pair.second.channel, pair.second.noteOrCtrl, pair.second.velOrVal);
                    else
                        encoder.noteOn(pair.second.channel, pair.second.noteOrCtrl, pair.second.velOrVal);
                    break;
                }
            }

            encoder.getResult().push_back(0);
            encoder.getResult().push_back(0xff);
            encoder.getResult().push_back(0x2f);
            encoder.getResult().push_back(0);

            /* Write out */
            ret.push_back('M');
            ret.push_back('T');
            ret.push_back('r');
            ret.push_back('k');
            uint32_t trkSz = SBig(uint32_t(encoder.getResult().size()));
            for (int i = 0; i < 4; ++i)
                ret.push_back(reinterpret_cast<uint8_t*>(&trkSz)[i]);
            ret.insert(ret.cend(), encoder.getResult().begin(), encoder.getResult().end());
        }
    }

    return ret;
}

std::vector<uint8_t> SongConverter::MIDIToSong(const std::vector<uint8_t>& data, int version, bool big)
{
    std::vector<uint8_t> ret;
    std::vector<uint8_t>::const_iterator it = data.cbegin();

    struct MIDIHeader
    {
        char magic[4];
        uint32_t length;
        uint16_t type;
        uint16_t count;
        uint16_t div;

        void swapBig()
        {
            length = SBig(length);
            type = SBig(type);
            count = SBig(count);
            div = SBig(div);
        }
    };

    MIDIHeader header = *reinterpret_cast<const MIDIHeader*>(&*it);
    header.swapBig();
    it += 8 + header.length;

    if (memcmp(header.magic, "MThd", 4))
        return {};

    /* Only Type 0 and 1 MIDI files supported as input */
    if (header.type == 0)
        header.count = 1;
    else if (header.type != 1)
        return {};

    std::vector<uint32_t> trackRegionIdxArr;
    std::vector<uint32_t> regionDataIdxArr;
    std::vector<SongState::TrackRegion> regionBuf;
    uint32_t initTempo = 120;
    std::vector<std::pair<uint32_t, uint32_t>> tempoBuf;

    std::array<uint8_t, 64> chanMap;
    for (int i = 0; i < 64; ++i)
        chanMap[i] = 0xff;

    struct Region
    {
        std::vector<uint8_t> eventBuf;
        std::vector<uint8_t> pitchBuf;
        std::vector<uint8_t> modBuf;
        int padding = 0;

        bool operator==(const Region& other) const
        {
            if (eventBuf.size() != other.eventBuf.size())
                return false;
            if (pitchBuf.size() != other.pitchBuf.size())
                return false;
            if (modBuf.size() != other.modBuf.size())
                return false;

            if (eventBuf.size() && memcmp(eventBuf.data(), other.eventBuf.data(), eventBuf.size()))
                return false;
            if (pitchBuf.size() && memcmp(pitchBuf.data(), other.pitchBuf.data(), pitchBuf.size()))
                return false;
            if (modBuf.size() && memcmp(modBuf.data(), other.modBuf.data(), modBuf.size()))
                return false;

            return true;
        }
    };
    std::vector<Region> regions;
    int curRegionOff = 0;

    /* Pre-iterate to extract loop events */
    int loopStart[16];
    int loopEnd[16];
    int loopChanCount = 0;
    {
        int loopChanIdx = -1;
        for (int c = 0; c < 16; ++c)
        {
            loopStart[c] = INT_MAX;
            loopEnd[c] = INT_MAX;
            std::vector<uint8_t>::const_iterator tmpIt = it;
            for (int i = 0; i < header.count; ++i)
            {
                if (memcmp(&*tmpIt, "MTrk", 4))
                    return {};
                tmpIt += 4;
                uint32_t length = SBig(*reinterpret_cast<const uint32_t*>(&*tmpIt));
                tmpIt += 4;

                std::vector<uint8_t>::const_iterator begin = tmpIt;
                std::vector<uint8_t>::const_iterator end = tmpIt + length;
                tmpIt = end;

                MIDIDecoder dec;
                dec.receiveBytes(begin, end);
                loopStart[c] = std::min(dec.getMinLoopStart(c), loopStart[c]);
                loopEnd[c] = std::min(dec.getMinLoopEnd(c), loopEnd[c]);
            }
            if (loopStart[c] == INT_MAX || loopEnd[c] == INT_MAX)
            {
                loopStart[c] = INT_MAX;
                loopEnd[c] = INT_MAX;
            }
            else
            {
                ++loopChanCount;
                loopChanIdx = c;
            }
        }
        if (loopChanCount == 1)
        {
            for (int c = 0; c < 16; ++c)
            {
                loopStart[c] = loopStart[loopChanIdx];
                loopEnd[c] = loopEnd[loopChanIdx];
            }
        }
    }

    for (int i = 0; i < header.count; ++i)
    {
        if (memcmp(&*it, "MTrk", 4))
            return {};
        it += 4;
        uint32_t length = SBig(*reinterpret_cast<const uint32_t*>(&*it));
        it += 4;

        if (i == 0)
        {
            /* Extract tempo events from first track */
            std::vector<uint8_t>::const_iterator begin = it;
            std::vector<uint8_t>::const_iterator end = it + length;

            MIDIDecoder dec;
            dec.receiveBytes(begin, end);

            std::multimap<int, int>& tempos = dec.getTempos();
            if (tempos.size() == 1)
                initTempo = tempos.begin()->second;
            else if (tempos.size() > 1)
            {
                auto it = tempos.begin();
                initTempo = it->second;
                ++it;
                for (auto& pair : tempos)
                {
                    if (big)
                        tempoBuf.emplace_back(SBig(uint32_t(pair.first * 384 / header.div)),
                                              SBig(uint32_t(pair.second)));
                    else
                        tempoBuf.emplace_back(pair.first * 384 / header.div, pair.second);
                }
            }

            if (header.type == 1)
            {
                it = end;
                continue;
            }
        }

        /* Extract channel events */
        std::vector<uint8_t>::const_iterator begin = it;
        std::vector<uint8_t>::const_iterator end = it + length;
        it = end;

        MIDIDecoder dec;
        int tmpLoopStart[16];
        int tmpLoopEnd[16];
        std::copy(std::begin(loopStart), std::end(loopStart), std::begin(tmpLoopStart));
        std::copy(std::begin(loopEnd), std::end(loopEnd), std::begin(tmpLoopEnd));
        dec.receiveBytes(begin, end, tmpLoopStart, tmpLoopEnd);

        for (int c = 0; c < 16; ++c)
        {
            std::vector<std::multimap<int, Event>>& results = dec.getResults(c);
            bool didChanInit = false;
            int lastEventTick = 0;
            for (auto& chanRegion : results)
            {
                bool didInit = false;
                int startTick = 0;
                lastEventTick = 0;
                int lastPitchTick = 0;
                int lastPitchVal = 0;
                int lastModTick = 0;
                int lastModVal = 0;
                Region region;

                for (auto& event : chanRegion)
                {
                    uint32_t eventTick = event.first * 384 / header.div;

                    if (event.second.channel == c)
                    {
                        if (!didInit)
                        {
                            didInit = true;
                            startTick = eventTick;
                            lastEventTick = startTick;
                            lastPitchTick = startTick;
                            lastPitchVal = 0;
                            lastModTick = startTick;
                            lastModVal = 0;
                        }

                        switch (event.second.m_type)
                        {
                        case Event::Type::Control:
                        {
                            if (event.second.noteOrCtrl == 1)
                            {
                                int newMod = event.second.velOrVal * 128;
                                EncodeDelta(region.modBuf, eventTick - lastModTick, newMod - lastModVal);
                                lastModTick = eventTick;
                                lastModVal = newMod;
                            }
                            else
                            {
                                if (version == 1)
                                {
                                    EncodeTime(region.eventBuf, uint32_t(eventTick - lastEventTick));
                                    lastEventTick = eventTick;
                                    region.eventBuf.push_back(0x80 | event.second.velOrVal);
                                    region.eventBuf.push_back(0x80 | event.second.noteOrCtrl);
                                }
                                else
                                {
                                    if (big)
                                    {
                                        uint32_t tickBig = SBig(uint32_t(eventTick - startTick));
                                        for (int i = 0; i < 4; ++i)
                                            region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&tickBig)[i]);
                                        region.eventBuf.push_back(0x80 | event.second.velOrVal);
                                        region.eventBuf.push_back(0x80 | event.second.noteOrCtrl);
                                    }
                                    else
                                    {
                                        uint32_t tick = uint32_t(eventTick - startTick);
                                        for (int i = 0; i < 4; ++i)
                                            region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&tick)[i]);
                                        region.eventBuf.push_back(0x80 | event.second.velOrVal);
                                        region.eventBuf.push_back(0x80 | event.second.noteOrCtrl);
                                    }
                                }
                            }
                            break;
                        }
                        case Event::Type::Program:
                        {
                            if (version == 1)
                            {
                                EncodeTime(region.eventBuf, uint32_t(eventTick - lastEventTick));
                                lastEventTick = eventTick;
                                region.eventBuf.push_back(0x80 | event.second.program);
                                region.eventBuf.push_back(0);
                            }
                            else
                            {
                                if (big)
                                {
                                    uint32_t tickBig = SBig(uint32_t(eventTick - startTick));
                                    for (int i = 0; i < 4; ++i)
                                        region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&tickBig)[i]);
                                    region.eventBuf.push_back(0x80 | event.second.program);
                                    region.eventBuf.push_back(0);
                                }
                                else
                                {
                                    uint32_t tick = uint32_t(eventTick - startTick);
                                    for (int i = 0; i < 4; ++i)
                                        region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&tick)[i]);
                                    region.eventBuf.push_back(0x80 | event.second.program);
                                    region.eventBuf.push_back(0);
                                }
                            }
                            break;
                        }
                        case Event::Type::Pitch:
                        {
                            int newPitch = event.second.pitchBend - 0x2000;
                            EncodeDelta(region.pitchBuf, eventTick - lastPitchTick, newPitch - lastPitchVal);
                            lastPitchTick = eventTick;
                            lastPitchVal = newPitch;
                            break;
                        }
                        case Event::Type::Note:
                        {
                            int lenTicks = event.second.length * 384 / header.div;
                            if (version == 1)
                            {
                                EncodeTime(region.eventBuf, uint32_t(eventTick - lastEventTick));
                                lastEventTick = eventTick;
                                region.eventBuf.push_back(event.second.noteOrCtrl);
                                region.eventBuf.push_back(event.second.velOrVal);
                                uint16_t lenBig = SBig(uint16_t(lenTicks));
                                region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&lenBig)[0]);
                                region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&lenBig)[1]);
                            }
                            else
                            {
                                if (big)
                                {
                                    uint32_t tickBig = SBig(uint32_t(eventTick - startTick));
                                    for (int i = 0; i < 4; ++i)
                                        region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&tickBig)[i]);
                                    uint16_t lenBig = SBig(uint16_t(lenTicks));
                                    region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&lenBig)[0]);
                                    region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&lenBig)[1]);
                                    region.eventBuf.push_back(event.second.noteOrCtrl);
                                    region.eventBuf.push_back(event.second.velOrVal);
                                }
                                else
                                {
                                    uint32_t tick = uint32_t(eventTick - startTick);
                                    for (int i = 0; i < 4; ++i)
                                        region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&tick)[i]);
                                    uint16_t len = uint16_t(lenTicks);
                                    region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&len)[0]);
                                    region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&len)[1]);
                                    region.eventBuf.push_back(event.second.noteOrCtrl);
                                    region.eventBuf.push_back(event.second.velOrVal);
                                }
                            }
                            break;
                        }
                        }
                    }
                }

                if (didInit)
                {
                    if (!didChanInit)
                    {
                        didChanInit = true;
                        if (trackRegionIdxArr.size() == 64)
                            return {};
                        chanMap[trackRegionIdxArr.size()] = c;
                        trackRegionIdxArr.push_back(regionBuf.size());
                    }

                    /* Terminate region */
                    if (version == 1)
                    {
                        size_t pitchDelta = 0;
                        size_t modDelta = 0;
                        if (lastPitchTick > lastEventTick)
                            pitchDelta = lastPitchTick - lastEventTick;
                        if (lastModTick > lastEventTick)
                            modDelta = lastModTick - lastEventTick;

                        EncodeTime(region.eventBuf, std::max(pitchDelta, modDelta));
                        region.eventBuf.push_back(0xff);
                        region.eventBuf.push_back(0xff);
                    }
                    else
                    {
                        if (big)
                        {
                            uint32_t selTick = std::max(std::max(lastEventTick - startTick, lastPitchTick - startTick),
                                                        lastModTick - startTick);
                            uint32_t tickBig = SBig(uint32_t(selTick));
                            for (int i = 0; i < 4; ++i)
                                region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&tickBig)[i]);
                            region.eventBuf.push_back(0);
                            region.eventBuf.push_back(0);
                            region.eventBuf.push_back(0xff);
                            region.eventBuf.push_back(0xff);
                        }
                        else
                        {
                            uint32_t selTick = std::max(std::max(lastEventTick - startTick, lastPitchTick - startTick),
                                                        lastModTick - startTick);
                            uint32_t tick = uint32_t(selTick);
                            for (int i = 0; i < 4; ++i)
                                region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&tick)[i]);
                            region.eventBuf.push_back(0);
                            region.eventBuf.push_back(0);
                            region.eventBuf.push_back(0xff);
                            region.eventBuf.push_back(0xff);
                        }
                    }

                    if (region.pitchBuf.size())
                    {
                        region.pitchBuf.push_back(0x80);
                        region.pitchBuf.push_back(0);
                    }

                    if (region.modBuf.size())
                    {
                        region.modBuf.push_back(0x80);
                        region.modBuf.push_back(0);
                    }

                    /* See if there's a matching region buffer already present */
                    int regIdx = 0;
                    for (Region& reg : regions)
                    {
                        if (reg == region)
                            break;
                        ++regIdx;
                    }
                    if (regIdx == regions.size())
                    {
                        regionDataIdxArr.push_back(curRegionOff);
                        curRegionOff += 12 + region.eventBuf.size() + region.pitchBuf.size() + region.modBuf.size();
                        int paddedRegOff = ((curRegionOff + 3) & ~3);
                        region.padding = paddedRegOff - curRegionOff;
                        curRegionOff = paddedRegOff;
                        regions.push_back(std::move(region));
                    }

                    /* Region header */
                    regionBuf.emplace_back();
                    SongState::TrackRegion& reg = regionBuf.back();
                    if (big)
                    {
                        reg.m_startTick = SBig(uint32_t(startTick));
                        reg.m_progNum = 0xff;
                        reg.m_unk1 = 0xff;
                        reg.m_unk2 = 0;
                        reg.m_regionIndex = SBig(uint16_t(regIdx));
                        reg.m_loopToRegion = 0;
                    }
                    else
                    {
                        reg.m_startTick = uint32_t(startTick);
                        reg.m_progNum = 0xff;
                        reg.m_unk1 = 0xff;
                        reg.m_unk2 = 0;
                        reg.m_regionIndex = uint16_t(regIdx);
                        reg.m_loopToRegion = 0;
                    }
                }
            }

            if (didChanInit)
            {
                /* Terminating region header */
                regionBuf.emplace_back();
                SongState::TrackRegion& reg = regionBuf.back();

                uint32_t termStartTick = 0;
                int16_t termRegionIdx = -1;
                int16_t termLoopToRegion = 0;
                if (loopEnd[c] != INT_MAX)
                {
                    termStartTick = loopEnd[c];
                    if (lastEventTick >= loopStart[c])
                    {
                        termRegionIdx = -2;
                        termLoopToRegion = results.size() - 1;
                    }
                }

                if (big)
                {
                    reg.m_startTick = SBig(termStartTick);
                    reg.m_progNum = 0xff;
                    reg.m_unk1 = 0xff;
                    reg.m_unk2 = 0;
                    reg.m_regionIndex = SBig(termRegionIdx);
                    reg.m_loopToRegion = SBig(termLoopToRegion);
                }
                else
                {
                    reg.m_startTick = termStartTick;
                    reg.m_progNum = 0xff;
                    reg.m_unk1 = 0xff;
                    reg.m_unk2 = 0;
                    reg.m_regionIndex = termRegionIdx;
                    reg.m_loopToRegion = termLoopToRegion;
                }
            }
        }
    }

    if (version == 1)
    {
        SongState::Header head;
        head.m_initialTempo = initTempo;
        head.m_loopStartTicks[0] = 0;
        if (loopChanCount == 1)
        {
            head.m_loopStartTicks[0] = loopStart[0] == INT_MAX ? 0 : loopStart[0];
        }
        else if (loopChanCount > 1)
        {
            for (int i = 0; i < 16; ++i)
                head.m_loopStartTicks[i] = loopStart[i] == INT_MAX ? 0 : loopStart[i];
            head.m_initialTempo |= 0x80000000;
        }
        size_t headSz = (head.m_initialTempo & 0x80000000) ? 0x58 : 0x18;
        head.m_trackIdxOff = headSz;
        head.m_regionIdxOff = headSz + 4 * 64 + regionBuf.size() * 12;
        head.m_chanMapOff = head.m_regionIdxOff + 4 * regionDataIdxArr.size() + curRegionOff;
        head.m_tempoTableOff = tempoBuf.size() ? head.m_chanMapOff + 64 : 0;
        head.m_chanMapOff2 = head.m_chanMapOff;

        uint32_t regIdxOff = head.m_regionIdxOff;
        if (big)
            head.swapToBig();
        *reinterpret_cast<SongState::Header*>(&*ret.insert(ret.cend(), headSz, 0)) = head;

        for (int i = 0; i < 64; ++i)
        {
            if (i >= trackRegionIdxArr.size())
            {
                ret.insert(ret.cend(), 4, 0);
                continue;
            }

            uint32_t idx = trackRegionIdxArr[i];
            *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                big ? SBig(uint32_t(headSz + 4 * 64 + idx * 12)) : uint32_t(headSz + 4 * 64 + idx * 12);
        }

        for (SongState::TrackRegion& reg : regionBuf)
            *reinterpret_cast<SongState::TrackRegion*>(&*ret.insert(ret.cend(), 12, 0)) = reg;

        uint32_t regBase = regIdxOff + 4 * regionDataIdxArr.size();
        for (uint32_t regOff : regionDataIdxArr)
            *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                big ? SBig(uint32_t(regBase + regOff)) : uint32_t(regBase + regOff);

        uint32_t curOffset = regBase;
        for (Region& reg : regions)
        {
            *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) = big ? SBig(uint32_t(8)) : 8;

            if (reg.pitchBuf.size())
                *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                    big ? SBig(uint32_t(curOffset + 12 + reg.eventBuf.size()))
                        : uint32_t(curOffset + 12 + reg.eventBuf.size());
            else
                ret.insert(ret.cend(), 4, 0);

            if (reg.modBuf.size())
                *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                    big ? SBig(uint32_t(curOffset + 12 + reg.eventBuf.size() + reg.pitchBuf.size()))
                        : uint32_t(curOffset + 12 + reg.eventBuf.size() + reg.pitchBuf.size());
            else
                ret.insert(ret.cend(), 4, 0);

            if (reg.eventBuf.size())
                memmove(&*ret.insert(ret.cend(), reg.eventBuf.size(), 0), reg.eventBuf.data(), reg.eventBuf.size());

            if (reg.pitchBuf.size())
                memmove(&*ret.insert(ret.cend(), reg.pitchBuf.size(), 0), reg.pitchBuf.data(), reg.pitchBuf.size());

            if (reg.modBuf.size())
                memmove(&*ret.insert(ret.cend(), reg.modBuf.size(), 0), reg.modBuf.data(), reg.modBuf.size());

            ret.insert(ret.cend(), reg.padding, 0);

            curOffset += 12 + reg.eventBuf.size() + reg.pitchBuf.size() + reg.modBuf.size() + reg.padding;
        }

        memmove(&*ret.insert(ret.cend(), 64, 0), chanMap.data(), 64);

        if (tempoBuf.size())
            memmove(&*ret.insert(ret.cend(), tempoBuf.size() * 8, 0), tempoBuf.data(), tempoBuf.size() * 8);

        *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) = uint32_t(0xffffffff);
    }
    else
    {
        SongState::Header head;
        head.m_initialTempo = initTempo;
        head.m_loopStartTicks[0] = 0;
        if (loopChanCount == 1)
        {
            head.m_loopStartTicks[0] = loopStart[0] == INT_MAX ? 0 : loopStart[0];
        }
        else if (loopChanCount > 1)
        {
            for (int i = 0; i < 16; ++i)
                head.m_loopStartTicks[i] = loopStart[i] == INT_MAX ? 0 : loopStart[i];
            head.m_initialTempo |= 0x80000000;
        }
        size_t headSz = (head.m_initialTempo & 0x80000000) ? 0x58 : 0x18;
        head.m_trackIdxOff = headSz + regionBuf.size() * 12;
        head.m_regionIdxOff = head.m_trackIdxOff + 4 * 64 + 64 + curRegionOff;
        head.m_chanMapOff = head.m_trackIdxOff + 4 * 64;
        head.m_tempoTableOff = tempoBuf.size() ? head.m_regionIdxOff + 4 * regionDataIdxArr.size() : 0;
        head.m_chanMapOff2 = head.m_chanMapOff;

        uint32_t chanMapOff = head.m_chanMapOff;
        if (big)
            head.swapToBig();
        *reinterpret_cast<SongState::Header*>(&*ret.insert(ret.cend(), headSz, 0)) = head;

        for (SongState::TrackRegion& reg : regionBuf)
            *reinterpret_cast<SongState::TrackRegion*>(&*ret.insert(ret.cend(), 12, 0)) = reg;

        for (int i = 0; i < 64; ++i)
        {
            if (i >= trackRegionIdxArr.size())
            {
                ret.insert(ret.cend(), 4, 0);
                continue;
            }

            uint32_t idx = trackRegionIdxArr[i];
            *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                big ? SBig(uint32_t(headSz + 4 * 64 + idx * 12)) : uint32_t(headSz + 4 * 64 + idx * 12);
        }

        memmove(&*ret.insert(ret.cend(), 64, 0), chanMap.data(), 64);

        uint32_t regBase = chanMapOff + 64;
        uint32_t curOffset = regBase;
        for (Region& reg : regions)
        {
            *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) = big ? SBig(uint32_t(8)) : 8;

            if (reg.pitchBuf.size())
                *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                    big ? SBig(uint32_t(curOffset + 12 + reg.eventBuf.size()))
                        : uint32_t(curOffset + 12 + reg.eventBuf.size());
            else
                ret.insert(ret.cend(), 4, 0);

            if (reg.modBuf.size())
                *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                    big ? SBig(uint32_t(curOffset + 12 + reg.eventBuf.size() + reg.pitchBuf.size()))
                        : uint32_t(curOffset + 12 + reg.eventBuf.size() + reg.pitchBuf.size());
            else
                ret.insert(ret.cend(), 4, 0);

            if (reg.eventBuf.size())
                memmove(&*ret.insert(ret.cend(), reg.eventBuf.size(), 0), reg.eventBuf.data(), reg.eventBuf.size());

            if (reg.pitchBuf.size())
                memmove(&*ret.insert(ret.cend(), reg.pitchBuf.size(), 0), reg.pitchBuf.data(), reg.pitchBuf.size());

            if (reg.modBuf.size())
                memmove(&*ret.insert(ret.cend(), reg.modBuf.size(), 0), reg.modBuf.data(), reg.modBuf.size());

            ret.insert(ret.cend(), reg.padding, 0);

            curOffset += 12 + reg.eventBuf.size() + reg.pitchBuf.size() + reg.modBuf.size();
        }

        for (uint32_t regOff : regionDataIdxArr)
            *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                big ? SBig(uint32_t(regBase + regOff)) : uint32_t(regBase + regOff);

        if (tempoBuf.size())
            memmove(&*ret.insert(ret.cend(), tempoBuf.size() * 8, 0), tempoBuf.data(), tempoBuf.size() * 8);

        *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) = uint32_t(0xffffffff);
    }

    return ret;
}
}