#include "amuse/SongConverter.hpp"
#include "amuse/SongState.hpp"
#include "amuse/Common.hpp"
#include <stdlib.h>
#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
{
    bool endEvent = false;
    bool controlChange = false;
    bool progChange = false;
    uint8_t channel;
    uint8_t noteOrCtrl;
    uint8_t velOrVal;
    uint8_t program;
    uint16_t length;

    bool isPitchBend = false;
    int pitchBend;

    Event(NoteEvent, uint8_t chan, uint8_t note, uint8_t vel, uint16_t len)
    : controlChange(false), channel(chan), noteOrCtrl(note), velOrVal(vel), length(len) {}

    Event(CtrlEvent, uint8_t chan, uint8_t note, uint8_t vel, uint16_t len)
    : controlChange(true), channel(chan), noteOrCtrl(note), velOrVal(vel), length(len) {}

    Event(ProgEvent, uint8_t chan, uint8_t prog)
    : progChange(true), channel(chan), program(prog) {}

    Event(PitchEvent, uint8_t chan, int pBend) : isPitchBend(true), channel(chan), pitchBend(pBend) {}
};

class MIDIDecoder
{
    int m_tick = 0;
    std::vector<std::pair<int, std::multimap<int, Event>>> m_results;
    std::multimap<int, int> m_tempos;
    std::array<std::multimap<int, Event>::iterator, 128> m_notes;

    void _addProgramChange(int prog)
    {
        m_results.emplace_back();
        m_results.back().first = prog;
        for (size_t i=0 ; i<128 ; ++i)
            m_notes[i] = m_results.back().second.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:
    std::vector<uint8_t>::const_iterator
    receiveBytes(std::vector<uint8_t>::const_iterator begin,
                 std::vector<uint8_t>::const_iterator end)
    {
        std::vector<uint8_t>::const_iterator it = begin;
        if (it == end)
            return begin;

        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--;

        /* Not actually used as such for now */
        if (m_results.empty())
            _addProgramChange(0);
        std::multimap<int, Event>& res = m_results.back().second;

        if (m_status == 0xff)
        {
            /* Meta events */
            if (it == end)
                return begin;
            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;
            switch (Status(m_status & 0xf0))
            {
            case Status::NoteOff:
            {
                if (it == end)
                    return begin;
                a = *it++;
                if (it == end)
                    return begin;
                b = *it++;

                uint8_t notenum = clamp7(a);
                std::multimap<int, Event>::iterator note = m_notes[notenum];
                if (note != res.end())
                {
                    note->second.length = uint16_t(m_tick - note->first);
                    m_notes[notenum] = res.end();
                }
                break;
            }
            case Status::NoteOn:
            {
                if (it == end)
                    return begin;
                a = *it++;
                if (it == end)
                    return begin;
                b = *it++;

                uint8_t notenum = clamp7(a);
                uint8_t vel = clamp7(b);
                std::multimap<int, Event>::iterator note = m_notes[notenum];
                if (note != res.end())
                    note->second.length = uint16_t(m_tick - note->first);

                m_notes[notenum] = res.emplace(m_tick, Event{NoteEvent{}, chan, notenum, vel, 0});
                break;
            }
            case Status::NotePressure:
            {
                if (it == end)
                    return begin;
                a = *it++;
                if (it == end)
                    return begin;
                b = *it++;
                break;
            }
            case Status::ControlChange:
            {
                if (it == end)
                    return begin;
                a = *it++;
                if (it == end)
                    return begin;
                b = *it++;
                res.emplace(m_tick, Event{CtrlEvent{}, chan, clamp7(a), clamp7(b), 0});
                break;
            }
            case Status::ProgramChange:
            {
                if (it == end)
                    return begin;
                a = *it++;
                res.emplace(m_tick, Event{ProgEvent{}, chan, a});
                break;
            }
            case Status::ChannelPressure:
            {
                if (it == end)
                    return begin;
                a = *it++;
                break;
            }
            case Status::PitchBend:
            {
                if (it == end)
                    return begin;
                a = *it++;
                if (it == end)
                    return begin;
                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)
                        return begin;
                    break;
                }
                case Status::TimecodeQuarterFrame:
                {
                    if (it == end)
                        return begin;
                    a = *it++;
                    break;
                }
                case Status::SongPositionPointer:
                {
                    if (it == end)
                        return begin;
                    a = *it++;
                    if (it == end)
                        return begin;
                    b = *it++;
                    break;
                }
                case Status::SongSelect:
                {
                    if (it == end)
                        return begin;
                    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::pair<int, std::multimap<int, Event>>>& getResults() {return m_results;}
    std::multimap<int, int>& getTempos() {return m_tempos;}
};

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)
    {
        uint32_t send[3] = {};
        uint32_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 uint32_t DecodeRLE(const unsigned char*& data)
{
    uint32_t ret = 0;

    while (true)
    {
        uint32_t thisPart = *data & 0x7f;
        if (*data & 0x80)
        {
            ++data;
            thisPart = thisPart * 256 + *data;
            if (thisPart == 0)
                return -1;
        }

        if (thisPart == 32767)
        {
            ret += 32767;
            data += 2;
            continue;
        }

        ret += thisPart;
        data += 1;
        break;
    }

    return ret;
}

static void EncodeRLE(std::vector<uint8_t>& vecOut, uint32_t val)
{
    while (val >= 32767)
    {
        vecOut.push_back(0xff);
        vecOut.push_back(0xff);
        vecOut.push_back(0);
        val -= 32767;
    }

    if (val >= 128)
    {
        vecOut.push_back(uint8_t(val / 256) | 0x80);
        vecOut.push_back(uint8_t(val % 256));
    }
    else
        vecOut.push_back(uint8_t(val));
}

static int32_t DecodeContinuousRLE(const unsigned char*& data)
{
    int32_t ret = int32_t(DecodeRLE(data));
    if (ret >= 16384)
        return ret - 32767;
    return ret;
}

static void EncodeContinuousRLE(std::vector<uint8_t>& vecOut, int32_t val)
{
    if (val < 0)
        val += 32767;
    EncodeRLE(vecOut, uint32_t(val));
}

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

    while (true)
    {
        uint16_t thisPart = SBig(*reinterpret_cast<const uint16_t*>(data));
        if (thisPart == 0xffff)
        {
            ret += 65535;
            data += 4;
            continue;
        }

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

    return ret;
}

static void EncodeTimeRLE(std::vector<uint8_t>& vecOut, uint32_t val)
{
    while (val >= 65535)
    {
        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, Target& targetOut)
{
    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;
    song.initialize(data);

    if (song.m_bigEndian)
    {
        if (song.m_header.m_trackIdxOff == 0x18 || song.m_header.m_trackIdxOff == 0x58)
            targetOut = Target::GCN;
        else
            targetOut = Target::N64;
    }
    else
        targetOut = Target::PC;

    size_t trkCount = 1;
    for (std::experimental::optional<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_tempo);
        for (int i=1 ; i<4 ; ++i)
            encoder.getResult().push_back(reinterpret_cast<uint8_t*>(&tempo24)[i]);

        /* Write out tempo changes */
        int lastTick = 0;
        while (song.m_tempoPtr && song.m_tempoPtr->m_tick != 0xffffffff)
        {
            SongState::TempoChange change = *song.m_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);
            for (int i=1 ; i<4 ; ++i)
                encoder.getResult().push_back(reinterpret_cast<uint8_t*>(&tempo24)[i]);

            ++song.m_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());
    }

    /* Iterate each SNG track into type-1 MIDI track */
    for (std::experimental::optional<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(nullptr);
                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)
                    {
                        /* See if there's an upcoming pitch change in this interval */
                        const unsigned char* ptr = trk->m_pitchWheelData;
                        uint32_t deltaTicks = DecodeRLE(ptr);
                        if (deltaTicks != 0xffffffff)
                        {
                            int32_t nextTick = trk->m_lastPitchTick + deltaTicks;
                            int32_t pitchDelta = DecodeContinuousRLE(ptr);
                            trk->m_lastPitchVal += pitchDelta;
                            trk->m_pitchWheelData = ptr;
                            trk->m_lastPitchTick = nextTick;
                            events.emplace(regStart + nextTick, Event{PitchEvent{}, trk->m_midiChan, clamp(0, trk->m_lastPitchVal / 2 + 0x2000, 0x4000)});
                        }
                        else
                            break;
                    }
                }

                /* Update continuous modulation data */
                if (trk->m_modWheelData)
                {
                    while (true)
                    {
                        /* See if there's an upcoming modulation change in this interval */
                        const unsigned char* ptr = trk->m_modWheelData;
                        uint32_t deltaTicks = DecodeRLE(ptr);
                        if (deltaTicks != 0xffffffff)
                        {
                            int32_t nextTick = trk->m_lastModTick + deltaTicks;
                            int32_t modDelta = DecodeContinuousRLE(ptr);
                            trk->m_lastModVal += modDelta;
                            trk->m_modWheelData = ptr;
                            trk->m_lastModTick = nextTick;
                            events.emplace(regStart + nextTick, Event{CtrlEvent{}, trk->m_midiChan, 1, uint8_t(clamp(0, trk->m_lastModVal * 128 / 16384, 127)), 0});
                        }
                        else
                            break;
                    }
                }

                /* Loop through as many commands as we can for this time period */
                if (song.m_header.m_trackIdxOff == 0x18 || song.m_header.m_trackIdxOff == 0x58)
                {
                    /* GameCube */
                    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(DecodeTimeRLE(trk->m_data));
                    }
                }
                else
                {
                    /* N64 */
                    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.controlChange)
                    {
                        auto it = allEvents.emplace(pair.first + pair.second.length, pair.second);
                        it->second.endEvent = true;
                    }
                }
            }

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

                if (pair.second.controlChange)
                {
                    encoder.controlChange(pair.second.channel, pair.second.noteOrCtrl, pair.second.velOrVal);
                }
                else if (pair.second.progChange)
                {
                    encoder.programChange(trk->m_midiChan, pair.second.program);
                }
                else if (pair.second.isPitchBend)
                {
                    encoder.pitchBend(trk->m_midiChan, pair.second.pitchBend);
                }
                else
                {
                    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);
                }
            }

            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, Target target)
{
    std::vector<uint8_t> ret;
    std::vector<uint8_t>::const_iterator it = data.cbegin();
    bool bigEndian = (target == Target::GCN || target == Target::N64);

    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;

        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;

    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;
            while (begin != end)
                begin = 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 (bigEndian)
                        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;
        while (begin != end)
            begin = dec.receiveBytes(begin, end);

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

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

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

                        if (event.second.controlChange)
                        {
                            if (event.second.noteOrCtrl == 1)
                            {
                                EncodeRLE(region.modBuf, uint32_t(eventTick - lastModTick));
                                lastModTick = eventTick;
                                int newMod = event.second.velOrVal * 16384 / 128;
                                EncodeContinuousRLE(region.modBuf, newMod - lastModVal);
                                lastModVal = newMod;
                            }
                            else
                            {
                                if (target == Target::GCN)
                                {
                                    EncodeTimeRLE(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 (target == Target::N64)
                                {
                                    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 if (target == Target::PC)
                                {
                                    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);
                                }
                            }
                        }
                        else if (event.second.progChange)
                        {
                            if (target == Target::GCN)
                            {
                                EncodeTimeRLE(region.eventBuf, uint32_t(eventTick - lastEventTick));
                                lastEventTick = eventTick;
                                region.eventBuf.push_back(0x80 | event.second.program);
                                region.eventBuf.push_back(0);
                            }
                            else if (target == Target::N64)
                            {
                                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 if (target == Target::PC)
                            {
                                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);
                            }
                        }
                        else if (event.second.isPitchBend)
                        {
                            EncodeRLE(region.pitchBuf, uint32_t(eventTick - lastPitchTick));
                            lastPitchTick = eventTick;
                            int newPitch = (event.second.pitchBend - 0x2000) * 2;
                            EncodeContinuousRLE(region.pitchBuf, newPitch - lastPitchVal);
                            lastPitchVal = newPitch;
                        }
                        else
                        {
                            if (target == Target::GCN)
                            {
                                EncodeTimeRLE(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(event.second.length));
                                region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&lenBig)[0]);
                                region.eventBuf.push_back(reinterpret_cast<const uint8_t*>(&lenBig)[1]);
                            }
                            else if (target == Target::N64)
                            {
                                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(event.second.length));
                                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 if (target == Target::PC)
                            {
                                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(event.second.length);
                                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);
                            }
                        }
                    }
                }

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

                    /* Terminate region */
                    if (target == Target::GCN)
                    {
                        size_t pitchDelta = 0;
                        size_t modDelta = 0;
                        if (lastPitchTick > lastEventTick)
                            pitchDelta = lastPitchTick - lastEventTick;
                        if (lastModTick > lastEventTick)
                            modDelta = lastModTick - lastEventTick;

                        EncodeTimeRLE(region.eventBuf, std::max(pitchDelta, modDelta));
                        region.eventBuf.push_back(0xff);
                        region.eventBuf.push_back(0xff);
                    }
                    else if (target == Target::N64)
                    {
                        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 if (target == Target::PC)
                    {
                        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();
                        regions.push_back(std::move(region));
                    }

                    /* Region header */
                    regionBuf.emplace_back();
                    SongState::TrackRegion& reg = regionBuf.back();
                    if (bigEndian)
                    {
                        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_unk3 = 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_unk3 = 0;
                    }
                }
            }

            if (didChanInit)
            {
                /* Terminating region header */
                regionBuf.emplace_back();
                SongState::TrackRegion& reg = regionBuf.back();
                if (bigEndian)
                {
                    reg.m_startTick = SBig(uint32_t(lastTrackStartTick));
                    reg.m_progNum = 0xff;
                    reg.m_unk1 = 0xff;
                    reg.m_unk2 = 0;
                    reg.m_regionIndex = 0xffff;
                    reg.m_unk3 = 0;
                }
                else
                {
                    reg.m_startTick = uint32_t(lastTrackStartTick);
                    reg.m_progNum = 0xff;
                    reg.m_unk1 = 0xff;
                    reg.m_unk2 = 0;
                    reg.m_regionIndex = 0xffff;
                    reg.m_unk3 = 0;
                }
            }
        }
    }

    if (target == Target::GCN)
    {
        SongState::Header head;
        head.m_trackIdxOff = 0x18;
        head.m_regionIdxOff = 0x18 + 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_initialTempo = initTempo;
        head.m_unkOff = 0;

        uint32_t regIdxOff = head.m_regionIdxOff;
        head.swapBig();
        *reinterpret_cast<SongState::Header*>(&*ret.insert(ret.cend(), 0x18, 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)) = SBig(uint32_t(0x18 + 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)) = SBig(uint32_t(regBase + regOff));

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

            if (reg.pitchBuf.size())
                *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                    SBig(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)) =
                    SBig(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());

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

        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 if (target == Target::N64)
    {
        SongState::Header head;
        head.m_trackIdxOff = 0x18 + 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_initialTempo = initTempo;
        head.m_unkOff = 0;

        uint32_t chanMapOff = head.m_chanMapOff;
        head.swapBig();
        *reinterpret_cast<SongState::Header*>(&*ret.insert(ret.cend(), 0x18, 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)) = SBig(uint32_t(0x18 + 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)) = SBig(uint32_t(8));

            if (reg.pitchBuf.size())
                *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                    SBig(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)) =
                    SBig(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());

            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)) = SBig(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);
    }
    else if (target == Target::PC)
    {
        SongState::Header head;
        head.m_trackIdxOff = 0x18 + 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_initialTempo = initTempo;
        head.m_unkOff = 0;

        *reinterpret_cast<SongState::Header*>(&*ret.insert(ret.cend(), 0x18, 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)) = uint32_t(0x18 + 4 * 64 + idx * 12);
        }

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

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

            if (reg.pitchBuf.size())
                *reinterpret_cast<uint32_t*>(&*ret.insert(ret.cend(), 4, 0)) =
                    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)) =
                    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());

            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)) = 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;
}

}