/*
 * SPDX-License-Identifier: GPL-3.0-only
 * MuseScore-Studio-CLA-applies
 *
 * MuseScore Studio
 * Music Composition & Notation
 *
 * Copyright (C) 2021 MuseScore Limited
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <set>

#include <QFile>

#include "translation.h"

#include "engraving/engravingerrors.h"
#include "engraving/rw/xmlwriter.h"

#include "infrastructure/messagebox.h"

#include "engraving/dom/factory.h"
#include "engraving/dom/masterscore.h"
#include "engraving/dom/key.h"
#include "engraving/dom/clef.h"
#include "engraving/dom/sig.h"
#include "engraving/dom/tempo.h"
#include "engraving/dom/note.h"
#include "engraving/dom/chord.h"
#include "engraving/dom/rest.h"
#include "engraving/dom/segment.h"
#include "engraving/dom/utils.h"
#include "engraving/dom/text.h"
#include "engraving/dom/slur.h"
#include "engraving/dom/tie.h"
#include "engraving/dom/staff.h"
#include "engraving/dom/measure.h"
#include "engraving/dom/part.h"
#include "engraving/dom/timesig.h"
#include "engraving/dom/barline.h"
#include "engraving/dom/pedal.h"
#include "engraving/dom/ottava.h"
#include "engraving/dom/lyrics.h"
#include "engraving/dom/bracket.h"
#include "engraving/dom/drumset.h"
#include "engraving/dom/box.h"
#include "engraving/dom/pitchspelling.h"
#include "engraving/dom/tuplet.h"
#include "engraving/dom/articulation.h"

#include "importmidi_meter.h"
#include "importmidi_chord.h"
#include "importmidi_quant.h"
#include "importmidi_tuplet.h"
#include "importmidi_tuplet_tonotes.h"
#include "importmidi_swing.h"
#include "importmidi_fraction.h"
#include "importmidi_drum.h"
#include "importmidi_inner.h"
#include "importmidi_clef.h"
#include "importmidi_lrhand.h"
#include "importmidi_lyrics.h"
#include "importmidi_tie.h"
#include "importmidi_beat.h"
#include "importmidi_tempo.h"
#include "importmidi_simplify.h"
#include "importmidi_voice.h"
#include "importmidi_operations.h"
#include "importmidi_key.h"
#include "importmidi_instrument.h"
#include "importmidi_chordname.h"
#include "../midishared/midifile.h"

#include "log.h"

using namespace mu::engraving;

namespace mu::iex::midi {
extern void updateNoteLines(Segment*, int track);

void lengthenTooShortNotes(std::multimap<int, MTrack>& tracks)
{
    for (auto& track: tracks) {
        MTrack& mtrack = track.second;
        for (auto& chord: mtrack.chords) {
            for (auto& note: chord.second.notes) {
                if (note.offTime - chord.first < MChord::minAllowedDuration()) {
                    note.offTime = chord.first + MChord::minAllowedDuration();
                }
            }
        }
    }
}

#ifdef QT_DEBUG

bool doNotesOverlap(const MTrack& track)
{
    const auto& chords = track.chords;
    for (auto i1 = chords.begin(); i1 != chords.end(); ++i1) {
        const auto& chord1 = i1->second;
        for (auto noteIt1 = chord1.notes.begin();
             noteIt1 != chord1.notes.end(); ++noteIt1) {
            for (auto noteIt2 = std::next(noteIt1);
                 noteIt2 != chord1.notes.end(); ++noteIt2) {
                if (noteIt2->pitch == noteIt1->pitch) {
                    return true;
                }
            }
            for (auto i2 = std::next(i1); i2 != chords.end(); ++i2) {
                if (i2->first >= noteIt1->offTime) {
                    break;
                }
                const auto& chord2 = i2->second;
                if (chord1.voice != chord2.voice) {
                    continue;
                }
                for (const auto& note2: chord2.notes) {
                    if (note2.pitch == noteIt1->pitch) {
                        return true;
                    }
                }
            }
        }
    }
    return false;
}

bool doNotesOverlap(const std::multimap<int, MTrack>& tracks)
{
    bool result = false;
    for (const auto& track: tracks) {
        result = doNotesOverlap(track.second);
    }
    return result;
}

bool noTooShortNotes(const std::multimap<int, MTrack>& tracks)
{
    for (const auto& track: tracks) {
        const auto& chords = track.second.chords;
        for (const auto& chord: chords) {
            for (const auto& note: chord.second.notes) {
                if (note.offTime - chord.first < MChord::minAllowedDuration()) {
                    return false;
                }
            }
        }
    }
    return true;
}

#endif

std::vector<std::multimap<ReducedFraction, MidiChord> >
separateDrumChordsTo2Voices(const std::multimap<ReducedFraction, MidiChord>& chords)
{
    std::vector<std::multimap<ReducedFraction, MidiChord> > separatedChords(2);
    for (const auto& chord: chords) {
        const MidiChord& c = chord.second;

        Q_ASSERT(c.voice == 0 || c.voice == 1);

        separatedChords[c.voice].insert({ chord.first, c });
    }
    return separatedChords;
}

void setChordVoice(MidiChord& chord, int voice)
{
    chord.voice = voice;
    if (chord.isInTuplet) {
        chord.tuplet->second.voice = voice;
    }
    for (auto& note: chord.notes) {
        if (note.isInTuplet) {
            note.tuplet->second.voice = voice;
        }
    }
}

void findAllTupletsForDrums(
    MTrack& mtrack,
    TimeSigMap* sigmap,
    const ReducedFraction& basicQuant)
{
    const size_t drumVoiceCount = 2;
    // drum track has 2 voices (stem up and stem down),
    // and tuplet detection is applicable for single voice drum tracks,
    // so split track chords into 2 voice groups,
    // detect tuplets and merge chords (and found tuplets) back;
    // it's a small hack due to the fact that tuplet detection
    // is designed to work before voice setting

    std::vector<std::multimap<ReducedFraction, MidiChord> > chords(drumVoiceCount);
    for (const auto& chord: mtrack.chords) {
        const MidiChord& c = chord.second;

        Q_ASSERT(c.voice == 0 || c.voice == 1);

        chords[c.voice].insert({ chord.first, c });
    }

    std::vector<std::multimap<ReducedFraction,
                              MidiTuplet::TupletData> > tuplets(drumVoiceCount);
    for (size_t voice = 0; voice < drumVoiceCount; ++voice) {
        if (!chords[voice].empty()) {
            MidiTuplet::findAllTuplets(tuplets[voice], chords[voice], sigmap, basicQuant);
        }
    }
    mtrack.chords.clear();
    for (size_t voice = 0; voice < drumVoiceCount; ++voice) {
        for (auto& chord: chords[voice]) {
            // correct voice because it can be changed during tuplet detection
            setChordVoice(chord.second, int(voice));
            mtrack.chords.insert({ chord.first, chord.second });
        }
    }
    mtrack.updateTupletsFromChords();
    // note: temporary local tuplets and chords are deleted here
}

void quantizeAllTracks(std::multimap<int, MTrack>& tracks,
                       TimeSigMap* sigmap,
                       const ReducedFraction& lastTick)
{
    auto& opers = midiImportOperations;

    for (auto& track: tracks) {
        MTrack& mtrack = track.second;
        if (mtrack.chords.empty()) {
            continue;
        }
        // pass current track index through MidiImportOperations
        // for further usage
        MidiOperations::CurrentTrackSetter setCurrentTrack{ opers, mtrack.indexOfOperation };

        if (opers.data()->processingsOfOpenedFile == 0) {
            opers.data()->trackOpers.isDrumTrack.setValue(
                opers.currentTrack(), mtrack.mtrack->drumTrack());
            if (mtrack.mtrack->drumTrack()) {
                opers.data()->trackOpers.maxVoiceCount.setValue(
                    opers.currentTrack(), MidiOperations::VoiceCount::V_1);
            }
        }
        const auto basicQuant = Quantize::quantValueToFraction(
            opers.data()->trackOpers.quantValue.value(mtrack.indexOfOperation));
#ifdef QT_DEBUG
        Q_ASSERT_X(MChord::isLastTickValid(lastTick, mtrack.chords),
                   "quantizeAllTracks", "Last tick is less than max note off time");
#endif
        MChord::setBarIndexes(mtrack.chords, basicQuant, lastTick, sigmap);

        if (mtrack.mtrack->drumTrack()) {
            findAllTupletsForDrums(mtrack, sigmap, basicQuant);
        } else {
            MidiTuplet::findAllTuplets(mtrack.tuplets, mtrack.chords, sigmap, basicQuant);
        }
#ifdef QT_DEBUG
        Q_ASSERT_X(!doNotesOverlap(track.second),
                   "quantizeAllTracks",
                   "There are overlapping notes of the same voice that is incorrect");
#endif
        // (4/3 of the smallest duration) tol is less sensitive
        // to on time inaccuracies than 1/2 earlier
        MChord::collectChords(mtrack, { 2, 1 }, { 4, 3 });
        Quantize::quantizeChords(mtrack.chords, sigmap, basicQuant);
        MidiTuplet::removeEmptyTuplets(mtrack);
#ifdef QT_DEBUG
        Q_ASSERT_X(MidiTuplet::areTupletRangesOk(mtrack.chords, mtrack.tuplets),
                   "quantizeAllTracks", "Tuplet chord/note is outside tuplet "
                                        "or non-tuplet chord/note is inside tuplet");
#endif
    }
}

//---------------------------------------------------------
//   processMeta
//---------------------------------------------------------

void MTrack::processMeta(int tick, const MidiEvent& mm)
{
    if (!staff) {
        LOGD("processMeta: no staff");
        return;
    }
    const uchar* data = mm.edata();
    Score* cs         = staff->score();

    switch (mm.metaType()) {
    case META_TEXT:
    case META_LYRIC:
        break;                // lyric and text are added in importmidi_lyrics.cpp
    case META_TRACK_NAME:
    {
        const std::string text = MidiCharset::fromUchar(data);

        auto& opers = midiImportOperations;
        if (opers.data()->processingsOfOpenedFile == 0) {
            const int currentTrack = indexOfOperation;
            opers.data()->trackOpers.staffName.setValue(currentTrack, text);
        }

        if (name.isEmpty()) {
            name = MidiCharset::convertToCharset(text);
        }
    }
    break;
    case META_TEMPO:          // add later, after adding of notes
        break;
    case META_KEY_SIGNATURE:
    {
        const signed char key = ((const signed char*)data)[0];
        if (key < -7 || key > 7) {
            LOGD("ImportMidi: illegal key %d", key);
            break;
        }
        KeySigEvent ke;
        Key tKey = Key(key);
        Key cKey = tKey;
        Fraction t = Fraction::fromTicks(tick);
        Interval v = staff->part()->instrument(t)->transpose();
        if (!v.isZero() && !cs->style().styleB(Sid::concertPitch)) {
            cKey = transposeKey(tKey, v);
            // if there are more than 6 accidentals in transposing key, it cannot be PreferSharpFlat::AUTO
            if ((tKey > 6 || tKey < -6) && staff->part()->preferSharpFlat() == PreferSharpFlat::AUTO) {
                staff->part()->setPreferSharpFlat(PreferSharpFlat::NONE);
            }
        }
        ke.setConcertKey(cKey);
        ke.setKey(tKey);
        staff->setKey(t, ke);
        hasKey = true;
    }
    break;
    case META_COMPOSER:             // mscore extension
    case META_POET:
    case META_TRANSLATOR:
    case META_SUBTITLE:
    case META_TITLE:
    {
        TextStyleType ssid = TextStyleType::DEFAULT;
        switch (mm.metaType()) {
        case META_COMPOSER:
            ssid = TextStyleType::COMPOSER;
            break;
        case META_TRANSLATOR:
            ssid = TextStyleType::TRANSLATOR;
            break;
        case META_POET:
            ssid = TextStyleType::LYRICIST;
            break;
        case META_SUBTITLE:
            ssid = TextStyleType::SUBTITLE;
            break;
        case META_TITLE:
            ssid = TextStyleType::TITLE;
            break;
        }

        MeasureBase* measure = cs->first();
        Text* text = Factory::createText(measure, ssid);
        text->setPlainText(String::fromUtf8((const char*)(mm.edata())));

        if (!measure->isVBox()) {
            measure = Factory::createVBox(cs->dummy()->system());
            measure->setTick(Fraction(0, 1));
            measure->setNext(cs->first());
            cs->measures()->add(measure);
        }
        measure->add(text);
    }
    break;
    case META_COPYRIGHT:
        cs->setMetaTag(u"copyright", QString((const char*)(mm.edata())));
        break;
    case META_TIME_SIGNATURE:
        break;                                  // added earlier
    case META_PORT_CHANGE:
        staff->part()->setMidiChannel(-1, (int)data[0]);
        break;
    default:
        if (MScore::debugMode) {
            LOGD("unknown meta type 0x%02x", mm.metaType());
        }
        break;
    }
}

QList<std::pair<ReducedFraction, TDuration> >
MTrack::toDurationList(const Measure* measure,
                       int voice,
                       const ReducedFraction& startTick,
                       const ReducedFraction& len,
                       Meter::DurationType durationType)
{
    // find tuplets over which duration goes
    auto barTick = ReducedFraction(measure->tick());
    auto tupletsData = MidiTuplet::findTupletsInBarForDuration(
        voice, barTick, startTick, len, tuplets);
    struct {
        bool operator()(const MidiTuplet::TupletData& d1,
                        const MidiTuplet::TupletData& d2)
        {
            return d1.len > d2.len;
        }
    } comparator;
    // sort by tuplet length in desc order
    sort(tupletsData.begin(), tupletsData.end(), comparator);

    const ReducedFraction startTickInBar = startTick - barTick;
    const ReducedFraction endTickInBar = startTickInBar + len;

    const auto& opers = midiImportOperations;
    const bool useDots = opers.data()->trackOpers.useDots.value(indexOfOperation);
    return Meter::toDurationList(startTickInBar, endTickInBar,
                                 ReducedFraction(measure->timesig()), tupletsData,
                                 durationType, useDots);
}

ReducedFraction splitDurationOnBarBoundary(const ReducedFraction& len,
                                           const ReducedFraction& onTime,
                                           const Measure* measure)
{
    const ReducedFraction barLimit = ReducedFraction(measure->endTick());
    if (onTime + len > barLimit) {
        return barLimit - onTime;
    }
    return len;
}

// fill the gap between successive chords with rests

void MTrack::fillGapWithRests(Score* score,
                              int voice,
                              const ReducedFraction& startChordTickFrac,
                              const ReducedFraction& restLength,
                              track_idx_t track)
{
    ReducedFraction startChordTick = startChordTickFrac;
    ReducedFraction restLen = restLength;
    while (restLen > ReducedFraction(0, 1)) {
        ReducedFraction len = restLen;
        Measure* measure = score->tick2measure(startChordTick.fraction());
        if (startChordTick >= ReducedFraction(measure->endTick())) {
            LOGD("tick2measure: %d end of score?", startChordTick.ticks());
            startChordTick += restLen;
            restLen = ReducedFraction(0, 1);
            break;
        }
        len = splitDurationOnBarBoundary(len, startChordTick, measure);

        if (len >= ReducedFraction(measure->ticks())) {
            // rest to the whole measure
            len = ReducedFraction(measure->ticks());
            if (voice == 0) {
                TDuration duration(DurationType::V_MEASURE);
                Segment* s = measure->getSegment(SegmentType::ChordRest, startChordTick.fraction());
                Rest* rest = Factory::createRest(s, duration);
                rest->setTicks(measure->ticks());
                rest->setTrack(track);
                s->add(rest);
            }
            restLen -= len;
            startChordTick += len;
        } else {
            const auto dl = toDurationList(measure, voice, startChordTick, len,
                                           Meter::DurationType::REST);
            if (dl.isEmpty()) {
                LOGD("cannot create duration list for len %d", len.ticks());
                restLen = ReducedFraction(0, 1);              // fake
                break;
            }
            for (const auto& durationPair: dl) {
                const TDuration& duration = durationPair.second;
                const ReducedFraction& tupletRatio = durationPair.first;
                len = ReducedFraction(duration.fraction()) / tupletRatio;
                Segment* s = measure->getSegment(SegmentType::ChordRest, startChordTick.fraction());
                Rest* rest = Factory::createRest(s, duration);
                rest->setTicks(duration.fraction());
                rest->setTrack(track);
                s->add(rest);
                MidiTuplet::addElementToTuplet(voice, startChordTick, len, rest, tuplets);
                restLen -= len;
                startChordTick += len;
            }
        }
    }
}

void setMusicNotesFromMidi(Score*,
                           const QList<MidiNote>& midiNotes,
                           Chord* chord,
                           const Drumset* drumset,
                           bool useDrumset)
{
    for (int i = 0; i < midiNotes.size(); ++i) {
        const MidiNote& mn = midiNotes[i];
        Note* note = Factory::createNote(chord);
        note->setTrack(chord->track());

        NoteVal nval(mn.pitch);
        note->setNval(nval, chord->tick());
        // TODO - does this need to be key-aware?
        //note->setPitch(mn.pitch);
        //note->setTpcFromPitch();

        chord->add(note);
        note->setUserVelocity(mn.velo);

        if (useDrumset) {
            if (!drumset->isValid(mn.pitch)) {
                LOGD("unmapped drum note 0x%02x %d", mn.pitch, mn.pitch);
            } else {
                DirectionV sd = drumset->stemDirection(mn.pitch);
                chord->setStemDirection(sd);
            }
        }

        if (midiNotes[i].tie) {
            midiNotes[i].tie->setEndNote(note);
            midiNotes[i].tie->setTrack(note->track());
            note->setTieBack(midiNotes[i].tie);
        }
    }
}

void setTies(Chord* chord,
             Score* score,
             QList<MidiNote>& midiNotes)
{
    for (int i = 0; i < midiNotes.size(); ++i) {
        const MidiNote& midiNote = midiNotes[i];
        Note* note = chord->findNote(midiNote.pitch);
        midiNotes[i].tie = new Tie(score->dummy());
        midiNotes[i].tie->setStartNote(note);
        note->setTieFor(midiNotes[i].tie);
    }
}

// convert midiChords with the same onTime value to music notation
// and fill the remaining empty duration with rests

void MTrack::processPendingNotes(QList<MidiChord>& midiChords,
                                 int voice,
                                 const ReducedFraction& startChordTickFrac,
                                 const ReducedFraction& nextChordTick)
{
    Score* score = staff->score();
    const track_idx_t track = staff->idx() * VOICES + voice;
    const Drumset* drumset = staff->part()->instrument()->drumset();
    const bool useDrumset  = staff->part()->instrument()->useDrumset();

    const auto& opers = midiImportOperations.data()->trackOpers;
    const int currentTrack = indexOfOperation;

    // all midiChords here should have the same onTime value
    // and all notes in each midiChord should have the same duration
    ReducedFraction startChordTick = startChordTickFrac;
    while (!midiChords.isEmpty()) {
        const ReducedFraction tick = startChordTick;
        ReducedFraction len = nextChordTick - tick;
        if (len <= ReducedFraction(0, 1)) {
            break;
        }
        len = MChord::findMinDuration(tick, midiChords, len);
        Measure* measure = score->tick2measure(tick.fraction());
        len = splitDurationOnBarBoundary(len, tick, measure);

        const auto dl = toDurationList(measure, voice, tick, len, Meter::DurationType::NOTE);
        if (dl.isEmpty()) {
            break;
        }
        const TDuration& d = dl[0].second;
        const ReducedFraction& tupletRatio = dl[0].first;
        len = ReducedFraction(d.fraction()) / tupletRatio;

        Segment* s = measure->getSegment(SegmentType::ChordRest, tick.fraction());
        Chord* chord = Factory::createChord(s);
        chord->setTrack(track);
        chord->setDurationType(d);
        chord->setTicks(d.fraction());

        if (opers.showStaccato.value(currentTrack)
            && startChordTick == startChordTickFrac               // first chord in tied chord sequence
            && midiChords.begin()->isStaccato()) {
            Articulation* a = Factory::createArticulation(chord);
            a->setSymId(SymId::articStaccatoAbove);
            chord->add(a);
        }

        s->add(chord);
        MidiTuplet::addElementToTuplet(voice, tick, len, chord, tuplets);

        for (int k = 0; k < midiChords.size(); ++k) {
            MidiChord& midiChord = midiChords[k];
            setMusicNotesFromMidi(score, midiChord.notes, chord, drumset, useDrumset);
            if (!midiChord.notes.empty() && midiChord.notes.first().offTime - tick <= len) {
                midiChords.removeAt(k);
                --k;
                continue;
            }
            setTies(chord, score, midiChord.notes);
        }
        startChordTick += len;
    }
    fillGapWithRests(score, voice, startChordTick, nextChordTick - startChordTick, track);
}

void MTrack::createKeys(Key defaultKey, const KeyList& allKeyList)
{
    KeyList& staffKeyList = *staff->keyList();

    if (!hasKey && !mtrack->drumTrack()) {
        if (allKeyList.empty()) {
            KeySigEvent ke;
            Interval v = staff->part()->instrument()->transpose();
            ke.setConcertKey(defaultKey);
            if (!v.isZero() && !staff->score()->style().styleB(Sid::concertPitch)) {
                v.flip();
                Key tKey = transposeKey(defaultKey, v);
                ke.setKey(tKey);
            }
            staffKeyList[0] = ke;
            MidiKey::assignKeyListToStaff(staffKeyList, staff);
        } else {
            hasKey = true;
            MidiKey::assignKeyListToStaff(allKeyList, staff);
        }
    } else {
        MidiKey::assignKeyListToStaff(staffKeyList, staff);
    }
}

void MTrack::createNotes(const ReducedFraction& lastTick)
{
    for (int voice = 0; voice < static_cast<int>(VOICES); ++voice) {
        // startChordTick is onTime value of all simultaneous notes
        // chords here are consist of notes with equal durations
        // several chords may have the same onTime value
        ReducedFraction startChordTick;
        QList<MidiChord> midiChords;

        for (auto it = chords.begin(); it != chords.end();) {
            const auto& nextChordTick = it->first;
            const MidiChord& midiChord = it->second;
            if (midiChord.voice != voice) {
                ++it;
                continue;
            }
            processPendingNotes(midiChords, voice, startChordTick, nextChordTick);
            // now 'midiChords' list is empty
            // so - fill it:
            // collect all midiChords on current tick position
            startChordTick = nextChordTick;             // debug
            for (; it != chords.end(); ++it) {
                const MidiChord& midiChord1 = it->second;
                if (it->first != startChordTick) {
                    break;
                }
                if (midiChord1.voice != voice) {
                    continue;
                }
                midiChords.append(midiChord1);
            }
            if (midiChords.isEmpty()) {
                break;
            }
        }
        // process last chords at the end of the score
        processPendingNotes(midiChords, voice, startChordTick, lastTick);
    }
}

Fraction metaTimeSignature(const MidiEvent& e)
{
    const unsigned char* data = e.edata();
    const int z  = data[0];
    const int nn = data[1];
    int n  = 1;
    for (int i = 0; i < nn; ++i) {
        n *= 2;
    }
    return Fraction(z, n);
}

QList<MTrack> prepareTrackList(const std::multimap<int, MTrack>& tracks)
{
    QList<MTrack> trackList;
    for (const auto& track: tracks) {
        // show track even if all initial notes were cleaned up
        if (track.second.hadInitialNotes) {
            trackList.push_back(track.second);
        }
    }
    return trackList;
}

std::multimap<int, MTrack> createMTrackList(TimeSigMap* sigmap, const MidiFile* mf)
{
    sigmap->clear();
    sigmap->add(0, Fraction(4, 4));     // default time signature

    std::multimap<int, MTrack> tracks;     // <track index, track>
    int trackIndex = -1;
    for (const auto& t: mf->tracks()) {
        MTrack track;
        track.mtrack = &t;
        track.division = mf->division();
        track.isDivisionInTps = mf->isDivisionInTps();
        bool hasNotes = false;
        //  - create time signature list from meta events
        //  - create MidiChord list
        //  - extract some information from track: program, min/max pitch
        for (const auto& i: t.events()) {
            const MidiEvent& e = i.second;
            const auto tick = toMuseScoreTicks(i.first, track.division,
                                               track.isDivisionInTps);
            // remove time signature events
            if ((e.type() == ME_META) && (e.metaType() == META_TIME_SIGNATURE)) {
                Fraction ts = metaTimeSignature(e);
                if (!ts.isValid() || ts <= Fraction(0, 1)) {
                    LOGW() << "skipping invalid time signature event from MIDI file at tick " << tick.ticks();
                    continue;
                }
                // because file can have incorrect data
                // like time sig event not at the beginning of bar
                // we need to round tick value to integral bar count
                int bars, beats, ticks;
                sigmap->tickValues(tick.ticks(), &bars, &beats, &ticks);
                sigmap->add(sigmap->bar2tick(bars, 0), ts);
            } else if (e.type() == ME_NOTE) {
                hasNotes = true;
                const int pitch = e.pitch();
                const auto len = toMuseScoreTicks(e.len(), track.division,
                                                  track.isDivisionInTps);
                MidiNote n;
                n.pitch           = pitch;
                n.velo            = e.velo();
                n.offTime         = tick + len;
                n.origOnTime      = tick;

                MidiChord c;
                c.notes.push_back(n);

                track.chords.insert({ tick, c });
            } else if (e.type() == ME_PROGRAM) {
                track.program = e.dataB();
            } else if (e.type() == ME_CONTROLLER && e.controller() == CTRL_VOLUME) {
                track.volumes.insert({ tick, e.value() });
            }
        }
        if (hasNotes) {
            ++trackIndex;
            track.hadInitialNotes = true;
            const auto* data = midiImportOperations.data();
            if (data->processingsOfOpenedFile > 0) {
                if (data->trackOpers.doImport.value(trackIndex)) {
                    track.indexOfOperation = trackIndex;
                    const int reorderedIndex
                        = data->trackOpers.trackIndexAfterReorder.value(trackIndex);
                    tracks.insert({ reorderedIndex, track });
                }
            } else {                // if it is an initial track-list query from MIDI import panel
                track.indexOfOperation = trackIndex;
                tracks.insert({ trackIndex, track });
            }
        } else {
            track.hadInitialNotes = false;             // it's a tempo track or something else
            tracks.insert({ -1, track });
        }
    }

    return tracks;
}

Measure* barFromIndex(const Score* score, int barIndex)
{
    const int tick = score->sigmap()->bar2tick(barIndex, 0);
    return score->tick2measure(Fraction::fromTicks(tick));
}

bool isPickupWithLessTimeSig(const Fraction& firstBarTimeSig, const Fraction& secondBarTimeSig)
{
    return firstBarTimeSig < secondBarTimeSig;
}

bool isPickupWithGreaterTimeSig(
    const Fraction& firstBarTimeSig,
    const Fraction& secondBarTimeSig,
    const ReducedFraction& firstTick)
{
    return firstBarTimeSig == secondBarTimeSig * 2
           && firstBarTimeSig.numerator() % 3 != 0
           && firstTick > ReducedFraction(0, 1);
}

// search for pickup measure only if next 3 bars have equal time signatures
bool areNextBarsEqual(const Score* score, int barCount)
{
    const int baseBarTick = score->sigmap()->bar2tick(1, 0);
    const Fraction baseTimeSig = score->sigmap()->timesig(baseBarTick).timesig();

    const int equalTimeSigCount = 3;
    for (int i = 2; i <= equalTimeSigCount - 1 && i < barCount; ++i) {
        const int barTick = score->sigmap()->bar2tick(i, 0);
        const Fraction timeSig = score->sigmap()->timesig(barTick).timesig();
        if (timeSig != baseTimeSig) {
            return false;
        }
    }
    return true;
}

void tryCreatePickupMeasure(
    const ReducedFraction& firstTick,
    Score* score,
    int* begBarIndex,
    int* barCount)
{
    const int firstBarTick  = score->sigmap()->bar2tick(0, 0);
    const int secondBarTick = score->sigmap()->bar2tick(1, 0);
    const Fraction firstTimeSig = score->sigmap()->timesig(firstBarTick).timesig();
    const Fraction secondTimeSig = score->sigmap()->timesig(secondBarTick).timesig();

    if (isPickupWithLessTimeSig(firstTimeSig, secondTimeSig)) {
        Measure* pickup = Factory::createMeasure(score->dummy()->system());
        pickup->setTick(Fraction::fromTicks(firstBarTick));
        pickup->setNo(0);
        pickup->setIrregular(true);
        pickup->setTimesig(secondTimeSig);           // nominal time signature
        pickup->setTicks(firstTimeSig);                // actual length
        score->measures()->add(pickup);
        *begBarIndex = 1;
    } else if (isPickupWithGreaterTimeSig(firstTimeSig, secondTimeSig, firstTick)) {
        // split measure into 2 equal measures
        // but for simplicity don't treat first bar as a pickup measure:
        // leave its actual length equal to nominal length
        ++(*barCount);

        score->sigmap()->add(firstBarTick, secondTimeSig);

        Measure* firstBar = Factory::createMeasure(score->dummy()->system());
        firstBar->setTick(Fraction::fromTicks(firstBarTick));
        firstBar->setNo(0);
        firstBar->setTimesig(secondTimeSig);
        firstBar->setTicks(secondTimeSig);
        score->measures()->add(firstBar);

        Measure* secondBar = Factory::createMeasure(score->dummy()->system());
        secondBar->setTick(Fraction::fromTicks(firstBarTick + secondTimeSig.ticks()));
        secondBar->setNo(1);
        secondBar->setTimesig(secondTimeSig);
        secondBar->setTicks(secondTimeSig);
        score->measures()->add(secondBar);

        *begBarIndex = 2;
    }
}

void createMeasures(const ReducedFraction& firstTick, ReducedFraction& lastTick, Score* score)
{
    int barCount, beat, tick;
    score->sigmap()->tickValues(lastTick.ticks(), &barCount, &beat, &tick);
    if (beat > 0 || tick > 0) {
        ++barCount;               // convert bar index to number of bars
    }
    auto& data = *midiImportOperations.data();
    if (data.processingsOfOpenedFile == 0) {
        if (!areNextBarsEqual(score, barCount)) {
            data.trackOpers.searchPickupMeasure.setValue(false);
        }
    }

    const bool tryDetectPickupMeasure = data.trackOpers.searchPickupMeasure.value();
    int begBarIndex = 0;

    if (tryDetectPickupMeasure && barCount > 1) {
        tryCreatePickupMeasure(firstTick, score, &begBarIndex, &barCount);
    }

    for (int i = begBarIndex; i < barCount; ++i) {
        Measure* m = Factory::createMeasure(score->dummy()->system());
        const int t = score->sigmap()->bar2tick(i, 0);
        m->setTick(Fraction::fromTicks(tick));
        m->setNo(i);
        const Fraction timeSig = score->sigmap()->timesig(t).timesig();
        m->setTimesig(timeSig);
        m->setTicks(timeSig);
        score->measures()->add(m);
    }

    const Measure* m = score->lastMeasure();
    if (m) {
        score->setUpTempoMap();
        lastTick = ReducedFraction(m->endTick());
    }
}

void setTrackInfo(MidiType midiType, MTrack& mt)
{
    auto& opers = midiImportOperations;

    const int currentTrack = mt.indexOfOperation;
    const QString instrName = MidiInstr::instrumentName(midiType, mt.program,
                                                        mt.mtrack->drumTrack());
    if (opers.data()->processingsOfOpenedFile == 0) {
        opers.data()->trackOpers.midiInstrName.setValue(currentTrack, instrName);
        // set channel number (from 1): number = index + 1
        opers.data()->trackOpers.channel.setValue(currentTrack, mt.mtrack->outChannel() + 1);
    }

    const QString msInstrName = MidiInstr::msInstrName(currentTrack);
    const QString trackInstrName = (msInstrName.isEmpty()) ? instrName : msInstrName;

    if (mt.staff->isTop()) {
        Part* part  = mt.staff->part();
        part->setLongName(XmlWriter::xmlString(MidiInstr::concatenateWithComma(trackInstrName, mt.name)));
        part->setPartName(part->longName());
        part->setMidiChannel(mt.mtrack->outChannel());
        int bank = 0;
        if (mt.mtrack->drumTrack()) {
            bank = 128;
        }
        part->setMidiProgram(mt.program & 0x7f, bank);      // only GM
    }

    if (mt.name.isEmpty() && !trackInstrName.isEmpty()) {
        mt.name = trackInstrName;
    }
}

void createTimeSignatures(Score* score)
{
    // Need to iterate over a copy, because adding a TimeSig modifies `score->sigmap()` (see TimeSig::added)
    TimeSigMap sigmap = *score->sigmap();

    for (auto is = sigmap.cbegin(); is != sigmap.cend(); ++is) {
        const SigEvent& se = is->second;
        const int tick = is->first;
        Measure* m = score->tick2measure(Fraction::fromTicks(tick));
        if (!m) {
            continue;
        }
        Fraction newTimeSig = se.timesig();

        const auto& opers = midiImportOperations;
        const bool pickupMeasure = opers.data()->trackOpers.searchPickupMeasure.value();

        if (pickupMeasure && is == sigmap.cbegin()) {
            auto next = std::next(is);
            if (next != sigmap.cend()) {
                Measure* mm = score->tick2measure(Fraction::fromTicks(next->first));
                if (m && mm && m == barFromIndex(score, 0) && mm == barFromIndex(score, 1)
                    && m->timesig() == mm->timesig() && newTimeSig != mm->timesig()) {
                    // it's a pickup measure - change timesig to nominal value
                    newTimeSig = mm->timesig();
                }
            }
        }
        for (size_t staffIdx = 0; staffIdx < score->nstaves(); ++staffIdx) {
            Segment* seg = m->getSegment(SegmentType::TimeSig, Fraction::fromTicks(tick));
            TimeSig* ts = Factory::createTimeSig(seg);
            ts->setSig(newTimeSig);
            ts->setTrack(static_cast<int>(staffIdx) * VOICES);
            seg->add(ts);
        }
        if (newTimeSig != se.timesig()) {     // was a pickup measure - skip next timesig
            ++is;
        }
    }
}

void processMeta(MTrack& mt, bool isLyric)
{
    for (const auto& ie : mt.mtrack->events()) {
        const MidiEvent& e = ie.second;
        const auto tick = toMuseScoreTicks(ie.first, mt.division, mt.isDivisionInTps);
        if ((e.type() == ME_META) && ((e.metaType() == META_LYRIC) == isLyric)) {
            mt.processMeta(tick.ticks(), e);
        }
    }
}

// key list with key signatures of all tracks
//   to assign it to tracks without any specified key signature
KeyList findAllKeyList(const QList<MTrack>& tracks)
{
    KeyList kl;
    for (int i = 0; i < tracks.size(); ++i) {
        if (tracks[i].hasKey) {
            for (const auto& key: *tracks[i].staff->keyList()) {
                kl.setKey(key.first, key.second);
            }
        }
    }
    return kl;
}

void createNotes(const ReducedFraction& lastTick, QList<MTrack>& tracks)
{
    for (int i = 0; i < tracks.size(); ++i) {
        MTrack& mt = tracks[i];
        mt.createNotes(lastTick);
        MidiTuplet::createTupletNotes(mt.staff, mt.tuplets);
    }
}

void processNonLyricMeta(QList<MTrack>& tracks)
{
    for (int i = 0; i < tracks.size(); ++i) {
        MTrack& mt = tracks[i];
        processMeta(mt, false);
    }
}

void setTrackInfo(QList<MTrack>& tracks, MidiType midiType)
{
    for (int i = 0; i < tracks.size(); ++i) {
        MTrack& mt = tracks[i];
        if (midiType == MidiType::UNKNOWN) {
            midiType = MidiType::GM;
        }
        setTrackInfo(midiType, mt);
    }
}

void processLyricMeta(QList<MTrack>& tracks)
{
    for (int i = 0; i < tracks.size(); ++i) {
        MTrack& mt = tracks[i];
        processMeta(mt, true);
    }
}

void createKeys(QList<MTrack>& tracks)
{
    const Key defaultKey = Key::C;       // TODO-LIB findKey(mtrack, score->sigmap());
    const KeyList& allKeyList = findAllKeyList(tracks);

    for (int i = 0; i < tracks.size(); ++i) {
        MTrack& mt = tracks[i];
        mt.createKeys(defaultKey, allKeyList);
    }
}

void applySwing(QList<MTrack>& tracks)
{
    for (int i = 0; i < tracks.size(); ++i) {
        MTrack& mt = tracks[i];

        const auto& opers = midiImportOperations.data()->trackOpers;
        const auto swingType = opers.swing.value(mt.indexOfOperation);
        Swing::detectSwing(mt.staff, swingType);
#ifdef QT_DEBUG
        Q_ASSERT_X(MidiTie::areTiesConsistent(mt.staff),
                   "applySwing", "Ties are inconsistent");

        Q_ASSERT_X(MidiTuplet::haveTupletsEnoughElements(mt.staff),
                   "MTrack::convertTrack",
                   "Tuplet has less than 2 elements or all elements are rests");
#endif
    }
}

void createClefs(QList<MTrack>& tracks)
{
    for (int i = 0; i < tracks.size(); ++i) {
        MTrack& mt = tracks[i];
        MidiClef::createClefs(mt.staff, mt.indexOfOperation, mt.mtrack->drumTrack());
    }
}

void setLeftRightHandSplit(const std::multimap<int, MTrack>& tracks)
{
    for (auto it = tracks.begin(); it != tracks.end(); ++it) {
        int trackIndex = it->first;
        const MTrack& mtrack = it->second;
        if (mtrack.mtrack->drumTrack() || mtrack.chords.empty()) {
            continue;
        }

        // don't split staff if it is already in Grand Staff
        const auto nextIt = std::next(it);
        if (nextIt != tracks.end()) {
            if (MidiInstr::isGrandStaff(mtrack, nextIt->second)) {
                ++it;
                continue;
            }
        }

        if (LRHand::needToSplit(mtrack.chords, mtrack.program, mtrack.mtrack->drumTrack())) {
            midiImportOperations.data()->trackOpers.doStaffSplit.setValue(
                trackIndex, true);
        }
    }
}

ReducedFraction findFirstChordTick(const QList<MTrack>& tracks)
{
    ReducedFraction firstTick(0, 1);
    for (const auto& track: tracks) {
        if (track.chords.empty()) {
            continue;
        }
        const auto& chordTick = track.chords.begin()->first;

        Q_ASSERT(chordTick >= ReducedFraction(0, 1));

        if (firstTick == ReducedFraction(0, 1) || chordTick < firstTick) {
            firstTick = chordTick;
        }
    }
    return firstTick;
}

ReducedFraction findLastChordTick(const std::multimap<int, MTrack>& tracks)
{
    ReducedFraction lastTick(0, 1);
    for (const auto& track: tracks) {
        for (const auto& chord: track.second.chords) {
            const auto offTime = MChord::maxNoteOffTime(chord.second.notes);
            if (offTime > lastTick) {
                lastTick = offTime;
            }
        }
    }
    return lastTick;
}

QList<MTrack> convertMidi(Score* score, const MidiFile* mf)
{
    auto* sigmap = score->sigmap();

    auto tracks = createMTrackList(sigmap, mf);

    auto& opers = midiImportOperations;
    if (opers.data()->processingsOfOpenedFile == 0) {         // for newly opened MIDI file
        MidiChordName::findChordNames(tracks);
    }

    lengthenTooShortNotes(tracks);

    if (opers.data()->processingsOfOpenedFile == 0) {         // for newly opened MIDI file
        opers.data()->trackCount = 0;
        for (const auto& track: tracks) {
            if (track.first != -1) {
                ++opers.data()->trackCount;
            }
        }
        MidiLyrics::extractLyricsToMidiData(mf);
    }
    // for newly opened MIDI file - detect if it is a human performance
    // if so - detect beats and set initial time signature
    if (opers.data()->processingsOfOpenedFile == 0) {
        Quantize::setIfHumanPerformance(tracks, sigmap);
    } else {      // user value
        MidiBeat::setTimeSignature(sigmap);
    }

    Q_ASSERT_X((opers.data()->trackOpers.isHumanPerformance.value())
               ? Meter::userTimeSigToFraction(opers.data()->trackOpers.timeSigNumerator.value(),
                                              opers.data()->trackOpers.timeSigDenominator.value())
               != ReducedFraction(0, 1) : true,
               "convertMidi", "Null time signature for human-performed MIDI file");

    MChord::collectChords(tracks, { 2, 1 }, { 1, 2 });
    MidiBeat::adjustChordsToBeats(tracks);
    MChord::mergeChordsWithEqualOnTimeAndVoice(tracks);

    // for newly opened MIDI file
    if (opers.data()->processingsOfOpenedFile == 0
        && opers.data()->trackOpers.doStaffSplit.canRedefineDefaultLater()) {
        setLeftRightHandSplit(tracks);
    }

    MChord::removeOverlappingNotes(tracks);
#ifdef QT_DEBUG
    Q_ASSERT_X(!doNotesOverlap(tracks),
               "convertMidi", "There are overlapping notes of the same voice that is incorrect");
#endif
    LRHand::splitIntoLeftRightHands(tracks);
    MidiDrum::splitDrumVoices(tracks);
    MidiDrum::splitDrumTracks(tracks);
    ReducedFraction lastTick = findLastChordTick(tracks);
    quantizeAllTracks(tracks, sigmap, lastTick);
    MChord::removeOverlappingNotes(tracks);
#ifdef QT_DEBUG
    Q_ASSERT_X(!doNotesOverlap(tracks),
               "convertMidi", "There are overlapping notes of the same voice that is incorrect");
    Q_ASSERT_X(noTooShortNotes(tracks),
               "convertMidi", "There are notes of length < min allowed duration");
#endif
    MChord::mergeChordsWithEqualOnTimeAndVoice(tracks);
    Simplify::simplifyDurationsNotDrums(tracks, sigmap);
    if (MidiVoice::separateVoices(tracks, sigmap)) {
        Simplify::simplifyDurationsNotDrums(tracks, sigmap);        // again
    }
    Simplify::simplifyDurationsForDrums(tracks, sigmap);
    MChord::splitUnequalChords(tracks);
    // no more track insertion/reordering/deletion from now
    QList<MTrack> trackList = prepareTrackList(tracks);
    MidiInstr::setGrandStaffProgram(trackList);
    MidiInstr::findInstrumentsForAllTracks(trackList);
    MidiInstr::createInstruments(score, trackList);
    MidiDrum::setStaffBracketForDrums(trackList);

    const auto firstTick = findFirstChordTick(trackList);

    createMeasures(firstTick, lastTick, score);
    processNonLyricMeta(trackList);
    setTrackInfo(trackList, mf->midiType());
    createKeys(trackList);
    MidiKey::recognizeMainKeySig(trackList);
    createNotes(lastTick, trackList);
    processLyricMeta(trackList);
    applySwing(trackList);
    createClefs(trackList);
    createTimeSignatures(score);
    score->connectTies();

    MidiLyrics::setLyricsToScore(trackList);
    MidiTempo::setTempo(tracks, score);
    MidiChordName::setChordNames(trackList);

    return trackList;
}

void loadMidiData(MidiFile& mf)
{
    mf.separateChannel();
    MidiType mt = MidiType::UNKNOWN;
    for (auto& track: mf.tracks()) {
        track.mergeNoteOnOffAndFindMidiType(&mt);
    }
    mf.setMidiType(mt);
}

Err importMidi(MasterScore* score, const QString& name)
{
    if (name.isEmpty()) {
        return Err::FileNotFound;
    }

    auto& opers = midiImportOperations;

    MidiOperations::CurrentMidiFileSetter setCurrentMidiFile(opers, name);
    if (!opers.hasMidiFile(name)) {
        opers.addNewMidiFile(name);
    }

    if (opers.data()->processingsOfOpenedFile == 0) {
        QFile fp(name);
        if (!fp.open(QIODevice::ReadOnly)) {
            LOGD("importMidi: file open error <%s>", qPrintable(name));
            return Err::FileOpenError;
        }
        MidiFile mf;
        try {
            mf.read(&fp);
        }
        catch (QString errorText) {
            if (!MScore::noGui) {
                MessageBox(score->iocContext()).warning(muse::trc("iex_midi", "Import MIDI"),
                                                        muse::qtrc("iex_midi", "Import failed: %1").arg(errorText).toStdString(),
                                                        { MessageBox::Ok });
            }
            fp.close();
            LOGD("importMidi: bad file format");
            return Err::FileBadFormat;
        }
        fp.close();

        loadMidiData(mf);
        opers.setMidiFileData(name, mf);
    }

    opers.data()->tracks = convertMidi(score, opers.midiFile(name));
    ++opers.data()->processingsOfOpenedFile;

    return Err::NoError;
}
}
