PMAlgTracking.cxx

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// Class:       PMAlgTracking
// Author:      D.Stefan (Dorota.Stefan@ncbj.gov.pl),
//              R.Sulej (Robert.Sulej@cern.ch),
//              L.Whitehead (leigh.howard.whitehead@cern.ch), June 2016

#include "larreco/RecoAlg/PMAlgTracking.h"
#include "larreco/RecoAlg/PMAlgStitching.h"

#include "larreco/RecoAlg/PMAlg/Utilities.h"

#include "messagefacility/MessageLogger/MessageLogger.h"

#include "TMath.h"

using Point_t      = recob::tracking::Point_t;
using Vector_t     = recob::tracking::Vector_t;
using SMatrixSym55 = recob::tracking::SMatrixSym55;

recob::Track pma::convertFrom(const pma::Track3D& src, unsigned int tidx, int pdg)
{
    std::vector<Point_t> positions;                    positions.reserve(src.size());
    std::vector<Vector_t> momenta;                     momenta.reserve(src.size());
    std::vector<recob::TrajectoryPointFlags> outFlags; outFlags.reserve(src.size());

        for (size_t i = 0, h = 0; i < src.size(); i++)
                if (src[i]->IsEnabled())
        {
        auto const & point3d = src[i]->Point3D();
        positions.emplace_back(point3d.X(), point3d.Y(), point3d.Z());
        momenta.push_back(src.GetDirection3D(i));
        outFlags.emplace_back(h++, recob::TrajectoryPointFlags::makeMask());
        }

    int ndof = 0;
    float totChi2 = 0;

    SMatrixSym55 covStart, covEnd;
    return recob::Track(
        recob::TrackTrajectory(std::move(positions), std::move(momenta), std::move(outFlags), false),
        pdg, totChi2, ndof, covStart, covEnd, tidx);
}
// ------------------------------------------------------

pma::PMAlgTrackingBase::PMAlgTrackingBase(const std::vector< art::Ptr<recob::Hit> > & allhitlist,
                                          const pma::ProjectionMatchingAlg::Config& pmalgConfig,
                                          const pma::PMAlgVertexing::Config& pmvtxConfig) :
        fProjectionMatchingAlg(pmalgConfig),
        fPMAlgVertexing(pmvtxConfig)
{
        unsigned int cryo, tpc, view;
        for (auto const& h : allhitlist)
        {
                cryo = h->WireID().Cryostat;
                tpc = h->WireID().TPC;
                view = h->WireID().Plane;

                fHitMap[cryo][tpc][view].push_back(h);
        }
}
// ------------------------------------------------------

pma::PMAlgTrackingBase::~PMAlgTrackingBase(void)
{
        for (auto t : fResult.tracks()) t.DeleteTrack();
}
// ------------------------------------------------------

void pma::PMAlgTrackingBase::guideEndpoints(pma::TrkCandidateColl & tracks)
{
        for (auto const & t : tracks.tracks())
        {
                auto & trk = *(t.Track());

                unsigned int tpc = trk.FrontTPC(), cryo = trk.FrontCryo();
                if ((tpc == trk.BackTPC()) && (cryo == trk.BackCryo()))
                {
                        fProjectionMatchingAlg.guideEndpoints(trk, fHitMap[cryo][tpc]);
                }
                else
                {
                        fProjectionMatchingAlg.guideEndpoints(trk, pma::Track3D::kBegin,
                                fHitMap[trk.FrontCryo()][trk.FrontTPC()]);
                        fProjectionMatchingAlg.guideEndpoints(trk, pma::Track3D::kEnd,
                                fHitMap[trk.BackCryo()][trk.BackTPC()]);
                }
        }
}
// ------------------------------------------------------
// ------------------------------------------------------
// ------------------------------------------------------

pma::PMAlgFitter::PMAlgFitter(const std::vector< art::Ptr<recob::Hit> > & allhitlist,
                              const std::vector< recob::Cluster > & clusters,
                              const std::vector< recob::PFParticle > & pfparticles,
                              const art::FindManyP< recob::Hit > & hitsFromClusters,
                              const art::FindManyP< recob::Cluster > & clusFromPfps,
                              const art::FindManyP< recob::Vertex > & vtxFromPfps,
                              const pma::ProjectionMatchingAlg::Config& pmalgConfig,
                              const pma::PMAlgFitter::Config& pmalgFitterConfig,
                              const pma::PMAlgVertexing::Config& pmvtxConfig) :
        PMAlgTrackingBase(allhitlist, pmalgConfig, pmvtxConfig),
        fTrackingOnlyPdg(pmalgFitterConfig.TrackingOnlyPdg()),
        fTrackingSkipPdg(pmalgFitterConfig.TrackingSkipPdg()),
        fRunVertexing(pmalgFitterConfig.RunVertexing())
{
        mf::LogVerbatim("PMAlgFitter") << "Found " << allhitlist.size() << "hits in the event.";
        mf::LogVerbatim("PMAlgFitter") << "Sort hits by clusters assigned to PFParticles...";

        fCluHits.resize(clusters.size());
        for (size_t i = 0; i < pfparticles.size(); ++i)
        {
                fPfpPdgCodes[i] = pfparticles[i].PdgCode();

                auto cv = clusFromPfps.at(i);
                for (const auto & c : cv)
                {
                        fPfpClusters[i].push_back(c);
                        if (fCluHits[c.key()].empty())
                        {
                                auto hv = hitsFromClusters.at(c.key());
                                fCluHits[c.key()].reserve(hv.size());
                                for (auto const & h : hv) fCluHits[c.key()].push_back(h);
                        }
                }

                if (vtxFromPfps.isValid() && vtxFromPfps.at(i).size())
                {
                        double xyz[3];
                        vtxFromPfps.at(i).front()->XYZ(xyz);
                        fPfpVtx[i] = pma::Vector3D(xyz[0], xyz[1], xyz[2]);
                }
        }

        mf::LogVerbatim("PMAlgFitter") << "...done, "
                << fCluHits.size() << " clusters from "
                << fPfpClusters.size() << " pfparticles for 3D tracking.";
}
// ------------------------------------------------------

// ------------------------------------------------------
// ------------------------------------------------------
int pma::PMAlgFitter::build(void)
{
    if (!fPfpClusters.empty() && !fCluHits.empty())
    {
                        // build pm tracks
                        buildTracks();

                        // add 3D ref.points for clean endpoints of wire-plae parallel tracks
                        guideEndpoints(fResult);

                        if (fRunVertexing) fPMAlgVertexing.run(fResult);

                        // build segment of shower
                        buildShowers();
    }
    else
    {
        mf::LogWarning("PMAlgFitter") << "no clusters, no pfparticles";
        return -1;
    }
    
    return fResult.size();
}
// ------------------------------------------------------
// ------------------------------------------------------

void pma::PMAlgFitter::buildTracks(void)
{
                bool skipPdg = true;
                if (!fTrackingSkipPdg.empty() && (fTrackingSkipPdg.front() == 0)) skipPdg = false;

                bool selectPdg = true;
                if (!fTrackingOnlyPdg.empty() && (fTrackingOnlyPdg.front() == 0)) selectPdg = false;

                for (const auto & pfpCluEntry : fPfpClusters)
                {
                        int pfPartIdx = pfpCluEntry.first;
                        int pdg = fPfpPdgCodes[pfPartIdx];

                        //if (pdg == 11) continue;
                        if (skipPdg && has(fTrackingSkipPdg, pdg)) continue;
                        if (selectPdg && !has(fTrackingOnlyPdg, pdg)) continue;

                        mf::LogVerbatim("PMAlgFitter") << "Process clusters from PFP:" << pfPartIdx << ", pdg:" << pdg;

                        std::vector< art::Ptr<recob::Hit> > allHits;

                        pma::TrkCandidate candidate;
                        std::unordered_map<geo::View_t, size_t> clu_count;
                        for (const auto & c : pfpCluEntry.second)
                        {
                                if (c->NHits() == 0) { continue; }

                                candidate.Clusters().push_back(c.key());
                                clu_count[c->View()]++;

                                allHits.reserve(allHits.size() + fCluHits.at(c.key()).size());
                                for (const auto & h : fCluHits.at(c.key()))
                                {
                                        allHits.push_back(h);
                                }
                        }
                        if (clu_count.size() > 1) // try building only if there are clusters from multiple views
                        {
                                candidate.SetKey(pfpCluEntry.first);

                                candidate.SetTrack(fProjectionMatchingAlg.buildMultiTPCTrack(allHits));

                                if (candidate.IsValid() &&
                                    candidate.Track()->HasTwoViews() &&
                                    (candidate.Track()->Nodes().size() > 1))
                                {
                                        if (!std::isnan(candidate.Track()->Length())) { fResult.push_back(candidate); }
                                        else
                                        {
                                                mf::LogError("PMAlgFitter") << "Trajectory fit lenght is nan.";
                                                candidate.DeleteTrack();
                                        }
                                }
                                else { candidate.DeleteTrack(); }
                        }
                }
}
// ------------------------------------------------------

void pma::PMAlgFitter::buildShowers(void)
{
                bool skipPdg = true;
                if (!fTrackingSkipPdg.empty() && (fTrackingSkipPdg.front() == 0))
                        skipPdg = false;

                bool selectPdg = true;
                if (!fTrackingOnlyPdg.empty() && (fTrackingOnlyPdg.front() == 0))
                        selectPdg = false;

                for (const auto & pfpCluEntry : fPfpClusters)
                {
                        int pfPartIdx = pfpCluEntry.first;
                        int pdg = fPfpPdgCodes[pfPartIdx];

                        if (pdg != 11) continue;
                        if (skipPdg && has(fTrackingSkipPdg, pdg)) continue;
                        if (selectPdg && !has(fTrackingOnlyPdg, pdg)) continue;

                        mf::LogVerbatim("PMAlgFitter") << "Process clusters from PFP:" << pfPartIdx << ", pdg:" << pdg;

                        std::vector< art::Ptr<recob::Hit> > allHits;

                        pma::TrkCandidate candidate;
                        std::unordered_map<geo::View_t, size_t> clu_count;
                        for (const auto & c : pfpCluEntry.second)
                        {
                                if (c->NHits() == 0) { continue; }

                                candidate.Clusters().push_back(c.key());
                                clu_count[c->View()]++;

                                allHits.reserve(allHits.size() + fCluHits.at(c.key()).size());
                                for (const auto & h : fCluHits.at(c.key()))
                                        allHits.push_back(h);
                        }
                        if (clu_count.size() > 1) // try building only if there are clusters from multiple views
                        {
                                candidate.SetKey(pfpCluEntry.first);

                                mf::LogVerbatim("PMAlgFitter") << "building..." << ", pdg:" << pdg;

                                auto search = fPfpVtx.find(pfPartIdx);
                                if (search != fPfpVtx.end())
                                {
                                        candidate.SetTrack(fProjectionMatchingAlg.buildShowerSeg(allHits, search->second));

                                        if (candidate.IsValid()
                                                && candidate.Track()->HasTwoViews()
                                                && (candidate.Track()->Nodes().size() > 1)
                                                && !std::isnan(candidate.Track()->Length()))
                                        {
                                                fResult.push_back(candidate);
                                        }
                                        else { candidate.DeleteTrack(); }
                                }
                        }
                }
}
// ------------------------------------------------------
// ------------------------------------------------------
// ------------------------------------------------------

pma::PMAlgTracker::PMAlgTracker(const std::vector< art::Ptr<recob::Hit> > & allhitlist, const std::vector<recob::Wire> & wires,
        const pma::ProjectionMatchingAlg::Config& pmalgConfig,
        const pma::PMAlgTracker::Config& pmalgTrackerConfig,
        const pma::PMAlgVertexing::Config& pmvtxConfig,
        const pma::PMAlgStitching::Config& pmstitchConfig,
        const pma::PMAlgCosmicTagger::Config& pmtaggerConfig,
        
        const std::vector< TH1F* > & hpassing, const std::vector< TH1F* > & hrejected) :

        PMAlgTrackingBase(allhitlist, pmalgConfig, pmvtxConfig),

    fWires(wires),

        fMinSeedSize1stPass(pmalgTrackerConfig.MinSeedSize1stPass()),
        fMinSeedSize2ndPass(pmalgTrackerConfig.MinSeedSize2ndPass()),
        fTrackLikeThreshold(pmalgTrackerConfig.TrackLikeThreshold()),

        fMinTwoViewFraction(pmalgConfig.MinTwoViewFraction()),

        fFlipToBeam(pmalgTrackerConfig.FlipToBeam()),
        fFlipDownward(pmalgTrackerConfig.FlipDownward()),
        fFlipToX(pmalgTrackerConfig.FlipToX()),
        fAutoFlip_dQdx(pmalgTrackerConfig.AutoFlip_dQdx()),

        fMergeWithinTPC(pmalgTrackerConfig.MergeWithinTPC()),
        fMergeTransverseShift(pmalgTrackerConfig.MergeTransverseShift()),
        fMergeAngle(pmalgTrackerConfig.MergeAngle()),

    fCosmicTagger(pmtaggerConfig),
    fTagCosmicTracks(fCosmicTagger.tagAny()),

        fStitchBetweenTPCs(pmalgTrackerConfig.StitchBetweenTPCs()),
        fStitchDistToWall(pmalgTrackerConfig.StitchDistToWall()),
        fStitchTransverseShift(pmalgTrackerConfig.StitchTransverseShift()),
        fStitchAngle(pmalgTrackerConfig.StitchAngle()),

        fMatchT0inAPACrossing(pmalgTrackerConfig.MatchT0inAPACrossing()),
        fMatchT0inCPACrossing(pmalgTrackerConfig.MatchT0inCPACrossing()),
    fStitcher(pmstitchConfig),

        fRunVertexing(pmalgTrackerConfig.RunVertexing()),

        fAdcInPassingPoints(hpassing), fAdcInRejectedPoints(hrejected),

    fGeom(&*(art::ServiceHandle<geo::Geometry>())),
        fDetProp(lar::providerFrom<detinfo::DetectorPropertiesService>())
{
    for (const auto v : fGeom->Views()) { fAvailableViews.push_back(v); }
    std::reverse(fAvailableViews.begin(), fAvailableViews.end());

    mf::LogVerbatim("PMAlgTracker") << "Using views in the following order:";
    for (const auto v : fAvailableViews) {  mf::LogInfo("PMAlgTracker") << " " << v; }
    
    // ************************* track validation settings: **************************
    mf::LogVerbatim("PMAlgTracker") << "Validation mode in config: " << pmalgTrackerConfig.Validation();

    size_t nplanes = fGeom->MaxPlanes();
    for (size_t p = 0; p < nplanes; ++p) { fAdcImages.emplace_back(pmalgTrackerConfig.AdcImageAlg()); }

    if (pmalgTrackerConfig.Validation() == "hits")         { fValidation = pma::PMAlgTracker::kHits;  }
    else if (pmalgTrackerConfig.Validation() == "adc")     { fValidation = pma::PMAlgTracker::kAdc;   }
    else if (pmalgTrackerConfig.Validation() == "calib")   { fValidation = pma::PMAlgTracker::kCalib; }
    else { throw cet::exception("pma::PMAlgTracker") << "validation name not supported" << std::endl; }

    if ((nplanes < 3) && (fValidation != pma::PMAlgTracker::kHits))
    {
        mf::LogWarning("PMAlgTracker") << "Not enough planes to perform validation, switch mode to hits.";
        fValidation = pma::PMAlgTracker::kHits;
    }

    fAdcValidationThr = pmalgTrackerConfig.AdcValidationThr();
    if (fValidation == pma::PMAlgTracker::kAdc)
    {
        mf::LogVerbatim("PMAlgTracker") << "Validation ADC thresholds per plane:";
        for (auto thr : fAdcValidationThr) { mf::LogVerbatim("PMAlgTracker") << "   " << thr; }
    }
}
// ------------------------------------------------------

void pma::PMAlgTracker::init(const art::FindManyP< recob::Hit > & hitsFromClusters)
{
        mf::LogVerbatim("PMAlgTracker") << "Sort hits by clusters...";
        fCluHits.clear(); fCluHits.reserve(hitsFromClusters.size());
        fCluWeights.clear(); fCluWeights.reserve(fCluHits.size());
        for (size_t i = 0; i < hitsFromClusters.size(); ++i)
        {
                auto v = hitsFromClusters.at(i);
                fCluHits.push_back(std::vector< art::Ptr<recob::Hit> >());
                for (auto const & h : v) fCluHits.back().push_back(h);
                fCluWeights.push_back(1);
        }
        mf::LogVerbatim("PMAlgTracker") << "...done, " << fCluHits.size() << " clusters for 3D tracking.";
}
// ------------------------------------------------------

void pma::PMAlgTracker::init(const art::FindManyP< recob::Hit > & hitsFromClusters,
                             const std::vector< float > & trackLike)
{
        mf::LogVerbatim("PMAlgTracker") << "Filter track-like clusters using likelihood values...";
        fCluHits.clear(); fCluHits.reserve(hitsFromClusters.size());
        fCluWeights.clear(); fCluWeights.reserve(fCluHits.size());
        for (size_t i = 0; i < hitsFromClusters.size(); ++i)
        {
                auto v = hitsFromClusters.at(i);
                fCluHits.push_back(std::vector< art::Ptr<recob::Hit> >());
                for (auto const & h : v) fCluHits.back().push_back(h);
                fCluWeights.push_back(trackLike[i]);
        }
}
// ------------------------------------------------------

void pma::PMAlgTracker::init(const art::FindManyP< recob::Hit > & hitsFromClusters,
                             const art::FindManyP< recob::Hit > & hitsFromEmParts)
{
        mf::LogVerbatim("PMAlgTracker") << "Filter track-like clusters...";
        fCluHits.clear(); fCluHits.reserve(hitsFromClusters.size());
        fCluWeights.clear(); fCluWeights.reserve(fCluHits.size());
        size_t n = 0; // count not-empty clusters
        for (size_t i = 0; i < hitsFromClusters.size(); ++i)
        {
                auto v = hitsFromClusters.at(i);
                fCluHits.push_back(std::vector< art::Ptr<recob::Hit> >());
                for (auto const & h : v)
                {
                        bool trkLike = true;
                        for (size_t j = 0; j < hitsFromEmParts.size(); ++j)
                        {
                                auto u = hitsFromEmParts.at(j);
                                for (auto const & g : u) // is hit clustered in one of em-like?
                                {
                                        if (g.key() == h.key()) { trkLike = false; break; }
                                }
                                if (!trkLike) break;
                        }
                        if (trkLike) fCluHits.back().push_back(h);
                }
                if (!fCluHits.back().empty()) { fCluWeights.push_back(1); ++n; }
                else { fCluWeights.push_back(0); }
        }
        mf::LogVerbatim("PMAlgTracker") << "...done, " << n << " clusters for 3D tracking.";
}
// ------------------------------------------------------

double pma::PMAlgTracker::validate(pma::Track3D& trk, unsigned int testView)
{
        if ((trk.FirstElement()->GetDistToWall() < -3.0) ||
            (trk.LastElement()->GetDistToWall() < -3.0))
        {
                mf::LogVerbatim("PMAlgTracker") << "first or last node too far out of its initial TPC";
                return 0.0;
        }

        if (testView != geo::kUnknown) { mf::LogVerbatim("PMAlgTracker") << "validation in plane: " << testView; }
        else { return 1.0; }

    double v = 0;
    switch (fValidation)
    {
        case pma::PMAlgTracker::kAdc:
            v = fProjectionMatchingAlg.validate_on_adc(trk, fAdcImages[testView], fAdcValidationThr[testView]);
            break;

        case pma::PMAlgTracker::kHits:
            v = fProjectionMatchingAlg.validate(trk, fHitMap[trk.FrontCryo()][trk.FrontTPC()][testView]);
            break;

        case pma::PMAlgTracker::kCalib:
            v = fProjectionMatchingAlg.validate_on_adc_test(
                trk, fAdcImages[testView], fHitMap[trk.FrontCryo()][trk.FrontTPC()][testView],
                fAdcInPassingPoints[testView], fAdcInRejectedPoints[testView]);
            break;
            
        default: throw cet::exception("pma::PMAlgTracker") << "validation mode not supported" << std::endl; break;
    }

        return v;
}
// ------------------------------------------------------

bool pma::PMAlgTracker::reassignHits_1(const std::vector< art::Ptr<recob::Hit> > & hits,
        pma::TrkCandidateColl & tracks, size_t trk_idx, double dist2)
{
        pma::Track3D* trk1 = tracks[trk_idx].Track();

        bool result = false;
        if ((hits.size() > 1) || (dist2 > 1.0)) // min. 2 hits or single hit separated from the rest
        {
                pma::Track3D* best_trk = 0;

                size_t best_u = 0, n_max = 0;
                for (size_t u = 0; u < tracks.size(); u++)
                        if (trk_idx != u)
                {
                        pma::Track3D* trk2 = tracks[u].Track();
                        size_t n = fProjectionMatchingAlg.testHits(*trk2, hits);
                        if (n > n_max) { n_max = n; best_u = u; best_trk = trk2; }
                }

                if (best_trk && (n_max >= hits.size() / 3)) // /2
                {
                        mf::LogVerbatim("PMAlgTrackMaker") << "  Reassign(v1) " << n_max << " hits." << std::endl;

                        trk1->RemoveHits(hits);
                        trk1->CleanupTails();
                        trk1->ShiftEndsToHits();

                        pma::Track3D* ext = fProjectionMatchingAlg.extendTrack(*best_trk, hits, false);
                        ext->SortHits(); ext->ShiftEndsToHits();
                        if (fProjectionMatchingAlg.isContained(*ext))
                        {
                                tracks[best_u].SetTrack(ext); // and this deletes best_trk stored at best_u
                                result = true;
                        }
                        else delete ext;
                }
                else if (hits.size() >= fMinSeedSize2ndPass)
                {
                        size_t minSizeCompl = hits.size() / 8;  // much smaller minimum required in complementary views
                        if (minSizeCompl < 3) minSizeCompl = 3; // but at least three hits!

                        geo::View_t first_view = (geo::View_t)hits.front()->WireID().Plane;
                        unsigned int tpc = hits.front()->WireID().TPC;
                        unsigned int cryo = hits.front()->WireID().Cryostat;

                        pma::TrkCandidate candidate = matchCluster(-1, hits, minSizeCompl, tpc, cryo, first_view);

                        if (candidate.IsGood())
                        {
                                mf::LogVerbatim("PMAlgTrackMaker") << "  Add new track, cut hits from source track." << std::endl;
                                tracks.push_back(candidate);

                                trk1->RemoveHits(hits);
                                trk1->CleanupTails();
                                trk1->ShiftEndsToHits();
                        }
                }
        }
        else if ((hits.size() == 1) || (dist2 > 2.25)) // dist > 1.5cm
        {
                mf::LogVerbatim("PMAlgTrackMaker") << "  Cut single-view isolated hit." << std::endl;
                trk1->RemoveHits(hits);
                trk1->CleanupTails();
                trk1->ShiftEndsToHits();
        }
        return result;
}

double pma::PMAlgTracker::collectSingleViewEnd(pma::Track3D & trk,
        std::vector< art::Ptr<recob::Hit> > & hits)
{
        size_t idx = 0;
        while ((idx < trk.size() - 1) && !(trk[idx]->IsEnabled()))
        {
                hits.push_back(trk[idx++]->Hit2DPtr());
        }

        double d2 = 0.0;
        if (idx > 0)
        {
                if ((idx < trk.size() - 1) &&
                    (trk[idx]->View2D() == trk[idx - 1]->View2D()))
                {
                        double dprev = pma::Dist2(trk[idx]->Point3D(), trk[idx - 1]->Point3D());
                        double dnext = pma::Dist2(trk[idx]->Point3D(), trk[idx + 1]->Point3D());
                        if (dprev < dnext)
                        {
                                hits.push_back(trk[idx++]->Hit2DPtr());
                        }
                }
                d2 = pma::Dist2(trk[idx]->Point3D(), trk[idx - 1]->Point3D());
        }
        return d2;
}

double pma::PMAlgTracker::collectSingleViewFront(pma::Track3D & trk,
        std::vector< art::Ptr<recob::Hit> > & hits)
{
        size_t idx = trk.size() - 1;
        while ((idx > 0) && !(trk[idx]->IsEnabled()))
        {
                hits.push_back(trk[idx--]->Hit2DPtr());
        }

        double d2 = 0.0;
        if (idx < trk.size() - 1)
        {
                if ((idx > 0) &&
                    (trk[idx]->View2D() == trk[idx + 1]->View2D()))
                {
                        double dprev = pma::Dist2(trk[idx]->Point3D(), trk[idx + 1]->Point3D());
                        double dnext = pma::Dist2(trk[idx]->Point3D(), trk[idx - 1]->Point3D());
                        if (dprev < dnext)
                        {
                                hits.push_back(trk[idx--]->Hit2DPtr());
                        }
                }
                d2 = pma::Dist2(trk[idx]->Point3D(), trk[idx + 1]->Point3D());
        }
        return d2;
}

bool pma::PMAlgTracker::reassignSingleViewEnds_1(pma::TrkCandidateColl & tracks)
{
        bool result = false;
        for (size_t t = 0; t < tracks.size(); t++)
        {
                pma::Track3D & trk = *(tracks[t].Track());
                if (trk.size() < 6) continue;

                trk.DisableSingleViewEnds();

                std::vector< art::Ptr<recob::Hit> > hits;

                double d2 = collectSingleViewEnd(trk, hits);
                result |= reassignHits_1(hits, tracks, t, d2);

                hits.clear();

                d2 = collectSingleViewFront(trk, hits);
                result |= reassignHits_1(hits, tracks, t, d2);

                trk.SelectHits();
        }
        return result;
}
// ------------------------------------------------------

bool pma::PMAlgTracker::reassignHits_2(const std::vector< art::Ptr<recob::Hit> > & hits,
        pma::TrkCandidateColl & tracks, size_t trk_idx, double dist2)
{
        pma::Track3D* trk1 = tracks[trk_idx].Track();

        bool result = false;
        if ((hits.size() > 1) || (dist2 > 1.0)) // min. 2 hits or single hit separated from the rest
        {
                pma::Track3D* best_trk = 0;

                size_t n_max = 0;
                for (size_t u = 0; u < tracks.size(); u++)
                        if (trk_idx != u)
                {
                        pma::Track3D* trk2 = tracks[u].Track();
                        size_t n = fProjectionMatchingAlg.testHits(*trk2, hits, 0.5);
                        if (n > n_max) { n_max = n; best_trk = trk2; }
                }

                if (best_trk && (n_max >= (size_t)(0.8 * hits.size()))) // most hits!
                {
                        mf::LogVerbatim("PMAlgTrackMaker") << "  Reassign(v2) " << n_max << " hits." << std::endl;

                        trk1->RemoveHits(hits);
                        trk1->CleanupTails();
                        trk1->ShiftEndsToHits();

                        best_trk->AddHits(hits);

                        result = true;
                }
        }
        else if ((hits.size() == 1) || (dist2 > 2.25)) // dist > 1.5cm
        {
                mf::LogVerbatim("PMAlgTrackMaker") << "  Cut single-view isolated hit." << std::endl;
                trk1->RemoveHits(hits);
                trk1->CleanupTails();
                trk1->ShiftEndsToHits();

                result = true;
        }

        if (result)
        {
                // reopt trees
        }

        return result;
}

bool pma::PMAlgTracker::reassignSingleViewEnds_2(pma::TrkCandidateColl & tracks)
{
        bool result = false;
        for (size_t t = 0; t < tracks.size(); t++)
        {
                pma::Track3D & trk = *(tracks[t].Track());
                if (trk.size() < 6) continue;

                trk.DisableSingleViewEnds();

                std::vector< art::Ptr<recob::Hit> > hits;

                double d2 = collectSingleViewEnd(trk, hits);
                result |= reassignHits_2(hits, tracks, t, d2);

                hits.clear();

                d2 = collectSingleViewFront(trk, hits);
                result |= reassignHits_2(hits, tracks, t, d2);

                trk.SelectHits();
        }
        return result;
}
// ------------------------------------------------------

bool pma::PMAlgTracker::areCoLinear(pma::Track3D* trk1, pma::Track3D* trk2,
        double& dist, double& cos3d, bool& reverseOrder,
        double distThr, double distThrMin,
        double distProjThr,
        double cosThr)
{
        double lmax;
        double l1 = trk1->Length();
        double l2 = trk2->Length();

        if (l1 > l2) lmax = l1;
        else lmax = l2;

        double d = lmax * distThr;
        if (d < distThrMin) d = distThrMin;

        unsigned int k = 0;
        double distFF = pma::Dist2(trk1->front()->Point3D(), trk2->front()->Point3D());
        dist = distFF;

        double distFB = pma::Dist2(trk1->front()->Point3D(), trk2->back()->Point3D());
        if (distFB < dist) { k = 1; dist = distFB; }

        double distBF = pma::Dist2(trk1->back()->Point3D(), trk2->front()->Point3D());
        if (distBF < dist) { k = 2; dist = distBF; }

        double distBB = pma::Dist2(trk1->back()->Point3D(), trk2->back()->Point3D());
        if (distBB < dist) { k = 3; dist = distBB; }

        dist = sqrt(dist);
        cos3d = 0.0;

        if (dist < d)
        {
                pma::Track3D* tmp = 0;
                switch (k) // swap or flip to get trk1 end before trk2 start
                {
                        case 0: trk1->Flip(); break;
                        case 1: tmp = trk1;     trk1 = trk2; trk2 = tmp; break;
                        case 2: break;
                        case 3: trk2->Flip(); break;
                        default: mf::LogError("PMAlgTracker") << "Should never happen.";
                }
                if (k == 1) reverseOrder = true;
                else reverseOrder = false;

                size_t nodeEndIdx = trk1->Nodes().size() - 1;

                TVector3 endpoint1 = trk1->back()->Point3D();
                TVector3 trk2front0 = trk2->Nodes()[0]->Point3D();
                TVector3 trk2front1 = trk2->Nodes()[1]->Point3D();
                TVector3 proj1 = pma::GetProjectionToSegment(endpoint1, trk2front0, trk2front1);
                double distProj1 = sqrt( pma::Dist2(endpoint1, proj1) );

                TVector3 endpoint2 = trk2->front()->Point3D();
                TVector3 trk1back0 = trk1->Nodes()[nodeEndIdx]->Point3D();
                TVector3 trk1back1 = trk1->Nodes()[nodeEndIdx - 1]->Point3D();
                TVector3 proj2 = pma::GetProjectionToSegment(endpoint2, trk1back1, trk1back0);
                double distProj2 = sqrt( pma::Dist2(endpoint2, proj2) );

                pma::Vector3D dir1 = trk1->Segments().back()->GetDirection3D();
                pma::Vector3D dir2 = trk2->Segments().front()->GetDirection3D();

                cos3d = dir1.Dot(dir2);

                if ((cos3d > cosThr) && (distProj1 < distProjThr) && (distProj2 < distProjThr))
                        return true;
                else // check if parallel to wires & colinear in 2D
                {
                        const double maxCosXZ = 0.996195; // 5 deg

                        pma::Vector3D dir1_xz(dir1.X(), 0., dir1.Z());
                        dir1_xz *= 1.0 / dir1_xz.R();

                        pma::Vector3D dir2_xz(dir2.X(), 0., dir2.Z());
                        dir2_xz *= 1.0 / dir2_xz.R();

                        if ((fabs(dir1_xz.Z()) > maxCosXZ) && (fabs(dir2_xz.Z()) > maxCosXZ))
                        {
                                endpoint1.SetY(0.);
                                trk2front0.SetY(0.);
                                trk2front1.SetY(0.);
                                proj1 = pma::GetProjectionToSegment(endpoint1, trk2front0, trk2front1);
                                distProj1 = sqrt( pma::Dist2(endpoint1, proj1) );

                                endpoint2.SetY(0.);
                                trk1back0.SetY(0.);
                                trk1back1.SetY(0.);
                                proj2 = pma::GetProjectionToSegment(endpoint2, trk1back1, trk1back0);
                                distProj2 = sqrt( pma::Dist2(endpoint2, proj2) );
                        
                                double cosThrXZ = cos(0.5 * acos(cosThr));
                                double distProjThrXZ = 0.5 * distProjThr;
                                double cosXZ = dir1_xz.Dot(dir2_xz);
                                if ((cosXZ > cosThrXZ) && (distProj1 < distProjThrXZ) && (distProj2 < distProjThrXZ))
                                        return true;
                        }
                }
        }
        return false;
}

bool pma::PMAlgTracker::mergeCoLinear(pma::TrkCandidateColl & tracks)
{
        double distThr = 0.25;    // max gap as a fraction of the longer track length
        double distThrMin = 0.5;  // lower limit of max gap threshold [cm]

        double distProjThr = fMergeTransverseShift;
        double cosThr = cos(TMath::Pi() * fMergeAngle / 180.0);

        bool foundMerge = false;

        std::sort(tracks.tracks().begin(), tracks.tracks().end(), pma::bTrack3DLonger());

        bool r;
        double d, dmin, c, cmax, l, lbest;
        size_t t = 0, u = 0;
        while (t < tracks.size())
        {
                pma::Track3D* trk1 = tracks[t].Track();

                pma::Track3D* trk2 = 0;
                pma::Track3D* best_trk2 = 0;
                dmin = 1.0e12; cmax = 0; lbest = 0;
                for (u = t + 1; u < tracks.size(); u++)
                {
                        trk2 = tracks[u].Track();
                        if (areCoLinear(trk1, trk2, d, c, r, distThr, distThrMin, distProjThr, cosThr))
                        {
                                l = std::sqrt(pma::Dist2(trk2->front()->Point3D(), trk2->back()->Point3D()));
                                if (((c > cmax) && (d < dmin + 0.5 * lbest)) ||
                                    ((d < dmin) && (l > 1.5 * lbest)))
                                {
                                        cmax = c; dmin = d;
                                        best_trk2 = trk2;
                                        lbest = l;
                                }
                        }
                        trk2 = 0;
                }
                trk2 = best_trk2;

                if (trk2)
                {
                        mf::LogVerbatim("PMAlgTracker") << "Merge track ("
                                << trk1->size() << ") with track (" << trk2->size() << ")";
                        if (r)
                        {
                                fProjectionMatchingAlg.mergeTracks(*trk2, *trk1, true);
                                tracks[t].SetTrack(trk2); // deletes old trk1
                        }
                        else
                        {
                                fProjectionMatchingAlg.mergeTracks(*trk1, *trk2, true);
                                tracks[u].DeleteTrack();
                        }
                        tracks.erase_at(u);
                        foundMerge = true;
                }
                else t++;
        }

        return foundMerge;
}
// ------------------------------------------------------


void pma::PMAlgTracker::freezeBranchingNodes(pma::TrkCandidateColl & tracks)
{
        for (auto const & trk : tracks.tracks())
                for (auto node : trk.Track()->Nodes())
                        if (node->IsBranching()) node->SetFrozen(true);
}
void pma::PMAlgTracker::releaseAllNodes(pma::TrkCandidateColl & tracks)
{
        for (auto const & trk : tracks.tracks())
                for (auto node : trk.Track()->Nodes())
                        node->SetFrozen(false);
}

void pma::PMAlgTracker::mergeCoLinear(pma::tpc_track_map& tracks)
{
        double distThr = 0.25;    // max gap as a fraction of the longer track length
        double distThrMin = 2.5;  // lower limit of max gap threshold [cm]

        double distProjThr = fStitchTransverseShift;
        double cosThr = cos(TMath::Pi() * fStitchAngle / 180.0);

        double wallDistThr = fStitchDistToWall;
        double dfront1, dback1, dfront2, dback2;

        //for (auto & tpc_entry : tracks) freezeBranchingNodes(tpc_entry.second);

        for (auto & tpc_entry1 : tracks)
        {
                unsigned int tpc1 = tpc_entry1.first;
                pma::TrkCandidateColl & tracks1 = tpc_entry1.second;

                size_t t = 0;
                while (t < tracks1.size())
                {
                        bool r, reverse = false;
                        double l, lbest = 0, d, dmin = 1.0e12, c, cmax = 0.0;
                        pma::Track3D* best_trk2 = 0;
                        unsigned int best_tpc = 0;
                        size_t best_idx = 0;

                        pma::Track3D* trk1 = tracks1[t].Track();
                        dfront1 = trk1->Nodes().front()->GetDistToWall();
                        dback1 = trk1->Nodes().back()->GetDistToWall();
                        if ((dfront1 < wallDistThr) || (dback1 < wallDistThr))
                        {
                                for (auto & tpc_entry2 : tracks)
                                {
                                        unsigned int tpc2 = tpc_entry2.first;
                                        if (tpc2 == tpc1) continue;

                                        pma::TrkCandidateColl & tracks2 = tpc_entry2.second;

                                        for (size_t u = 0; u < tracks2.size(); u++)
                                        {
                                                pma::Track3D* trk2 = tracks2[u].Track();
                                                dfront2 = trk2->Nodes().front()->GetDistToWall();
                                                dback2 = trk2->Nodes().back()->GetDistToWall();
                                                if ((dfront2 < wallDistThr) || (dback2 < wallDistThr))
                                                {
                                                        if (areCoLinear(trk1, trk2, d, c, r, distThr, distThrMin, distProjThr, cosThr))
                                                        {
                                                                l = std::sqrt(pma::Dist2(trk2->front()->Point3D(), trk2->back()->Point3D()));
                                                                if (((c > cmax) && (d < dmin + 0.5 * lbest)) || (0.75 * l < dmin))
                                                                {
                                                                        cmax = c; dmin = d; lbest = l;
                                                                        best_trk2 = trk2;
                                                                        best_tpc = tpc2;
                                                                        best_idx = u;
                                                                        reverse = r;
                                                                }
                                                        }
                                                }
                                        }
                                }
                        }

                        if (best_trk2)
                        {
                                mf::LogVerbatim("PMAlgTracker") << "Merge track ("
                                        << tpc1 << ":" << tracks1.size() << ":" << trk1->size() << ") with track ("
                                        << best_tpc  << ":" << tracks[best_tpc].size() << ":" << best_trk2->size() << ")";
        auto const* geom = lar::providerFrom<geo::Geometry>();
        const geo::TPCGeo &tpc1 = geom->TPC(trk1->Nodes().front()->TPC(),trk1->Nodes().front()->Cryo());
        const geo::TPCGeo &tpc2 = geom->TPC(best_trk2->Nodes().front()->TPC(),best_trk2->Nodes().front()->Cryo());
                                if (reverse)
                                {
                                        fProjectionMatchingAlg.mergeTracks(*best_trk2, *trk1, true);
          // This track will have a shift in x equal to zero. This will
          // properly set the track T0
          if(tpc1.DetectDriftDirection() * tpc2.DetectDriftDirection() < 0){
            best_trk2->ApplyDriftShiftInTree(0.0);
          }
                                        tracks1[t].SetTrack(best_trk2);
                                }
                                else
                                {
                                        fProjectionMatchingAlg.mergeTracks(*trk1, *best_trk2, true);
          // This track will have a shift in x equal to zero. This will
          // properly set the track T0
          if(tpc1.DetectDriftDirection() * tpc2.DetectDriftDirection() < 0){
            trk1->ApplyDriftShiftInTree(0.0);
          }
                                        tracks[best_tpc][best_idx].DeleteTrack();
                                }
                                tracks[best_tpc].erase_at(best_idx);
                        }
                        else t++;
                }
        }

        //for (auto & tpc_entry : tracks) releaseAllNodes(tpc_entry.second);
}
// ------------------------------------------------------

size_t pma::PMAlgTracker::matchTrack(const pma::TrkCandidateColl & tracks, const std::vector< art::Ptr<recob::Hit> > & hits) const
{
    size_t max_hits = 0;
    for (auto const & t : tracks.tracks())
    {
        size_t n = fProjectionMatchingAlg.testHits(*(t.Track()), hits);
        if (n > max_hits) { max_hits = n; }
    }
    return max_hits;
}

// ------------------------------------------------------
// ------------------------------------------------------
int pma::PMAlgTracker::build(void)
{
        fInitialClusters.clear();
        fTriedClusters.clear();
        fUsedClusters.clear();

    size_t nplanes = fGeom->MaxPlanes();

        pma::tpc_track_map tracks; // track parts in tpc's

        for (auto tpc_iter = fGeom->begin_TPC_id();
                  tpc_iter != fGeom->end_TPC_id();
                  tpc_iter++)
        {
            mf::LogVerbatim("PMAlgTracker")
                << "Reconstruct tracks within Cryo:" << tpc_iter->Cryostat
                << " / TPC:" << tpc_iter->TPC << ".";

            if (fValidation != pma::PMAlgTracker::kHits) // initialize ADC images for all planes in this TPC (in "adc" and "calib")
            {
                mf::LogVerbatim("PMAlgTracker") << "Prepare validation ADC images...";
                bool ok = true;
            for (size_t p = 0; p < nplanes; ++p) { ok &= fAdcImages[p].setWireDriftData(fWires, p, tpc_iter->TPC, tpc_iter->Cryostat); }
            if (ok) { mf::LogVerbatim("PMAlgTracker") << "  ...done."; }
            else { mf::LogVerbatim("PMAlgTracker") << "  ...failed."; continue; }
        }

        // find reasonably large parts
                fromMaxCluster_tpc(tracks[tpc_iter->TPC], fMinSeedSize1stPass, tpc_iter->TPC, tpc_iter->Cryostat);
                // loop again to find small things
                fromMaxCluster_tpc(tracks[tpc_iter->TPC], fMinSeedSize2ndPass, tpc_iter->TPC, tpc_iter->Cryostat);

        //tryClusterLeftovers();

        mf::LogVerbatim("PMAlgTracker") << "Found tracks: " << tracks[tpc_iter->TPC].size();
        if (tracks[tpc_iter->TPC].empty()) { continue; }

            // add 3D ref.points for clean endpoints of wire-plane parallel track
                guideEndpoints(tracks[tpc_iter->TPC]);
                // try correcting single-view sections spuriously merged on 2D clusters level
                reassignSingleViewEnds_1(tracks[tpc_iter->TPC]);

            if (fMergeWithinTPC)
            {
                        mf::LogVerbatim("PMAlgTracker") << "Merge co-linear tracks within TPC " << tpc_iter->TPC << ".";
                        while (mergeCoLinear(tracks[tpc_iter->TPC]))
                        {
                                mf::LogVerbatim("PMAlgTracker") << "  found co-linear tracks";
                        }
            }
        }

        if (fStitchBetweenTPCs)
        {
                mf::LogVerbatim("PMAlgTracker") << "Stitch co-linear tracks between TPCs.";
                mergeCoLinear(tracks);
        }

        for (auto & tpc_entry : tracks) // put tracks in the single collection
                for (auto & trk : tpc_entry.second.tracks())
                {
                        if (trk.Track()->HasTwoViews() && (trk.Track()->Nodes().size() > 1)) { fResult.push_back(trk); }
                        else { trk.DeleteTrack(); }
                }

    if (fTagCosmicTracks)
    {
        mf::LogVerbatim("PMAlgTracker") << "Tag cosmic tracks activity.";
        fCosmicTagger.tag(fResult);
    }

        if (fRunVertexing)
        {
                mf::LogVerbatim("PMAlgTracker") << "Vertex finding / track-vertex reoptimization.";
                fPMAlgVertexing.run(fResult);

                //reassignSingleViewEnds(result); // final check for correct hit-track assignments
        }

        fResult.setTreeIds();

  if(fMatchT0inCPACrossing)
  {
                mf::LogVerbatim("PMAlgTracker") << "Find co-linear CPA-crossing tracks with any T0.";
    fStitcher.StitchTracksCPA(fResult);
  }

        if (fMatchT0inAPACrossing)
        {
                mf::LogVerbatim("PMAlgTracker") << "Find co-linear APA-crossing tracks with any T0.";
    fStitcher.StitchTracksAPA(fResult);
        }

  if (fTagCosmicTracks)
  {
    mf::LogVerbatim("PMAlgTracker") << "Second pass cosmic tagging for stitched tracks";
    fCosmicTagger.tag(fResult);
  }

        //double dQdxFlipThr = 0.0;
        //if (fFlipToBeam) dQdxFlipThr = 0.4;
        if (fFlipToBeam) fResult.flipTreesToCoordinate(2);        // flip the tracks / trees to the beam direction (Z)
        else if (fFlipDownward) fResult.flipTreesToCoordinate(1); // flip the tracks / trees to point downward (-Y)
        else if (fFlipToX) fResult.flipTreesToCoordinate(0);      // flip the tracks / trees to point in -X direction (downwards for dual phase)

        if (fAutoFlip_dQdx) fResult.flipTreesByDQdx();            // flip the tracks / trees to get best dQ/dx sequences

        fResult.setParentDaughterConnections();

        listUsedClusters();
        return fResult.size();
}
// ------------------------------------------------------
// ------------------------------------------------------

void pma::PMAlgTracker::fromMaxCluster_tpc(pma::TrkCandidateColl & result,
        size_t minBuildSize, unsigned int tpc, unsigned int cryo)
{
        fInitialClusters.clear();

        size_t minSizeCompl = minBuildSize / 8;  // smaller minimum required in complementary views
        if (minSizeCompl < 2) minSizeCompl = 2;  // but at least two hits!

        int max_first_idx = 0;
        while (max_first_idx >= 0) // loop over clusters, any view, starting from the largest
        {
                mf::LogVerbatim("PMAlgTracker") << "Find max cluster...";
                max_first_idx = maxCluster(minBuildSize, geo::kUnknown, tpc, cryo); // any view, but must be track-like
                if ((max_first_idx >= 0) && !fCluHits[max_first_idx].empty())
                {
                        geo::View_t first_view = fCluHits[max_first_idx].front()->View();

                        pma::TrkCandidate candidate = matchCluster(max_first_idx,
                                minSizeCompl, tpc, cryo, first_view);

                        if (candidate.IsGood()) result.push_back(candidate);
                }
                else mf::LogVerbatim("PMAlgTracker") << "small clusters only";
        }

        fInitialClusters.clear();
}
// ------------------------------------------------------

pma::TrkCandidate pma::PMAlgTracker::matchCluster(
        int first_clu_idx, const std::vector< art::Ptr<recob::Hit> > & first_hits,
        size_t minSizeCompl, unsigned int tpc, unsigned int cryo, geo::View_t first_view)
{
        pma::TrkCandidate result;

    for (auto av : fAvailableViews) { fTriedClusters[av].clear(); }

        if (first_clu_idx >= 0)
        {
                fTriedClusters[first_view].push_back((size_t)first_clu_idx);
                fInitialClusters.push_back((size_t)first_clu_idx);
        }

    unsigned int nFirstHits = first_hits.size(), first_plane_idx = first_hits.front()->WireID().Plane;
        mf::LogVerbatim("PMAlgTracker") << std::endl << "--- start new candidate ---";
        mf::LogVerbatim("PMAlgTracker") << "use view  *** " << first_view << " *** plane idx " << first_plane_idx << " ***  size: " << nFirstHits;

        float x, xmax = fDetProp->ConvertTicksToX(first_hits.front()->PeakTime(), first_plane_idx, tpc, cryo), xmin = xmax;
        //mf::LogVerbatim("PMAlgTracker") << "  *** x max0: " << xmax;
        for (size_t j = 1; j < first_hits.size(); ++j)
        {
                x = fDetProp->ConvertTicksToX(first_hits[j]->PeakTime(), first_plane_idx, tpc, cryo);
                if (x > xmax) { xmax = x; }
                if (x < xmin) { xmin = x; }
        }
        //mf::LogVerbatim("PMAlgTracker") << "  *** x max: " << xmax << " min:" << xmin;

        pma::TrkCandidateColl candidates; // possible solutions of the selected cluster and clusters in complementary views

        size_t imatch = 0;
        bool try_build = true;
        while (try_build) // loop over complementary views
        {
                pma::TrkCandidate candidate;
                if (first_clu_idx >= 0) candidate.Clusters().push_back((size_t)first_clu_idx);

        try_build = false;
        int idx = -1, av_idx = -1;
        unsigned int nMaxHits = 0, nHits = 0;
        unsigned int testView = geo::kUnknown, bestView = geo::kUnknown;
        for (auto av : fAvailableViews)
        {
            if (av == first_view) continue;

            av_idx = maxCluster(first_clu_idx, candidates, xmin, xmax, minSizeCompl, av, tpc, cryo);
            if (av_idx >= 0)
            {
                nHits = fCluHits[av_idx].size();
                if ((nHits > nMaxHits) && (nHits >= minSizeCompl))
                {
                    nMaxHits = nHits; idx = av_idx; bestView = av;
                    fTriedClusters[av].push_back(idx);
                    try_build = true;
                }
            }
        }
        for (auto av : fAvailableViews)
        {
            if ((av != first_view) && (av != bestView)) { testView = av; break; }
        }

                if (try_build)
                {
            mf::LogVerbatim("PMAlgTracker") << "--> " << imatch++ << " match with:";
                    mf::LogVerbatim("PMAlgTracker") << "    cluster in view  *** " << bestView << " ***  size: " << nMaxHits;

                        if (!fGeom->TPC(tpc, cryo).HasPlane(testView)) { mf::LogVerbatim("PMAlgTracker") << "    no validation plane  *** "; testView = geo::kUnknown; }
                        else { mf::LogVerbatim("PMAlgTracker") << "    validation plane  *** " << testView << " ***"; }

                        double m0 = 0.0, v0 = 0.0;
                        double mseThr = 0.15, validThr = 0.7; // cuts for a good track candidate

                        candidate.Clusters().push_back(idx);
                        candidate.SetTrack(fProjectionMatchingAlg.buildTrack(first_hits, fCluHits[idx]));

                        if (candidate.IsValid() && // no track if hits from 2 views do not alternate
                            fProjectionMatchingAlg.isContained(*(candidate.Track()), 2.0F)) // sticks out of TPC's?
                        {
                                m0 = candidate.Track()->GetMse();
                                if (m0 < mseThr) // check validation only if MSE is OK - thanks for Tracy for noticing this
                                { v0 = validate(*(candidate.Track()), testView); }
                        }

                        if (candidate.Track() && (m0 < mseThr) && (v0 > validThr)) // good candidate, try to extend it
                        {
                                mf::LogVerbatim("PMAlgTracker") << "  good track candidate, MSE = " << m0 << ", v = " << v0;

                                candidate.SetMse(m0);
                                candidate.SetValidation(v0);
                                candidate.SetGood(true);

                                size_t minSize = 5;      // min size for clusters matching
                                double fraction = 0.5;   // min fraction of close hits

                                idx = 0;
                                while (idx >= 0) // try to collect matching clusters, use **any** plane except validation
                                {
                                        idx = matchCluster(candidate, minSize, fraction, geo::kUnknown, testView, tpc, cryo);
                                        if (idx >= 0)
                                        {
                                                // try building extended copy:
                                                //                src,        hits,      valid.plane, add nodes
                                                if (extendTrack(candidate, fCluHits[idx],  testView,    true))
                                                {
                                                        candidate.Clusters().push_back(idx);
                                                }
                                                else idx = -1;
                                        }
                                }

                                mf::LogVerbatim("PMAlgTracker") << "merge clusters from the validation plane";
                                fraction = 0.7; // only well matching the existing track

                                idx = 0;
                                bool extended = false;
                                while ((idx >= 0) && (testView != geo::kUnknown))
                                {       //                     match clusters from the plane used previously for the validation
                                        idx = matchCluster(candidate, minSize, fraction, testView, geo::kUnknown, tpc, cryo);
                                        if (idx >= 0)
                                        {
                                                // validation not checked here, no new nodes:
                                                if (extendTrack(candidate, fCluHits[idx], geo::kUnknown, false))
                                                {
                                                        candidate.Clusters().push_back(idx);
                                                        extended = true;
                                                }
                                                else idx = -1;
                                        }
                                }
                                // need to calculate again only if trk was extended w/o checking validation:
                                if (extended) candidate.SetValidation(validate(*(candidate.Track()), testView));
                        }
                        else
                        {
                                mf::LogVerbatim("PMAlgTracker") << "track REJECTED, MSE = " << m0 << "; v = " << v0;
                                candidate.SetGood(false); // save also bad matches to avoid trying again the same pair of clusters
                        }
                        candidates.push_back(candidate);
                }
                else
                {
                        mf::LogVerbatim("PMAlgTracker") << "no matching clusters";
                }
        } // end loop over complementary views

        if (!candidates.empty()) // return best candidate, release other tracks and clusters
        {
                int best_trk = -1;
                double f, max_f = 0., min_mse = 10., max_v = 0.;
                for (size_t t = 0; t < candidates.size(); t++)
                        if (candidates[t].IsGood() &&
                            (candidates[t].Track()->Nodes().size() > 1) &&
                            candidates[t].Track()->HasTwoViews())
                {
                        f = fProjectionMatchingAlg.twoViewFraction(*(candidates[t].Track()));

                        if ((f > max_f) || ((f == max_f) &&
                                ((candidates[t].Validation() > max_v) || (candidates[t].Mse() < min_mse))))
                        {
                                max_f = f;
                                min_mse = candidates[t].Mse();
                                max_v = candidates[t].Validation();
                                best_trk = t;
                        }
                }

                if ((best_trk > -1) && candidates[best_trk].IsGood() && (max_f > fMinTwoViewFraction))
                {
                        candidates[best_trk].Track()->ShiftEndsToHits();

                        for (auto c : candidates[best_trk].Clusters())
                                fUsedClusters.push_back(c);

                        result = candidates[best_trk];
                }

                for (size_t t = 0; t < candidates.size(); t++)
                {
                        if (int(t) != best_trk) candidates[t].DeleteTrack();
                }
        }

        return result;
}
// ------------------------------------------------------

bool pma::PMAlgTracker::extendTrack(pma::TrkCandidate& candidate,
        const std::vector< art::Ptr<recob::Hit> >& hits,
        unsigned int testView, bool add_nodes)
{
        double m_max = 2.0 * candidate.Mse(); // max acceptable MSE value
        if (m_max < 0.05) m_max = 0.05;     // this is still good, low MSE value

        double v_min1 = 0.98 * candidate.Validation();
        double v_min2 = 0.9 * candidate.Validation();

        pma::Track3D* copy = fProjectionMatchingAlg.extendTrack(*(candidate.Track()), hits, add_nodes);
        double m1 = copy->GetMse();
        double v1 = validate(*copy, testView);

        if (((m1 < candidate.Mse()) && (v1 >= v_min2)) ||
            ((m1 < 0.5) && (m1 <= m_max) && (v1 >= v_min1)))
        {
                mf::LogVerbatim("PMAlgTracker")
                        << "  track EXTENDED, MSE = " << m1 << ", v = " << v1;
                candidate.SetTrack(copy);  // replace with the new track (deletes old one)
                copy->SortHits();          // sort hits in the new track

                candidate.SetMse(m1);      // save info
                candidate.SetValidation(v1);

                return true;
        }
        else
        {
                mf::LogVerbatim("PMAlgTracker")
                        << "  track NOT extended, MSE = " << m1 << ", v = " << v1;
                delete copy;
                return false;
        }
}
// ------------------------------------------------------

int pma::PMAlgTracker::matchCluster(const pma::TrkCandidate& trk,
        size_t minSize, double fraction,
        unsigned int preferedView, unsigned int testView,
        unsigned int tpc, unsigned int cryo) const
{
        double f, fmax = 0.0;
        unsigned int n, max = 0;
        int idx = -1;
        for (size_t i = 0; i < fCluHits.size(); ++i)
        {
                if (fCluHits[i].empty()) continue;

                unsigned int view = fCluHits[i].front()->View();
                unsigned int nhits = fCluHits[i].size();

                if (has(fUsedClusters, i) ||                             // don't try already used clusters
                        has(trk.Clusters(), i) ||                            // don't try clusters from this candidate
                    (view == testView) ||                                // don't use clusters from validation view
                    ((preferedView != geo::kUnknown)&&(view != preferedView)) || // only prefered view if specified
                    (nhits < minSize))                                   // skip small clusters
                    continue;

                n = fProjectionMatchingAlg.testHits(*(trk.Track()), fCluHits[i]);
                f = n / (double)nhits;
                if ((f > fraction) && (n > max))
                {
                        max = n; fmax = f; idx = i;
                }
        }

        if (idx >= 0) mf::LogVerbatim("PMAlgTracker") << "max matching hits: " << max << " (" << fmax << ")";
        else mf::LogVerbatim("PMAlgTracker") << "no clusters to extend the track";

        return idx;
}
// ------------------------------------------------------

int pma::PMAlgTracker::maxCluster(int first_idx_tag,
        const pma::TrkCandidateColl & candidates,
        float xmin, float xmax, size_t min_clu_size,
        geo::View_t view, unsigned int tpc, unsigned int cryo) const
{
        int idx = -1;
        size_t s_max = 0, s;
        double fraction = 0.0;
        float x;

        size_t first_idx = 0;
        bool has_first = false;
        if (first_idx_tag >= 0)
        {
                first_idx = (size_t)first_idx_tag;
                has_first = true;
        }

        for (size_t i = 0; i < fCluHits.size(); ++i)
        {
                if ((fCluHits[i].size() <  min_clu_size) || (fCluHits[i].front()->View() != view) ||
                    has(fUsedClusters, i) || has(fInitialClusters, i) || has(fTriedClusters[view], i))
                        continue;

                bool pair_checked = false;
                for (auto const & c : candidates.tracks())
                        if (has_first && has(c.Clusters(), first_idx) && has(c.Clusters(), i))
                        {
                                pair_checked = true; break;
                        }
                if (pair_checked) continue;
                    
                const auto & v = fCluHits[i];

                if ((v.front()->WireID().TPC == tpc) &&
                    (v.front()->WireID().Cryostat == cryo))
                {
                        s = 0;
                        for (size_t j = 0; j < v.size(); ++j)
                        {
                                x = fDetProp->ConvertTicksToX(v[j]->PeakTime(), v[j]->WireID().Plane, tpc, cryo);
                                if ((x >= xmin) && (x <= xmax)) s++;
                        }

                        if (s > s_max)
                        {
                                s_max = s; idx = i; fraction = s / (double)v.size();
                        }
                }
        }
        if (fraction > 0.4) return idx;
        else return -1;
}
// ------------------------------------------------------

int pma::PMAlgTracker::maxCluster(size_t min_clu_size,
        geo::View_t view, unsigned int tpc, unsigned int cryo) const
{
        int idx = -1;
        size_t s_max = 0, s;

        for (size_t i = 0; i < fCluHits.size(); ++i)
        {
                const auto & v = fCluHits[i];

                if (v.empty() || (fCluWeights[i] < fTrackLikeThreshold) ||
                    has(fUsedClusters, i) || has(fInitialClusters, i) || has(fTriedClusters[view], i) ||
                   ((view != geo::kUnknown) && (v.front()->View() != view)))
                continue;

                if ((v.front()->WireID().TPC == tpc) &&
                    (v.front()->WireID().Cryostat == cryo))
                {
                        s = v.size();
                        if ((s >= min_clu_size) && (s > s_max))
                        {
                                s_max = s; idx = i;
                        }
                }
        }
        return idx;
}
// ------------------------------------------------------
// ------------------------------------------------------

void pma::PMAlgTracker::listUsedClusters(void) const
{
    //std::ofstream hits_file("pma_event_hits.prn");

        mf::LogVerbatim("PMAlgTracker") << std::endl << "----------- matched clusters: -----------";
        for (size_t i = 0; i < fCluHits.size(); ++i)
        {
                if (!fCluHits[i].empty() && has(fUsedClusters, i))
                {
                        mf::LogVerbatim("PMAlgTracker")
                                << "    tpc: " << fCluHits[i].front()->WireID().TPC
                                << ";\tview: " << fCluHits[i].front()->View()
                                << ";\tsize: " << fCluHits[i].size()
                                << ";\tweight: " << fCluWeights[i];
                //for (const auto & h : fCluHits[i])
                //{
                //    hits_file << h->WireID().TPC << " " << h->View() << " "
                    //        <<  h->WireID().Wire << " " << h->PeakTime() << " " << h->Integral() << " "
                    //        << fCluHits[i].size() << " " << i << " "
                //              << fCluWeights[i] << " -1" << std::endl;
                //}
                }
        }

        mf::LogVerbatim("PMAlgTracker") << "--------- not matched clusters: ---------";
        size_t nsingles = 0;
        for (size_t i = 0; i < fCluHits.size(); ++i)
        {
                if (!fCluHits[i].empty() && !has(fUsedClusters, i))
                {
                    if (fCluHits[i].size() == 1) { nsingles++; }
                    else
                    {
                        mf::LogVerbatim("PMAlgTracker")
                                << "    tpc: " << fCluHits[i].front()->WireID().TPC
                                << ";\tview: " << fCluHits[i].front()->View()
                                << ";\tsize: " << fCluHits[i].size()
                                << ";\tweight: " << fCluWeights[i]
                                << ";\tmatch: " << matchTrack(fResult, fCluHits[i]);
                }
                //for (const auto & h : fCluHits[i])
                //{
                //    hits_file << h->WireID().TPC << " " << h->View() << " "
                    //        <<  h->WireID().Wire << " " << h->PeakTime() << " " << h->Integral() << " "
                    //        << fCluHits[i].size() << " " << i << " "
                //              << fCluWeights[i] << " " << matchTrack(fResult, fCluHits[i])/(float)fCluHits[i].size()
                //              << std::endl;
                //}
                }
        }
        //hits_file.close();
        mf::LogVerbatim("PMAlgTracker") << "    single hits: " << nsingles;
        mf::LogVerbatim("PMAlgTracker") << "-----------------------------------------";
}
// ------------------------------------------------------
// ------------------------------------------------------