/***************************************************************************
 *   Copyright (c) 2022 WandererFan <wandererfan@gmail.com>                *
 *                                                                         *
 *   This file is part of the FreeCAD CAx development system.              *
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 *   This library is free software; you can redistribute it and/or         *
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 *   This library  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 Library General Public License for more details.                  *
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 ***************************************************************************/
//DrawComplexSection processing overview
//for Strategy = Offset, DCS is much the same as DVS
//for Strategy = Aligned, there are many differences

//execute
//    sectionExec(getShapeToCut()*)

//sectionExec
//    makeSectionCut(baseShape)

//makeSectionCut (separate thread)
//    note that the section cut is not required for Aligned strategy,
//    but it is useful for debugging
//    m_cuttingTool = makeCuttingTool* (DVSTool.brep)
//    m_cutPieces = (baseShape - m_cuttingTool) (DVSCutPieces.brep)

//onSectionCutFinished
//    m_preparedShape = prepareShape(m_cutPieces)* - centered, scaled, rotated
//    geometryObject = DVP::buildGeometryObject(m_preparedShape)  (HLR)

//postHlrTasks
//    faceIntersections = findSectionPlaneIntersections
//    m_sectionTopoDSFaces = alignSectionFaces(faceIntersections)
//    m_tdSectionFaces = makeTDSectionFaces(m_sectionTopoDSFaces)

//* for Aligned, we use a different ShapeToCut, as the standard one will
//  cause many coincident face problems later
//* the cutting tool is built up from the profile, instead of the simple plane in DVS
//* for Aligned, preparing the shape is much different than Offset or DVS
//    - most of the work is done in makeAlignedPieces
//    - for each segment of the profile, make a cutting tool, then get the boolean
//      intersection of the tool and the shape to cut
//    - align and distribute the intersections along an "effective" section plane
//      which is a flattened version of the profile

#include <BRepAdaptor_Curve.hxx>
#include <BRepAdaptor_Surface.hxx>
#include <Mod/Part/App/FCBRepAlgoAPI_Common.h>
#include <Mod/Part/App/FCBRepAlgoAPI_Cut.h>
#include <BRepAlgo_NormalProjection.hxx>
#include <BRepBndLib.hxx>
#include <BRepBuilderAPI_Copy.hxx>
#include <BRepBuilderAPI_MakeEdge.hxx>
#include <BRepBuilderAPI_MakeFace.hxx>
#include <BRepBuilderAPI_MakeWire.hxx>
#include <BRepBuilderAPI_Transform.hxx>
#include <BRepGProp.hxx>
#include <BRepLProp_SLProps.hxx>
#include <BRepLib.hxx>
#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepPrimAPI_MakeHalfSpace.hxx>
#include <BRepPrimAPI_MakePrism.hxx>
#include <BRepTools.hxx>
#include <BRep_Builder.hxx>
#include <Bnd_Box.hxx>
#include <Bnd_OBB.hxx>
#include <GC_MakeArcOfCircle.hxx>
#include <GProp_GProps.hxx>
#include <Geom_Plane.hxx>
#include <HLRAlgo_Projector.hxx>
#include <QFuture>
#include <QFutureWatcher>
#include <QtConcurrentRun>
#include <ShapeExtend_WireData.hxx>
#include <TopExp.hxx>
#include <TopExp_Explorer.hxx>
#include <TopoDS.hxx>
#include <TopoDS_Compound.hxx>
#include <TopoDS_Edge.hxx>
#include <TopoDS_Face.hxx>
#include <TopoDS_Shape.hxx>
#include <TopoDS_Vertex.hxx>
#include <gp_Ax2.hxx>
#include <gp_Ax3.hxx>
#include <gp_Dir.hxx>
#include <gp_Pln.hxx>
#include <gp_Pnt.hxx>

#include <GeomAdaptor_Surface.hxx>
#include <BRepBuilderAPI_MakeVertex.hxx>
#include <GeomLib_IsPlanarSurface.hxx>

#include <cmath>

#include <sstream>

#include <App/Application.h>
#include <App/Document.h>
#include <App/Material.h>
#include <Base/BoundBox.h>
#include <Base/Console.h>
#include <Base/Converter.h>
#include <Base/Exception.h>
#include <Base/FileInfo.h>
#include <Base/Interpreter.h>
#include <Base/Parameter.h>
#include <Base/Tools.h>

#include <Mod/Part/App/PartFeature.h>

#include "DrawComplexSection.h"
#include "DrawUtil.h"
#include "GeometryObject.h"
#include "ShapeUtils.h"

using namespace TechDraw;
using namespace std;
using DU = DrawUtil;

//===========================================================================
// DrawComplexSection
//===========================================================================

//NOLINTBEGIN
PROPERTY_SOURCE(TechDraw::DrawComplexSection, TechDraw::DrawViewSection)

const char* DrawComplexSection::ProjectionStrategyEnums[] = {"Offset", "Aligned", "NoParallel",
                                                             nullptr};
//NOLINTEND

DrawComplexSection::DrawComplexSection() :
    m_waitingForAlign(false)
{
    static const char* fgroup = "Cutting Tool";

//NOLINTBEGIN
    ADD_PROPERTY_TYPE(CuttingToolWireObject, (nullptr), fgroup, App::Prop_None,
                      "A sketch that describes the cutting tool");
    CuttingToolWireObject.setScope(App::LinkScope::Global);
    ProjectionStrategy.setEnums(ProjectionStrategyEnums);
    ADD_PROPERTY_TYPE(ProjectionStrategy, ((long)0), fgroup, App::Prop_None,
                      "Make a single cut, or use the profile in pieces");
//NOLINTEND
}

TopoDS_Shape DrawComplexSection::makeCuttingTool(double dMax)
{
    TopoDS_Wire profileWire = makeProfileWire();
    if (profileWire.IsNull()) {
        throw Base::RuntimeError("Can not make wire from cutting tool (1)");
    }

    if (debugSection()) {
        BRepTools::Write(profileWire, "DCSmakeCuttingTool_profileWire.brep");//debug
    }

    // use "canBuild(profile, sectionnormal)" or validateProfileDirection?
    if (ProjectionStrategy.getValue() == 0) {
        // Offset. Warn if profile is not quite aligned with section normal. if
        // the profile and normal are misaligned, the check below for empty "solids"
        // will not be correct.
        constexpr double AngleThresholdDeg{5.0};
        // bool isOK =
        validateOffsetProfile(profileWire, SectionNormal.getValue(), AngleThresholdDeg);
    }

    // TODO: this check should be in TaskComplexSection also.  here it prevents a hard occ crash
    //       if the sketch can't be made into an appropriate face/prism.
    if (CuttingToolWireObject.getValue()->isDerivedFrom(Base::Type::fromName("Sketcher::SketchObject"))) {
        if (!validateSketchNormal(CuttingToolWireObject.getValue())) {
            Base::Console().warning("cutting object not aligned with section normal in %s\n", Label.getValue());
        }
    }

    if (BRep_Tool::IsClosed(profileWire)) {
        return makeCuttingToolFromClosedProfile(profileWire, dMax);
    }

    TopoDS_Shape cuttingTool = cuttingToolFromProfile(profileWire, dMax);
    if (debugSection()) {
        BRepTools::Write(cuttingTool, "DCSmakeCuttingTool_cuttingToo.brep");//debug
    }

    // save the tool face for shading/hatching of cut surface
    auto extrudeDir = Base::convertTo<gp_Dir>(getReferenceAxis());
    gp_Vec extrudeVec = 2 * dMax * extrudeDir;
    m_toolFaceShape = BRepPrimAPI_MakePrism(profileWire, extrudeVec).Shape();
    m_toolFaceShape = ShapeUtils::moveShape(m_toolFaceShape, Base::convertTo<Base::Vector3d>(extrudeDir) * -dMax);
    if (debugSection()) {
        BRepTools::Write(m_toolFaceShape, "DCSmakeCuttingTool_m_toolFaceShape.brep");   //debug
    }

    if (cuttingTool.ShapeType() == TopAbs_COMPSOLID ||
        cuttingTool.ShapeType() == TopAbs_COMPOUND) {
        //Composite Solids do not cut well if they contain "solids" with no volume. This
        //happens if the profile has segments parallel to the extrude direction.
        //We need to disassemble it and only keep the real solids.
        return removeEmptyShapes(cuttingTool);
    }

    return cuttingTool;
}

TopoDS_Shape DrawComplexSection::getShapeToPrepare() const
{
    if (ProjectionStrategy.getValue() == 0) {
        //Offset. Use regular section behaviour
        return DrawViewSection::getShapeToPrepare();
    }
    //Aligned (or NoParallel) strategy
    return m_saveShape;//the original input shape
}

//get the shape ready for projection and cut surface finding
TopoDS_Shape DrawComplexSection::prepareShape(const TopoDS_Shape& cutShape, double shapeSize)
{
    if (ProjectionStrategy.getValue() == 0) {
        //Offset. Use regular section behaviour
        return DrawViewSection::prepareShape(cutShape, shapeSize);
    }

    //"Aligned" projection (Aligned Section)
    if (m_alignResult.IsNull()) {
        return {};
    }

    // our shape is already centered "left/right" and "up/down" so we don't need to
    // center it here
    m_preparedShape = ShapeUtils::scaleShape(m_alignResult, getScale());
    if (!DrawUtil::fpCompare(Rotation.getValue(), 0.0)) {
        m_preparedShape =
            ShapeUtils::rotateShape(m_preparedShape, getProjectionCS(), Rotation.getValue());
    }

    if (debugSection()) {
        BRepTools::Write(m_preparedShape, "DCSprepareShape_preparedShape.brep"); //debug
    }

    return m_preparedShape;
}


void DrawComplexSection::makeSectionCut(const TopoDS_Shape& baseShape)
{
    if (ProjectionStrategy.getValue() == 0) {
        //Offset. Use regular section behaviour
        return DrawViewSection::makeSectionCut(baseShape);
    }

    try {
        connectAlignWatcher =
            QObject::connect(&m_alignWatcher, &QFutureWatcherBase::finished, &m_alignWatcher,
                             [this] { this->onSectionCutFinished(); });

        // We create a lambda closure to hold a copy of baseShape.
        // This is important because this variable might be local to the calling
        // function and might get destructed before the parallel processing finishes.
        auto lambda = [this, baseShape]{this->makeAlignedPieces(baseShape);};
        m_alignFuture = QtConcurrent::run(std::move(lambda));
        m_alignWatcher.setFuture(m_alignFuture);
        waitingForAlign(true);
    }
    catch (...) {
        Base::Console().warning("%s failed to make alignedPieces\n", Label.getValue());
        return;
    }

    return DrawViewSection::makeSectionCut(baseShape);
}


void DrawComplexSection::onSectionCutFinished()
{
    if (m_cutFuture.isRunning() ||  //waitingForCut()
        m_alignFuture.isRunning()) {//waitingForAlign()
        //can not continue yet.  return until the other thread ends
        return;
    }

    DrawViewSection::onSectionCutFinished();

    QObject::disconnect(connectAlignWatcher);
}

//! for Aligned strategy, cut the rawShape by each segment of the tool profile and arrange the
//! cut results in order.
void DrawComplexSection::makeAlignedPieces(const TopoDS_Shape& rawShape)
{
    if (!canBuild(getSectionCS(), CuttingToolWireObject.getValue())) {
        throw Base::RuntimeError("Profile is parallel to Section Normal");
    }

    TopoDS_Wire profileWire = makeProfileWire();
    if (profileWire.IsNull()) {
        throw Base::RuntimeError("ComplexSection failed to make profileWire");
    }
    auto edgesAll = getUniqueEdges(profileWire);
    if (edgesAll.empty()) {
        // this is bad!
        throw Base::RuntimeError("Complex section: profile wire has no edges.");
    }

    // the reversers control left to right vs right to left (or top to bottom vs bottom to top)
    // arrangement of the cut pieces.
    double horizReverser{1.0};
    double verticalReverser{1.0};
    gp_Vec gProfileVec = makeProfileVector(profileWire);
    auto isProfileVertical = getReversers(gProfileVec, horizReverser, verticalReverser);

    // we should wind up with one entry per segment of the profile
    // this should be done with map and a response class
    std::vector<TopoDS_Shape> pieces(edgesAll.size());       // results of cutting source with each segment's tool shape
    std::vector<double> pieceXSizeAll(edgesAll.size());      //size in sectionCS.XDirection (width)
    std::vector<double> pieceYSizeAll(edgesAll.size());      //size in sectionCS.YDirection (height)
    std::vector<double> pieceZSizeAll(edgesAll.size());    //size in sectionCS.Direction (depth)
    std::vector<double> pieceVerticalAll(edgesAll.size());   // displacement of piece in vertical direction

    auto uSectionNormal = SectionNormal.getValue();
    uSectionNormal.Normalize();
    auto uRotateAxis = getReferenceAxis();
    uRotateAxis.Normalize();

    // these normals will be pointing into a tool made from the profile. We want the normal pointing into
    // the remaining material shape, so we will reverse the normal at time of use.
    std::vector<std::pair<int, Base::Vector3d>> faceNormals = getSegmentViewDirections(profileWire, uSectionNormal);

    // faceNormals are not in the same order as the faces(sometimes??).
    TopExp_Explorer expFaces(m_toolFaceShape, TopAbs_FACE);
    for (int iPiece = 0; expFaces.More(); expFaces.Next(), iPiece++) {
        TopoDS_Face face = TopoDS::Face(expFaces.Current());
        if (!isFacePlanar(face)) {
            // TODO: continue blocks curved profile segments (which doesn't work right).
            continue;
        }

        // faceNormals point into toolShape. we want to intersect with remaining material, so reverse
        // the normal.
        std::pair<int, Base::Vector3d> segmentPair = findNormalForFace(face, faceNormals, edgesAll);
        int segmentIndex = segmentPair.first;
        Base::Vector3d segmentNormal = segmentPair.second * -1;
        segmentNormal.Normalize();

        // always true for aligned, but not for no-parallel
        if (!showSegment(segmentNormal)) {
            continue;
        }

        double pieceVertical{0};
        TopoDS_Shape rotatedPiece = cutAndRotatePiece(rawShape, face, segmentIndex, segmentNormal, pieceVertical);
        if (debugSection()) {
            stringstream ss;
            ss << "DCSmakeAlignedPieces_cutAndRotatedPiece" << segmentIndex << ".brep";
            BRepTools::Write(rotatedPiece, ss.str().c_str());//debug
        }

        AlignedSizeResponse sizeResponse = getAlignedSize(rotatedPiece, segmentIndex);
        Base::Vector3d pieceSize = sizeResponse.pieceSize;
        pieceXSizeAll.at(segmentIndex) = pieceSize.x;    // size in ProjectionCS.
        pieceYSizeAll.at(segmentIndex) = pieceSize.y;
        pieceZSizeAll.at(segmentIndex) = pieceSize.z;
        pieceVerticalAll.at(segmentIndex) = pieceVertical;

        if (debugSection()) {
            stringstream ss;
            ss << "DCSAlignedPiece" << segmentIndex << ".brep";
            BRepTools::Write(sizeResponse.alignedPiece, ss.str().c_str());//debug
        }

        auto pieceOnPlane = movePieceToPaperPlane(sizeResponse.alignedPiece, sizeResponse.zMax);
        if (debugSection()) {
            stringstream ss;
            ss << "DCSpieceOnPlane" << segmentIndex << ".brep";
            BRepTools::Write(pieceOnPlane, ss.str().c_str());//debug
        }
        // pieceOnPlane is on the paper plane, with piece centroid at the origin
        pieces.at(segmentIndex) = pieceOnPlane;
    }

    if (pieces.empty()) {
        m_alignResult = TopoDS_Compound();
        Base::Console().message("DCS::makeAlignedPieces - no result\n");
        return;
    }

    //space the pieces "horizontally" or "vertically" in OXYZ
    double movementReverser = isProfileVertical ? verticalReverser : horizReverser;
    auto movementAxis = gp_Vec(gp::OX().Direction());
    auto alignmentAxis = gp_Vec(gp::OY().Direction().Reversed());
    if (isProfileVertical) {
        movementAxis = gp_Vec(gp::OY().Direction());
        alignmentAxis = gp_Vec(gp::OX().Direction());
    }
    gp_Vec gMovementVector = movementAxis * movementReverser;

    size_t stopAt = pieces.size();
    double cursorPosition = 0.0;
    for (size_t iPiece = 0; iPiece < stopAt; iPiece++) {
        double pieceSizeMoveDist = pieceXSizeAll.at(iPiece);
        if (isProfileVertical) {
            pieceSizeMoveDist = pieceYSizeAll.at(iPiece);
        }
        auto movedPiece = distributePiece(pieces.at(iPiece), pieceSizeMoveDist, pieceVerticalAll.at(iPiece),
                                   alignmentAxis, gMovementVector, cursorPosition);
        pieces.at(iPiece) = movedPiece;
        cursorPosition += pieceSizeMoveDist;

        if (debugSection()) {
            stringstream ss;
            ss << "DCSMovedPiece" << iPiece << ".brep";
            BRepTools::Write(pieces.at(iPiece), ss.str().c_str());//debug
        }
    }

    //make a compound of the aligned pieces
    BRep_Builder builder;
    TopoDS_Compound comp;
    builder.MakeCompound(comp);
    for (auto& piece : pieces) {
        builder.Add(comp, piece);
    }

    //center the compound along SectionCS XDirection
    Base::Vector3d centerVector = Base::convertTo<Base::Vector3d>(gMovementVector) * cursorPosition / -2;
    TopoDS_Shape centeredCompound = ShapeUtils::moveShape(comp, centerVector);

    if (debugSection()) {
        BRepTools::Write(centeredCompound, "DCSmap40CenteredCompound.brep");//debug
    }

    // re-align our shape with the projection CS
    gp_Ax3 stdCS;                                 //OXYZ
    gp_Trsf xPieceAlign;
    xPieceAlign.SetTransformation(getProjectionCS(), stdCS);
    BRepBuilderAPI_Transform mkTransAlign(centeredCompound, xPieceAlign);
    TopoDS_Shape alignedCompound = mkTransAlign.Shape();

    if (debugSection()) {
        BRepTools::Write(alignedCompound, "DCSmap50AlignedCompound.brep");//debug
    }

    m_alignResult = alignedCompound;
}

//! tries to find the intersection faces of the cut shape and the cutting tool.
//! Aligned complex sections need to intersect the final cut shape (which in this
//! case is a compound of individual cuts) with the "effective" (flattened) section plane.
//! Profiles containing curves need special handling (not implemented).
TopoDS_Compound
DrawComplexSection::findSectionPlaneIntersections(const TopoDS_Shape& shapeToIntersect)
{
    if (shapeToIntersect.IsNull()) {
        // this shouldn't happen
        Base::Console().warning("DCS::findSectionPlaneInter - %s - cut shape is Null\n",
                                getNameInDocument());
        return {};
    }
    if (ProjectionStrategy.getValue() == 0) {//Offset
        return singleToolIntersections(shapeToIntersect);
    }

    return alignedToolIntersections(shapeToIntersect);
}

//Intersect cutShape with each segment of the cutting tool
TopoDS_Compound DrawComplexSection::singleToolIntersections(const TopoDS_Shape& cutShape)
{
    App::DocumentObject* toolObj = CuttingToolWireObject.getValue();
    if (!isLinearProfile(toolObj)) {
        //TODO: special handling required here
        //        Base::Console().message("DCS::singleToolIntersection - profile has curves\n");
    }

    BRep_Builder builder;
    TopoDS_Compound result;
    builder.MakeCompound(result);

    if (m_toolFaceShape.IsNull()) {
        return result;
    }

    TopExp_Explorer expFaces(cutShape, TopAbs_FACE);
    for (; expFaces.More(); expFaces.Next()) {
        TopoDS_Face face = TopoDS::Face(expFaces.Current());
        if (!boxesIntersect(face, m_toolFaceShape)) {
            continue;
        }
        std::vector<TopoDS_Face> commonFaces = faceShapeIntersect(face, m_toolFaceShape);
        for (auto& cFace : commonFaces) {
            builder.Add(result, cFace);
        }
    }
    return result;
}

//Intersect cutShape with the effective (flattened paper plane) cutting plane to generate cut surface faces
TopoDS_Compound DrawComplexSection::alignedToolIntersections(const TopoDS_Shape& cutShape)
{
    BRep_Builder builder;
    TopoDS_Compound result;
    builder.MakeCompound(result);

    App::DocumentObject* toolObj = CuttingToolWireObject.getValue();
    if (!isLinearProfile(toolObj)) {
        //TODO: special handling here?
        //        Base::Console().message("DCS::alignedToolIntersection - profile has curves\n");
    }

    gp_Pln effectivePlane = getSectionPlane();
    //aligned result can be much wider than the shape itself, so we use an
    //infinite face.
    BRepBuilderAPI_MakeFace mkFace(effectivePlane, -Precision::Infinite(), Precision::Infinite(),
                                   -Precision::Infinite(), Precision::Infinite());
    TopoDS_Face cuttingFace = mkFace.Face();

    TopExp_Explorer expFaces(cutShape, TopAbs_FACE);
    for (; expFaces.More(); expFaces.Next()) {
        TopoDS_Face face = TopoDS::Face(expFaces.Current());
        if (!boxesIntersect(face, cuttingFace)) {
            continue;
        }
        std::vector<TopoDS_Face> commonFaces = faceShapeIntersect(face, cuttingFace);
        for (auto& cFace : commonFaces) {
            builder.Add(result, cFace);
        }
    }
    if (debugSection()) {
        BRepTools::Write(result, "DCSmakeAlignedPieces_AlignedIntersectionResult.brep");//debug
    }
    return result;
}

TopoDS_Compound DrawComplexSection::alignSectionFaces(const TopoDS_Shape& faceIntersections)
{
    if (ProjectionStrategy.getValue() == 0) {
        //Offset. Use regular section behaviour
        return DrawViewSection::alignSectionFaces(faceIntersections);
    }

    return TopoDS::Compound(mapToPage(faceIntersections));
}

TopoDS_Shape DrawComplexSection::getShapeToIntersect()
{
    if (ProjectionStrategy.getValue() == 0) {//Offset
        return DrawViewSection::getShapeToIntersect();
    }
    //Aligned
    return m_preparedShape;
}

TopoDS_Shape DrawComplexSection::getShapeForDetail() const
{
    if (ProjectionStrategy.getValue() == 0) {//Offset
        return DrawViewSection::getShapeForDetail();
    }
    //Aligned
    return m_preparedShape;
}

TopoDS_Wire DrawComplexSection::makeProfileWire() const
{
    App::DocumentObject* toolObj = CuttingToolWireObject.getValue();
    return makeProfileWire(toolObj);
}

TopoDS_Wire DrawComplexSection::makeProfileWire(App::DocumentObject* toolObj)
{
    if (!isProfileObject(toolObj)) {
        return {};
    }

    TopoDS_Shape toolShape = Part::Feature::getShape(toolObj, Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform);
    if (toolShape.IsNull()) {
        return {};
    }

    TopoDS_Wire profileWire;
    if (toolShape.ShapeType() == TopAbs_WIRE) {
        profileWire = makeNoseToTailWire(toolShape);
    }
    else {
        //we have already checked that the shape is a wire or an edge in isProfileObject
        TopoDS_Edge edge = TopoDS::Edge(toolShape);
        profileWire = BRepBuilderAPI_MakeWire(edge).Wire();
    }
    return profileWire;
}

gp_Vec DrawComplexSection::makeProfileVector(const TopoDS_Wire& profileWire)
{
    auto ends = getWireEnds(profileWire);
    auto vec = ends.second - ends.first;
    vec.Normalize();
    return Base::convertTo<gp_Vec>(vec);
}


//make drawable td geometry for section line
BaseGeomPtrVector DrawComplexSection::makeSectionLineGeometry()
{
    BaseGeomPtrVector result;
    auto* baseDvp = freecad_cast<DrawViewPart*>(BaseView.getValue());
    if (baseDvp) {
        TopoDS_Wire lineWire = makeSectionLineWire();
        // projectedWire will be Y inverted
        TopoDS_Shape projectedWire =
            GeometryObject::projectSimpleShape(lineWire, baseDvp->getProjectionCS());
        TopExp_Explorer expEdges(projectedWire, TopAbs_EDGE);
        for (; expEdges.More(); expEdges.Next()) {
            BaseGeomPtr edge = BaseGeom::baseFactory(TopoDS::Edge(expEdges.Current()));
            result.push_back(edge);
        }
    }
    return result;
}

//get the end points of the section wire
std::pair<Base::Vector3d, Base::Vector3d> DrawComplexSection::sectionLineEnds()
{
    std::pair<Base::Vector3d, Base::Vector3d> result;
    TopoDS_Wire lineWire = makeSectionLineWire();
    if (lineWire.IsNull()) {
        return result;
    }

    auto ends = getWireEnds(lineWire);
    Base::Vector3d first = ends.first;
    Base::Vector3d last = ends.second;

    auto* baseDvp = freecad_cast<DrawViewPart*>(BaseView.getValue());
    if (baseDvp) {
        first = baseDvp->projectPoint(first);
        last = baseDvp->projectPoint(last);
    }
    result.first = first;
    result.second = last;
    return result;
}

//! get the directions (in 3d) of the section line arrows.
//! the arrows on the section line are line of sight - from eye to preserved material.  In a simple section,
//! this is opposite to the section normal.  In the complex section, we need the perpendicular direction most
//! opposite to the SectionNormal. The arrows should be perpendicular to their profile segment.
std::pair<Base::Vector3d, Base::Vector3d> DrawComplexSection::sectionLineArrowDirs()
{
    App::DocumentObject* toolObj = CuttingToolWireObject.getValue();
    TopoDS_Wire profileWire = makeProfileWire(toolObj);
    if (profileWire.IsNull()) {
        throw Base::RuntimeError("Complex section profile wire is null");
    }

    std::vector<std::pair<int, Base::Vector3d>> segmentNormals =
                                getSegmentViewDirections(profileWire, SectionNormal.getValue());
    if (segmentNormals.empty()) {
        throw Base::RuntimeError("A complex section failed to create profile segment view directions");
    }

    Base::Vector3d firstArrowDir = segmentNormals.front().second * -1;
    Base::Vector3d lastArrowDir = segmentNormals.back().second * -1;

    return { firstArrowDir, lastArrowDir };
}


//! makes a representation of the 3d arrow directions on the base view's coord system
std::pair<Base::Vector3d, Base::Vector3d>
            DrawComplexSection::sectionLineArrowDirsMapped()
{
    std::pair<Base::Vector3d, Base::Vector3d> arrowDirsRaw = sectionLineArrowDirs();
    TopoDS_Edge firstMapped = mapEdgeToBase(arrowDirsRaw.first);
    TopoDS_Edge lastMapped = mapEdgeToBase(arrowDirsRaw.second);
    std::pair<Base::Vector3d, Base::Vector3d> arrowEnds = getSegmentEnds(firstMapped);
    Base::Vector3d firstDir = arrowEnds.second - arrowEnds.first;
    arrowEnds = getSegmentEnds(lastMapped);
    Base::Vector3d lastDir = arrowEnds.second - arrowEnds.first;

    return { firstDir, lastDir };
}


//! find an axis for measuring rotation vs the line of sight
Base::Vector3d DrawComplexSection::getReferenceAxis() const
{
    Base::Vector3d rawDirection = getBaseDVP()->Direction.getValue();
    rawDirection.Normalize();

    return DU::closestBasisOriented(rawDirection);
}


//make a wire suitable for projection on a base view
TopoDS_Wire DrawComplexSection::makeSectionLineWire()
{
    TopoDS_Wire lineWire;
    App::DocumentObject* toolObj = CuttingToolWireObject.getValue();
    auto* baseDvp = freecad_cast<DrawViewPart*>(BaseView.getValue());
    if (baseDvp) {
        TopoDS_Shape toolShape = Part::Feature::getShape(toolObj, Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform);
        if (toolShape.IsNull()) {
            // CuttingToolWireObject is likely still restoring and has no shape yet
            return {};
        }
        Base::Vector3d centroid = baseDvp->getCurrentCentroid();
        TopoDS_Shape sTrans =
            ShapeUtils::ShapeUtils::moveShape(toolShape, centroid * -1.0);
        TopoDS_Shape sScaled = ShapeUtils::scaleShape(sTrans, baseDvp->getScale());
        //we don't mirror the scaled shape here as it will be mirrored by the projection

        if (sScaled.ShapeType() == TopAbs_WIRE) {
            lineWire = makeNoseToTailWire(sScaled);
        }
        else if (sScaled.ShapeType() == TopAbs_EDGE) {
            TopoDS_Edge edge = TopoDS::Edge(sScaled);
            lineWire = BRepBuilderAPI_MakeWire(edge).Wire();
        }
        else {
            //probably can't happen as cut profile has been checked before this
            Base::Console().warning("DCS::makeSectionLineGeometry - profile is type: %d\n",
                                    static_cast<int>(sScaled.ShapeType()));
            return {};
        }
    }
    return lineWire;
}


//find the points where the section line changes direction, and the direction
//of the profile before and after the point
ChangePointVector DrawComplexSection::getChangePointsFromSectionLine()
{
    ChangePointVector result;
    std::vector<gp_Pnt> allPoints;
    auto* baseDvp = freecad_cast<DrawViewPart*>(BaseView.getValue());
    if (baseDvp) {
        TopoDS_Wire lineWire = makeSectionLineWire();
        // projectedWire will be Y inverted
        TopoDS_Shape projectedWire =
            GeometryObject::projectSimpleShape(lineWire, baseDvp->getProjectionCS());
        if (projectedWire.IsNull()) {
            return result;
        }
        //get UNIQUE points along the projected profile
        TopExp_Explorer expVertex(projectedWire, TopAbs_VERTEX);
        gp_Pnt previousPoint(Precision::Infinite(), Precision::Infinite(), Precision::Infinite());
        for (; expVertex.More(); expVertex.Next()) {
            TopoDS_Vertex vert = TopoDS::Vertex(expVertex.Current());
            gp_Pnt gPoint = BRep_Tool::Pnt(vert);
            if (gPoint.IsEqual(previousPoint, 2 * EWTOLERANCE)) {
                continue;
            }
            allPoints.push_back(gPoint);
            previousPoint = gPoint;
        }

        //make the intermediate marks
        for (size_t iPoint = 1; iPoint < allPoints.size() - 1; iPoint++) {
            gp_Pnt location = allPoints.at(iPoint);
            gp_Dir preDir = gp_Dir(allPoints.at(iPoint - 1).XYZ() - allPoints.at(iPoint).XYZ());
            gp_Dir postDir = gp_Dir(allPoints.at(iPoint + 1).XYZ() - allPoints.at(iPoint).XYZ());
            ChangePoint point(location, preDir, postDir);
            result.push_back(point);
        }

        //make start and end marks
        gp_Pnt location0 = allPoints.at(0);
        gp_Pnt location1 = allPoints.at(1);
        gp_Dir postDir = gp_Dir(location1.XYZ() - location0.XYZ());
        gp_Dir preDir = postDir.Reversed();
        ChangePoint startPoint(location0, preDir, postDir);
        result.push_back(startPoint);
        location0 = allPoints.at(allPoints.size() - 1);
        location1 = allPoints.at(allPoints.size() - 2);
        preDir = gp_Dir(location0.XYZ() - location1.XYZ());
        postDir = preDir.Reversed();
        ChangePoint endPoint(location0, preDir, postDir);
        result.push_back(endPoint);
    }
    return result;
}

gp_Ax2 DrawComplexSection::getCSFromBase(const std::string& sectionName) const
{
    App::DocumentObject* base = BaseView.getValue();
    if (!base
        || !base->isDerivedFrom<TechDraw::DrawViewPart>()) {//is second clause necessary?
        //if this DCS does not have a baseView, we must use the existing SectionCS
        return getSectionCS();
    }
    return DrawViewSection::getCSFromBase(sectionName);
}

// check for profile segments that are almost, but not quite in the same direction
// as the section normal direction.  this often indicates a problem with the direction
// being slightly wrong.  see https://forum.freecad.org/viewtopic.php?t=79017&sid=612a62a60f5db955ee071a7aaa362dbb
bool DrawComplexSection::validateOffsetProfile(const TopoDS_Wire& profile, Base::Vector3d direction, double angleThresholdDeg) const
{
    constexpr double HalfCircleDegrees{180.0};
    double angleThresholdRad = angleThresholdDeg * std::numbers::pi / HalfCircleDegrees;
    TopExp_Explorer explEdges(profile, TopAbs_EDGE);
    for (; explEdges.More(); explEdges.Next()) {
        std::pair<Base::Vector3d, Base::Vector3d> segmentEnds = getSegmentEnds(TopoDS::Edge(explEdges.Current()));
        Base::Vector3d segmentDir = segmentEnds.second - segmentEnds.first;
        double angleRad = segmentDir.GetAngle(direction);
        if (angleRad < angleThresholdRad &&
            angleRad > 0.0) {
            // profile segment is slightly skewed. possible bad SectionNormal?
            Base::Console().warning("%s profile is slightly skewed. Check SectionNormal low decimal places\n",
                                    getNameInDocument());
            return false;
        }
    }
    return true;
}


// next two methods could be templated (??) to handle edge/wire
std::pair<Base::Vector3d, Base::Vector3d>
                            DrawComplexSection::getSegmentEnds(const TopoDS_Edge& segment)
{
    TopoDS_Vertex tvFirst;
    TopoDS_Vertex tvLast;
    TopExp::Vertices(segment, tvFirst, tvLast);
    gp_Pnt gpFirst = BRep_Tool::Pnt(tvFirst);
    gp_Pnt gpLast = BRep_Tool::Pnt(tvLast);
    std::pair<Base::Vector3d, Base::Vector3d> result;
    result.first = Base::convertTo<Base::Vector3d>(gpFirst);
    result.second = Base::convertTo<Base::Vector3d>(gpLast);
    return result;
}

std::pair<Base::Vector3d, Base::Vector3d>
                            DrawComplexSection::getWireEnds(const TopoDS_Wire& wire)
{
    TopoDS_Vertex tvFirst;
    TopoDS_Vertex tvLast;
    TopExp::Vertices(wire, tvFirst, tvLast);
    gp_Pnt gpFirst = BRep_Tool::Pnt(tvFirst);
    gp_Pnt gpLast = BRep_Tool::Pnt(tvLast);
    std::pair<Base::Vector3d, Base::Vector3d> result;
    result.first = Base::convertTo<Base::Vector3d>(gpFirst);
    result.second = Base::convertTo<Base::Vector3d>(gpLast);
    return result;
}


//get the "effective" (flattened paper plane) section plane for Aligned and
//the regular sectionPlane for Offset.
gp_Pln DrawComplexSection::getSectionPlane() const
{
    if (ProjectionStrategy.getValue() == 0) {
        //Offset. Use regular section behaviour
        return DrawViewSection::getSectionPlane();
    }

    //"Aligned" projection (Aligned Section)
    //this is the same as DVS::getSectionPlane except that the plane origin is not the SectionOrigin
    Base::Vector3d vSectionNormal = SectionNormal.getValue();
    gp_Dir gSectionNormal(vSectionNormal.x, vSectionNormal.y, vSectionNormal.z);
    gp_Pnt gOrigin(0.0, 0.0, 0.0);
    gp_Ax3 gPlaneCS(gOrigin, gSectionNormal);

    return {gPlaneCS};
}

bool DrawComplexSection::isBaseValid() const
{
    App::DocumentObject* base = BaseView.getValue();
    if (!base) {
        //complex section is not based on an existing DVP
        return true;
    }
    if (!base->isDerivedFrom<TechDraw::DrawViewPart>()) {
        //this is probably an error somewhere. the valid options are base = a DVP,
        //or no base
        return false;
    }
    //have a base and it is a DVP
    return true;
}


//if the profile is not nicely positioned within the vertical span of the shape, we might not overlap
//the shape after extrusion.  As long as the profile is within the extent of the shape in the
//extrude direction we should be ok.
bool DrawComplexSection::validateProfilePosition(const TopoDS_Wire& profileWire, const gp_Ax2& sectionCS) const
{
    auto wireEnds = getWireEnds(profileWire);
    auto gpFirst = Base::convertTo<gp_Pnt>(wireEnds.first);
    gp_Vec gProfileVector = makeProfileVector(profileWire);

    //since bounding boxes are aligned with the cardinal directions, we need to find
    //the appropriate direction to use when validating the profile position
    gp_Vec gSectionVector = getSectionCS().Direction().Reversed();
    gp_Vec gExtrudeVector = gSectionVector.Crossed(gProfileVector);
    Base::Vector3d vClosestBasis = DrawUtil::closestBasis(gp_Dir(gExtrudeVector), sectionCS);
    auto gClosestBasis = gp_Dir(vClosestBasis.x, vClosestBasis.y, vClosestBasis.z);

    Bnd_Box shapeBox;
    shapeBox.SetGap(0.0);
    BRepBndLib::AddOptimal(m_saveShape, shapeBox);
    double xMin = 0, xMax = 0, yMin = 0, yMax = 0, zMin = 0, zMax = 0;   //NOLINT
    shapeBox.Get(xMin, yMin, zMin, xMax, yMax, zMax);
    double spanLow = xMin;
    double spanHigh = xMax;
    double spanCheck = gpFirst.X();
    if (gClosestBasis.IsParallel(sectionCS.YDirection(), Precision::Angular())) {
        spanLow = yMin;
        spanHigh = yMax;
        spanCheck = gpFirst.Y();
    }
    else if (gClosestBasis.IsParallel(sectionCS.Direction(), Precision::Angular())) {
        spanLow = zMin;
        spanHigh = zMax;
        spanCheck = gpFirst.Z();
    }

    if (spanLow > spanCheck || spanHigh < spanCheck) {
        //profile is not within span of shape
        return false;
    }
    //profile is within span of shape
    return true;
}

bool DrawComplexSection::showSegment(gp_Dir segmentNormal) const
{
    if (ProjectionStrategy.getValue() < 2) {
        //Offset or Aligned are always true
        return true;
    }

    Base::Vector3d vSectionNormal = SectionNormal.getValue();
    gp_Dir gSectionNormal(vSectionNormal.x, vSectionNormal.y, vSectionNormal.z);
    //segment normal is perpendicular to section normal, so segment is parallel to section normal,
    //and for ProjectionStrategy "NoParallel", we don't display these segments.
    return !DU::fpCompare(fabs(gSectionNormal.Dot(segmentNormal)), 0.0);
}

bool DrawComplexSection::showSegment(const Base::Vector3d& segmentNormal) const
{
    return showSegment(Base::convertTo<gp_Dir>(segmentNormal));
}

//Can we make a ComplexSection using this profile and sectionNormal?
bool DrawComplexSection::canBuild(gp_Ax2 sectionCS, App::DocumentObject* profileObject)
{
    if (!isProfileObject(profileObject)) {
        return false;
    }

    TopoDS_Shape shape = Part::Feature::getShape(profileObject, Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform);
    if (BRep_Tool::IsClosed(shape)) {
        //closed profiles don't have a profile vector but should always make a section?
        return true;
    }

    // profile should be ortho to section normal, but this is a weak test
    gp_Vec gProfileVec = makeProfileVector(makeProfileWire(profileObject));
    double dot = fabs(gProfileVec.Dot(sectionCS.Direction()));
    return !DU::fpCompare(dot, 1.0, EWTOLERANCE);
}

// general purpose geometry methods

// returns the normal of the face.
gp_Dir DrawComplexSection::getFaceNormal(TopoDS_Face& face)
{
    BRepAdaptor_Surface adapt(face);
    double uParmFirst = adapt.FirstUParameter();
    double uParmLast = adapt.LastUParameter();
    double vParmFirst = adapt.FirstVParameter();
    double vParmLast = adapt.LastVParameter();
    double uMid = (uParmFirst + uParmLast) / 2;
    double vMid = (vParmFirst + vParmLast) / 2;

    constexpr double PropTolerance{0.01};
    BRepLProp_SLProps prop(adapt, uMid, vMid, 1, PropTolerance);
    gp_Dir normalDir(0.0, 0.0, 1.0);//default
    if (prop.IsNormalDefined()) {
        normalDir = prop.Normal();
    }
    return normalDir;
}

bool DrawComplexSection::boxesIntersect(TopoDS_Face& face, TopoDS_Shape& shape)
{
    constexpr double OverlapTolerance{0.1};
    Bnd_Box box0;
    Bnd_Box box1;
    BRepBndLib::Add(face, box0);
    box0.SetGap(OverlapTolerance);//generous
    BRepBndLib::Add(shape, box1);
    box1.SetGap(OverlapTolerance);
    return !box0.IsOut(box1);
}

TopoDS_Shape DrawComplexSection::shapeShapeIntersect(const TopoDS_Shape& shape0,
                                                     const TopoDS_Shape& shape1)
{
    FCBRepAlgoAPI_Common anOp;
    anOp.SetFuzzyValue(EWTOLERANCE);
    TopTools_ListOfShape anArg1;
    TopTools_ListOfShape anArg2;
    anArg1.Append(shape0);
    anArg2.Append(shape1);
    anOp.SetArguments(anArg1);
    anOp.SetTools(anArg2);
    anOp.Build();
    TopoDS_Shape result = anOp.Shape();//always a compound
    if (isTrulyEmpty(result)) {
        return {};
    }
    return result;
}

//find all the intersecting regions of face and shape
std::vector<TopoDS_Face> DrawComplexSection::faceShapeIntersect(const TopoDS_Face& face,
                                                                const TopoDS_Shape& shape)
{
    TopoDS_Shape intersect = shapeShapeIntersect(face, shape);
    if (intersect.IsNull()) {
        return {};
    }
    std::vector<TopoDS_Face> intersectFaceList;
    TopExp_Explorer expFaces(intersect, TopAbs_FACE);
    for (int i = 1; expFaces.More(); expFaces.Next(), i++) {
        intersectFaceList.push_back(TopoDS::Face(expFaces.Current()));
    }
    return intersectFaceList;
}

//! ensure that the edges in the output wire are in nose to tail order
//! this doesn't need to be a wire, it could be just a shape?
TopoDS_Wire DrawComplexSection::makeNoseToTailWire(const TopoDS_Shape& inShape)
{
    if (inShape.IsNull()) {
        return {};
    }

    std::list<TopoDS_Edge> inList;
    TopExp_Explorer expEdges(inShape, TopAbs_EDGE);
    for (; expEdges.More(); expEdges.Next()) {
        TopoDS_Edge edge = TopoDS::Edge(expEdges.Current());
        inList.push_back(edge);
    }

    std::list<TopoDS_Edge> sortedList;
    if (inList.empty() || inList.size() == 1) {
        return {};
    }

    sortedList = DrawUtil::sort_Edges(EWTOLERANCE, inList);
    BRepBuilderAPI_MakeWire mkWire;
    for (auto& edge : sortedList) {
        mkWire.Add(edge);
    }
    return mkWire.Wire();
}

//static
bool DrawComplexSection::isProfileObject(App::DocumentObject* obj)
{
    //if the object's shape is a wire or an edge, then it can be a profile object
    TopoDS_Shape shape = Part::Feature::getShape(obj, Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform);
    if (shape.IsNull()) {
        return false;
    }
    if (shape.ShapeType() == TopAbs_WIRE || shape.ShapeType() == TopAbs_EDGE) {
        return true;
    }
    //don't know what this is, but it isn't suitable as a profile
    return false;
}

bool DrawComplexSection::isMultiSegmentProfile(App::DocumentObject* obj)
{
    //if the object's shape is a wire or an edge, then it can be a profile object
    TopoDS_Shape shape = Part::Feature::getShape(obj, Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform);
    if (shape.IsNull()) {
        return false;
    }
    if (shape.ShapeType() == TopAbs_EDGE) {
        //only have 1 edge, can't be multisegment;
        return false;
    }
    if (shape.ShapeType() == TopAbs_WIRE) {
        std::vector<TopoDS_Edge> edgesInWire;
        TopExp_Explorer expEdges(shape, TopAbs_EDGE);
        for (; expEdges.More(); expEdges.Next()) {
            TopoDS_Edge edge = TopoDS::Edge(expEdges.Current());
            BRepAdaptor_Curve adapt(edge);
            if (adapt.GetType() == GeomAbs_Line) {
                edgesInWire.push_back(edge);
            }
        }
        if (edgesInWire.size() > 1) {
            return true;
        }
    }
    return false;
}

//check if the profile has curves in it
bool DrawComplexSection::isLinearProfile(App::DocumentObject* obj)
{
    TopoDS_Shape shape = Part::Feature::getShape(obj, Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform);
    if (shape.IsNull()) {
        return false;
    }
    if (shape.ShapeType() == TopAbs_EDGE) {
        //only have 1 edge
        TopoDS_Edge edge = TopoDS::Edge(shape);
        BRepAdaptor_Curve adapt(edge);
        return (adapt.GetType() == GeomAbs_Line);
    }

    if (shape.ShapeType() == TopAbs_WIRE) {
        std::vector<TopoDS_Edge> edgesInWire;
        TopExp_Explorer expEdges(shape, TopAbs_EDGE);
        for (; expEdges.More(); expEdges.Next()) {
            TopoDS_Edge edge = TopoDS::Edge(expEdges.Current());
            BRepAdaptor_Curve adapt(edge);
            if (adapt.GetType() != GeomAbs_Line) {
                return false;
            }
        }
        //all the edges in the wire are lines
        return true;
    }

    //this shouldn't happen
    return false;
}

//a compound with no content is not considered IsNull by OCC.  A more thorough check
//is required.
//https://dev.opencascade.org/content/compound-empty
bool DrawComplexSection::isTrulyEmpty(const TopoDS_Shape& inShape)
{
    bool hasContent = !inShape.IsNull() && TopoDS_Iterator(inShape).More();
    return !hasContent;
}


TopoDS_Shape DrawComplexSection::removeEmptyShapes(const TopoDS_Shape& roughTool)
{
    BRep_Builder builder;
    TopoDS_Compound comp;
    builder.MakeCompound(comp);
    TopExp_Explorer expSolids(roughTool, TopAbs_SOLID);
    for (; expSolids.More(); expSolids.Next()) {
        TopoDS_Solid solid = TopoDS::Solid(expSolids.Current());
        GProp_GProps gprops;
        BRepGProp::VolumeProperties(solid, gprops);
        double volume = gprops.Mass();
        if (volume > EWTOLERANCE) {
            builder.Add(comp, solid);
        }
    }
    return comp;
}

//! reversers determine if the cut pieces are arranged left to right or right to left (down to up/up to down)
//! returns true if the profile vector is vertical.
bool DrawComplexSection::getReversers(const gp_Vec& gProfileVec, double& horizReverser, double& verticalReverser)
{
    bool isProfileVertical = true;
    auto sectionCS = getSectionCS();
    auto sectionCSX = sectionCS.XDirection();
    auto sectionCSY = sectionCS.YDirection();
    auto verticalDot = gProfileVec.Dot(sectionCSY);
    if (DU::fpCompare(fabs(verticalDot), 0, EWTOLERANCE)) {
        //profile is +/- normal to Y.
        isProfileVertical = false;
    }

    horizReverser = 1.0;     //profile vector points to right, so we move to right
    if (gProfileVec.Dot(sectionCSX) < 0.0) {
        //profileVec does not point towards stdX (right in paper space)
        horizReverser = -1.0;
    }

    verticalReverser = 1.0;//profile vector points to top, so we will move pieces upwards
    if (gProfileVec.Dot(sectionCSY) < 0.0) {
        //profileVec does not point towards stdY (up in paper space)
        verticalReverser = -1.0;
    }

    return isProfileVertical;
}


//! align a copy of the piece with OXYZ so we can use bounding box to get
//! width, depth, height of the piece. We copy the piece so the transformation
//! does not affect the original.
AlignedSizeResponse DrawComplexSection::getAlignedSize(const TopoDS_Shape& pieceRotated,
                                                  int iPiece) const
{
    gp_Ax3 stdCS;                                 //OXYZ
    BRepBuilderAPI_Copy BuilderPieceCopy(pieceRotated);
    TopoDS_Shape copyPieceRotatedShape = BuilderPieceCopy.Shape();
    gp_Trsf xPieceAlign;
    xPieceAlign.SetTransformation(stdCS, getProjectionCS());
    BRepBuilderAPI_Transform mkTransAlign(copyPieceRotatedShape, xPieceAlign);
    TopoDS_Shape pieceAligned = mkTransAlign.Shape();
    // we may have shifted our piece off center, so we better recenter here
    gp_Trsf xPieceRecenter;
    gp_Vec rotatedCentroid = gp_Vec(ShapeUtils::findCentroid(pieceAligned).XYZ());
    xPieceRecenter.SetTranslation(rotatedCentroid * -1.0);
    BRepBuilderAPI_Transform mkTransRecenter(pieceAligned, xPieceRecenter, true);
    pieceAligned = mkTransRecenter.Shape();

    if (debugSection()) {
        stringstream ss;
        ss << "DCSDpieceAligned" << iPiece << ".brep";
        BRepTools::Write(pieceAligned, ss.str().c_str());//debug
        ss.clear();
        ss.str(std::string());
    }
    Bnd_Box shapeBox;
    shapeBox.SetGap(0.0);
    BRepBndLib::AddOptimal(pieceAligned, shapeBox);
    double xMin = 0, xMax = 0, yMin = 0, yMax = 0, zMin = 0, zMax = 0;  //NOLINT
    shapeBox.Get(xMin, yMin, zMin, xMax, yMax, zMax);
    double pieceXSize(xMax - xMin);
    double pieceYSize(yMax - yMin);
    double pieceZSize(zMax - zMin);
    Base::Vector3d pieceSize{pieceXSize, pieceYSize, pieceZSize};
    return {pieceAligned, pieceSize, zMax};
}

//! cut the rawShape with a tool derived from the segmentFace and align the result with the
//! page plane.  Also supplies the piece size.
TopoDS_Shape DrawComplexSection::cutAndRotatePiece(const TopoDS_Shape& rawShape,
                                                      const TopoDS_Face& segmentFace,
                                                      int iPiece,               // for debug only
                                                      Base::Vector3d uOrientedSegmentNormal,
                                                      double& pieceVertical)
{
    auto segmentNormal = Base::convertTo<gp_Vec>(uOrientedSegmentNormal);
    auto rotateAxis = Base::convertTo<gp_Vec>(getReferenceAxis());
    gp_Vec extrudeVec = segmentNormal * m_shapeSize;

    BRepPrimAPI_MakePrism mkPrism(segmentFace, extrudeVec);
    TopoDS_Shape segmentTool = mkPrism.Shape();
    TopoDS_Shape intersect = shapeShapeIntersect(segmentTool, rawShape);
    if (intersect.IsNull()) {
        return {};
    }
    if (debugSection()) {
        stringstream ss;
        ss << "DCSAintersect" << iPiece << ".brep";
        BRepTools::Write(intersect, ss.str().c_str());//debug
        ss.clear();
        ss.str(std::string());
    }

    // move intersection shape to the origin so we can rotate it without worrying about
    // center of rotation.
    gp_Trsf xPieceCenter;
    gp_Vec pieceCentroid = gp_Vec(ShapeUtils::findCentroid(intersect).XYZ());

    // save the amount we moved this piece in the vertical direction so we can
    // put it back in the right place later
    gp_Vec maskedVertical = DU::maskDirection(pieceCentroid, rotateAxis);
    maskedVertical = pieceCentroid - maskedVertical;
    pieceVertical = maskedVertical.X() + maskedVertical.Y() + maskedVertical.Z();

    xPieceCenter.SetTranslation(pieceCentroid * -1.0);
    BRepBuilderAPI_Transform mkTransXLate(intersect, xPieceCenter, true);
    TopoDS_Shape pieceCentered = mkTransXLate.Shape();
    if (debugSection()) {
        stringstream ss;
        ss << "DCSBpieceCentered" << iPiece << ".brep";
        BRepTools::Write(pieceCentered, ss.str().c_str());//debug
        ss.clear();
        ss.str(std::string());
    }

    //rotate the intersection so interesting face is aligned with what will
    // become the paper plane.
    double faceAngle =
        gp_Vec(getSectionCS().Direction().Reversed()).AngleWithRef(segmentNormal, rotateAxis);
    gp_Ax1 faceAxis(gp_Pnt(0.0, 0.0, 0.0), rotateAxis);
    gp_Ax3 stdCS;
    gp_Ax3 pieceCS;
    pieceCS.Rotate(faceAxis, faceAngle);
    gp_Trsf xPieceRotate;
    xPieceRotate.SetTransformation(stdCS, pieceCS);
    BRepBuilderAPI_Transform mkTransRotate(pieceCentered, xPieceRotate, true);
    TopoDS_Shape pieceRotated = mkTransRotate.Shape();

    return pieceRotated;
}

TopoDS_Shape DrawComplexSection::movePieceToPaperPlane(const TopoDS_Shape& piece, double sizeMax)
{
    //now we need to move the piece so that the interesting face is coincident
    //with the paper plane (stdXY).  This will be a move along stdZ by -zMax.
    gp_Vec toPaperPlane = gp::OZ().Direction().XYZ() * sizeMax * -1.0;
    gp_Trsf xPieceToPlane;
    xPieceToPlane.SetTranslation(toPaperPlane);
    BRepBuilderAPI_Transform mkTransDisplace(piece, xPieceToPlane, true);
    TopoDS_Shape pieceToPlane = mkTransDisplace.Shape();

    // piece is on the paper plane, with piece centroid at the origin
    return pieceToPlane;
}

//! move the piece to its position across the page (X for a left right profile)
TopoDS_Shape DrawComplexSection::distributePiece(const TopoDS_Shape& piece,
                                                 double pieceSizeInDirection,
                                                 double verticalDisplace,
                                                 const gp_Vec& alignmentAxis,
                                                 const gp_Vec& gMovementVector,
                                                 double cursorPosition)
{
    double pieceTotalDistanceToMove = cursorPosition + pieceSizeInDirection / 2;
    gp_Vec alignmentVector = alignmentAxis * verticalDisplace * -1;
    gp_Vec netDisplacementVector = gMovementVector * pieceTotalDistanceToMove + alignmentVector;

    gp_Trsf xPieceDistribute;
    xPieceDistribute.SetTranslation(netDisplacementVector);
    BRepBuilderAPI_Transform mkTransDistribute(piece, xPieceDistribute, true);
    auto distributedPiece = mkTransDistribute.Shape();

    return distributedPiece;
}


// are these in the correct order? no guarantee.  profile wires should be in nose to tail order
std::vector<TopoDS_Edge> DrawComplexSection::getUniqueEdges(const TopoDS_Wire& wireIn)
{
    std::vector<TopoDS_Edge> ret;
    TopTools_IndexedMapOfShape shapeMap;
    TopExp_Explorer Ex(wireIn, TopAbs_EDGE);
    while (Ex.More()) {
        shapeMap.Add(Ex.Current());
        Ex.Next();
    }

    for (Standard_Integer k = 1; k <= shapeMap.Extent(); k++) {
        const TopoDS_Shape& shape = shapeMap(k);
        auto edge = TopoDS::Edge(shape);
        ret.push_back(edge);
    }

    return ret;
}

//! Find the correct view directions for the profile segments by making a face from the profile and
//! extruding it into a solid, then examining the faces of the solid.
std::vector<std::pair<int, Base::Vector3d>>
DrawComplexSection::getSegmentViewDirections(const TopoDS_Wire& profileWire,
                                             Base::Vector3d sectionNormal) const
{
    auto edgesAll = getUniqueEdges(profileWire);
    if (edgesAll.empty()) {
        // this is bad!
        throw Base::RuntimeError("Complex section: profile wire has no edges.");
    }

    // self-protection code should be elsewhere
    if (!checkSectionCS()) {
        // results will likely be incorrect
        // this message will show for every recompute of the complex section.
        Base::Console().warning("Coordinate system for ComplexSection is invalid. Check SectionNormal, Direction or XDirection.\n");
    }

    auto profileVector = Base::convertTo<Base::Vector3d>(makeProfileVector(profileWire));
    auto parallelDot = profileVector.Dot(sectionNormal);
    if (DU::fpCompare(std::fabs(parallelDot), 1, EWTOLERANCE)) {
        Base::Console().warning("Section normal is parallel to profile vector. Results may be incorrect.\n");
    }


    TopoDS_Shape profileSolidTool = cuttingToolFromProfile(profileWire, m_shapeSize);
    // this should be the flattened profile?  should not matter with disttoshape version of isonface.
    std::vector<TopoDS_Edge> relocatedEdgesAll = getUniqueEdges(profileWire);

    if (debugSection()) {
        BRepTools::Write(profileSolidTool, "DCStoolFromProfile.brep");//debug
    }

    std::vector<Base::Vector3d> profileNormals;
    std::vector<std::pair<int, Base::Vector3d>> normalKV;
    TopExp_Explorer expFaces(profileSolidTool, TopAbs_FACE);
    // are all these shenanigans necessary?
    // no guarantee of order from TopExp_Explorer??  Need to match faces to the profile segment that
    // generated it?
    for (int iFace = 0; expFaces.More(); expFaces.Next(), iFace++) {
        auto shape = expFaces.Current();
        auto face = TopoDS::Face(shape);
        auto normal = Base::convertTo<Base::Vector3d>(getFaceNormal(face));

        if (face.Orientation() == TopAbs_FORWARD) {
            // face on solid with Forward orientation will have a normal that points out of the
            // solid.  With Reverse orientation the normal will point into the solid. We want the
            // direction into the solid.
            // "Face normal shows where body material is – it lies ‘behind' the face. In a correct solid body all face normals go ‘outward' (see below):"
            // https://opencascade.blogspot.com/2009/02/continued.html
            normal *= -1;
        }

        // skip top and bottom faces of the prism
        auto topOrBottomDot = std::fabs(normal.Dot(getReferenceAxis()));
        if (DU::fpCompare(topOrBottomDot, 1, EWTOLERANCE)) {
            continue;
        }
        if (!isFacePlanar(face)) {
            // TODO: continue blocks curved profile segments
            // ?? but also blocks "surface of extrusion"
            continue;
        }
        // this is an interesting face, get the normal and edge
        int iSegment{0};
        for (auto& segment : edgesAll) {
            if (faceContainsEndpoints(segment, face)) {
                std::pair<int, Base::Vector3d> newEntry;
                newEntry.first = iSegment;
                newEntry.second = normal;
                normalKV.push_back(newEntry);
                break;
            }
            iSegment++;
         }
    }
    std::sort(normalKV.begin(), normalKV.end(), DrawComplexSection::normalLess);

    return normalKV;
}

//! true if the endpoints of edgeToMatch are vertexes of faceToSearch
bool DrawComplexSection::faceContainsEndpoints(const TopoDS_Edge& edgeToMatch, const TopoDS_Face& faceToSearch)
{
    std::pair<Base::Vector3d, Base::Vector3d> edgeEnds = getSegmentEnds(edgeToMatch);
    bool matchedFirst = pointOnFace(edgeEnds.first, faceToSearch);
    bool matchedLast = pointOnFace(edgeEnds.second, faceToSearch);
    return matchedFirst && matchedLast;
}


//! extrudes a face made from a wire along the reference axis
TopoDS_Shape DrawComplexSection::profileToSolid(const TopoDS_Wire& closedProfileWire,
                                                double dMax) const
{
    BRepBuilderAPI_MakeFace mkFace(closedProfileWire);
    if (!mkFace.IsDone()) {
        throw Base::RuntimeError("Complex section could not create face from closed profile");
    }

    auto extrudeVector = getReferenceAxis() * dMax * 2;

    BRepPrimAPI_MakePrism mkPrism(mkFace.Face(), Base::convertTo<gp_Vec>(extrudeVector));
    auto profileSolid = mkPrism.Shape();

     return profileSolid;
}


//! transform an edge to the base view's projection coordinate system
TopoDS_Edge DrawComplexSection::mapEdgeToBase(const TopoDS_Edge& inEdge)
{
    App::DocumentObject* baseObj = BaseView.getValue();
    auto* baseDvp = freecad_cast<DrawViewPart*>(baseObj);

    BRepBuilderAPI_Copy BuilderEdgeCopy(inEdge);
    TopoDS_Edge edgeCopy = TopoDS::Edge(BuilderEdgeCopy.Shape());

    gp_Ax3 stdCS;                                 //OXYZ
    gp_Trsf xmapEdgeToBase;
    xmapEdgeToBase.SetTransformation(stdCS, baseDvp->getProjectionCS());
    BRepBuilderAPI_Transform mkMappedEdge(edgeCopy, xmapEdgeToBase);
    TopoDS_Edge mappedEdge = TopoDS::Edge(mkMappedEdge.Shape());
    return mappedEdge;
}

TopoDS_Edge DrawComplexSection::mapEdgeToBase(const Base::Vector3d& inVector)
{
    if (inVector.Length() == 0) {
        throw Base::RuntimeError("Complex section received a request to map a null edge");
    }
    gp_Pnt origin(0,0,0);
    gp_Pnt endPoint{Base::convertTo<gp_Pnt>(inVector)};
    TopoDS_Edge edgeToMap = BRepBuilderAPI_MakeEdge(origin, endPoint);
    return mapEdgeToBase(edgeToMap);
}


//! +/- same code as in Import::SketchExportHelper
std::pair< Base::Vector3d, Base::Vector3d> DrawComplexSection::sketchNormalAndX(App::DocumentObject* sketchObj)
{
    auto sketch = dynamic_cast<Part::Feature*>(sketchObj);
    if (!sketch ||
        !sketchObj->isDerivedFrom(Base::Type::fromName("Sketcher::SketchObject"))) {
        // should be a throw? up to the caller to enforce this??
        return { Base::Vector3d(0,0,0), Base::Vector3d(0,0,0) };
    }

    auto plm = sketch->Placement.getValue();
    Base::Rotation rot = plm.getRotation();

    Base::Vector3d stdZ {0.0, 0.0, 1.0};
    Base::Vector3d sketchNormal;
    rot.multVec(stdZ, sketchNormal);

    Base::Vector3d stdX {1.0, 0.0, 0.0};
    Base::Vector3d sketchX;
    rot.multVec(stdX, sketchX);

    return {sketchNormal, sketchX};
}

//! true if sketch normal is +/- parallel to base view's projection direction.
bool DrawComplexSection::validateSketchNormal(App::DocumentObject* sketchObject) const
{
    if (!sketchObject ||
        !sketchObject->isDerivedFrom(Base::Type::fromName("Sketcher::SketchObject"))) {
        return false;
    }

    std::pair<Base::Vector3d, Base::Vector3d> normalX = sketchNormalAndX(sketchObject);
    auto* baseDvp = freecad_cast<DrawViewPart*>(BaseView.getValue());
    double dot = std::fabs((normalX.first).Dot(baseDvp->Direction.getValue()));
    return DU::fpCompare(dot, 1, EWTOLERANCE);
}


// find the index of the profile segment that corresponds to a face in the cutting tool
int DrawComplexSection::getSegmentIndex(const TopoDS_Face& face,
                                        const std::vector<TopoDS_Edge>& edgesAll)
{
    int iSegment{0};
    for (auto& segment : edgesAll) {
        if (faceContainsEndpoints(segment, face)) {
            return iSegment;
        }
        iSegment++;
    }
    return -1;  // not found!
}


//! find the normal for a face in a key-value pair of (index, normal).
std::pair<int, Base::Vector3d>
DrawComplexSection::findNormalForFace(const TopoDS_Face& face,
                                      const std::vector<std::pair<int, Base::Vector3d>>& normalKV,
                                      const std::vector<TopoDS_Edge>& segmentEdges)
{
    size_t index = getSegmentIndex(face, segmentEdges);
    if (index < 0  ||
        index >= segmentEdges.size()) {     //NOLINT
        throw Base::RuntimeError("DCS::findNormalForFace - did not find normal for face!");
    }
    for (auto& keyValue : normalKV) {
        if (static_cast<size_t>(keyValue.first) == index) {
            return keyValue;
        }
    }
     throw Base::RuntimeError("DCS::findNormalForFace - no keyValue pair for segment!");
}


bool DrawComplexSection::pointOnFace(Base::Vector3d point, const TopoDS_Face& face)
{
    TopoDS_Vertex vert = BRepBuilderAPI_MakeVertex(Base::convertTo<gp_Pnt>(point));
    double dist = DU::simpleMinDist(vert, face);
    return (dist < EWTOLERANCE);
}


//! make a cutting tool from a closed shape.  up to the caller to make sure the face is sensible.
TopoDS_Shape DrawComplexSection::makeCuttingToolFromClosedProfile(const TopoDS_Wire& profileWire, double dMax)
{
    TopoDS_Face toolFace;
    try {
        BRepBuilderAPI_MakeFace mkFace(profileWire);
        toolFace = mkFace.Face();
        if (toolFace.IsNull()) {
            return {};
        }
    }
    catch (...) {
        Base::Console().error("%s could not make tool from closed profile\n", Label.getValue());
        return {};
    }
    gp_Dir gpNormal = getFaceNormal(toolFace);
    auto extrudeDir = 2 * dMax * gpNormal;
    TopoDS_Shape prism = BRepPrimAPI_MakePrism(toolFace, extrudeDir).Shape();
    prism = ShapeUtils::moveShape(prism, Base::convertTo<Base::Vector3d>(gpNormal) * -dMax);
    return prism;
}

bool DrawComplexSection::validateProfileAlignment(const TopoDS_Wire& profileWire) const
{
    // use "canBuild(profile, sectionnormal)"?
    if (ProjectionStrategy.getValue() == 0) {
        // Offset. Warn if profile is not quite aligned with section normal. if
        // the profile and normal are misaligned, the check below for empty "solids"
        // will not be correct.
        // just a warning here, so don't fail on this
        constexpr double AngleThresholdDeg{5.0};
        if (!validateOffsetProfile(profileWire, SectionNormal.getValue(), AngleThresholdDeg)) {
            Base::Console().warning("%s: profile and section normal are misaligned\n", Label.getValue());
        }
    }

    // TODO: this check should be in TaskComplexSection also.  In complex section, it prevents a hard occ crash
    //       if the sketch can't be made into an appropriate face/prism.
    if (CuttingToolWireObject.getValue()->isDerivedFrom(Base::Type::fromName("Sketcher::SketchObject"))) {
        if (!validateSketchNormal(CuttingToolWireObject.getValue())) {
            Base::Console().error("%s: cutting object not aligned with section normal\n", Label.getValue());
            return false;
        }
    }

    return true;
}


//! make a cutting tool from the profile and section normal.
TopoDS_Shape DrawComplexSection::cuttingToolFromProfile(const TopoDS_Wire& inProfileWire,
                                                        double dMax) const
{
    TopoDS_Wire profileWireClosed = closeProfileForCut(inProfileWire, dMax);

    if (debugSection()) {
        BRepTools::Write(profileWireClosed, "DCSprofileWireClosed.brep");     //debug
    }

    TopoDS_Shape solid = profileToSolid(profileWireClosed, dMax);
    solid = ShapeUtils::moveShape(solid, getReferenceAxis() * -dMax);
    return solid;
}

TopoDS_Wire DrawComplexSection::closeProfileForCut(const TopoDS_Wire& profileWire,
                                             double dMax) const
{
    // TODO: do these conversions gp_Pnt <-> Base::Vector3d <-> QPointF cause our problems with low
    //       digits?

    auto* baseDvp = freecad_cast<DrawViewPart*>(BaseView.getValue());
    TopoDS_Shape flatShape = GeometryObject::simpleProjection(profileWire, baseDvp->getProjectionCS());
    TopoDS_Wire flatWire = makeNoseToTailWire(flatShape);
    if (debugSection()) {
        BRepTools::Write(flatWire, "DCSflatCloseWire.brep");     //debug
    }

    std::pair<Base::Vector3d, Base::Vector3d> pvEnds = getWireEnds(flatWire);
    Base::Vector3d firstPWPoint = pvEnds.first;
    Base::Vector3d lastPWPoint = pvEnds.second;

    Base::Vector3d midPWPoint = (firstPWPoint + lastPWPoint) / 2;
    Base::Vector3d SNPoint = SectionNormal.getValue() * dMax;
    Base::Vector3d awayDirection = SNPoint - midPWPoint;   // from midpoint to snpoint
    awayDirection.Normalize();

    std::vector<TopoDS_Edge> profileEdges = DU::shapeToVector(flatWire);
    TopoDS_Edge firstEdge = profileEdges.front();
    std::pair<Base::Vector3d, Base::Vector3d> edgeEnds = getSegmentEnds(firstEdge);
    Base::Vector3d firstExtendDir = edgeEnds.first - edgeEnds.second;
    firstExtendDir.Normalize();
    Base::Vector3d firstExtendStartPoint = edgeEnds.second;
    double firstInternalDistance = (midPWPoint - firstExtendStartPoint).Length();
    Base::Vector3d firstExtendEndPoint = firstExtendStartPoint + firstExtendDir * (dMax - firstInternalDistance);
    TopoDS_Edge firstReplacementEdge = BRepBuilderAPI_MakeEdge(Base::convertTo<gp_Pnt>(firstExtendStartPoint),
                                                               Base::convertTo<gp_Pnt>(firstExtendEndPoint));

    TopoDS_Edge lastEdge = profileEdges.back();
    edgeEnds = getSegmentEnds(lastEdge);
    Base::Vector3d lastExtendDir = edgeEnds.second - edgeEnds.first;
    lastExtendDir.Normalize();
    Base::Vector3d lastExtendStartPoint = edgeEnds.first;
    double lastInternalDistance = (midPWPoint - lastExtendStartPoint).Length();
    Base::Vector3d lastExtendEndPoint = lastExtendStartPoint + lastExtendDir * (dMax - lastInternalDistance);
    TopoDS_Edge lastReplacementEdge = BRepBuilderAPI_MakeEdge(Base::convertTo<gp_Pnt>(lastExtendStartPoint),
                                                               Base::convertTo<gp_Pnt>(lastExtendEndPoint));

    Base::Vector3d pointOnArc = midPWPoint + awayDirection * dMax;

    Handle(Geom_TrimmedCurve) circleArc;
    try {
        GC_MakeArcOfCircle mkArc(Base::convertTo<gp_Pnt>(lastExtendEndPoint),
                                 Base::convertTo<gp_Pnt>(pointOnArc),
                                 Base::convertTo<gp_Pnt>(firstExtendEndPoint));
        circleArc = mkArc.Value();
        if (!mkArc.IsDone()) {
            throw Base::RuntimeError("Complex section failed to create arc");
        }
    }
    catch (...) {
        throw Base::RuntimeError("Complex section failed to create circular arc to close profile");
    }

    TopoDS_Edge circleEdge = BRepBuilderAPI_MakeEdge(circleArc);

    // replace first and last edges and add circular arc
    std::vector<TopoDS_Edge> oldProfileEdges = DU::shapeToVector(flatWire);
    std::vector<TopoDS_Edge> newProfileEdges;
    newProfileEdges.emplace_back(firstReplacementEdge);
    if (oldProfileEdges.size() > 2) {
        newProfileEdges.insert(newProfileEdges.end(), oldProfileEdges.begin()+1, oldProfileEdges.end()-1);
    }
    newProfileEdges.emplace_back(lastReplacementEdge);
    newProfileEdges.emplace_back(circleEdge);
    BRepBuilderAPI_MakeWire mkWire;
    for (auto& edge : newProfileEdges) {
        mkWire.Add(edge);
    }

    return mkWire.Wire();
}


bool DrawComplexSection::isFacePlanar(const TopoDS_Face& face)
{
    BRepAdaptor_Surface adaptSurface(face);
    const GeomAdaptor_Surface& surf = adaptSurface.Surface();
    Handle(Geom_Surface) hsurf = surf.Surface();
    return GeomLib_IsPlanarSurface(hsurf).IsPlanar();
}


//! compare 2 normal entries for sorting on segment index
bool DrawComplexSection::normalLess(const std::pair<int, Base::Vector3d>& n1, const std::pair<int, Base::Vector3d>& n2)
{
    return n1.first < n2.first;
}


// Python Drawing feature ---------------------------------------------------------

namespace App
{
/// @cond DOXERR
PROPERTY_SOURCE_TEMPLATE(TechDraw::DrawComplexSectionPython, TechDraw::DrawComplexSection)
template<> const char* TechDraw::DrawComplexSectionPython::getViewProviderName() const
{
    return "TechDrawGui::ViewProviderDrawingView";
}
/// @endcond

// explicit template instantiation
template class TechDrawExport FeaturePythonT<TechDraw::DrawComplexSection>;
}// namespace App