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/** @file  IFCProfile.cpp
 *  @brief Read profile and curves entities from IFC files
 */

#ifndef ASSIMP_BUILD_NO_IFC_IMPORTER
#include "IFCUtil.h"

namespace Assimp {
namespace IFC {
namespace {


// --------------------------------------------------------------------------------
// Conic is the base class for Circle and Ellipse
// --------------------------------------------------------------------------------
class Conic : public Curve {
public:
    // --------------------------------------------------
    Conic(const Schema_2x3::IfcConic& entity, ConversionData& conv)
    : Curve(entity,conv) {
        IfcMatrix4 trafo;
        ConvertAxisPlacement(trafo,*entity.Position,conv);

        // for convenience, extract the matrix rows
        location = IfcVector3(trafo.a4,trafo.b4,trafo.c4);
        p[0] = IfcVector3(trafo.a1,trafo.b1,trafo.c1);
        p[1] = IfcVector3(trafo.a2,trafo.b2,trafo.c2);
        p[2] = IfcVector3(trafo.a3,trafo.b3,trafo.c3);
    }

    // --------------------------------------------------
    bool IsClosed() const {
        return true;
    }

    // --------------------------------------------------
    size_t EstimateSampleCount(IfcFloat a, IfcFloat b) const {
        ai_assert( InRange( a ) );
        ai_assert( InRange( b ) );

        a *= conv.angle_scale;
        b *= conv.angle_scale;

        a = std::fmod(a,static_cast<IfcFloat>( AI_MATH_TWO_PI ));
        b = std::fmod(b,static_cast<IfcFloat>( AI_MATH_TWO_PI ));
        const IfcFloat setting = static_cast<IfcFloat>( AI_MATH_PI * conv.settings.conicSamplingAngle / 180.0 );
        return static_cast<size_t>( std::ceil(std::abs( b-a)) / setting);
    }

    // --------------------------------------------------
    ParamRange GetParametricRange() const {
        return std::make_pair(static_cast<IfcFloat>( 0. ), static_cast<IfcFloat>( AI_MATH_TWO_PI / conv.angle_scale ));
    }

protected:
    IfcVector3 location, p[3];
};

// --------------------------------------------------------------------------------
// Circle
// --------------------------------------------------------------------------------
class Circle : public Conic {
public:
    // --------------------------------------------------
    Circle(const Schema_2x3::IfcCircle& entity, ConversionData& conv)
        : Conic(entity,conv)
        , entity(entity)
    {
    }

    // --------------------------------------------------
    IfcVector3 Eval(IfcFloat u) const {
        u = -conv.angle_scale * u;
        return location + static_cast<IfcFloat>(entity.Radius)*(static_cast<IfcFloat>(std::cos(u))*p[0] +
            static_cast<IfcFloat>(std::sin(u))*p[1]);
    }

private:
    const Schema_2x3::IfcCircle& entity;
};

// --------------------------------------------------------------------------------
// Ellipse
// --------------------------------------------------------------------------------
class Ellipse : public Conic {
public:
    // --------------------------------------------------
    Ellipse(const Schema_2x3::IfcEllipse& entity, ConversionData& conv)
    : Conic(entity,conv)
    , entity(entity) {
        // empty
    }

    // --------------------------------------------------
    IfcVector3 Eval(IfcFloat u) const {
        u = -conv.angle_scale * u;
        return location + static_cast<IfcFloat>(entity.SemiAxis1)*static_cast<IfcFloat>(std::cos(u))*p[0] +
            static_cast<IfcFloat>(entity.SemiAxis2)*static_cast<IfcFloat>(std::sin(u))*p[1];
    }

private:
    const Schema_2x3::IfcEllipse& entity;
};

// --------------------------------------------------------------------------------
// Line
// --------------------------------------------------------------------------------
class Line : public Curve {
public:
    // --------------------------------------------------
    Line(const Schema_2x3::IfcLine& entity, ConversionData& conv)
    : Curve(entity,conv) {
        ConvertCartesianPoint(p,entity.Pnt);
        ConvertVector(v,entity.Dir);
    }

    // --------------------------------------------------
    bool IsClosed() const {
        return false;
    }

    // --------------------------------------------------
    IfcVector3 Eval(IfcFloat u) const {
        return p + u*v;
    }

    // --------------------------------------------------
    size_t EstimateSampleCount(IfcFloat a, IfcFloat b) const {
        ai_assert( InRange( a ) );
        ai_assert( InRange( b ) );
        // two points are always sufficient for a line segment
        return a==b ? 1 : 2;
    }


    // --------------------------------------------------
    void SampleDiscrete(TempMesh& out,IfcFloat a, IfcFloat b) const {
        ai_assert( InRange( a ) );
        ai_assert( InRange( b ) );

        if (a == b) {
            out.mVerts.push_back(Eval(a));
            return;
        }
        out.mVerts.reserve(out.mVerts.size()+2);
        out.mVerts.push_back(Eval(a));
        out.mVerts.push_back(Eval(b));
    }

    // --------------------------------------------------
    ParamRange GetParametricRange() const {
        const IfcFloat inf = std::numeric_limits<IfcFloat>::infinity();

        return std::make_pair(-inf,+inf);
    }

private:
    IfcVector3 p,v;
};

// --------------------------------------------------------------------------------
// CompositeCurve joins multiple smaller, bounded curves
// --------------------------------------------------------------------------------
class CompositeCurve : public BoundedCurve {
    typedef std::pair< std::shared_ptr< BoundedCurve >, bool > CurveEntry;

public:
    // --------------------------------------------------
    CompositeCurve(const Schema_2x3::IfcCompositeCurve& entity, ConversionData& conv)
    : BoundedCurve(entity,conv)
    , total() {
        curves.reserve(entity.Segments.size());
        for(const Schema_2x3::IfcCompositeCurveSegment& curveSegment :entity.Segments) {
            // according to the specification, this must be a bounded curve
            std::shared_ptr< Curve > cv(Curve::Convert(curveSegment.ParentCurve,conv));
            std::shared_ptr< BoundedCurve > bc = std::dynamic_pointer_cast<BoundedCurve>(cv);

            if (!bc) {
                IFCImporter::LogError("expected segment of composite curve to be a bounded curve");
                continue;
            }

            if ( (std::string)curveSegment.Transition != "CONTINUOUS" ) {
                IFCImporter::LogVerboseDebug("ignoring transition code on composite curve segment, only continuous transitions are supported");
            }

            curves.push_back( CurveEntry(bc,IsTrue(curveSegment.SameSense)) );
            total += bc->GetParametricRangeDelta();
        }

        if (curves.empty()) {
            throw CurveError("empty composite curve");
        }
    }

    // --------------------------------------------------
    IfcVector3 Eval(IfcFloat u) const {
        if (curves.empty()) {
            return IfcVector3();
        }

        IfcFloat acc = 0;
        for(const CurveEntry& entry : curves) {
            const ParamRange& range = entry.first->GetParametricRange();
            const IfcFloat delta = std::abs(range.second-range.first);
            if (u < acc+delta) {
                return entry.first->Eval( entry.second ? (u-acc) + range.first : range.second-(u-acc));
            }

            acc += delta;
        }
        // clamp to end
        return curves.back().first->Eval(curves.back().first->GetParametricRange().second);
    }

    // --------------------------------------------------
    size_t EstimateSampleCount(IfcFloat a, IfcFloat b) const {
        ai_assert( InRange( a ) );
        ai_assert( InRange( b ) );
        size_t cnt = 0;

        IfcFloat acc = 0;
        for(const CurveEntry& entry : curves) {
            const ParamRange& range = entry.first->GetParametricRange();
            const IfcFloat delta = std::abs(range.second-range.first);
            if (a <= acc+delta && b >= acc) {
                const IfcFloat at =  std::max(static_cast<IfcFloat>( 0. ),a-acc), bt = std::min(delta,b-acc);
                cnt += entry.first->EstimateSampleCount( entry.second ? at + range.first : range.second - bt, entry.second ? bt + range.first : range.second - at );
            }

            acc += delta;
        }

        return cnt;
    }

    // --------------------------------------------------
    void SampleDiscrete(TempMesh& out,IfcFloat a, IfcFloat b) const {
        ai_assert( InRange( a ) );
        ai_assert( InRange( b ) );

        const size_t cnt = EstimateSampleCount(a,b);
        out.mVerts.reserve(out.mVerts.size() + cnt);

        for(const CurveEntry& entry : curves) {
            const size_t curCnt = out.mVerts.size();
            entry.first->SampleDiscrete(out);

            if (!entry.second && curCnt != out.mVerts.size()) {
                std::reverse(out.mVerts.begin() + curCnt, out.mVerts.end());
            }
        }
    }

    // --------------------------------------------------
    ParamRange GetParametricRange() const {
        return std::make_pair(static_cast<IfcFloat>( 0. ),total);
    }

private:
    std::vector< CurveEntry > curves;
    IfcFloat total;
};

// --------------------------------------------------------------------------------
// TrimmedCurve can be used to trim an unbounded curve to a bounded range
// --------------------------------------------------------------------------------
class TrimmedCurve : public BoundedCurve {
public:
    // --------------------------------------------------
    TrimmedCurve(const Schema_2x3::IfcTrimmedCurve& entity, ConversionData& conv)
        : BoundedCurve(entity,conv),
          base(std::shared_ptr<const Curve>(Curve::Convert(entity.BasisCurve,conv)))
    {
        typedef std::shared_ptr<const STEP::EXPRESS::DataType> Entry;

        // for some reason, trimmed curves can either specify a parametric value
        // or a point on the curve, or both. And they can even specify which of the
        // two representations they prefer, even though an information invariant
        // claims that they must be identical if both are present.
        // oh well.
        bool have_param = false, have_point = false;
        IfcVector3 point;
        for(const Entry& sel :entity.Trim1) {
            if (const ::Assimp::STEP::EXPRESS::REAL* const r = sel->ToPtr<::Assimp::STEP::EXPRESS::REAL>()) {
                range.first = *r;
                have_param = true;
                break;
            }
            else if (const Schema_2x3::IfcCartesianPoint* const curR = sel->ResolveSelectPtr<Schema_2x3::IfcCartesianPoint>(conv.db)) {
                ConvertCartesianPoint(point, *curR);
                have_point = true;
            }
        }
        if (!have_param) {
            if (!have_point || !base->ReverseEval(point,range.first)) {
                throw CurveError("IfcTrimmedCurve: failed to read first trim parameter, ignoring curve");
            }
        }
        have_param = false, have_point = false;
        for(const Entry& sel :entity.Trim2) {
            if (const ::Assimp::STEP::EXPRESS::REAL* const r = sel->ToPtr<::Assimp::STEP::EXPRESS::REAL>()) {
                range.second = *r;
                have_param = true;
                break;
            }
            else if (const Schema_2x3::IfcCartesianPoint* const curR = sel->ResolveSelectPtr<Schema_2x3::IfcCartesianPoint>(conv.db)) {
                ConvertCartesianPoint(point, *curR);
                have_point = true;
            }
        }
        if (!have_param) {
            if (!have_point || !base->ReverseEval(point,range.second)) {
                throw CurveError("IfcTrimmedCurve: failed to read second trim parameter, ignoring curve");
            }
        }

        agree_sense = IsTrue(entity.SenseAgreement);
        if( !agree_sense ) {
            std::swap(range.first,range.second);
        }

        // "NOTE In case of a closed curve, it may be necessary to increment t1 or t2
        // by the parametric length for consistency with the sense flag."
        if (base->IsClosed()) {
            if( range.first > range.second ) {
                range.second += base->GetParametricRangeDelta();
            }
        }

        maxval = range.second-range.first;
        ai_assert(maxval >= 0);
    }

    // --------------------------------------------------
    IfcVector3 Eval(IfcFloat p) const {
        ai_assert(InRange(p));
        return base->Eval( TrimParam(p) );
    }

    // --------------------------------------------------
    size_t EstimateSampleCount(IfcFloat a, IfcFloat b) const {
        ai_assert( InRange( a ) );
        ai_assert( InRange( b ) );
        return base->EstimateSampleCount(TrimParam(a),TrimParam(b));
    }

    // --------------------------------------------------
    void SampleDiscrete(TempMesh& out,IfcFloat a,IfcFloat b) const {
        ai_assert(InRange(a));
        ai_assert(InRange(b));
        return base->SampleDiscrete(out,TrimParam(a),TrimParam(b));
    }

    // --------------------------------------------------
    ParamRange GetParametricRange() const {
        return std::make_pair(static_cast<IfcFloat>( 0. ),maxval);
    }

private:
    // --------------------------------------------------
    IfcFloat TrimParam(IfcFloat f) const {
        return agree_sense ? f + range.first :  range.second - f;
    }

private:
    ParamRange range;
    IfcFloat maxval;
    bool agree_sense;

    std::shared_ptr<const Curve> base;
};


// --------------------------------------------------------------------------------
// PolyLine is a 'curve' defined by linear interpolation over a set of discrete points
// --------------------------------------------------------------------------------
class PolyLine : public BoundedCurve {
public:
    // --------------------------------------------------
    PolyLine(const Schema_2x3::IfcPolyline& entity, ConversionData& conv)
        : BoundedCurve(entity,conv)
    {
        points.reserve(entity.Points.size());

        IfcVector3 t;
        for(const Schema_2x3::IfcCartesianPoint& cp : entity.Points) {
            ConvertCartesianPoint(t,cp);
            points.push_back(t);
        }
    }

    // --------------------------------------------------
    IfcVector3 Eval(IfcFloat p) const {
        ai_assert(InRange(p));

        const size_t b = static_cast<size_t>(std::floor(p));
        if (b == points.size()-1) {
            return points.back();
        }

        const IfcFloat d = p-static_cast<IfcFloat>(b);
        return points[b+1] * d + points[b] * (static_cast<IfcFloat>( 1. )-d);
    }

    // --------------------------------------------------
    size_t EstimateSampleCount(IfcFloat a, IfcFloat b) const {
        ai_assert(InRange(a));
        ai_assert(InRange(b));
        return static_cast<size_t>( std::ceil(b) - std::floor(a) );
    }

    // --------------------------------------------------
    ParamRange GetParametricRange() const {
        return std::make_pair(static_cast<IfcFloat>( 0. ),static_cast<IfcFloat>(points.size()-1));
    }

private:
    std::vector<IfcVector3> points;
};

} // anon

// ------------------------------------------------------------------------------------------------
Curve* Curve::Convert(const IFC::Schema_2x3::IfcCurve& curve,ConversionData& conv) {
    if(curve.ToPtr<Schema_2x3::IfcBoundedCurve>()) {
        if(const Schema_2x3::IfcPolyline* c = curve.ToPtr<Schema_2x3::IfcPolyline>()) {
            return new PolyLine(*c,conv);
        }
        if(const Schema_2x3::IfcTrimmedCurve* c = curve.ToPtr<Schema_2x3::IfcTrimmedCurve>()) {
            return new TrimmedCurve(*c,conv);
        }
        if(const Schema_2x3::IfcCompositeCurve* c = curve.ToPtr<Schema_2x3::IfcCompositeCurve>()) {
            return new CompositeCurve(*c,conv);
        }
    }

    if(curve.ToPtr<Schema_2x3::IfcConic>()) {
        if(const Schema_2x3::IfcCircle* c = curve.ToPtr<Schema_2x3::IfcCircle>()) {
            return new Circle(*c,conv);
        }
        if(const Schema_2x3::IfcEllipse* c = curve.ToPtr<Schema_2x3::IfcEllipse>()) {
            return new Ellipse(*c,conv);
        }
    }

    if(const Schema_2x3::IfcLine* c = curve.ToPtr<Schema_2x3::IfcLine>()) {
        return new Line(*c,conv);
    }

    // XXX OffsetCurve2D, OffsetCurve3D not currently supported
    return nullptr;
}

#ifdef ASSIMP_BUILD_DEBUG
// ------------------------------------------------------------------------------------------------
bool Curve::InRange(IfcFloat u) const {
    const ParamRange range = GetParametricRange();
    if (IsClosed()) {
        return true;
    }
    const IfcFloat epsilon = Math::getEpsilon<float>();
    return u - range.first > -epsilon && range.second - u > -epsilon;
}
#endif

// ------------------------------------------------------------------------------------------------
IfcFloat Curve::GetParametricRangeDelta() const {
    const ParamRange& range = GetParametricRange();
    return std::abs(range.second - range.first);
}

// ------------------------------------------------------------------------------------------------
size_t Curve::EstimateSampleCount(IfcFloat a, IfcFloat b) const {
    (void)(a); (void)(b);  
    ai_assert( InRange( a ) );
    ai_assert( InRange( b ) );

    // arbitrary default value, deriving classes should supply better suited values
    return 16;
}

// ------------------------------------------------------------------------------------------------
IfcFloat RecursiveSearch(const Curve* cv, const IfcVector3& val, IfcFloat a, IfcFloat b,
        unsigned int samples, IfcFloat threshold, unsigned int recurse = 0, unsigned int max_recurse = 15) {
    ai_assert(samples>1);

    const IfcFloat delta = (b-a)/samples, inf = std::numeric_limits<IfcFloat>::infinity();
    IfcFloat min_point[2] = {a,b}, min_diff[2] = {inf,inf};
    IfcFloat runner = a;

    for (unsigned int i = 0; i < samples; ++i, runner += delta) {
        const IfcFloat diff = (cv->Eval(runner)-val).SquareLength();
        if (diff < min_diff[0]) {
            min_diff[1] = min_diff[0];
            min_point[1] = min_point[0];

            min_diff[0] = diff;
            min_point[0] = runner;
        }
        else if (diff < min_diff[1]) {
            min_diff[1] = diff;
            min_point[1] = runner;
        }
    }

    ai_assert( min_diff[ 0 ] != inf );
    ai_assert( min_diff[ 1 ] != inf );
    if ( std::fabs(a-min_point[0]) < threshold || recurse >= max_recurse) {
        return min_point[0];
    }

    // fix for closed curves to take their wrap-over into account
    if (cv->IsClosed() && std::fabs(min_point[0]-min_point[1]) > cv->GetParametricRangeDelta()*0.5  ) {
        const Curve::ParamRange& range = cv->GetParametricRange();
        const IfcFloat wrapdiff = (cv->Eval(range.first)-val).SquareLength();

        if (wrapdiff < min_diff[0]) {
            const IfcFloat t = min_point[0];
            min_point[0] = min_point[1] > min_point[0] ? range.first : range.second;
             min_point[1] = t;
        }
    }

    return RecursiveSearch(cv,val,min_point[0],min_point[1],samples,threshold,recurse+1,max_recurse);
}

// ------------------------------------------------------------------------------------------------
bool Curve::ReverseEval(const IfcVector3& val, IfcFloat& paramOut) const
{
    // note: the following algorithm is not guaranteed to find the 'right' parameter value
    // in all possible cases, but it will always return at least some value so this function
    // will never fail in the default implementation.

    // XXX derive threshold from curve topology
    static const IfcFloat threshold = 1e-4f;
    static const unsigned int samples = 16;

    const ParamRange& range = GetParametricRange();
    paramOut = RecursiveSearch(this,val,range.first,range.second,samples,threshold);

    return true;
}

// ------------------------------------------------------------------------------------------------
void Curve::SampleDiscrete(TempMesh& out,IfcFloat a, IfcFloat b) const {
    ai_assert( InRange( a ) );
    ai_assert( InRange( b ) );

    const size_t cnt = std::max(static_cast<size_t>(0),EstimateSampleCount(a,b));
    out.mVerts.reserve( out.mVerts.size() + cnt + 1);

    IfcFloat p = a, delta = (b-a)/cnt;
    for(size_t i = 0; i <= cnt; ++i, p += delta) {
        out.mVerts.push_back(Eval(p));
    }
}

// ------------------------------------------------------------------------------------------------
bool BoundedCurve::IsClosed() const {
    return false;
}

// ------------------------------------------------------------------------------------------------
void BoundedCurve::SampleDiscrete(TempMesh& out) const {
    const ParamRange& range = GetParametricRange();
    ai_assert( range.first != std::numeric_limits<IfcFloat>::infinity() );
    ai_assert( range.second != std::numeric_limits<IfcFloat>::infinity() );

    return SampleDiscrete(out,range.first,range.second);
}

} // IFC
} // Assimp

#endif // ASSIMP_BUILD_NO_IFC_IMPORTER
