/***************************************************************************
                         qgsnurbscurve.h
                         -----------------
    begin                : September 2025
    copyright            : (C) 2025 by Loïc Bartoletti
    email                : loic dot bartoletti at oslandia dot com
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef QGSNURBSCURVE_H
#define QGSNURBSCURVE_H

#include <float.h>
#include <memory>

#include "qgis_core.h"
#include "qgis_sip.h"
#include "qgscurve.h"

#include <QPolygonF>
#include <QString>

using namespace Qt::StringLiterals;

/**
 * \ingroup core
 * \class QgsNurbsCurve
 * \brief Represents a NURBS (Non-Uniform Rational B-Spline) curve geometry in 2D/3D.
 *
 * NURBS curves are a mathematical model commonly used in computer graphics
 * for representing curves. They are parametric curves defined by control points,
 * weights, knot vectors, and a degree.
 *
 * \since QGIS 4.0
 */
class CORE_EXPORT QgsNurbsCurve : public QgsCurve
{
  public:
    /**
     * Constructor for an empty NURBS curve geometry.
     */
    QgsNurbsCurve();

    /**
     * Constructs a NURBS curve from control points, degree, knot vector and weights.
     * \param controlPoints control points defining the curve. The number of control points must be strictly greater than \a degree
     * \param degree degree of the NURBS curve (must be >= 1, typically 1-3)
     * \param knots knot vector (must have size = control points count + degree + 1, values must be non-decreasing)
     * \param weights weight vector for rational curves (same size as control points)
     */
    QgsNurbsCurve( const QVector<QgsPoint> &controlPoints, int degree, const QVector<double> &knots, const QVector<double> &weights );

    QgsNurbsCurve *clone() const override SIP_FACTORY;

#ifndef SIP_RUN

    /**
     * Evaluates the NURBS curve at parameter t ∈ [0,1].
     * Uses the Cox-de Boor algorithm for B-spline basis function evaluation.
     * \param t parameter value between 0 and 1
     * \returns point on the curve at parameter t
     */
    [[nodiscard]] QgsPoint evaluate( double t ) const;
#else
    // clang-format off

    /**
     * Evaluates the NURBS curve at parameter t ∈ [0,1].
     * Uses the Cox-de Boor algorithm for B-spline basis function evaluation.
     * \param t parameter value between 0 and 1
     * \returns point on the curve at parameter t
     * \throws ValueError if t is not in range [0, 1]
     */
    SIP_PYOBJECT evaluate( double t ) const SIP_TYPEHINT( QgsPoint );
    % MethodCode
    if ( a0 < 0.0 || a0 > 1.0 )
    {
      PyErr_SetString( PyExc_ValueError, "Parameter t must be in range [0, 1]" );
      sipIsErr = 1;
    }
    else
    {
      sipRes = sipConvertFromType( new QgsPoint( sipCpp->evaluate( a0 ) ), sipType_QgsPoint, Py_None );
    }
    % End
// clang-format on
#endif

    // clang-format off
    /**
     * Returns TRUE if this curve represents a Bézier curve.
     * A Bézier curve is a special case of NURBS with uniform weights and specific knot vector.
     */
    bool isBezier() const SIP_HOLDGIL;
    // clang-format on

    /**
     * Returns TRUE if this curve represents a B-spline (non-rational NURBS).
     */
    bool isBSpline() const SIP_HOLDGIL;

    /**
     * Returns TRUE if this curve is rational (has non-uniform weights).
     */
    bool isRational() const SIP_HOLDGIL;


    /**
     * Returns TRUE if this curve represents a poly-Bézier curve structure.
     *
     * A poly-Bézier is a piecewise Bézier curve with C0 continuity
     * (positional continuity only) used for editing. It requires:
     *
     * - Control points: (controlPointCount - 1) % degree == 0
     * - Knot vector with multiplicity 'degree' at internal junctions
     * - Can have 1 or more segments (like MultiPolygon can have 1+ polygons)
     *
     * Works for any degree ≥ 1. Note that a single-segment poly-Bézier
     * will also return TRUE for isBezier() (degree = n-1 condition).
     */
    bool isPolyBezier() const SIP_HOLDGIL;

    bool isClosed() const override SIP_HOLDGIL;
    bool isClosed2D() const override SIP_HOLDGIL;

    // QgsCurve interface
    QgsLineString *curveToLine( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const override SIP_FACTORY;
    void draw( QPainter &p ) const override;
    void drawAsPolygon( QPainter &p ) const override;
    QgsPoint endPoint() const override SIP_HOLDGIL;
    bool equals( const QgsCurve &other ) const override;
    int indexOf( const QgsPoint &point ) const override;
    QgsPoint *interpolatePoint( double distance ) const override SIP_FACTORY;
    int numPoints() const override SIP_HOLDGIL;
    bool pointAt( int node, QgsPoint &point SIP_OUT, Qgis::VertexType &type SIP_OUT ) const override;
    void points( QgsPointSequence &pts SIP_OUT ) const override;
    QgsCurve *reversed() const override SIP_FACTORY;
    void scroll( int firstVertexIndex ) override;
    std::tuple<std::unique_ptr<QgsCurve>, std::unique_ptr<QgsCurve>> splitCurveAtVertex( int index ) const override SIP_SKIP;
    QgsPoint startPoint() const override SIP_HOLDGIL;
    void sumUpArea( double &sum SIP_OUT ) const override;
    void sumUpArea3D( double &sum SIP_OUT ) const override;
    double xAt( int index ) const override;
    double yAt( int index ) const override;
    double zAt( int index ) const override;
    double mAt( int index ) const override;

    QPolygonF asQPolygonF() const override;

    void addToPainterPath( QPainterPath &path ) const override;
    QgsCurve *curveSubstring( double startDistance, double endDistance ) const override SIP_FACTORY;
    double length() const override SIP_HOLDGIL;
    double segmentLength( QgsVertexId startVertex ) const override;
    double distanceBetweenVertices( QgsVertexId fromVertex, QgsVertexId toVertex ) const override;
    QgsAbstractGeometry *snappedToGrid( double hSpacing, double vSpacing, double dSpacing = 0, double mSpacing = 0, bool removeRedundantPoints = false ) const override SIP_FACTORY;
    QgsAbstractGeometry *simplifyByDistance( double tolerance ) const override SIP_FACTORY;
    bool removeDuplicateNodes( double epsilon = 4 * std::numeric_limits<double>::epsilon(), bool useZValues = false ) override;
    double vertexAngle( QgsVertexId vertex ) const override;
    void swapXy() override;
    bool transform( QgsAbstractGeometryTransformer *transformer, QgsFeedback *feedback = nullptr ) override;
    QgsAbstractGeometry *createEmptyWithSameType() const override SIP_FACTORY;
    double closestSegment( const QgsPoint &pt, QgsPoint &segmentPt SIP_OUT, QgsVertexId &vertexAfter SIP_OUT, int *leftOf SIP_OUT = nullptr, double epsilon = 4 * std::numeric_limits<double>::epsilon() ) const override;
    void transform( const QgsCoordinateTransform &ct, Qgis::TransformDirection d = Qgis::TransformDirection::Forward, bool transformZ = false ) override SIP_THROW( QgsCsException );
    void transform( const QTransform &t, double zTranslate = 0.0, double zScale = 1.0, double mTranslate = 0.0, double mScale = 1.0 ) override;
    QgsRectangle boundingBox() const override;
    QgsBox3D boundingBox3D() const override;
    bool moveVertex( QgsVertexId position, const QgsPoint &newPos ) override;
    bool insertVertex( QgsVertexId position, const QgsPoint &vertex ) override;
    int wkbSize( QgsAbstractGeometry::WkbFlags flags = QgsAbstractGeometry::WkbFlags() ) const override;
    QByteArray asWkb( QgsAbstractGeometry::WkbFlags flags = QgsAbstractGeometry::WkbFlags() ) const override;
    QString asWkt( int precision = 17 ) const override;
    QDomElement asGml2( QDomDocument &doc, int precision = 17, const QString &ns = "gml", QgsAbstractGeometry::AxisOrder axisOrder = QgsAbstractGeometry::AxisOrder::XY ) const override;
    QDomElement asGml3( QDomDocument &doc, int precision = 17, const QString &ns = "gml", QgsAbstractGeometry::AxisOrder axisOrder = QgsAbstractGeometry::AxisOrder::XY ) const override;
    json asJsonObject( int precision = 17 ) const override SIP_SKIP;
    QString asKml( int precision = 17 ) const override;
    int dimension() const override SIP_HOLDGIL;
    bool isEmpty() const override SIP_HOLDGIL;
    void clear() override;
    bool boundingBoxIntersects( const QgsRectangle &rectangle ) const override SIP_HOLDGIL;
    bool boundingBoxIntersects( const QgsBox3D &box3d ) const override SIP_HOLDGIL;
    QgsPoint centroid() const override;

    // QgsAbstractGeometry interface
    bool addZValue( double zValue = 0 ) override;
    bool addMValue( double mValue = 0 ) override;
    bool dropZValue() override;
    bool dropMValue() override;
    bool deleteVertex( QgsVertexId position ) override;
#ifndef SIP_RUN
    void filterVertices( const std::function<bool( const QgsPoint & )> &filter ) override;
#endif
    bool fromWkb( QgsConstWkbPtr &wkb ) override;
    bool fromWkt( const QString &wkt ) override;
    bool fuzzyEqual( const QgsAbstractGeometry &other, double epsilon = 1e-8 ) const override SIP_HOLDGIL;
    bool fuzzyDistanceEqual( const QgsAbstractGeometry &other, double epsilon = 1e-8 ) const override SIP_HOLDGIL;
    QString geometryType() const override SIP_HOLDGIL;
    bool hasCurvedSegments() const override SIP_HOLDGIL;
    int partCount() const override SIP_HOLDGIL;
    QgsCurve *toCurveType() const override;
    QgsPoint vertexAt( QgsVertexId id ) const override;
    int vertexCount( int part = 0, int ring = 0 ) const override SIP_HOLDGIL;
    int vertexNumberFromVertexId( QgsVertexId id ) const override;
    bool isValid( QString &error SIP_OUT, Qgis::GeometryValidityFlags flags = Qgis::GeometryValidityFlags() ) const override;

    /**
     * Returns the degree of the NURBS curve.
     */
    int degree() const SIP_HOLDGIL { return mDegree; }

    /**
     * Sets the degree of the NURBS curve.
     * \param degree curve degree (typically 1-3)
     */
    void setDegree( int degree )
    {
      mDegree = degree;
      clearCache();
    }

    /**
     * Returns the control points of the NURBS curve.
     */
    QVector<QgsPoint> controlPoints() const SIP_HOLDGIL { return mControlPoints; }

    /**
     * Sets the control points of the NURBS curve.
     * \param points control points
     */
    void setControlPoints( const QVector<QgsPoint> &points )
    {
      mControlPoints = points;
      clearCache();
    }

    /**
     * Returns the knot vector of the NURBS curve.
     */
    QVector<double> knots() const SIP_HOLDGIL { return mKnots; }

    /**
     * Sets the knot vector of the NURBS curve.
     * \param knots knot vector (must have size = control points count + degree + 1, values must be non-decreasing)
     */
    void setKnots( const QVector<double> &knots )
    {
      mKnots = knots;
      clearCache();
    }

    /**
     * Returns the weight vector of the NURBS curve.
     */
    QVector<double> weights() const SIP_HOLDGIL { return mWeights; }

    /**
     * Sets the weight vector of the NURBS curve.
     * \param weights weight vector (same size as control points)
     */
    void setWeights( const QVector<double> &weights )
    {
      mWeights = weights;
      clearCache();
    }

#ifndef SIP_RUN

    /**
     * Returns the weight at the specified control point \a index.
     * Returns 1.0 if index is out of range.
     * \since QGIS 4.0
     */
    double weight( int index ) const SIP_HOLDGIL;

    /**
     * Sets the \a weight at the specified control point \a index.
     * Weight must be positive (> 0).
     * \returns TRUE if successful, FALSE if index is out of range or weight is invalid.
     * \since QGIS 4.0
     */
    bool setWeight( int index, double weight );
#else
// clang-format off

    /**
     * Returns the weight at the specified control point \a index.
     *
     * \throws IndexError if no control point with the specified index exists.
     * \since QGIS 4.0
     */
    double weight( int index ) const SIP_HOLDGIL;
    % MethodCode
    const int count = sipCpp->controlPoints().size();
    if ( a0 < 0 || a0 >= count )
    {
      PyErr_SetString( PyExc_IndexError, QByteArray::number( a0 ) );
      sipIsErr = 1;
    }
    else
    {
      sipRes = sipCpp->weight( a0 );
    }
    % End

    /**
     * Sets the \a weight at the specified control point \a index.
     * Weight must be positive (> 0).
     *
     * \throws IndexError if no control point with the specified index exists.
     * \throws ValueError if weight is not positive.
     * \since QGIS 4.0
     */
    void setWeight( int index, double weight );
    % MethodCode
    const int count = sipCpp->controlPoints().size();
    if ( a0 < 0 || a0 >= count )
    {
      PyErr_SetString( PyExc_IndexError, QByteArray::number( a0 ) );
      sipIsErr = 1;
    }
    else if ( a1 <= 0 )
    {
      PyErr_SetString( PyExc_ValueError, "Weight must be positive (> 0)" );
      sipIsErr = 1;
    }
    else
    {
      sipCpp->setWeight( a0, a1 );
    }
    % End
// clang-format on
#endif

    /**
     * Generates a uniform clamped knot vector for a NURBS curve.
     *
     * The generated knot vector has size = numControlPoints + degree + 1, with:
     *
     * - The first (degree + 1) knots are set to 0.0 (indices 0 to degree).
     * - The last (degree + 1) knots are set to 1.0 (indices numControlPoints to numControlPoints + degree).
     * - Interior knots uniformly spaced
     *
     * \param numControlPoints number of control points
     * \param degree degree of the NURBS curve (must be >= 1)
     * \returns the generated knot vector
     * \since QGIS 4.0
     */
    static QVector<double> generateUniformKnots( int numControlPoints, int degree );

    /**
     * Generates a knot vector for converting piecewise Bézier curves to NURBS.
     *
     * Creates a knot vector with multiplicity 'degree' at junctions for C0 continuity.
     * Format: [0 repeated (degree+1), 1 repeated degree, ..., s repeated (degree+1)]
     * where s = nAnchors - 1 (number of segments)
     *
     * \param nAnchors number of anchor points (must be >= 2)
     * \param degree degree of the curve (must be >= 1), defaults to 3 (cubic)
     * \returns the generated knot vector, or empty if invalid parameters
     * \since QGIS 4.0
     */
    static QVector<double> generateKnotsForBezierConversion( int nAnchors, int degree = 3 );

    /**
     * Returns TRUE if the control point at localIndex is an anchor vertex
     * in a poly-Bézier curve. Anchor vertices are at positions 0, degree, 2*degree, etc.
     *
     * \param localIndex the control point index to check
     * \returns TRUE if this is an anchor vertex, FALSE otherwise
     * \since QGIS 4.0
     */
    bool isAnchorVertex( int localIndex ) const SIP_HOLDGIL;

    /**
     * Cast the \a geom to a QgsNurbsCurve.
     * Should be used by qgsgeometry_cast<QgsNurbsCurve *>( geometry ).
     * \note Not available in Python.
     */
    inline static const QgsNurbsCurve *cast( const QgsAbstractGeometry *geom ) SIP_SKIP // cppcheck-suppress duplInheritedMember
    {
      if ( geom && geom->geometryType() == "NurbsCurve"_L1 )
        return static_cast<const QgsNurbsCurve *>( geom );
      return nullptr;
    }

    /**
     * Cast the \a geom to a QgsNurbsCurve.
     * Should be used by qgsgeometry_cast<QgsNurbsCurve *>( geometry ).
     * \note Not available in Python.
     */
    inline static QgsNurbsCurve *cast( QgsAbstractGeometry *geom ) SIP_SKIP // cppcheck-suppress duplInheritedMember
    {
      if ( geom && geom->geometryType() == "NurbsCurve"_L1 )
        return static_cast<QgsNurbsCurve *>( geom );
      return nullptr;
    }

  protected:
    void clearCache() const override;
    int compareToSameClass( const QgsAbstractGeometry *other ) const final;
    QgsBox3D calculateBoundingBox3D() const override;

  private:
    /**
     * Generates a uniform knot vector based on current degree and control points count.
     * Clears the existing knot vector and generates a new one following the formula:
     *
     * - The first (degree + 1) knots are set to 0.0 (indices 0 to degree).
     * - The last (degree + 1) knots are set to 1.0 (indices numControlPoints to numControlPoints + degree).
     * - Interior knots are uniformly spaced
     */
    void generateUniformKnots();

    QVector<QgsPoint> mControlPoints;       //! Control points defining the curve shape
    QVector<double> mKnots;                 //! Knot vector for B-spline basis functions
    QVector<double> mWeights;               //! Weight vector for rational curves
    int mDegree = 0;                        //! Degree of the NURBS curve
    mutable bool mValidityComputed = false; //! Whether validity has been computed
    mutable bool mIsValid = false;          //! Cached validity state
};

#endif // QGSNURBSCURVE_H
