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#pragma once

#include "base/std/container/vector.h"
#include "core/geometry/Enums.h"
#include "math/Vec3.h"

namespace cc {
namespace geometry {

enum class SplineMode {
    /**
     * Broken line:
     * Each knot is connected with a straight line from the beginning to the end to form a curve. At least two knots.
     */
    LINEAR = 0,

    /**
     * Piecewise Bezier curve:
     * Every four knots form a curve. Total knots number must be a multiple of 4.
     * Each curve passes only the first and fourth knots, and does not pass through the middle two control knots.
     * 
     * If you need a whole continuous curve:
     * (1) Suppose the four knots of the previous curve are A, B, C, D
     * (2) The four knots of the next curve must be D, E, F, G
     * (3) C and E need to be symmetrical about D
     */
    BEZIER = 1,

    /**
     * Catmull Rom curve:
     * All knots(including start & end knots) form a whole continuous curve. At least two knots.
     * The whole curve passes through all knots.
     */
    CATMULL_ROM = 2
};

constexpr uint32_t SPLINE_WHOLE_INDEX = 0xffffffff;

/**
 * @en
 * Basic Geometry: Spline.
 * @zh
 * 基础几何 Spline。
 */

class Spline final : public ShapeBase {
public:
    explicit Spline(SplineMode mode = SplineMode::CATMULL_ROM, ccstd::vector<Vec3> knots = {});

    Spline(const Spline &) = default;
    Spline(Spline &&) = default;
    ~Spline() override = default;
    Spline &operator=(const Spline &) = default;
    Spline &operator=(Spline &&) = default;

    static Spline *create(SplineMode mode, const ccstd::vector<Vec3> &knots = {});
    static Spline *clone(const Spline &s);
    static Spline *copy(Spline *out, const Spline &s);

    inline void setMode(SplineMode mode) { _mode = mode; }
    inline SplineMode getMode() const { return _mode; }
    inline void setKnots(const ccstd::vector<Vec3> &knots) { _knots = knots; }
    inline const ccstd::vector<Vec3> &getKnots() const { return _knots; }
    inline void clearKnots() { _knots.clear(); }
    inline uint32_t getKnotCount() const { return static_cast<uint32_t>(_knots.size()); }
    inline void addKnot(const Vec3 &knot) { _knots.push_back(knot); }
    void setModeAndKnots(SplineMode mode, const ccstd::vector<Vec3> &knots);
    void insertKnot(uint32_t index, const Vec3 &knot);
    void removeKnot(uint32_t index);
    void setKnot(uint32_t index, const Vec3 &knot);
    const Vec3 &getKnot(uint32_t index) const;
    Vec3 &getKnot(uint32_t index);

    // get a point at t with repect to the `index` segment of curve or the whole curve.
    Vec3 getPoint(float t, uint32_t index = SPLINE_WHOLE_INDEX) const;

    // get num points from 0 to 1 uniformly with repect to the `index` segment of curve or the whole curve
    ccstd::vector<Vec3> getPoints(uint32_t num, uint32_t index = SPLINE_WHOLE_INDEX) const;

private:
    uint32_t getSegments() const;
    static Vec3 calcLinear(const Vec3 &v0, const Vec3 &v1, float t);
    static Vec3 calcBezier(const Vec3 &v0, const Vec3 &v1, const Vec3 &v2, const Vec3 &v3, float t);
    static Vec3 calcCatmullRom(const Vec3 &v0, const Vec3 &v1, const Vec3 &v2, const Vec3 &v3, float t);

    SplineMode _mode{SplineMode::CATMULL_ROM};
    ccstd::vector<Vec3> _knots; // control points of the curve.
};

} // namespace geometry
} // namespace cc