#pragma once
#include "vde/core/point.h"
#include "vde/core/aabb.h"
#include <vector>
#include <array>

namespace vde::core {

class Polygon2D {
public:
    Polygon2D() = default;
    explicit Polygon2D(std::vector<Point2D> vertices) : vertices_(std::move(vertices)) {}

    [[nodiscard]] const std::vector<Point2D>& vertices() const { return vertices_; }
    [[nodiscard]] size_t size() const { return vertices_.size(); }
    [[nodiscard]] bool empty() const { return vertices_.empty(); }

    /// Signed area (positive = CCW)
    [[nodiscard]] double signed_area() const;

    /// Absolute area
    [[nodiscard]] double area() const { return std::abs(signed_area()); }

    /// Perimeter (sum of edge lengths)
    [[nodiscard]] double perimeter() const;

    /// Area-weighted centroid
    [[nodiscard]] Point2D centroid() const;

    /// Axis-aligned bounding box (2D, stored in AABB3D with z=0)
    [[nodiscard]] AABB<double> bounding_box() const;

    /// Point-in-polygon test (ray casting)
    [[nodiscard]] bool contains(const Point2D& p) const;

    /// Is the polygon counter-clockwise?
    [[nodiscard]] bool is_ccw() const { return signed_area() > 0; }

    /// Douglas-Peucker simplification. Returns a new simplified polygon.
    [[nodiscard]] Polygon2D simplify(double tolerance) const;

    /// Ear-clipping triangulation. Returns triangles as triples of vertex indices.
    /// Assumes a simple polygon (no self-intersections). CCW ordering required.
    [[nodiscard]] std::vector<std::array<int, 3>> triangulate() const;

    /// Andrew's monotone chain convex hull of a point set.
    static Polygon2D convex_hull_2d(const std::vector<Point2D>& points);

private:
    std::vector<Point2D> vertices_;
};

}  // namespace vde::core