/*         +------------------------------------------------------+
  ____/  \____   /| - Open source game framework licensed to freely use, |
  \          /  / |   copy, modify and sell without restriction          |
+--\ ^__^   /--+  |                                                      |
| ~/        \~ |  | - created for <https://foam.shampoo.ooo>             |
| ~~~~~~~~~~~~ |  +------------------------------------------------------+
| SPACE ~~~~~  | /
|  ~~~~~~~ BOX |/
+-------------*/

#pragma once

#include <ostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <functional>
#include <optional>

#include "glm/vec2.hpp"

class Box;

class Segment
{

private:

    glm::vec2 start_, end_;

public:

    Segment(const glm::vec2&, const glm::vec2&);
    Segment();
    Segment(const glm::vec2&);
    Segment(const Box&, const Box&);
    glm::vec2 start() const;
    void start(const glm::vec2&);
    glm::vec2 end() const;
    void end(const glm::vec2&);

    /*!
     * Check for an intersection with another segment object. If the intersection argument is given a reference to a 2D vector,
     * it will be filled with the point of intersection.
     * 
     * Original source: http://www.realtimerendering.com/resources/GraphicsGems/gemsii/xlines.c
     *
     * @param segment        segment to collide with
     * @param intersection   optional reference to a 2D vector to fill with the intersection point
     * @return               `true` if the two segments intersect, `false` otherwise
     */
    bool intersect(const Segment& segment, std::optional<std::reference_wrapper<glm::vec2>> intersection = std::nullopt) const;

    float dx() const;
    float dy() const;
    float length() const;
    Box box() const;
    void move(const glm::vec2&);
    glm::vec2 center() const;

    /*!
     * @return   angle in radians between the start and end points
     */
    float angle() const;

    /*!
     * @param distance   length of the step
     * @return           a 2D vector representing a step along the segment at the given distance
     */
    glm::vec2 step(float distance) const;
    
    glm::vec2 step_relative(float) const;
    std::vector<Segment> subsegments(int) const;
    inline bool operator<(const Segment& segment) const { return operator<(segment.length()); }

    template<typename N>
    inline bool operator<(const N& other) const { return length() < other; }

    template<typename N>
    inline bool operator>(const N& other) const { return other < length(); }

    template<typename N>
    inline bool operator<=(const N& other) const { return !operator>(other); }

    template<typename N>
    inline bool operator>=(const N& other) const { return !operator<(other); }

};

namespace std
{
    std::ostream& operator<<(std::ostream&, const Segment&);
}

/* Add Segment class to the sb namespace. This should be the default location, but Segment is left in the global namespace
 * for backward compatibility.
 */
namespace sb
{
    using ::Segment;
}