/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2021                                                               *
 *                                                                                       *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this  *
 * software and associated documentation files (the "Software"), to deal in the Software *
 * without restriction, including without limitation the rights to use, copy, modify,    *
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to    *
 * permit persons to whom the Software is furnished to do so, subject to the following   *
 * conditions:                                                                           *
 *                                                                                       *
 * The above copyright notice and this permission notice shall be included in all copies *
 * or substantial portions of the Software.                                              *
 *                                                                                       *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,   *
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A         *
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT    *
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF  *
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE  *
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                                         *
 ****************************************************************************************/

#ifndef __OPENSPACE_MODULE_DEBUGGING___DEBUGRENDERER___H__
#define __OPENSPACE_MODULE_DEBUGGING___DEBUGRENDERER___H__

#include <openspace/util/updatestructures.h>

#include <ghoul/glm.h>
#include <ghoul/opengl/ghoul_gl.h>
#include <memory>
#include <vector>

namespace ghoul::opengl { class ProgramObject; }

namespace openspace {

/**
 * A helper class for quick rendering of vertices IN clipping space.
 * The class is practically stateless. It only stores a ghoul::opengl::ProgramObject
 * which can be reused despite the fact that rendering calls are invoked from different
 * callers. Therefore a static reference is provided for convenience which is accessed
 * through ref(). Note: That constructors are still public and the class is not a strict
 * singleton.
 */
class DebugRenderer {
public:
    using Vertices = std::vector<glm::vec4>;

    /**
     *  Consider using ref() before creating a new default instance!
     */
    DebugRenderer();

    /**
     *  Instantiate a new DebugRenderer with a custom shader program
     */
    DebugRenderer(std::unique_ptr<ghoul::opengl::ProgramObject> programObject);
    ~DebugRenderer() = default;

    /**
     *  Access the static reference
     */
    static const DebugRenderer& ref();

    /**
     *  Render the vector of clipping space points in the specified mode and color.
     */
    void renderVertices(const Vertices& clippingSpacePoints, GLenum mode,
        const glm::vec4& color = { 1.f, 0.f, 0.f, 1.f }) const;

    /**
     *  Takes a vector of exactly 8 vertices, i.e. corner points in a box.
     *  The box corners should be ordered from smaller to larger,
     *  first by x, the, y and finally z.
     *
     *  6-------7
     *  |\      |\
     *  | 2-------3
     *  4 | - - 5 |
     *   \|      \|
     *    0-------1
     *
     */
    void renderBoxFaces(const Vertices& clippingSpaceBoxCorners,
        const glm::vec4& rgba = { 1.f, 0.f, 0.f, 1.f }) const;

    /**
     *  Takes a vector of exactly 8 vertices, i.e. corner points in a box.
     *  The box corners should be ordered from smaller to larger,
     *  first by x, the, y and finally z.
     *
     *  6-------7
     *  |\      |\
     *  | 2-------3
     *  4 | - - 5 |
     *   \|      \|
     *    0-------1
     *
     */
    void renderBoxEdges(const Vertices& clippingSpaceBoxCorners,
        const glm::vec4& rgba = { 1.f, 0.f, 0.f, 1.f }) const;

    /**
      *  Takes a vector of exactly 8 vertices, i.e. corner points in a box.
      *  The box corners should be ordered from smaller to larger,
      *  first by x, the, y and finally z.
      *
      *  6-------7
      *  |\      |\
      *  | 2-------3
      *  4 | - - 5 |
      *   \|      \|
      *    0-------1
      *
      */
    void renderNiceBox(const Vertices& clippingSpaceBoxCorners,
        const glm::vec4& rgba = { 1.f, 0.f, 0.f, 0.3f }) const;

    /**
     *  Input arguments:
     *  1. const RenderData& data:     defines position and camera that we will see the
     *                                 other cameras view frustum from
     *  2. const Camera& otherCamera:  The camera who's view frustum is to be rendered
     *  3. RGBA rgba                   Color to draw the view frustum with
     */
    void renderCameraFrustum(const RenderData& data, const Camera& otherCamera,
        const glm::vec4& rgba = { 1.f, 1.f, 1.f, 0.3f }) const;

protected:
    std::unique_ptr<ghoul::opengl::ProgramObject> _programObject;


    // A raw pointer for the reason that it should not be deleted by the static
    // destructor and the normal destructor. This class has ownership
    static DebugRenderer* _reference;
};

} // namespace openspace

#endif // __OPENSPACE_MODULE_DEBUGGING___DEBUGRENDERER___H__