/*=========================================================================

   Library: iMSTK

   Copyright (c) Kitware, Inc. & Center for Modeling, Simulation,
   & Imaging in Medicine, Rensselaer Polytechnic Institute.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0.txt

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

=========================================================================*/

#pragma once

#include "imstkCollisionData.h"
#include "imstkGeometryAlgorithm.h"

namespace imstk
{
class Geometry;

///
/// \class CollisionDetectionAlgorithm
///
/// \brief Base class for all collision detection classes. CollisionDetection
/// classes produce CollisionData between two geometries A and B. CollisionData
/// has two sides. That is, the contact information to resolve collision for
/// geometry A and the contact info to resolve geometry B.
///
/// Subclassed algorithms may produce A, B, or both. To implement, one should
/// implement computeCollisionDataAB, or computeCollisionDataA and
/// computeCollisionDataB. If A or B is not implemented, AB will be called. If AB
/// is not implemented, A and B will be called.
///
/// CollisionDetection::setGenerateCD(bool, bool) can be used to request sides.
/// CD subclasses can provide defaults for this as well and not expect the user
/// to touch it.
///
class CollisionDetectionAlgorithm : public GeometryAlgorithm
{
protected:
    CollisionDetectionAlgorithm();

public:
    virtual ~CollisionDetectionAlgorithm() = default;

    ///
    /// \brief Returns collision detection type string name
    ///
    virtual const std::string getTypeName() const = 0;

public:
    ///
    /// \brief Returns output collision data
    ///
    const std::shared_ptr<CollisionData> getCollisionData() const { return m_colData; }

    ///
    /// \brief If generateA is false, CD data will not be generated for input0,A
    /// Similarly, if generateB is false, CD data will not be generated for input1,B
    ///
    void setGenerateCD(const bool generateA, const bool generateB)
    {
        m_generateCD_A = generateA;
        m_generateCD_B = generateB;
    }

    void setInputGeometryA(std::shared_ptr<Geometry> geometryA) { setInput(geometryA, 0); }

    void setInputGeometryB(std::shared_ptr<Geometry> geometryB) { setInput(geometryB, 1); }

protected:
    ///
    /// \brief Check inputs are correct (always works reversibly)
    /// \return true if all inputs match the requirements, false if not
    ///
    virtual bool areInputsValid() override;

    ///
    /// \brief Compute the collision data
    ///
    virtual void requestUpdate() override;

    ///
    /// \brief Compute collision data for both sides at once, default implementation
    /// just calls computeCollisionDataA and computeCollisionDataB
    ///
    virtual void computeCollisionDataAB(
        std::shared_ptr<Geometry>      geomA,
        std::shared_ptr<Geometry>      geomB,
        std::vector<CollisionElement>& elementsA,
        std::vector<CollisionElement>& elementsB)
    {
        computeCollisionDataA(geomA, geomB, elementsA);
        computeCollisionDataB(geomA, geomB, elementsB);
    }

    ///
    /// \brief Compute collision data for side A (implement as if flip=true)
    ///
    virtual void computeCollisionDataA(
        std::shared_ptr<Geometry>      imstkNotUsed(geomA),
        std::shared_ptr<Geometry>      imstkNotUsed(geomB),
        std::vector<CollisionElement>& imstkNotUsed(elementsA)) { m_computeColDataAImplemented = false; }

    ///
    /// \brief Compute collision data for side B (implement as if flip=true)
    ///
    virtual void computeCollisionDataB(
        std::shared_ptr<Geometry>      imstkNotUsed(geomA),
        std::shared_ptr<Geometry>      imstkNotUsed(geomB),
        std::vector<CollisionElement>& imstkNotUsed(elementsB)) { m_computeColDataBImplemented = false; }

protected:
    std::shared_ptr<CollisionData> m_colData = nullptr;     ///> Collision data

    bool m_flipOutput   = false;
    bool m_generateCD_A = true;
    bool m_generateCD_B = true;

    bool m_computeColDataAImplemented = true;
    bool m_computeColDataBImplemented = true;
};
}