/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  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
 *
 *         https://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.
 *
 *=========================================================================*/
#ifndef itkQuadEdgeMeshFunctionBase_h
#define itkQuadEdgeMeshFunctionBase_h

#include "itkObject.h"
#include "itkObjectFactory.h"

namespace itk
{
/**
 * \class QuadEdgeMeshFunctionBase
 * \ingroup QEMeshModifierFunctions
 * \brief Base class for mesh function object modifiers.
 *
 * QuadEdgeMeshFunctionBase is the base class for itkQE function objects specialised
 * in Mesh "small" (reduced in range) modification.
 * Subclasses of itk::FunctionBase cannot modify their InputType since
 * the signature of their Evaluate( const InputType& ) method guarantees it.
 * Consider a method that modifies (the geometry, the connectivity or both)
 * a mesh.
 * For large modifications of this mesh we follow the classical itk Filter
 * schema, which implies duplicating the mesh which can be space consuming.
 * But for small modifications (think of the Euler operators) that an
 * algorithm needs to apply many times, this systematic duplication can
 * be daunting.
 * QuadEdgeMeshFunctionBase thus offers a lightweight alternative to itk Filter.
 * Subclasses of QuadEdgeMeshFunctionBase, which should override Evaluate(), are
 * function objects that apply reduced and localised modifications
 * (geometry, or connectivity) on the InputType mesh.
 *
 * This class is template over the mesh type (to be modified) and
 * the output (usually a created/deleted vertex or face) type.
 *
 * \ingroup QEMeshModifierFunctions
 *
 * \ingroup ITKQuadEdgeMesh
 */
template <typename TMesh, typename TOutput>
class QuadEdgeMeshFunctionBase : public Object
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(QuadEdgeMeshFunctionBase);

  /** Standard class type aliases. */
  using Self = QuadEdgeMeshFunctionBase;
  using Superclass = Object;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  /** \see LightObject::GetNameOfClass() */
  itkOverrideGetNameOfClassMacro(QuadEdgeMeshFunctionBase);

  /** Mesh type that must be modified */
  using MeshType = TMesh;
  using EdgeCellType = typename MeshType::EdgeCellType;

  /** Output type */
  using OutputType = TOutput;

  /** Set the mesh to be modified */
  virtual void
  SetInput(MeshType * input)
  {
    this->m_Mesh = input;
  }

  /** Evaluate at the specified input position */
  // virtual OutputType Evaluate( )
  //  {
  //  return( (OutputType) 0 );
  //  }

protected:
  QuadEdgeMeshFunctionBase()
    : m_Mesh((MeshType *)nullptr)
  {}

  ~QuadEdgeMeshFunctionBase() override = default;

private:
protected:
  /** Mesh on which to apply the modification */
  MeshType * m_Mesh{};
};
} // end namespace itk

#endif
