/*=========================================================================
 *
 *  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 itkChildTreeIterator_h
#define itkChildTreeIterator_h

#include "itkTreeIteratorBase.h"

namespace itk
{
template <typename TTreeType>
class ITK_TEMPLATE_EXPORT ChildTreeIterator : public TreeIteratorBase<TTreeType>
{
public:
  /** Typedefs */
  using Self = ChildTreeIterator;
  using Superclass = TreeIteratorBase<TTreeType>;
  using TreeType = TTreeType;
  using ValueType = typename TTreeType::ValueType;
  using typename Superclass::TreeNodeType;
  using ChildIdentifier = typename TreeNodeType::ChildIdentifier;
  using typename Superclass::NodeType;

  /** Constructor */
  ChildTreeIterator(TreeType * tree, const TreeNodeType * start = nullptr);

  /** Constructor */
  ChildTreeIterator(const TreeIteratorBase<TTreeType> & iterator);

  /** Get the type of the iterator. */
  NodeType
  GetType() const override;

  /** Go to a specific child node. */
  bool
  GoToChild(ChildIdentifier number = 0) override;

  /** Go to the parent node. */
  bool
  GoToParent() override;

  /** Clone function */
  TreeIteratorBase<TTreeType> *
  Clone() override;

  /** operator = */
  Self &
  operator=(Superclass & iterator)
  {
    if (this != &iterator)
    {
      Superclass::operator=(iterator);
      auto &      it = static_cast<ChildTreeIterator<TTreeType> &>(iterator);
      m_ListPosition = it.m_ListPosition;
      m_ParentNode = it.m_ParentNode;
    }
    return *this;
  }

protected:
  /** Get the next node. */
  const ValueType &
  Next() override;

  /** Return true if the next node exists. */
  bool
  HasNext() const override;

private:
  mutable ChildIdentifier m_ListPosition{};
  TreeNodeType *          m_ParentNode{};
};

} // end namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkChildTreeIterator.hxx"
#endif

#endif