/*=========================================================================
 *
 *  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 itkLevelOrderTreeIterator_hxx
#define itkLevelOrderTreeIterator_hxx


namespace itk
{

template <typename TTreeType>
LevelOrderTreeIterator<TTreeType>::LevelOrderTreeIterator(TTreeType * tree, int endLevel, const TreeNodeType * start)
  : TreeIteratorBase<TTreeType>(tree, start)
{
  m_StartLevel = -1;
  m_EndLevel = endLevel;
  if (start != nullptr)
  {
    m_Queue.push(start);
    this->m_Position = const_cast<TreeNodeType *>(start);
  }
  else
  {
    if (tree->GetRoot())
    {
      m_Queue.push(dynamic_cast<const TreeNodeType *>(tree->GetRoot()));
      this->m_Position = const_cast<TreeNodeType *>(dynamic_cast<const TreeNodeType *>(tree->GetRoot()));
    }
  }
  this->m_Begin = this->m_Position;
}

template <typename TTreeType>
LevelOrderTreeIterator<TTreeType>::LevelOrderTreeIterator(TTreeType *          tree,
                                                          int                  startLevel,
                                                          int                  endLevel,
                                                          const TreeNodeType * start)
  : TreeIteratorBase<TTreeType>(tree, start)
{
  m_StartLevel = startLevel;
  m_EndLevel = endLevel;
  if (start != nullptr)
  {
    m_Queue.push(start);
    this->m_Position = const_cast<TreeNodeType *>(start);
  }
  else
  {
    if (tree->GetRoot())
    {
      m_Queue.push(dynamic_cast<const TreeNodeType *>(tree->GetRoot()));
      this->m_Position = const_cast<TreeNodeType *>(dynamic_cast<const TreeNodeType *>(tree->GetRoot()));
    }
  }
  this->m_Begin = this->m_Position;
}

template <typename TTreeType>
auto
LevelOrderTreeIterator<TTreeType>::GetType() const -> NodeType
{
  return TreeIteratorBaseEnums::TreeIteratorBaseNode::LEVELORDER;
}

template <typename TTreeType>
bool
LevelOrderTreeIterator<TTreeType>::HasNext() const
{
  if (const_cast<TreeNodeType *>(FindNextNode()))
  {
    return true;
  }
  return false;
}

template <typename TTreeType>
auto
LevelOrderTreeIterator<TTreeType>::Next() -> const ValueType &
{
  this->m_Position = const_cast<TreeNodeType *>(FindNextNode());
  if (this->m_Position == nullptr)
  {
    return this->m_Root->Get(); // value irrelevant, but we have to return something
  }
  return this->m_Position->Get();
}

template <typename TTreeType>
int
LevelOrderTreeIterator<TTreeType>::GetStartLevel() const
{
  return m_StartLevel;
}

template <typename TTreeType>
int
LevelOrderTreeIterator<TTreeType>::GetEndLevel() const
{
  return m_EndLevel;
}

template <typename TTreeType>
auto
LevelOrderTreeIterator<TTreeType>::FindNextNode() const -> const TreeNodeType *
{
  int                  level;
  const TreeNodeType * node;

  do
  {
    node = FindNextNodeHelp();
    if (node == nullptr)
    {
      return nullptr;
    }
    level = GetLevel(node);
    if (level > m_EndLevel)
    {
      return nullptr;
    }
  } while (level < m_StartLevel);

  return node;
}

template <typename TTreeType>
int
LevelOrderTreeIterator<TTreeType>::GetLevel() const
{
  if (this->m_Position == nullptr)
  {
    return -1;
  }

  int            level = 0;
  TreeNodeType * node = this->m_Position;
  while (node->HasParent() && node != this->m_Root)
  {
    node = dynamic_cast<TreeNodeType *>(node->GetParent());
    ++level;
  }
  return level;
}

template <typename TTreeType>
int
LevelOrderTreeIterator<TTreeType>::GetLevel(const TreeNodeType * node) const
{
  if (node == nullptr)
  {
    return -1;
  }
  int level = 0;

  while (node->HasParent() && node != this->m_Root)
  {
    node = dynamic_cast<const TreeNodeType *>(node->GetParent());
    ++level;
  }
  return level;
}

template <typename TTreeType>
auto
LevelOrderTreeIterator<TTreeType>::FindNextNodeHelp() const -> const TreeNodeType *
{
  if (m_Queue.empty())
  {
    return nullptr;
  }

  const TreeNodeType * currentNode = m_Queue.front();
  m_Queue.pop();

  if (currentNode == nullptr)
  {
    return nullptr;
  }

  int size = currentNode->CountChildren();

  for (int i = 0; i < size; ++i)
  {
    auto * child = dynamic_cast<TreeNodeType *>(currentNode->GetChild(i));
    if (child != nullptr)
    {
      m_Queue.push(child);
    }
  }

  // If the current node is the root we try again
  if (currentNode == this->m_Root)
  {
    currentNode = const_cast<TreeNodeType *>(FindNextNodeHelp());
  }
  return currentNode;
}

template <typename TTreeType>
TreeIteratorBase<TTreeType> *
LevelOrderTreeIterator<TTreeType>::Clone()
{
  auto * clone = new LevelOrderTreeIterator<TTreeType>(const_cast<TTreeType *>(this->m_Tree), m_StartLevel, m_EndLevel);
  *clone = *this;
  return clone;
}
} // end namespace itk

#endif