#ifndef RTREE_H
#define RTREE_H

// NOTE This file compiles under MSVC 6 SP5 and MSVC .Net 2003 it may not work on other compilers without modification.

// NOTE These next few lines may be win32 specific, you may need to modify them to compile on other platform

//#define RTREE_STDIO

#ifdef RTREE_STDIO
#include <stdio.h>
#endif

#include <vector>

//
// RTree.h
//

//#define RTREE_DONT_USE_MEMPOOLS // This version does not contain a fixed memory allocator, fill in lines with EXAMPLE to implement one.
#define RTREE_USE_SPHERICAL_VOLUME // Better split classification, may be slower on some systems

#ifdef RTREE_STDIO
// Fwd decl
class RTFileStream;  // File I/O helper class, look below for implementation and notes.
#endif

#define RTREE_TEMPLATE template<class DATATYPE, class ELEMTYPE, int NUMDIMS, class ELEMTYPEREAL, int TMAXNODES, int TMINNODES>
#define RTREE_QUAL RTree<DATATYPE, ELEMTYPE, NUMDIMS, ELEMTYPEREAL, TMAXNODES, TMINNODES>

namespace floormat::detail {

template<typename T> struct rtree_pool final
{
    rtree_pool() noexcept;
    rtree_pool(const rtree_pool&) = delete;
    rtree_pool& operator=(const rtree_pool&) = delete;
    ~rtree_pool();
    T* construct();
    void free(T* pool);

    union node_u {
        union { T data; };
        node_u* next;
    };
    union node_p {
        T* ptr;
        node_u* data_ptr;
    };

private:
    node_u* free_list = nullptr;
};

} // namespace floormat::detail

/// \class RTree
/// Implementation of RTree, a multidimensional bounding rectangle tree.
/// Example usage: For a 3-dimensional tree use RTree<Object*, float, 3> myTree;
///
/// This modified, templated C++ version by Greg Douglas at Auran (http://www.auran.com)
///
/// DATATYPE Referenced data, should be int, void*, obj* etc. no larger than sizeof<void*> and simple type
/// ELEMTYPE Type of element such as int or float
/// NUMDIMS Number of dimensions such as 2 or 3
/// ELEMTYPEREAL Type of element that allows fractional and large values such as float or double, for use in volume calcs
///
/// NOTES: Inserting and removing data requires the knowledge of its constant Minimal Bounding Rectangle.
///        This version uses new/delete for nodes, I recommend using a fixed size allocator for efficiency.
///        Instead of using a callback function for returned results, I recommend and efficient pre-sized, grow-only memory
///        array similar to MFC CArray or STL Vector for returning search query result.
///
template<class DATATYPE, class ELEMTYPE, int NUMDIMS,
         class ELEMTYPEREAL = ELEMTYPE, int TMAXNODES = 8, int TMINNODES = TMAXNODES / 2>
class RTree final
{

public:

  struct Node;  // Fwd decl.  Used by other internal structs and iterator
  struct ListNode;

  // These constant must be declared after Branch and before Node struct
  // Stuck up here for MSVC 6 compiler.  NSVC .NET 2003 is much happier.
  enum
  {
    MAXNODES = TMAXNODES,                         ///< Max elements in node
    MINNODES = TMINNODES,                         ///< Min elements in node
  };

public:

  RTree();
  RTree(const RTree& other);
  ~RTree() noexcept;
  RTree& operator=(const RTree&);

  /// Insert entry
  /// \param a_min Min of bounding rect
  /// \param a_max Max of bounding rect
  /// \param a_dataId Positive Id of data.  Maybe zero, but negative numbers not allowed.
  void Insert(const ELEMTYPE a_min[NUMDIMS], const ELEMTYPE a_max[NUMDIMS], const DATATYPE& a_dataId);

  /// Remove entry
  /// \param a_min Min of bounding rect
  /// \param a_max Max of bounding rect
  /// \param a_dataId Positive Id of data.  Maybe zero, but negative numbers not allowed.
  void Remove(const ELEMTYPE a_min[NUMDIMS], const ELEMTYPE a_max[NUMDIMS], const DATATYPE& a_dataId);

  /// Find all within search rectangle
  /// \param a_min Min of search bounding rect
  /// \param a_max Max of search bounding rect
  /// \param a_searchResult Search result array.  Caller should set grow size. Function will reset, not append to array.
  /// \param a_resultCallback Callback function to return result.  Callback should return 'true' to continue searching
  /// \param a_context User context to pass as parameter to a_resultCallback
  /// \return Returns the number of entries found
  template<typename F> int Search(const ELEMTYPE a_min[NUMDIMS], const ELEMTYPE a_max[NUMDIMS], F&& callback) const;

  /// Remove all entries from tree
  void RemoveAll();

  /// Count the data elements in this container.  This is slow as no internal counter is maintained.
  int Count() const;

#ifdef RTREE_STDIO
  /// Load tree contents from file
  bool Load(const char* a_fileName);
  /// Load tree contents from stream
  bool Load(RTFileStream& a_stream);


  /// Save tree contents to file
  bool Save(const char* a_fileName);
  /// Save tree contents to stream
  bool Save(RTFileStream& a_stream);
#endif

  /// Iterator is not remove safe.
  class Iterator
  {
  private:

    enum { MAX_STACK = 32 }; //  Max stack size. Allows almost n^32 where n is number of branches in node

    struct StackElement
    {
      Node* m_node;
      int m_branchIndex;
    };

  public:

    Iterator()                                    { Init(); }

    ~Iterator()                                   { }

    /// Is iterator invalid
    bool IsNull()                                 { return (m_tos <= 0); }

    /// Is iterator pointing to valid data
    bool IsNotNull() const                        { return (m_tos > 0); }

    /// Access the current data element. Caller must be sure iterator is not NULL first.
    DATATYPE& operator*();

    /// Access the current data element. Caller must be sure iterator is not NULL first.
    const DATATYPE& operator*() const;

    /// Find the next data element
    bool operator++()                             { return FindNextData(); }

    /// Get the bounds for this node
    void GetBounds(ELEMTYPE a_min[NUMDIMS], ELEMTYPE a_max[NUMDIMS]);

  private:

    /// Reset iterator
    void Init()                                   { m_tos = 0; }

    /// Find the next data element in the tree (For internal use only)
    bool FindNextData();

    /// Push node and branch onto iteration stack (For internal use only)
    void Push(Node* a_node, int a_branchIndex);

    /// Pop element off iteration stack (For internal use only)
    StackElement& Pop();

    StackElement m_stack[MAX_STACK];              ///< Stack as we are doing iteration instead of recursion
    int m_tos;                                    ///< Top Of Stack index

    friend class RTree; // Allow hiding of non-public functions while allowing manipulation by logical owner
  };

  /// Get 'first' for iteration
  void GetFirst(Iterator& a_it);

  /// Get Next for iteration
  void GetNext(Iterator& a_it)                    { ++a_it; }

  /// Is iterator NULL, or at end?
  bool IsNull(Iterator& a_it)                     { return a_it.IsNull(); }

  /// Get object at iterator position
  DATATYPE& GetAt(Iterator& a_it)                 { return *a_it; }

  /// Minimal bounding rectangle (n-dimensional)
  struct Rect
  {
    ELEMTYPE m_min[NUMDIMS];                      ///< Min dimensions of bounding box
    ELEMTYPE m_max[NUMDIMS];                      ///< Max dimensions of bounding box
  };

  /// May be data or may be another subtree
  /// The parents level determines this.
  /// If the parents level is 0, then this is data
  struct Branch
  {
    Rect m_rect;                                  ///< Bounds
    Node* m_child;                                ///< Child node
    DATATYPE m_data;                              ///< Data Id
  };

  /// Node for each branch level
  struct Node
  {
    bool IsInternalNode()                         { return (m_level > 0); } // Not a leaf, but a internal node
    bool IsLeaf()                                 { return (m_level == 0); } // A leaf, contains data

    int m_count;                                  ///< Count
    int m_level;                                  ///< Leaf is zero, others positive
    Branch m_branch[MAXNODES];                    ///< Branch
  };

  /// A link list of nodes for reinsertion after a delete operation
  struct ListNode
  {
    ListNode* m_next;                             ///< Next in list
    Node* m_node;                                 ///< Node
  };

  static floormat::detail::rtree_pool<Node> node_pool;
  static floormat::detail::rtree_pool<ListNode> list_node_pool;

protected:
  /// Variables for finding a split partition
  struct PartitionVars
  {
    enum { NOT_TAKEN = -1 }; // indicates that position

    int m_partition[MAXNODES+1];
    int m_total;
    int m_minFill;
    int m_count[2];
    Rect m_cover[2];
    ELEMTYPEREAL m_area[2];

    Branch m_branchBuf[MAXNODES+1];
    int m_branchCount;
    Rect m_coverSplit;
    ELEMTYPEREAL m_coverSplitArea;
  };

  Node* AllocNode();
  void FreeNode(Node* a_node);
  void InitNode(Node* a_node);
  void InitRect(Rect* a_rect);
  bool InsertRectRec(const Branch& a_branch, Node* a_node, Node** a_newNode, int a_level);
  bool InsertRect(const Branch& a_branch, Node** a_root, int a_level);
  Rect NodeCover(Node* a_node);
  bool AddBranch(const Branch* a_branch, Node* a_node, Node** a_newNode);
  void DisconnectBranch(Node* a_node, int a_index);
  int PickBranch(const Rect* a_rect, Node* a_node);
  Rect CombineRect(const Rect* a_rectA, const Rect* a_rectB);
  void SplitNode(Node* a_node, const Branch* a_branch, Node** a_newNode);
  ELEMTYPEREAL RectSphericalVolume(Rect* a_rect);
  ELEMTYPEREAL RectVolume(Rect* a_rect);
  ELEMTYPEREAL CalcRectVolume(Rect* a_rect);
  void GetBranches(Node* a_node, const Branch* a_branch, PartitionVars* a_parVars);
  void ChoosePartition(PartitionVars* a_parVars, int a_minFill);
  void LoadNodes(Node* a_nodeA, Node* a_nodeB, PartitionVars* a_parVars);
  void InitParVars(PartitionVars* a_parVars, int a_maxRects, int a_minFill);
  void PickSeeds(PartitionVars* a_parVars);
  void Classify(int a_index, int a_group, PartitionVars* a_parVars);
  bool RemoveRect(Rect* a_rect, const DATATYPE& a_id, Node** a_root);
  bool RemoveRectRec(Rect* a_rect, const DATATYPE& a_id, Node* a_node, ListNode** a_listNode);
  ListNode* AllocListNode();
  void FreeListNode(ListNode* a_listNode);
  bool Overlap(Rect* a_rectA, Rect* a_rectB) const;
  void ReInsert(Node* a_node, ListNode** a_listNode);
  template<typename F> bool Search(Node* a_node, Rect* a_rect, int& a_foundCount, F&& callback) const;
  void RemoveAllRec(Node* a_node);
  void Reset();
  void CountRec(Node* a_node, int& a_count) const;

#ifdef RTREE_STDIO
  bool SaveRec(Node* a_node, RTFileStream& a_stream);
  bool LoadRec(Node* a_node, RTFileStream& a_stream);
#endif
  void CopyRec(Node* current, Node* other);

  Node* m_root;                                    ///< Root of tree
  ELEMTYPEREAL m_unitSphereVolume;                 ///< Unit sphere constant for required number of dimensions

public:
  // return all the AABBs that form the RTree
  void ListTree(std::vector<Rect>& vec, std::vector<Node*>& temp) const;
};


#ifndef RTREE_NO_EXTERN_TEMPLATE
extern template struct floormat::detail::rtree_pool<RTree<floormat::uint64_t, float, 2, float>::Node>;
extern template struct floormat::detail::rtree_pool<RTree<floormat::uint64_t, float, 2, float>::ListNode>;
extern template class RTree<floormat::uint64_t, float, 2, float>;
#endif
//#undef RTREE_TEMPLATE
//#undef RTREE_QUAL

#endif //RTREE_H