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/** @author Jia Pan  */

#ifndef HPP_FCL_HIERARCHY_TREE_H

#define HPP_FCL_HIERARCHY_TREE_H

#include <vector>

#include <map>

#include <functional>

#include <iostream>

#include "hpp/fcl/warning.hh"

#include "hpp/fcl/BV/AABB.h"

#include "hpp/fcl/broadphase/detail/morton.h"

#include "hpp/fcl/broadphase/detail/node_base.h"

namespace hpp {

namespace fcl {

namespace detail {

/// @brief Class for hierarchy tree structure

template <typename BV>

class HierarchyTree {

 public:

  typedef NodeBase<BV> Node;

  /// @brief Create hierarchy tree with suitable setting.

  /// bu_threshold decides the height of tree node to start bottom-up

  /// construction / optimization; topdown_level decides different methods to

  /// construct tree in topdown manner. lower level method constructs tree with

  /// better quality but is slower.

  HierarchyTree(int bu_threshold_ = 16, int topdown_level_ = 0);

  ~HierarchyTree();

  /// @brief Initialize the tree by a set of leaves using algorithm with a given

  /// level.

  void init(std::vector<Node*>& leaves, int level = 0);

  /// @brief Insest a node

  Node* insert(const BV& bv, void* data);

  /// @brief Remove a leaf node

  void remove(Node* leaf);

  /// @brief Clear the tree

  void clear();

  /// @brief Whether the tree is empty

  bool empty() const;

  /// @brief Updates a `leaf` node. A use case is when the bounding volume

  /// of an object changes. Ensure every parent node has its bounding volume

  /// expand or shrink to fit the bounding volumes of its children.

  /// @note Strangely the structure of the tree may change even if the

  ///       bounding volume of the `leaf` node does not change. It is just

  ///       another valid tree of the same set of objects.  This is because

  ///       update() works by first removing `leaf` and then inserting `leaf`

  ///       back. The structural change could be as simple as switching the

  ///       order of two leaves if the sibling of the `leaf` is also a leaf.

  ///       Or it could be more complicated if the sibling is an internal

  ///       node.

  void update(Node* leaf, int lookahead_level = -1);

  /// @brief update the tree when the bounding volume of a given leaf has

  /// changed

  bool update(Node* leaf, const BV& bv);

  /// @brief update one leaf's bounding volume, with prediction

  bool update(Node* leaf, const BV& bv, const Vec3f& vel, FCL_REAL margin);

  /// @brief update one leaf's bounding volume, with prediction

  bool update(Node* leaf, const BV& bv, const Vec3f& vel);

  /// @brief get the max height of the tree

  size_t getMaxHeight() const;

  /// @brief get the max depth of the tree

  size_t getMaxDepth() const;

  /// @brief balance the tree from bottom

  void balanceBottomup();

  /// @brief balance the tree from top

  void balanceTopdown();

  /// @brief balance the tree in an incremental way

  void balanceIncremental(int iterations);

  /// @brief refit the tree, i.e., when the leaf nodes' bounding volumes change,

  /// update the entire tree in a bottom-up manner

  void refit();

  /// @brief extract all the leaves of the tree

  void extractLeaves(const Node* root, std::vector<Node*>& leaves) const;

  /// @brief number of leaves in the tree

  size_t size() const;

  /// @brief get the root of the tree

  Node* getRoot() const;

  Node*& getRoot();

  /// @brief print the tree in a recursive way

  void print(Node* root, int depth);

 private:

  typedef typename std::vector<NodeBase<BV>*>::iterator NodeVecIterator;

  typedef

      typename std::vector<NodeBase<BV>*>::const_iterator NodeVecConstIterator;

  struct SortByMorton {

    }

  };

  /// @brief construct a tree for a set of leaves from bottom -- very heavy way

  void bottomup(const NodeVecIterator lbeg, const NodeVecIterator lend);

  /// @brief construct a tree for a set of leaves from top

  Node* topdown(const NodeVecIterator lbeg, const NodeVecIterator lend);

  /// @brief compute the maximum height of a subtree rooted from a given node

  size_t getMaxHeight(Node* node) const;

  /// @brief compute the maximum depth of a subtree rooted from a given node

  void getMaxDepth(Node* node, size_t depth, size_t& max_depth) const;

  /// @brief construct a tree from a list of nodes stored in [lbeg, lend) in a

  /// topdown manner. During construction, first compute the best split axis as

  /// the axis along with the longest AABB edge. Then compute the median of all

  /// nodes' center projection onto the axis and using it as the split

  /// threshold.

  Node* topdown_0(const NodeVecIterator lbeg, const NodeVecIterator lend);

  /// @brief construct a tree from a list of nodes stored in [lbeg, lend) in a

  /// topdown manner. During construction, first compute the best split

  /// thresholds for different axes as the average of all nodes' center. Then

  /// choose the split axis as the axis whose threshold can divide the nodes

  /// into two parts with almost similar size. This construction is more

  /// expensive then topdown_0, but also can provide tree with better quality.

  Node* topdown_1(const NodeVecIterator lbeg, const NodeVecIterator lend);

  /// @brief init tree from leaves in the topdown manner (topdown_0 or

  /// topdown_1)

  void init_0(std::vector<Node*>& leaves);

  /// @brief init tree from leaves using morton code. It uses morton_0, i.e.,

  /// for nodes which is of depth more than the maximum bits of the morton code,

  /// we use bottomup method to construct the subtree, which is slow but can

  /// construct tree with high quality.

  void init_1(std::vector<Node*>& leaves);

  /// @brief init tree from leaves using morton code. It uses morton_0, i.e.,

  /// for nodes which is of depth more than the maximum bits of the morton code,

  /// we split the leaves into two parts with the same size simply using the

  /// node index.

  void init_2(std::vector<Node*>& leaves);

  /// @brief init tree from leaves using morton code. It uses morton_2, i.e.,

  /// for all nodes, we simply divide the leaves into parts with the same size

  /// simply using the node index.

  void init_3(std::vector<Node*>& leaves);

  Node* mortonRecurse_0(const NodeVecIterator lbeg, const NodeVecIterator lend,

                        const uint32_t& split, int bits);

  Node* mortonRecurse_1(const NodeVecIterator lbeg, const NodeVecIterator lend,

                        const uint32_t& split, int bits);

  Node* mortonRecurse_2(const NodeVecIterator lbeg, const NodeVecIterator lend);

  /// @brief update one leaf node's bounding volume

  void update_(Node* leaf, const BV& bv);

  /// @brief sort node n and its parent according to their memory position

  Node* sort(Node* n, Node*& r);

  /// @brief Insert a leaf node and also update its ancestors. Maintain the

  /// tree as a full binary tree (every interior node has exactly two children).

  /// Furthermore, adjust the BV of interior nodes so that each parent's BV

  /// tightly fits its children's BVs.

  /// @param sub_root The root of the subtree into which we will insert the

  //                  leaf node.

  void insertLeaf(Node* const sub_root, Node* const leaf);

  /// @brief Remove a leaf. Maintain the tree as a full binary tree (every

  /// interior node has exactly two children). Furthermore, adjust the BV of

  /// interior nodes so that each parent's BV tightly fits its children's BVs.

  /// @note The leaf node itself is not deleted yet, but all the unnecessary

  ///       internal nodes are deleted.

  /// @returns the root of the subtree containing the nodes whose BVs were

  //           adjusted.

  Node* removeLeaf(Node* const leaf);

  /// @brief Delete all internal nodes and return all leaves nodes with given

  /// depth from root

  void fetchLeaves(Node* root, std::vector<Node*>& leaves, int depth = -1);

  static size_t indexOf(Node* node);

  /// @brief create one node (leaf or internal)

  Node* createNode(Node* parent, const BV& bv, void* data);

  Node* createNode(Node* parent, const BV& bv1, const BV& bv2, void* data);

  Node* createNode(Node* parent, void* data);

  void deleteNode(Node* node);

  void recurseDeleteNode(Node* node);

  void recurseRefit(Node* node);

 protected:

  Node* root_node;

  size_t n_leaves;

  unsigned int opath;

  /// This is a one Node cache, the reason is that we need to remove a node and

  /// then add it again frequently.

  Node* free_node;

  int max_lookahead_level;

 public:

  /// @brief decide which topdown algorithm to use

  int topdown_level;

  /// @brief decide the depth to use expensive bottom-up algorithm

  int bu_threshold;

};

/// @brief Compare two nodes accoording to the d-th dimension of node center

template <typename BV>

bool nodeBaseLess(NodeBase<BV>* a, NodeBase<BV>* b, int d);

/// @brief select from node1 and node2 which is close to a given query. 0 for

/// node1 and 1 for node2

template <typename BV>

size_t select(const NodeBase<BV>& query, const NodeBase<BV>& node1,

              const NodeBase<BV>& node2);

/// @brief select from node1 and node2 which is close to a given query bounding

/// volume. 0 for node1 and 1 for node2

template <typename BV>

size_t select(const BV& query, const NodeBase<BV>& node1,

              const NodeBase<BV>& node2);

}  // namespace detail

}  // namespace fcl

}  // namespace hpp

#include "hpp/fcl/broadphase/detail/hierarchy_tree-inl.h"

#endif