/****************************************************************************
* VCGLib                                                            o o     *
* Visual and Computer Graphics Library                            o     o   *
*                                                                _   O  _   *
* Copyright(C) 2004                                                \/)\/    *
* Visual Computing Lab                                            /\/|      *
* ISTI - Italian National Research Council                           |      *
*                                                                    \      *
* All rights reserved.                                                      *
*                                                                           *
* This program is free software; you can redistribute it and/or modify      *   
* it under the terms of the GNU General Public License as published by      *
* the Free Software Foundation; either version 2 of the License, or         *
* (at your option) any later version.                                       *
*                                                                           *
* This program is distributed in the hope that it will be useful,           *
* but WITHOUT ANY WARRANTY; without even the implied warranty of            *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             *
* GNU General Public License (http://www.gnu.org/licenses/gpl.txt)          *
* for more details.                                                         *
*                                                                           *
****************************************************************************/

#ifndef OCTREE_H
#define OCTREE_H

#include <stdlib.h>
#include <algorithm>
#include <vector>
#include <iterator>

#include <vcg/space/color4.h>
#include <vcg/space/index/base.h>
#include <vcg/space/index/octree_template.h>
#include <vcg/space/box3.h>
#include <wrap/callback.h>

namespace vcg
{
	/*!
	* Given an object or an object pointer, return the reference to the object
	*/
	template <typename TYPE>
	struct Dereferencer
	{
		static				TYPE& Ref(TYPE &t)				{ return ( t);	}
		static				TYPE& Ref(TYPE* &t)				{ return (*t);	}
		static const	TYPE& Ref(const TYPE &t)	{ return ( t);	}
		static const	TYPE& Ref(const TYPE* &t) { return (*t);	}
	};

	
	/*!
	* Given a type, return the type
	*/
	template <typename T>
	class ReferenceType
	{
	public:
		typedef T Type;
	};

	
	/*!
	* Given as type a pointer to type, return the type
	*/
	template <typename T>
	class ReferenceType<T *>
	{
	public:
		typedef typename ReferenceType<T>::Type Type;
	};


	
	/*!
	* The type of the octree voxels
	*/
	struct Voxel
	{
		Voxel() { count = begin = end = -1; }

		void SetRange(const int begin, const int end)
		{
			this->begin = begin;
			this->end		= end;
			count				= end-begin;
		};

		void AddRange(const Voxel *voxel)
		{
			assert(voxel->end>end);

			count += voxel->count;
			end		 = voxel->end;
		};

		int begin;
		int end;
		int count;
	};
	
	
	template < class OBJECT_TYPE, class SCALAR_TYPE>
	class Octree : public OctreeTemplate< Voxel >, public vcg::SpatialIndex< OBJECT_TYPE, SCALAR_TYPE >
	{
	public: 
		typedef						OBJECT_TYPE													ObjectType;
		typedef						vcg::Box3<ScalarType>								BoundingBoxType;	
		typedef typename	Octree::Leaf											* LeafPointer;
		typedef typename	Octree::InnerNode									* InnerNodePointer;
		typedef typename	ReferenceType<OBJECT_TYPE>::Type	* ObjectPointer;

		/*!
		* Structure which holds the rendering settings
		*/
		struct OcreeRenderingSetting
		{
			OcreeRenderingSetting()
			{
				color						= vcg::Color4b(155, 155, 155, 255);
				isVisible				= false;
				minVisibleDepth	= 1;
				maxVisibleDepth	= 4;
			};

			int						isVisible;
			int						minVisibleDepth;
			int						maxVisibleDepth;
			vcg::Color4b	color;
		};




		
	protected:
		/***********************************************
		*     INNER DATA STRUCTURES AND PREDICATES     *
		***********************************************/
		/*!
		* Structure used during the sorting of the dataset
		*/
		template < typename LEAF_TYPE >
		struct ObjectPlaceholder
		{
			typedef LEAF_TYPE* LeafPointer;

			ObjectPlaceholder() { z_order = object_index = -1, leaf_pointer = NULL;}

			ObjectPlaceholder(unsigned long long z_order, void* leaf_pointer, unsigned int object_index)
			{
				this->z_order				= z_order;
				this->leaf_pointer	= leaf_pointer;
				this->object_index	= object_index;
			}

			unsigned long long	z_order;
			LeafPointer					leaf_pointer;
			unsigned int				object_index;
		};

		
		/*!
		* Predicate used during the sorting of the dataset
		*/
		template <typename LEAF_TYPE >
		struct ObjectSorter
		{
			inline bool operator()(const ObjectPlaceholder< LEAF_TYPE > &first, const ObjectPlaceholder< LEAF_TYPE > &second)
			{
				return (first.z_order<second.z_order);
			}
		};

		/*!
		* Structure which holds the reference to the object and the position of the mark for that object
		*/
		struct ObjectReference
		{
			ObjectReference() {mark_position=-1; pObject=NULL;}

			int						mark_position;
			ObjectPointer pObject;
		};

		/*
		* The generic item in the neighbors vector computed by GetNearestNeighbors;
		*/
		struct Neighbour
		{
			Neighbour() 
			{
				this->object	 = NULL;
				this->distance = -1.0f;
			};

			Neighbour(ObjectPointer &object, CoordType &point, float distance)
			{
				this->object	 = object;
				this->point		 = point;
				this->distance = distance;
			}


			ObjectPointer		object;
			CoordType				point;
			float						distance;
		};

		/*
		* The operator used for sorting the items in neighbors based on the distances
		*/
		struct DistanceCompare
		{
			inline bool operator()( const Neighbour &p1, const Neighbour &p2) const { return p1.distance<p2.distance; }
		}; //end of DistanceCompare



public:
		~Octree()
		{
			delete []marks;
			int node_count = NodeCount();
			for (int i=0; i<node_count; i++)
				delete nodes[i];
			nodes.clear();
		}


		/*!
		* Populate the octree
		*/
		template <class OBJECT_ITERATOR, class BOUNDING_BOX_FUNCTOR>
		void Set(const OBJECT_ITERATOR & bObj, const OBJECT_ITERATOR & eObj, const BoundingBoxType &bounding_box, const BOUNDING_BOX_FUNCTOR &bb_functor/*, vcg::CallBackPos *callback=NULL*/) 
		{
			typedef Dereferencer<typename ReferenceType<typename OBJECT_ITERATOR::value_type>::Type >	DereferencerType;

			// Compute the bounding-box enclosing the whole dataset
			BoundingBoxType resulting_bb(bounding_box);
			CoordType offset = bounding_box.Dim()*Octree::EXPANSION_FACTOR;
			CoordType center = bounding_box.Center();
			resulting_bb.Offset(offset);
			float longest_side = vcg::math::Max( resulting_bb.DimX(), vcg::math::Max(resulting_bb.DimY(), resulting_bb.DimZ()) )/2.0f;
			resulting_bb.Set(center);
			resulting_bb.Offset(longest_side);
			boundingBox = resulting_bb;

			// Try to find a reasonable octree depth 
			int dataset_dimension = std::distance(bObj, eObj);

			// Allocate the mark array
			global_mark				= 1;
			marks							= new unsigned char[dataset_dimension];
			memset(&marks[0], 0, sizeof(unsigned char)*dataset_dimension);

			int primitives_per_voxel;
			int depth = 4;
			do 
			{
				int		number_of_voxel = 1<<(3*depth); // i.e. 8^depth
				float density					= float(number_of_voxel)/float(depth);
				primitives_per_voxel	= int(float(dataset_dimension)/density);
				depth++;
			}
			while (primitives_per_voxel>25 && depth<15);
			Initialize(depth);

			// Sort the dataset (using the lebesgue space filling curve...)
			std::string message("Indexing dataset...");
			Octree::NodePointer *route = new Octree::NodePointer[depth+1];
			OBJECT_ITERATOR iObj = bObj;

			//if (callback!=NULL) callback(int((i+1)*100/dataset_dimension), message.c_str());

			std::vector< ObjectPlaceholder< Octree::Node > > placeholders/*(dataset_dimension)*/;
			vcg::Box3<ScalarType>		object_bb;
			vcg::Point3<ScalarType> hit_leaf;
			for (int i=0; i<dataset_dimension; i++, iObj++)
			{
				object_bb = bb_functor(*iObj);
				hit_leaf  = object_bb.min;

				while (object_bb.IsIn(hit_leaf))
				{
					int placeholder_index = placeholders.size();
					placeholders.push_back( ObjectPlaceholder< Octree::Node >() ); 
					placeholders[placeholder_index].z_order			 = BuildRoute(hit_leaf, route);
					placeholders[placeholder_index].leaf_pointer = route[depth];
					placeholders[placeholder_index].object_index = i;					
					
					hit_leaf.X() += leafDimension.X();
					if (hit_leaf.X()>object_bb.max.X())
					{
						hit_leaf.X() = object_bb.min.X();
						hit_leaf.Z()+= leafDimension.Z();
						if (hit_leaf.Z()>object_bb.max.Z())
						{
							hit_leaf.Z() = object_bb.min.Z();
							hit_leaf.Y()+= leafDimension.Y();
						}
					}
				}
			}
			delete []route;

			int placeholder_count = int(placeholders.size());
			std::sort(placeholders.begin(), placeholders.end(), ObjectSorter< Octree::Node >());
			std::vector< Octree::Node* > filled_leaves(placeholder_count);
			sorted_dataset.resize( dataset_dimension );
			for (int i=0; i<placeholder_count; i++)
			{
				std::advance((iObj=bObj), placeholders[i].object_index);
				sorted_dataset[i].pObject				= &DereferencerType::Ref(*iObj);
				sorted_dataset[i].mark_position = i;
				filled_leaves[i]								= placeholders[i].leaf_pointer;
			}

			// The dataset is sorted and the octree is built, but the indexing information aren't stored yet in the octree:
			// we assign to each leaf the range inside the sorted dataset of the primitives contained inside the leaf
			int begin									= -1;
			NodePointer initial_leaf	= NULL;
			for (int end=0; end<placeholder_count; )
			{
				begin = end;
				initial_leaf = filled_leaves[begin];
				do end++;
				while (end<placeholder_count && initial_leaf==filled_leaves[end]);

				VoxelType *voxel = Voxel(initial_leaf);
				voxel->SetRange(begin, end);	
			}

			// The octree is built, the dataset is sorted but only the leaves are indexed: 
			// we propaget the indexing information bottom-up to the root
			IndexInnerNodes( Root() );
		} //end of Set

		/*!
		* Retrive the k closest element to the query point
		*/
		template <class OBJECT_POINT_DISTANCE_FUNCTOR, class OBJECT_MARKER, class OBJECT_POINTER_CONTAINER, class DISTANCE_CONTAINER, class POINT_POINTER_CONTAINER>
		unsigned int GetKClosest
			(
			OBJECT_POINT_DISTANCE_FUNCTOR &distance_functor, 
			OBJECT_MARKER									&/*marker*/, 
			const unsigned int						 k, 
			const CoordType								&query_point, 
			const ScalarType							&max_distance,
			OBJECT_POINTER_CONTAINER			&objects, 
			DISTANCE_CONTAINER						&distances, 
			POINT_POINTER_CONTAINER				&points,
			bool													 sort_per_distance   = false,
			bool													 allow_zero_distance = false
			)
		{
			// costruisco una bounging box centrata in query di dimensione pari a quella di una foglia.
			// e controllo se in tale bounging box sono contenute un numero di elementi >= a k.
			// Altrimenti espando il bounding box.
			BoundingBoxType query_bb;
			query_bb.Set(query_point);

			// Il raggio della sfera centrata nel punto query
			float sphere_radius = 0.0f;

			// se il bounding-box non interseca il bounding-box dell'octree, lo espando subito
			if (!query_bb.IsIn(query_point))
			{
				do
				{ 
					query_bb.Offset(leafDiagonal); 
					sphere_radius += leafDiagonal;
				}
				while ( !boundingBox.Collide(query_bb) || sphere_radius>max_distance); // TODO check the termination condintion
			}

			std::vector< NodePointer > leaves;
			std::vector< Neighbour	 > neighbors;

			unsigned int object_count;
			int					 leaves_count;
			float				 k_distance = leafDiagonal;
			do
			{
				// update the marks
				global_mark = (global_mark+1)%255;
				if (global_mark == 0)
				{
					memset(&marks[0], 0, sizeof(unsigned char)*int(sorted_dataset.size()));
					global_mark++;
				}

				do
				{
					leaves.clear();
					object_count = 0;
					query_bb.Offset(k_distance);
					sphere_radius += vcg::math::Max<float>(leafDiagonal, k_distance);

					ContainedLeaves(query_bb, leaves, Root(), boundingBox);

					leaves_count = int(leaves.size());
					object_count = 0;
					for (int i=0; i<leaves_count; i++)
						object_count += Voxel( leaves[i] )->count;
				}
				while (object_count<k && sphere_radius>max_distance); // TODO check the termination condintion

				// i punti contenuti nelle foglie sono sufficienti. 
				// seleziono solamente i k punti pił vicini.
				CoordType				 closest_point;
				VoxelType				*voxel;
				ObjectReference *ref;
				int							 begin;
				int							 end;
				float						 distance;

				neighbors.clear();
				for (int i=0; i<leaves_count; i++)
				{
					voxel = Voxel(leaves[i]);
					begin = voxel->begin;
					end		= voxel->end;
					for ( ; begin<end; begin++)
					{
						ref				= &sorted_dataset[begin];
						if (marks[ref->mark_position]==global_mark)
							continue;
						
						distance = max_distance;
						if (!distance_functor(*ref->pObject, query_point, distance, closest_point))
							continue;

						marks[ref->mark_position]=global_mark;
						if ((distance!=0.0f || allow_zero_distance)/* && distance<max_distance*/)
							neighbors.push_back( Neighbour(ref->pObject, closest_point, distance) );
					} //end of for ( ; begin<end; begin++)
				} // end of for (int i=0; i<leavesCount; i++)


				if (sphere_radius<max_distance)
				{
					if (int(neighbors.size())<k)
					{
						k_distance = 2.0f*sphere_radius;
						continue;
					}
					else
						object_count = k;
				}
				else 
					object_count=int(neighbors.size());

				std::vector< Neighbour >::iterator first = neighbors.begin();
				std::vector< Neighbour >::iterator last	 = neighbors.end();

				if (sort_per_distance)  std::partial_sort(first, first+object_count, last, DistanceCompare());
				else										std::nth_element (first, first+object_count, last, DistanceCompare()); 
				k_distance = neighbors[object_count-1].distance;
			} 
			while (k_distance>sphere_radius && sphere_radius<max_distance);

			// copy the nearest object into  
			if (points.size()!=object_count) 
			{
				points.resize(object_count);
				distances.resize(object_count);
				objects.resize(object_count);
			}

			POINT_POINTER_CONTAINER::iterator  iPoint			= points.begin();
			DISTANCE_CONTAINER::iterator			 iDistance	= distances.begin();
			OBJECT_POINTER_CONTAINER::iterator iObject		= objects.begin();
			for (unsigned int n=0; n<object_count; n++, iPoint++, iDistance++, iObject++)
			{
				(*iPoint)		 = neighbors[n].point;
				(*iDistance) = neighbors[n].distance;
				(*iObject)	 = neighbors[n].object;
			}
			return object_count;
		}; //end of GetKClosest


		/*!
		* Draw the octree in a valid OpenGL context according to the rendering settings
		*/
		void Octree::DrawOctree(vcg::Box3f &boundingBox, NodePointer n)
		{
			char level = Level(n);
			NodePointer son;
			if (rendering_settings.minVisibleDepth>level)
			{
				for (int s=0; s<8; s++)
					if ((son=Son(n, s))!=0)
						DrawOctree(SubBox(boundingBox, s), son);
			}
			else
			{
				vcg::glBoxWire(boundingBox);
				if (level<rendering_settings.maxVisibleDepth)
					for (int s=0; s<8; s++)
						if ((son=Son(n, s))!=0)
							DrawOctree(SubBox(boundingBox, s), son);
			}
		};

	protected:
		/*!
		* Contains pointer to the objects in the dataset. 
		* The pointers are sorted so that the object pointed to result ordered in the space
		*/
		std::vector< ObjectReference >	sorted_dataset;

		/*!
		* Markers used to avoid duplication of the same result during a query
		*/
		unsigned char	*marks;
		unsigned char  global_mark;

	public:
		OcreeRenderingSetting					rendering_settings;

	protected:
		/*!
		* When all the leaves are indexed, this procedure is called in order to propagate the indexing information to the inner nodes
		*/
		void IndexInnerNodes(NodePointer n)
		{
			assert(n!=NULL);

			VoxelPointer current_voxel = Voxel(n);
			VoxelPointer son_voxel;
			for (int s=0; s<8; s++)
			{
				NodePointer son_index = Son(n, s);
				if (son_index!=NULL)
				{
					if (Level(son_index)!=maximumDepth)
						IndexInnerNodes(son_index);

					son_voxel = Voxel(son_index);
					current_voxel->AddRange( son_voxel );
				}
			}
		}; // end of IndexInnerNodes
	};


} //end of namespace vcg

#endif //OCTREE_H