/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (C) 2006 Refractions Research Inc.
 *
 * This is free software; you can redistribute and/or modify it under
 * the terms of the GNU Lesser General Public Licence as published
 * by the Free Software Foundation. 
 * See the COPYING file for more information.
 *
 **********************************************************************/

#ifndef GEOS_INDEX_STRTREE_ABSTRACTSTRTREE_H
#define GEOS_INDEX_STRTREE_ABSTRACTSTRTREE_H

#include <geos/export.h>

#include <geos/index/strtree/AbstractNode.h> // for inlines

#include <vector>
#include <list>
#include <memory> // for auto_ptr
#include <cassert> // for inlines
#include <algorithm>

// Forward declarations
namespace geos {
	namespace index { 
		class ItemVisitor;
		namespace strtree { 
			class Boundable;
			class AbstractNode;
		}
	}
}

namespace geos {
namespace index { // geos::index
namespace strtree { // geos::index::strtree

/// A list of boundables. TODO: use a list
typedef std::vector<Boundable*> BoundableList;
//typedef std::list<Boundable*> BoundableList;

/// list contains boundables or lists of boundables. The lists are owned by 
/// this class, the plain boundables are held by reference only.
class ItemsList;

class ItemsListItem
{
public:
    enum type {
        item_is_geometry,
        item_is_list
    };

    ItemsListItem(void *item_)
      : t(item_is_geometry)
    {
        item.g = item_;
    }
    ItemsListItem(ItemsList* item_)
      : t(item_is_list)
    {
        item.l = item_;
    }

    type get_type() const { return t; }

    void* get_geometry() const
    {
        assert(t == item_is_geometry);
        return item.g;
    }
    ItemsList* get_itemslist() const
    {
        assert(t == item_is_list);
        return item.l;
    }

    type t;
    union {
        void* g;
        ItemsList* l;
    } item;
};

class ItemsList : public std::vector<ItemsListItem>
{
private:
    typedef std::vector<ItemsListItem> base_type;

    static void delete_item(ItemsListItem& item)
    {
        if (ItemsListItem::item_is_list == item.t)
            delete item.item.l;
    }

public:
    ~ItemsList()
    {
        std::for_each(begin(), end(), &ItemsList::delete_item);
    }

    // lists of items need to be deleted in the end
    void push_back(void* item)
    {
        this->base_type::push_back(ItemsListItem(item));
    }

    // lists of items need to be deleted in the end
    void push_back_owned(ItemsList* itemList)
    {
        this->base_type::push_back(ItemsListItem(itemList));
    }
};

/** \brief
 * Base class for STRtree and SIRtree.
 *
 * STR-packed R-trees are described in:
 * P. Rigaux, Michel Scholl and Agnes Voisard. Spatial Databases With
 * Application To GIS. Morgan Kaufmann, San Francisco, 2002.
 * 
 * This implementation is based on Boundables rather than just AbstractNodes, 
 * because the STR algorithm operates on both nodes and 
 * data, both of which are treated here as Boundables.
 * 
 */
class GEOS_DLL AbstractSTRtree {

private:
	bool built;
	BoundableList* itemBoundables;

	/**
	 * Creates the levels higher than the given level
	 * 
	 * @param boundablesOfALevel
	 *            the level to build on
	 * @param level
	 *            the level of the Boundables, or -1 if the boundables are item
	 *            boundables (that is, below level 0)
	 * @return the root, which may be a ParentNode or a LeafNode
	 */
	virtual AbstractNode* createHigherLevels(
			BoundableList* boundablesOfALevel,
			int level);

	virtual std::auto_ptr<BoundableList> sortBoundables(const BoundableList* input)=0;

	bool remove(const void* searchBounds, AbstractNode& node, void* item);
	bool removeItem(AbstractNode& node, void* item);

    ItemsList* itemsTree(AbstractNode* node);

protected:

	/** \brief
	 * A test for intersection between two bounds, necessary because
	 * subclasses of AbstractSTRtree have different implementations of
	 * bounds. 
	 */
	class GEOS_DLL IntersectsOp {
		public:
			/**
			 * For STRtrees, the bounds will be Envelopes; for
			 * SIRtrees, Intervals; for other subclasses of
			 * AbstractSTRtree, some other class.
			 * @param aBounds the bounds of one spatial object
			 * @param bBounds the bounds of another spatial object
			 * @return whether the two bounds intersect
			 */
			virtual bool intersects(const void* aBounds,
					const void* bBounds)=0;

			virtual ~IntersectsOp() {}
	};

	AbstractNode *root;

	std::vector <AbstractNode *> *nodes;

	// Ownership to caller (TODO: return by auto_ptr)
	virtual AbstractNode* createNode(int level)=0;

	/**
	 * Sorts the childBoundables then divides them into groups of size M, where
	 * M is the node capacity.
	 */
	virtual std::auto_ptr<BoundableList> createParentBoundables(
			BoundableList* childBoundables, int newLevel);

	virtual AbstractNode* lastNode(BoundableList* nodes)
	{
		assert(!nodes->empty());
		// Cast from Boundable to AbstractNode
		return static_cast<AbstractNode*>( nodes->back() );
	}

	virtual AbstractNode* getRoot() {
                assert(built);
		return root;
	}

	///  Also builds the tree, if necessary.
	virtual void insert(const void* bounds,void* item);

	///  Also builds the tree, if necessary.
	void query(const void* searchBounds, std::vector<void*>& foundItems);

#if 0
	///  Also builds the tree, if necessary.
	std::vector<void*>* query(const void* searchBounds) {
		vector<void*>* matches = new vector<void*>();
		query(searchBounds, *matches);
		return matches;
	}
#endif
	///  Also builds the tree, if necessary.
	void query(const void* searchBounds, ItemVisitor& visitor);

	void query(const void* searchBounds, const AbstractNode& node, ItemVisitor& visitor);
  
	///  Also builds the tree, if necessary.
	bool remove(const void* itemEnv, void* item);

	std::auto_ptr<BoundableList> boundablesAtLevel(int level);

	// @@ should be size_t, probably
	std::size_t nodeCapacity;

	/**
	 * @return a test for intersection between two bounds,
	 * necessary because subclasses
	 * of AbstractSTRtree have different implementations of bounds.
	 * @see IntersectsOp
	 */
	virtual IntersectsOp *getIntersectsOp()=0;
 

public:

	/**
	 * Constructs an AbstractSTRtree with the specified maximum number of child
	 * nodes that a node may have
	 */
	AbstractSTRtree(std::size_t newNodeCapacity)
		:
		built(false),
		itemBoundables(new BoundableList()),
		nodes(new std::vector<AbstractNode *>()),
		nodeCapacity(newNodeCapacity)
	{
		assert(newNodeCapacity>1);
	}

	static bool compareDoubles(double a, double b) {
		// NOTE - strk:
		// Ternary operation is a workaround for
		// a probable MingW bug, see
		// http://trac.osgeo.org/geos/ticket/293
		return ( a < b ) ? true : false;
	}

	virtual ~AbstractSTRtree();

	/**
	 * Creates parent nodes, grandparent nodes, and so forth up to the root
	 * node, for the data that has been inserted into the tree. Can only be
	 * called once, and thus can be called only after all of the data has been
	 * inserted into the tree.
	 */
	virtual void build();

	/**
	 * Returns the maximum number of child nodes that a node may have
	 */
	virtual std::size_t getNodeCapacity() { return nodeCapacity; }

	virtual void query(const void* searchBounds, const AbstractNode* node, std::vector<void*>* matches);

	/**
         * Iterate over all items added thus far.  Explicitly does not build
         * the tree.
         */
	void iterate(ItemVisitor& visitor);


	/**
	 * @param level -1 to get items
	 */
	virtual void boundablesAtLevel(int level, AbstractNode* top,
			BoundableList* boundables);

    /**
     * Gets a tree structure (as a nested list) 
     * corresponding to the structure of the items and nodes in this tree.
     * <p>
     * The returned {@link List}s contain either {@link Object} items, 
     * or Lists which correspond to subtrees of the tree
     * Subtrees which do not contain any items are not included.
     * <p>
     * Builds the tree if necessary.
     * 
     * @note The caller is responsible for releasing the list
     *
     * @return a List of items and/or Lists
     */
    ItemsList* itemsTree();
};


} // namespace geos::index::strtree
} // namespace geos::index
} // namespace geos

#endif // GEOS_INDEX_STRTREE_ABSTRACTSTRTREE_H
