#ifndef _GtpVisibilityHierarchyInterface_H__
#define _GtpVisibilityHierarchyInterface_H__

#include "DistanceQueue.h"

namespace GtpVisibility {

/**	Class which implements a hierarchy interface for a scene hierarchy.
*/
class HierarchyInterface
{
public:
	/** Default constructor.
	*/
	HierarchyInterface();
	virtual ~HierarchyInterface();
	/** Returns true if current node is leaf of the hierarchy. 
		@param node hierarchy node
		@returns true if node is leaf
	*/
    virtual bool IsLeaf(HierarchyNode *node) const = 0;
	/** Traverses the given node. 
		@param node the hierarchy node
	*/
	virtual void TraverseNode(HierarchyNode *node) = 0;
	/** Renders current scene node .
		@param node current scene node to be rendered
	*/
	virtual void RenderNode(HierarchyNode *node) = 0;
	/** Pulls up the visibility from the current node recursively to the parent nodes. 
		@param node the current node 
	*/
	virtual void PullUpVisibility(HierarchyNode *node) = 0;
	/** Issue a occlusion query for this node. 
		@param node the current hierarchy node
		@returns occlusion query for this node
	*/
	virtual OcclusionQuery *IssueOcclusionQuery(HierarchyNode *node) = 0;
	/** Sets the root of the scene hierarchy.
		@param root the hierarchy root
	*/
	void SetSceneRoot(HierarchyNode *root);
    /** Get the root of the scene hierarchy.
		@return the hierarchy root
	*/
	HierarchyNode *GetSceneRoot() const;
	/** Sets the scene root and initialises this scene traverser for a traversal.
		@param root current scene root
		@remark initialises some parameters, and also the statistics.
	*/
	void InitFrame(HierarchyNode *root);
	/** Returns current frame id.
		@returns frame id
	*/
	unsigned int GetFrameId() const;
	/** Returns the current distance queue.
		@returns current distance queue
	*/
	DistanceQueue *GetQueue();
	/** Returns true if node 1 has greater distance to the view
		plane than node 2.
		@param node1 the first node to be compared
		@param node2 the second node to be compared
	*/			
	virtual bool HasGreaterDistance(HierarchyNode *node1, HierarchyNode *node2) const = 0;
	/** Checks if the node is visible from the current view frustum.
		@param node the current node
		@param intersects returns true if the current node intersects the near plane
	*/
	virtual bool CheckFrustumVisible(HierarchyNode *node, bool &intersects) = 0;
	/** Checks if the node is visible from the current view frustum.
		@param node the current node
	*/
	bool CheckFrustumVisible(HierarchyNode *node);
	/** Returns next available occlusion query or creates new one.
		@return the next occlusion query
	*/
	virtual OcclusionQuery *GetNextOcclusionQuery() = 0;
	/** Returns true if there is renderable geometry attached to this node
		@param node the current node
		@returns if the node has renderable geometry
	*/
    virtual bool HasGeometry(HierarchyNode *node) const = 0;
	/** Sets the visible flag for this node.
		@param node the current node
		@param visible the visible flag
	*/
	virtual void SetNodeVisible(HierarchyNode *node, const bool visible) = 0;
	/** Returns true if node has the visible flag set. See set
	*/
	virtual bool IsNodeVisible(HierarchyNode *node) const = 0;
	/** Sets the last visited frame id for this node.
		@param node the current node
		@param frameId the current frame id
	*/
	virtual void SetLastVisited(HierarchyNode *node, 
								const unsigned int frameId) = 0;
	/** Returns frame id when this node was last visited by the traverser. See set
	*/
	virtual unsigned int LastVisited(HierarchyNode *node) const = 0;
	/** Returns number of traversed nodes.
	*/
	unsigned int GetNumTraversedNodes();
	/** Returns number of rendered nodes.
	*/
	unsigned int GetNumRenderedNodes();

protected:
	
	unsigned int mFrameId;

	int mCurrentTestIdx;
	
	//--- statistics
	unsigned int mNumTraversedNodes;
	unsigned int mNumRenderedNodes;

	DistanceQueue *mDistanceQueue;
	HierarchyNode *mSceneRoot;
	//HierarchyNode *mCurrentNode;
};
} // namespace GtpVisibility
#endif // GtpVisisibilityHierarchyInterface_H