#include <iostream>
#include <stack>
#include "ObjectPvs.h"
#include "Intersectable.h"
#include "IntersectableWrapper.h"
#include "KdTree.h"
#include "common.h"
#include "BvHierarchy.h"

using namespace std;

namespace GtpVisibilityPreprocessor {


/** the pvs is the number of different objects in the node leaves
	We eliminate already accounted kd nodes and objects using mailboxing. 
*/
static int EvalKdNodeContribution(KdIntersectable *kdobj)
{
	int pvs = 0;
	stack<KdNode *> tStack;

	tStack.push(kdobj->GetItem());

	while (!tStack.empty())
	{
		KdNode *node = tStack.top();
		tStack.pop();

		// already processed node (=> objects already in pvs)?
		if (!node->Mailed())
		{
			node->Mail();

			if (node->IsLeaf())
			{
				KdLeaf *leaf = static_cast<KdLeaf *>(node);
                       
				// add #objects exclusivly in this node
				pvs += (int)(leaf->mObjects.size() - leaf->mMultipleObjects.size());

				// Objects already accounted for can only be found among those
				// which are referenced in more than one leaf
				ObjectContainer::const_iterator oit, oit_end = leaf->mMultipleObjects.end();
						
				for (oit = leaf->mMultipleObjects.begin(); oit != oit_end; ++ oit)
				{
					Intersectable *object = *oit;						
                            
					if (!object->Mailed())
					{
						object->Mail();
						++ pvs;
					}
				}
			}
			else // traverse tree
			{
				KdInterior *interior = static_cast<KdInterior *>(node);

				tStack.push(interior->mFront);
				tStack.push(interior->mBack);
			}
		}
	}

	return pvs;
}


/** Returns the the number of new (unmailed) objects in the leaves of the node.
	We eliminate already accounted bvh nodes and objects using mailboxing. 
*/
static float EvalBvhNodeContribution(BvhNode *bvhObj)
{
	BvhNode *node;

	// hack for choosing which node to account for
	if (bvhObj->IsLeaf())
		node = static_cast<BvhLeaf *>(bvhObj)->GetActiveNode();
	else
		node = bvhObj;

	// early exit
	if (node->IsLeaf())	
	{	
		BvhLeaf *leaf = static_cast<BvhLeaf *>(node);
		// objects already accounted for
		if (leaf->Mailed())
			return 0;

		leaf->Mail();
		return BvHierarchy::EvalAbsCost(leaf->mObjects);
	}			 

	// compute leaf pvs
	float pvs = 0;
	stack<BvhNode *> tStack;
	tStack.push(node);

	while (!tStack.empty())
	{
		node = tStack.top();
		tStack.pop();

		// already processed node (=> objects already in pvs)?
		if (!node->Mailed())
		{
			node->Mail();

			if (node->IsLeaf())
			{
				BvhLeaf *leaf = static_cast<BvhLeaf *>(node);

				// add #objects exclusivly in this node
				pvs += BvHierarchy::EvalAbsCost(leaf->mObjects);
			}
			else // traverse tree
			{
				BvhInterior *interior = static_cast<BvhInterior *>(node);

				tStack.push(interior->GetFront());
				tStack.push(interior->GetBack());
			}
		}
	}

	return pvs;
}


float ObjectPvs::EvalPvsCost() const
{
	float pvs = 0;

	Intersectable::NewMail();
	KdLeaf::NewMail();

	ObjectPvsIterator pit = GetIterator();

	while (pit.HasMoreEntries())
	{		
		Intersectable *obj = pit.Next();

		switch (obj->Type())
		{
			case Intersectable::KD_INTERSECTABLE:
				{
					// found kd node
					KdIntersectable *kdObj = static_cast<KdIntersectable *>(obj);
					pvs += EvalKdNodeContribution(kdObj);	
					break;
				}
			case Intersectable::BVH_INTERSECTABLE:
				{
					BvhNode *bvhObj = static_cast<BvhNode *>(obj);
					pvs += EvalBvhNodeContribution(bvhObj);
					break;
				}
			default:
				// hack: should use assigned cost here
				++ pvs;
				
				break;
		}
	}

	return pvs;
}

}