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/*
 * Java port of Bullet (c) 2008 Martin Dvorak 
 *
 * Bullet Continuous Collision Detection and Physics Library
 * Copyright (c) 2003-2008 Erwin Coumans  http://www.bulletphysics.com/
 *
 * This software is provided 'as-is', without any express or implied warranty.
 * In no event will the authors be held liable for any damages arising from
 * the use of this software.
 * 
 * Permission is granted to anyone to use this software for any purpose, 
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 * 
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 */

package com.bulletphysics.collision.broadphase;

import com.bulletphysics.BulletStats;
import com.bulletphysics.util.ObjectPool;
import com.bulletphysics.linearmath.MiscUtil;
import com.bulletphysics.util.IntArrayList;
import com.bulletphysics.util.ObjectArrayList;

/**
 * Hash-space based {@link OverlappingPairCache}.
 * 
 * @author jezek2
 */
public class HashedOverlappingPairCache extends OverlappingPairCache {

	private final ObjectPool pairsPool = ObjectPool.get(BroadphasePair.class);
	
	private static final int NULL_PAIR = 0xffffffff;
	
	private ObjectArrayList overlappingPairArray = new ObjectArrayList();
	private OverlapFilterCallback overlapFilterCallback;
	private boolean blockedForChanges = false;
	
	private IntArrayList hashTable = new IntArrayList();
	private IntArrayList next = new IntArrayList();
	protected OverlappingPairCallback ghostPairCallback;

	public HashedOverlappingPairCache() {
		int initialAllocatedSize = 2;
		// JAVA TODO: overlappingPairArray.ensureCapacity(initialAllocatedSize);
		growTables();
	}

	/**
	 * Add a pair and return the new pair. If the pair already exists,
	 * no new pair is created and the old one is returned.
	 */
	public BroadphasePair addOverlappingPair(BroadphaseProxy proxy0, BroadphaseProxy proxy1) {
		BulletStats.gAddedPairs++;

		if (!needsBroadphaseCollision(proxy0, proxy1)) {
			return null;
		}

		return internalAddPair(proxy0,proxy1);
	}

	public Object removeOverlappingPair(BroadphaseProxy proxy0, BroadphaseProxy proxy1, Dispatcher dispatcher) {
		BulletStats.gRemovePairs++;
		if (proxy0.getUid() > proxy1.getUid()) {
			BroadphaseProxy tmp = proxy0;
			proxy0 = proxy1;
			proxy1 = tmp;
		}
		int proxyId1 = proxy0.getUid();
		int proxyId2 = proxy1.getUid();

		/*if (proxyId1 > proxyId2) 
		btSwap(proxyId1, proxyId2);*/

		int hash = getHash(proxyId1, proxyId2) & (overlappingPairArray.capacity() - 1);

		BroadphasePair pair = internalFindPair(proxy0, proxy1, hash);
		if (pair == null) {
			return null;
		}

		cleanOverlappingPair(pair, dispatcher);

		Object userData = pair.userInfo;

		assert (pair.pProxy0.getUid() == proxyId1);
		assert (pair.pProxy1.getUid() == proxyId2);

		// JAVA TODO: optimize
		//int pairIndex = int(pair - &m_overlappingPairArray[0]);
		int pairIndex = overlappingPairArray.indexOf(pair);
		assert (pairIndex != -1);

		assert (pairIndex < overlappingPairArray.size());

		// Remove the pair from the hash table.
		int index = hashTable.get(hash);
		assert (index != NULL_PAIR);

		int previous = NULL_PAIR;
		while (index != pairIndex) {
			previous = index;
			index = next.get(index);
		}

		if (previous != NULL_PAIR) {
			assert (next.get(previous) == pairIndex);
			next.set(previous, next.get(pairIndex));
		}
		else {
			hashTable.set(hash, next.get(pairIndex));
		}

		// We now move the last pair into spot of the
		// pair being removed. We need to fix the hash
		// table indices to support the move.

		int lastPairIndex = overlappingPairArray.size() - 1;

		if (ghostPairCallback != null) {
			ghostPairCallback.removeOverlappingPair(proxy0, proxy1, dispatcher);
		}

		// If the removed pair is the last pair, we are done.
		if (lastPairIndex == pairIndex) {
			overlappingPairArray.removeQuick(overlappingPairArray.size() - 1);
			return userData;
		}

		// Remove the last pair from the hash table.
		BroadphasePair last = overlappingPairArray.getQuick(lastPairIndex);
		/* missing swap here too, Nat. */
		int lastHash = getHash(last.pProxy0.getUid(), last.pProxy1.getUid()) & (overlappingPairArray.capacity() - 1);

		index = hashTable.get(lastHash);
		assert (index != NULL_PAIR);

		previous = NULL_PAIR;
		while (index != lastPairIndex) {
			previous = index;
			index = next.get(index);
		}

		if (previous != NULL_PAIR) {
			assert (next.get(previous) == lastPairIndex);
			next.set(previous, next.get(lastPairIndex));
		}
		else {
			hashTable.set(lastHash, next.get(lastPairIndex));
		}

		// Copy the last pair into the remove pair's spot.
		overlappingPairArray.getQuick(pairIndex).set(overlappingPairArray.getQuick(lastPairIndex));

		// Insert the last pair into the hash table
		next.set(pairIndex, hashTable.get(lastHash));
		hashTable.set(lastHash, pairIndex);

		overlappingPairArray.removeQuick(overlappingPairArray.size() - 1);

		return userData;
	}

	public boolean needsBroadphaseCollision(BroadphaseProxy proxy0, BroadphaseProxy proxy1) {
		if (overlapFilterCallback != null) {
			return overlapFilterCallback.needBroadphaseCollision(proxy0, proxy1);
		}

		boolean collides = (proxy0.collisionFilterGroup & proxy1.collisionFilterMask) != 0;
		collides = collides && (proxy1.collisionFilterGroup & proxy0.collisionFilterMask) != 0;

		return collides;
	}
	
	@Override
	public void processAllOverlappingPairs(OverlapCallback callback, Dispatcher dispatcher) {
		//	printf("m_overlappingPairArray.size()=%d\n",m_overlappingPairArray.size());
		for (int i=0; i getOverlappingPairArray() {
		return overlappingPairArray;
	}

	@Override
	public void cleanOverlappingPair(BroadphasePair pair, Dispatcher dispatcher) {
		if (pair.algorithm != null) {
			//pair.algorithm.destroy();
			dispatcher.freeCollisionAlgorithm(pair.algorithm);
			pair.algorithm = null;
		}
	}

	@Override
	public BroadphasePair findPair(BroadphaseProxy proxy0, BroadphaseProxy proxy1) {
		BulletStats.gFindPairs++;
		if (proxy0.getUid() > proxy1.getUid()) {
			BroadphaseProxy tmp = proxy0;
			proxy0 = proxy1;
			proxy1 = proxy0;
		}
		int proxyId1 = proxy0.getUid();
		int proxyId2 = proxy1.getUid();

		/*if (proxyId1 > proxyId2) 
			btSwap(proxyId1, proxyId2);*/

		int hash = getHash(proxyId1, proxyId2) & (overlappingPairArray.capacity()-1);

		if (hash >= hashTable.size())
		{
			return null;
		}

		int index = hashTable.get(hash);
		while (index != NULL_PAIR && equalsPair(overlappingPairArray.getQuick(index), proxyId1, proxyId2) == false)
		{
			index = next.get(index);
		}

		if (index == NULL_PAIR)
		{
			return null;
		}

		assert(index < overlappingPairArray.size());

		return overlappingPairArray.getQuick(index);
	}

	public int getCount() {
		return overlappingPairArray.size();
	}

//	btBroadphasePair* GetPairs() { return m_pairs; }
	public OverlapFilterCallback getOverlapFilterCallback() {
		return overlapFilterCallback;
	}

	@Override
	public void setOverlapFilterCallback(OverlapFilterCallback overlapFilterCallback) {
		this.overlapFilterCallback = overlapFilterCallback;
	}

	@Override
	public int getNumOverlappingPairs() {
		return overlappingPairArray.size();
	}

	@Override
	public boolean hasDeferredRemoval() {
		return false;
	}
	
	private BroadphasePair internalAddPair(BroadphaseProxy proxy0, BroadphaseProxy proxy1) {
		if (proxy0.getUid() > proxy1.getUid()) {
			BroadphaseProxy tmp = proxy0;
			proxy0 = proxy1;
			proxy1 = tmp;
		}
		int proxyId1 = proxy0.getUid();
		int proxyId2 = proxy1.getUid();

		/*if (proxyId1 > proxyId2) 
		btSwap(proxyId1, proxyId2);*/

		int hash = getHash(proxyId1, proxyId2) & (overlappingPairArray.capacity() - 1); // New hash value with new mask

		BroadphasePair pair = internalFindPair(proxy0, proxy1, hash);
		if (pair != null) {
			return pair;
		}
		/*for(int i=0;i%u\r\n",proxyId1,proxyId2);
		internalFindPair(proxy0, proxy1, hash);
		}
		}*/
		int count = overlappingPairArray.size();
		int oldCapacity = overlappingPairArray.capacity();
		overlappingPairArray.add(null);

		// this is where we add an actual pair, so also call the 'ghost'
		if (ghostPairCallback != null) {
			ghostPairCallback.addOverlappingPair(proxy0, proxy1);
		}

		int newCapacity = overlappingPairArray.capacity();

		if (oldCapacity < newCapacity) {
			growTables();
			// hash with new capacity
			hash = getHash(proxyId1, proxyId2) & (overlappingPairArray.capacity() - 1);
		}

		pair = new BroadphasePair(proxy0, proxy1);
		//	pair->m_pProxy0 = proxy0;
		//	pair->m_pProxy1 = proxy1;
		pair.algorithm = null;
		pair.userInfo = null;

		overlappingPairArray.setQuick(overlappingPairArray.size() - 1, pair);

		next.set(count, hashTable.get(hash));
		hashTable.set(hash, count);

		return pair;
	}

	private void growTables() {
		int newCapacity = overlappingPairArray.capacity();

		if (hashTable.size() < newCapacity) {
			// grow hashtable and next table
			int curHashtableSize = hashTable.size();

			MiscUtil.resize(hashTable, newCapacity, 0);
			MiscUtil.resize(next, newCapacity, 0);

			for (int i=0; i proxyId2) 
				btSwap(proxyId1, proxyId2);*/
				int hashValue = getHash(proxyId1, proxyId2) & (overlappingPairArray.capacity() - 1); // New hash value with new mask
				next.set(i, hashTable.get(hashValue));
				hashTable.set(hashValue, i);
			}
		}
	}

	private boolean equalsPair(BroadphasePair pair, int proxyId1, int proxyId2) {
		return pair.pProxy0.getUid() == proxyId1 && pair.pProxy1.getUid() == proxyId2;
	}

	private int getHash(int proxyId1, int proxyId2) {
		int key = (proxyId1) | (proxyId2 << 16);
		// Thomas Wang's hash

		key += ~(key << 15);
		key ^= (key >>> 10);
		key += (key << 3);
		key ^= (key >>> 6);
		key += ~(key << 11);
		key ^= (key >>> 16);
		return key;
	}

	private BroadphasePair internalFindPair(BroadphaseProxy proxy0, BroadphaseProxy proxy1, int hash) {
		int proxyId1 = proxy0.getUid();
		int proxyId2 = proxy1.getUid();
		//#if 0 // wrong, 'equalsPair' use unsorted uids, copy-past devil striked again. Nat.
		//if (proxyId1 > proxyId2) 
		//	btSwap(proxyId1, proxyId2);
		//#endif

		int index = hashTable.get(hash);

		while (index != NULL_PAIR && equalsPair(overlappingPairArray.getQuick(index), proxyId1, proxyId2) == false) {
			index = next.get(index);
		}

		if (index == NULL_PAIR) {
			return null;
		}

		assert (index < overlappingPairArray.size());

		return overlappingPairArray.getQuick(index);
	}

	public void setInternalGhostPairCallback(OverlappingPairCallback ghostPairCallback) {
		this.ghostPairCallback = ghostPairCallback;
	}
	
	////////////////////////////////////////////////////////////////////////////

	private static class RemovePairCallback extends OverlapCallback {
		private BroadphaseProxy obsoleteProxy;

		public RemovePairCallback(BroadphaseProxy obsoleteProxy) {
			this.obsoleteProxy = obsoleteProxy;
		}

		public boolean processOverlap(BroadphasePair pair) {
			return ((pair.pProxy0 == obsoleteProxy) ||
					(pair.pProxy1 == obsoleteProxy));
		}
	}

	private static class CleanPairCallback extends OverlapCallback {
		private BroadphaseProxy cleanProxy;
		private OverlappingPairCache pairCache;
		private Dispatcher dispatcher;

		public CleanPairCallback(BroadphaseProxy cleanProxy, OverlappingPairCache pairCache, Dispatcher dispatcher) {
			this.cleanProxy = cleanProxy;
			this.pairCache = pairCache;
			this.dispatcher = dispatcher;
		}

		public boolean processOverlap(BroadphasePair pair) {
			if ((pair.pProxy0 == cleanProxy) ||
					(pair.pProxy1 == cleanProxy)) {
				pairCache.cleanOverlappingPair(pair, dispatcher);
			}
			return false;
		}
	}
	
}