#ifndef GLTB_REFERENCEDOBJECT_H_
#define GLTB_REFERENCEDOBJECT_H_

#include "GLTB/atomicops.h"

namespace gltb {
	class ReferencedObject;

	struct ReferenceCounters {
	    ReferenceCounters() : object(nullptr), referenceCount(0), weakReferenceCount(0), spinlock(0) {}

	    ReferencedObject *object;
	    int referenceCount;
	    int weakReferenceCount;
	    unsigned char spinlock;

	    void lock() { while(atomicCAS(&spinlock, 0, 1) != 0); }
	    void unlock() { atomicDec(&spinlock); }
	};
	
	class ReferencedObject {
		public:
			ReferencedObject()
			{
				refCounters = new ReferenceCounters();
				refCounters->object = this;
			}

			virtual ~ReferencedObject() {}

			void increaseReferenceCount()
			{
				int oldRefCount, newRefCount;

				do {
					oldRefCount = refCounters->referenceCount;
					if(oldRefCount < 0) {
						return;
					}
					newRefCount = oldRefCount + 1;
				} while(atomicCAS(&refCounters->referenceCount, oldRefCount, newRefCount) != oldRefCount);
			}

			void decreaseReferenceCount()
			{
		        int oldRefCount, newRefCount;

		        refCounters->lock();

		        do {
					oldRefCount = refCounters->referenceCount;
					newRefCount = oldRefCount - 1;
					// if reference count would be 0, set it to -1 instead to immediately block increments
					if(newRefCount == 0) {
							newRefCount = -1;
					}
		        } while(atomicCAS(&refCounters->referenceCount, oldRefCount, newRefCount) != oldRefCount);

		        // test against newRefCount here because referenceCount may have been modified again after the compare_exchange
		        if(newRefCount == -1) {
					// delete reference counters if no weak references left, either
					if(refCounters->weakReferenceCount == 0) {
						delete refCounters;
					} else {
						refCounters->object = nullptr;
			        	refCounters->unlock();
					}

					delete this;
		        } else {
		        	refCounters->unlock();
		        }
			}

			int getReferenceCount() { return refCounters->referenceCount; };

			// internal method to get to reference counters; required by WeakPtr class
			ReferenceCounters *_getReferenceCounters() { return refCounters; }

		private:
			ReferenceCounters *refCounters;
	};
}

#endif /*GLTB_REFERENCEDOBJECT_H_*/