/**
 * Copyright - See the COPYRIGHT that is included with this distribution.
 * pvAccessCPP is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution.
 */

#ifndef NAMEDLOCKPATTERN_H
#define NAMEDLOCKPATTERN_H

#include <map>
#include <iostream>

#include <pv/lock.h>
#include <pv/pvType.h>
#include <pv/sharedPtr.h>

#include <pv/referenceCountingLock.h>

// TODO implement using smart pointers

namespace epics { namespace pvAccess {

/**
 * NamedLockPattern
 */
template <class Key, class Compare = std::less<Key> >
class NamedLockPattern
{
public:
	/**
	 * Constructor.
	 */
	NamedLockPattern() {};
	/**
	 * Destructor.
	 */
	virtual ~NamedLockPattern() {};
	/**
	 * Acquire synchronization lock for named object.
	 *
	 * NOTE: Argument msecs is currently not supported due to
	 * Darwin OS not supporting pthread_mutex_timedlock. May be changed in the future.
	 *
	 * @param	name	name of the object whose lock to acquire.
	 * @param	msec	the number of milleseconds to wait.
	 * 					An argument less than or equal to zero means not to wait at all.
	 * @return	<code>true</code> if acquired, <code>false</code> othwerwise.
	 * 			NOTE: currently this routine always returns true. Look above for explanation.
	 */
	bool acquireSynchronizationObject(const Key& name, const epics::pvData::int64 msec);
	/**
	 * Release synchronization lock for named object.
	 * @param	name	name of the object whose lock to release.
	 */
	void releaseSynchronizationObject(const Key& name);
private:
	epics::pvData::Mutex _mutex;
	std::map<const Key,ReferenceCountingLock::shared_pointer,Compare> _namedLocks;
	typename std::map<const Key,ReferenceCountingLock::shared_pointer,Compare>::iterator _namedLocksIter;

	/**
	 * Release synchronization lock for named object.
	 * @param	name	name of the object whose lock to release.
	 * @param	release	set to <code>false</code> if there is no need to call release
	 * 					on synchronization lock.
	 */
	void releaseSynchronizationObject(const Key& name,const bool release);
};

template <class Key, class Compare>
bool NamedLockPattern<Key,Compare>::acquireSynchronizationObject(const Key& name, const epics::pvData::int64 msec)
{
	ReferenceCountingLock::shared_pointer lock;
	{	//due to guard
		epics::pvData::Lock guard(_mutex);

		_namedLocksIter = _namedLocks.find(name);
		// get synchronization object

		// none is found, create and return new one
		// increment references
		if(_namedLocksIter == _namedLocks.end())
		{
			lock.reset(new ReferenceCountingLock());
			_namedLocks[name] = lock;
		}
		else
		{
			lock = _namedLocksIter->second;
			lock->increment();
		}
	} // end of guarded area

	bool success = lock->acquire(msec);

	if(!success)
	{
		releaseSynchronizationObject(name, false);
	}

	return success;
}

template <class Key, class Compare>
void NamedLockPattern<Key,Compare>::releaseSynchronizationObject(const Key& name)
{
	releaseSynchronizationObject(name, true);
}

template <class Key, class Compare>
void NamedLockPattern<Key,Compare>::releaseSynchronizationObject(const Key& name,const bool release)
{
	epics::pvData::Lock guard(_mutex);
	ReferenceCountingLock::shared_pointer lock;
	_namedLocksIter = _namedLocks.find(name);

	// release lock
	if (_namedLocksIter != _namedLocks.end())
	{
		lock = _namedLocksIter->second;

		// release the lock
		if (release)
		{
			lock->release();
		}

		// if there only one current lock exists
		// remove it from the map
		if (lock->decrement() <= 0)
		{
			_namedLocks.erase(_namedLocksIter);
		}
	}
}

template <class Key, class Compare>
class NamedLock : private epics::pvData::NoDefaultMethods
{
public:
	NamedLock(NamedLockPattern<Key,Compare>* namedLockPattern): _namedLockPattern(namedLockPattern) {}
	bool acquireSynchronizationObject(const Key& name, const epics::pvData::int64 msec) {_name = name; return _namedLockPattern->acquireSynchronizationObject(name,msec);}
	~NamedLock(){_namedLockPattern->releaseSynchronizationObject(_name);}
private:
	Key _name;
	NamedLockPattern<Key,Compare>* _namedLockPattern;
};

}}

#endif  /* NAMEDLOCKPATTERN_H */