/*
 * =====================================================================================
 *
 *       Filename:  msg.h
 *
 *    Description:  
 *
 *        Version:  1.0
 *        Created:  2021年03月24日 16时49分20秒
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Li Chao (), 
 *   Organization:  
 *
 * =====================================================================================
 */
#ifndef MSG_5BILLZET
#define MSG_5BILLZET

#include "bhome_msg.pb.h"
#include "shm.h"
#include <boost/interprocess/offset_ptr.hpp>
#include <boost/uuid/uuid_generators.hpp>
#include <stdint.h>

namespace bhome_msg
{
using namespace bhome_shm;
using namespace bhome::msg; // for serialized data in MsgI

// MsgI is safe to be stored in shared memory, so POD data or offset_ptr is required.
// message format: header(meta) + body(data).

typedef boost::uuids::uuid MQId;

// store ref count, msgs shareing the same data should also hold a pointer of the same RefCount object.
class RefCount : private boost::noncopyable
{
public:
	int Inc()
	{
		Guard lk(mutex_);
		return ++num_;
	}
	int Dec()
	{
		Guard lk(mutex_);
		return --num_;
	}
	int Get()
	{
		Guard lk(mutex_);
		return num_;
	}

private:
	Mutex mutex_;
	int num_ = 1;
};

BHMsg MakeQueryTopic(const std::string &topic);
BHMsg MakeRequest(const MQId &src_id, const void *data, const size_t size);
BHMsg MakeRequest(const MQId &src_id, const std::string &topic, const void *data, const size_t size);
BHMsg MakeReply(const void *data, const size_t size);
BHMsg MakeSub(const MQId &client, const std::vector<std::string> &topics);
BHMsg MakeUnsub(const MQId &client, const std::vector<std::string> &topics);
BHMsg MakePub(const std::string &topic, const void *data, const size_t size);

class MsgI
{
private:
	offset_ptr<void> ptr_;
	offset_ptr<RefCount> count_;

	bool BuildSubOrUnsub(SharedMemory &shm, const std::vector<std::string> &topics, const MsgType sub_unsub);

public:
	MsgI(void *p = 0, RefCount *c = 0) :
	    ptr_(p), count_(c) {}

	void swap(MsgI &a)
	{
		std::swap(ptr_, a.ptr_);
		std::swap(count_, a.count_);
	}
	template <class T = void>
	T *get() { return static_cast<T *>(ptr_.get()); }

	// AddRef and Release works for both counted and not counted msg.
	int AddRef() const { return IsCounted() ? count_->Inc() : 1; }
	int Release(SharedMemory &shm);

	int Count() const { return IsCounted() ? count_->Get() : 1; }
	bool IsCounted() const { return static_cast<bool>(count_); }

	bool Make(SharedMemory &shm, const BHMsg &msg);
	bool MakeRC(SharedMemory &shm, const BHMsg &msg);
	bool Unpack(BHMsg &msg) const;
};

inline void swap(MsgI &m1, MsgI &m2) { m1.swap(m2); }

} // namespace bhome_msg

#endif // end of include guard: MSG_5BILLZET