/*
 * =====================================================================================
 *
 *       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 "bh_util.h"
#include "proto.h"
#include "shm.h"
#include <atomic>
#include <stdint.h>

class ShmSocket;
namespace bhome_msg
{
using namespace bhome_shm;

// ShmMsg is safe to be stored in shared memory, so POD data or offset_ptr is required.
// message content layout: (meta) / header_size + header + data_size + data

class ShmMsg
{
private:
	// store ref count, msgs shareing the same data should also hold a pointer of the same RefCount object.
	class RefCount : private boost::noncopyable
	{
		std::atomic<int> num_;

	public:
		RefCount() :
		    num_(1) { }
		    // num_(1) { static_assert(std::is_pod<decltype(num_)>::value); }
		int Inc() { return ++num_; }
		int Dec() { return --num_; }
		int Get() { return num_.load(); }
	};

	typedef int64_t OffsetType;
	static OffsetType Addr(void *ptr) { return reinterpret_cast<OffsetType>(ptr); }
	static void *Ptr(const OffsetType offset) { return reinterpret_cast<void *>(offset); }
	OffsetType BaseAddr() const { return Addr(shm().get_address()); }

	static const uint32_t kMsgTag = 0xf1e2d3c4;
	struct Meta {
		static int64_t NewId()
		{
			static std::atomic<int64_t> id(0);
			return ++id;
		}

		RefCount count_;
		const uint32_t tag_ = kMsgTag;
		const uint32_t capacity_ = 0;
		const int64_t id_ = 0;
		std::atomic<int64_t> timestamp_;
		bool managed_ = false;
		uint32_t size_ = 0;
		Meta(uint32_t size) :
		    capacity_(size), id_(NewId()), timestamp_(NowSec()) {}
	};
	OffsetType offset_;
	SharedMemory *pshm_;

	void *Alloc(const size_t size, const void *src = nullptr)
	{
		void *p = shm().Alloc(sizeof(Meta) + size);
		if (p) {
			auto pmeta = new (p) Meta(size);
			p = pmeta + 1;
			if (src) {
				memcpy(p, src, size);
			}
		}
		return p;
	}

private:
	Meta *meta() const { return get<Meta>() - 1; }

	template <class Body>
	void *Pack(const BHMsgHead &head, const uint32_t head_len, const Body &body, const uint32_t body_len)
	{
		void *addr = get();
		if (addr) {
			auto p = static_cast<char *>(addr);
			auto Pack1 = [&p](auto len, auto &&writer) {
				Put32(p, len);
				p += sizeof(len);
				writer(p, len);
				p += len;
			};
			Pack1(head_len, [&](void *p, int len) { head.SerializeToArray(p, len); });
			Pack1(body_len, [&](void *p, int len) { body.SerializeToArray(p, len); });
			meta()->size_ = 4 + head_len + 4 + body_len;
		}
		return addr;
	}
	void *Pack(const BHMsgHead &head, const uint32_t head_len, const std::string &body_content)
	{
		void *addr = get();
		if (addr) {
			auto p = static_cast<char *>(addr);
			auto Pack1 = [&p](uint32_t len, auto &&writer) {
				Put32(p, len);
				p += sizeof(len);
				writer(p, len);
				p += len;
			};
			Pack1(head_len, [&](void *p, int len) { head.SerializeToArray(p, len); });
			Pack1(body_content.size(), [&](void *p, int len) { memcpy(p, body_content.data(), len); });
			meta()->size_ = 4 + head_len + 4 + body_content.size();
		}
		return addr;
	}

	void *Pack(const void *src, const size_t size)
	{
		void *addr = get();
		if (addr && src) {
			memcpy(addr, src, size);
			meta()->size_ = size;
		}
		return addr;
	}

	void *Pack(const std::string &content) { return Pack(content.data(), content.size()); }

	bool Make(void *addr)
	{
		if (!addr) {
			return false;
		}
		offset_ = Addr(addr) - BaseAddr();
		return true;
	}

	template <class T = void>
	T *get() const { return offset_ != 0 ? static_cast<T *>(Ptr(offset_ + BaseAddr())) : nullptr; }

public:
	explicit ShmMsg(SharedMemory &shm) :
	    offset_(0), pshm_(&shm) {}
	ShmMsg(const OffsetType offset, SharedMemory &shm) :
	    offset_(offset), pshm_(&shm) {}
	OffsetType Offset() const { return offset_; }
	OffsetType &OffsetRef() { return offset_; }
	SharedMemory &shm() const { return *pshm_; }

	void swap(ShmMsg &a)
	{
		std::swap(offset_, a.offset_);
		std::swap(pshm_, a.pshm_);
	}
	bool valid() const { return offset_ != 0 && meta()->tag_ == kMsgTag; }
	int64_t id() const { return valid() ? meta()->id_ : 0; }
	int64_t timestamp() const { return valid() ? meta()->timestamp_.load() : 0; }
	size_t Size() const { return valid() ? meta()->size_ : 0; }
	int Count() const { return valid() ? meta()->count_.Get() : 1; }
	int AddRef() const { return valid() ? meta()->count_.Inc() : 1; }
	int Release();
	void Free();
	void reset_managed(const bool val) const
	{
		if (valid()) { meta()->managed_ = val; }
	}

	template <class Body>
	inline bool Make(const BHMsgHead &head, const Body &body)
	{
		uint32_t head_len = head.ByteSizeLong();
		uint32_t body_len = body.ByteSizeLong();
		uint32_t size = sizeof(head_len) + head_len + sizeof(body_len) + body_len;
		return Make(size) && Pack(head, head_len, body, body_len);
	}
	inline bool Make(const BHMsgHead &head, const std::string &body_content)
	{
		uint32_t head_len = head.ByteSizeLong();
		uint32_t size = sizeof(head_len) + head_len + sizeof(uint32_t) + body_content.size();
		return Make(size) && Pack(head, head_len, body_content);
	}

	template <class Body>
	inline bool Fill(const BHMsgHead &head, const Body &body)
	{
		uint32_t head_len = head.ByteSizeLong();
		uint32_t body_len = body.ByteSizeLong();
		uint32_t size = sizeof(head_len) + head_len + sizeof(body_len) + body_len;
		return valid() && (meta()->capacity_ >= size) && Pack(head, head_len, body, body_len);
	}

	inline bool Make(const void *src, const size_t size) { return Make(Alloc(size, src)); }
	inline bool Fill(const void *src, const size_t size) { return valid() && (meta()->capacity_ >= size) && Pack(src, size); }

	inline bool Make(const std::string &content) { return Make(content.data(), content.size()); }
	inline bool Fill(const std::string &content) { return Fill(content.data(), content.size()); }

	inline bool Make(const size_t size) { return Make(Alloc(size)); }

	template <class Body>
	static inline std::string Serialize(const BHMsgHead &head, const Body &body)
	{
		uint32_t head_len = head.ByteSizeLong();
		uint32_t body_len = body.ByteSizeLong();
		std::string s(4 + head_len + 4 + body_len, '\0');
		size_t pos = 0;
		auto add1 = [&](auto &&msg, auto &&size) {
			Put32(&s[pos], size);
			pos += 4;
			msg.SerializeToArray(&s[pos], size);
			pos += size;
		};
		add1(head, head_len);
		add1(body, body_len);
		assert(pos == s.size());
		return s;
	}

	bool ParseHead(BHMsgHead &head) const
	{
		auto p = get<char>();
		assert(p);
		uint32_t msg_size = Get32(p);
		p += 4;
		return head.ParseFromArray(p, msg_size);
	}
	std::string content() const
	{
		auto p = get<char>();
		return p ? std::string(p, meta()->size_) : std::string();
	}
	std::string body() const
	{
		auto p = get<char>();
		assert(p);
		uint32_t size = Get32(p);
		p += 4;
		p += size;
		size = Get32(p);
		p += 4;
		return std::string(p, size);
	}
	template <class Body>
	bool ParseBody(Body &body) const
	{
		auto p = get<char>();
		assert(p);
		uint32_t size = Get32(p);
		p += 4;
		p += size;
		size = Get32(p);
		p += 4;
		return body.ParseFromArray(p, size);
	}
};

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

typedef ShmMsg MsgI;

constexpr inline int EncodeCmd(int cmd) { return ((cmd & MaskBits(3)) << 1) | 1; }
constexpr inline int DecodeCmd(int64_t msg) { return (msg >> 1) & MaskBits(3); }
constexpr inline bool IsCmd(int64_t msg) { return (msg & 1) != 0; }
// int64_t pack format: cmd data ,3bit cmd, 1bit flag.
enum MsgCmd {
	eCmdNodeInit = 0,      // upto 56bit ssn id
	eCmdNodeInitReply = 1, // 31bit proc index,
	eCmdAllocRequest0 = 2, // 8bit size, 4bit socket index, 16bit proc index, 28bit id
	eCmdAllocReply0 = 3,   // 31bit ptr, 28bit id,
	eCmdFree = 4,          // upto 59bit msg id,
};

} // namespace bhome_msg

#endif // end of include guard: MSG_5BILLZET