// Copyright (c) 2006-2013, Andrey N. Sabelnikov, www.sabelnikov.net
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of the Andrey N. Sabelnikov nor the
// names of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER  BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// 



#ifndef _LEVIN_BASE_H_
#define _LEVIN_BASE_H_

#include <cstdint>

#include "byte_slice.h"
#include "net_utils_base.h"
#include "span.h"

#define LEVIN_SIGNATURE  0x0101010101012101LL  //Bender's nightmare

namespace epee
{
namespace levin
{
#pragma pack(push)
#pragma pack(1)
	struct bucket_head
	{
		uint64_t m_signature;
		uint64_t m_cb;
		bool     m_have_to_return_data;
		uint32_t m_command;
		int32_t  m_return_code;
		uint32_t m_reservedA; //probably some flags in future
		uint32_t m_reservedB; //probably some check sum in future
	};
#pragma pack(pop)


#pragma pack(push)
#pragma pack(1)
  struct bucket_head2
  {
    uint64_t m_signature;
    uint64_t m_cb;
    bool     m_have_to_return_data;
    uint32_t m_command;
    int32_t  m_return_code;
    uint32_t m_flags;
    uint32_t m_protocol_version;
  };
#pragma pack(pop)


#define LEVIN_DEFAULT_TIMEOUT_PRECONFIGURED 0
#define LEVIN_INITIAL_MAX_PACKET_SIZE  256*1024      // 256 KiB before handshake
#define LEVIN_DEFAULT_MAX_PACKET_SIZE 100000000      //100MB by default after handshake

#define LEVIN_PACKET_REQUEST			0x00000001
#define LEVIN_PACKET_RESPONSE		0x00000002
#define LEVIN_PACKET_BEGIN		0x00000004
#define LEVIN_PACKET_END		0x00000008
  

#define LEVIN_PROTOCOL_VER_0         0
#define LEVIN_PROTOCOL_VER_1         1
 
  template<class t_connection_context = net_utils::connection_context_base>
  struct levin_commands_handler
  {
    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out, t_connection_context& context)=0;
    virtual int notify(int command, const epee::span<const uint8_t> in_buff, t_connection_context& context)=0;
    virtual void callback(t_connection_context& context){};

    virtual void on_connection_new(t_connection_context& context){};
    virtual void on_connection_close(t_connection_context& context){};

    virtual ~levin_commands_handler(){}
  };

#define LEVIN_OK                                        0
#define LEVIN_ERROR_CONNECTION                         -1
#define LEVIN_ERROR_CONNECTION_NOT_FOUND               -2
#define LEVIN_ERROR_CONNECTION_DESTROYED               -3
#define LEVIN_ERROR_CONNECTION_TIMEDOUT                -4
#define LEVIN_ERROR_CONNECTION_NO_DUPLEX_PROTOCOL      -5
#define LEVIN_ERROR_CONNECTION_HANDLER_NOT_DEFINED     -6
#define LEVIN_ERROR_FORMAT                             -7

#define DESCRIBE_RET_CODE(code) case code: return #code;
  inline
  const char* get_err_descr(int err)
  {
    switch(err)
    {
      DESCRIBE_RET_CODE(LEVIN_OK);
      DESCRIBE_RET_CODE(LEVIN_ERROR_CONNECTION);
      DESCRIBE_RET_CODE(LEVIN_ERROR_CONNECTION_NOT_FOUND);
      DESCRIBE_RET_CODE(LEVIN_ERROR_CONNECTION_DESTROYED);
      DESCRIBE_RET_CODE(LEVIN_ERROR_CONNECTION_TIMEDOUT);
      DESCRIBE_RET_CODE(LEVIN_ERROR_CONNECTION_NO_DUPLEX_PROTOCOL);
      DESCRIBE_RET_CODE(LEVIN_ERROR_CONNECTION_HANDLER_NOT_DEFINED);
      DESCRIBE_RET_CODE(LEVIN_ERROR_FORMAT);
    default:
      return "unknown code";
    }
  }

  //! \return Intialized levin header.
  bucket_head2 make_header(uint32_t command, uint64_t msg_size, uint32_t flags, bool expect_response) noexcept;

  //! \return A levin notification message.
  byte_slice make_notify(int command, epee::span<const std::uint8_t> payload);

  /*! Generate a dummy levin message.

      \param noise_bytes Total size of the returned `byte_slice`.
      \return `nullptr` if `noise_size` is smaller than the levin header.
        Otherwise, a dummy levin message. */
  byte_slice make_noise_notify(std::size_t noise_bytes);

  /*! Generate 1+ levin messages that are identical to the noise message size.

   \param noise Each levin message will be identical to the size of this
      message. The bytes from this message will be used for padding.
   \return `nullptr` if `noise.size()` is less than the levin header size.
      Otherwise, a levin notification message OR 2+ levin fragment messages.
      Each message is `noise.size()` in length. */
  byte_slice make_fragmented_notify(const byte_slice& noise, int command, epee::span<const std::uint8_t> payload);
}
}


#endif //_LEVIN_BASE_H_

