text: // MIT License
  //
  // Copyright (c) 2016-2017 Simon Ninon <simon.ninon@gmail.com>
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in all
  // copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  // SOFTWARE.
  
  #pragma once
  
  #include <cstdint>
  #include <functional>
  #include <string>
  #include <vector>
  
  namespace cpp_redis {
  
  namespace network {
  
  //!
  //! interface defining how tcp client should be implemented to be used inside cpp_redis
  //!
  class tcp_client_iface {
  public:
    //! ctor
    tcp_client_iface(void) = default;
    //! dtor
    virtual ~tcp_client_iface(void) = default;
  
  public:
    //!
    //! start the tcp client
    //!
    //! \param addr host to be connected to
    //! \param port port to be connected to
    //! \param timeout_msecs max time to connect in ms
    //!
    virtual void connect(const std::string& addr, std::uint32_t port, std::uint32_t timeout_msecs = 0) = 0;
  
    //!
    //! stop the tcp client
    //!
    //! \param wait_for_removal when sets to true, disconnect blocks until the underlying TCP client has been effectively removed from the io_service and that all the underlying callbacks have completed.
    //!
    virtual void disconnect(bool wait_for_removal = false) = 0;
  
    //!
    //! \return whether the client is currently connected or not
    //!
    virtual bool is_connected(void) const = 0;
  
  public:
    //!
    //! structure to store read requests result
    //!
    struct read_result {
      //!
      //! whether the operation succeeded or not
      //!
      bool success;
  
      //!
      //! read bytes
      //!
      std::vector<char> buffer;
    };
  
    //!
    //! structure to store write requests result
    //!
    struct write_result {
      //!
      //! whether the operation succeeded or not
      //!
      bool success;
  
      //!
      //! number of bytes written
      //!
      std::size_t size;
    };
  
  public:
    //!
    //! async read completion callbacks
    //! function taking read_result as a parameter
    //!
    typedef std::function<void(read_result&)> async_read_callback_t;
  
    //!
    //! async write completion callbacks
    //! function taking write_result as a parameter
    //!
    typedef std::function<void(write_result&)> async_write_callback_t;
  
  public:
    //!
    //! structure to store read requests information
    //!
    struct read_request {
      //!
      //! number of bytes to read
      //!
      std::size_t size;
  
      //!
      //! callback to be called on operation completion
      //!
      async_read_callback_t async_read_callback;
    };
  
    //!
    //! structure to store write requests information
    //!
    struct write_request {
      //!
      //! bytes to write
      //!
      std::vector<char> buffer;
  
      //!
      //! callback to be called on operation completion
      //!
      async_write_callback_t async_write_callback;
    };
  
  public:
    //!
    //! async read operation
    //!
    //! \param request information about what should be read and what should be done after completion
    //!
    virtual void async_read(read_request& request) = 0;
  
    //!
    //! async write operation
    //!
    //! \param request information about what should be written and what should be done after completion
    //!
    virtual void async_write(write_request& request) = 0;
  
  public:
    //!
    //! disconnection handler
    //!
    typedef std::function<void()> disconnection_handler_t;
  
    //!
    //! set on disconnection handler
    //!
    //! \param disconnection_handler handler to be called in case of a disconnection
    //!
    virtual void set_on_disconnection_handler(const disconnection_handler_t& disconnection_handler) = 0;
  };
  
  } // namespace network
  
  } // namespace cpp_redis
  