// Copyright (c) 2022, The Monero Project
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#pragma once

#include <string>
#include <system_error>
#include "byte_stream.h"
#include "serialization/wire/json/fwd.h"
#include "span.h"

//! Declare functions that convert `type` to/from json bytes
#define WIRE_JSON_DECLARE_CONVERSION(type)                              \
  std::error_code convert_from_json(::epee::span<const char>, type&);   \
  std::error_code convert_to_json(std::string&, const type&)            \

//! Declare functions that convert `type::request` and `type::response` to/from json bytes
#define WIRE_JSON_DECLARE_COMMAND(type)	       \
  WIRE_JSON_DECLARE_CONVERSION(type::request); \
  WIRE_JSON_DECLARE_CONVERSION(type::response)

namespace wire
{
  struct json
  {
    using input_type = json_reader;
    using output_type = json_string_writer;

    //! Only enabled if `T` has templated method `from_bytes`.
    template<typename T>
    static auto from_bytes(const epee::span<const char> source, T& dest) -> decltype(dest.template from_bytes<input_type>(source))
    {
      return dest.template from_bytes<input_type>(source);
    }

    //! Only enabled if `T` has templated method `to_bytes`.
    template<typename T>
    static auto to_bytes(std::string& dest, const T& source) -> decltype(source.template to_bytes<output_type>(dest))
    {
      return source.template to_bytes<output_type>(dest);
    }


    // Parameters packs have lower precedence; above functions are preferred.

    template<typename... T>
    static std::error_code from_bytes(const epee::span<const char> source, T&... dest)
    {
      return convert_from_json(source, dest...); // ADL (searches every associated namespace)
    }

    template<typename... T>
    static std::error_code to_bytes(std::string& dest, const T&... source)
    {
      return convert_to_json(dest, source...); // ADL (searches every associated namespace)
    }

    template<typename T>
    static std::error_code to_bytes(epee::byte_stream& dest, const T& source)
    {
      std::string buf{};
      const std::error_code error = to_bytes(buf, source);
      if (!error)
        dest.write(epee::to_span(buf));
      return error;
    }
  };
}

