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#pragma once

#include <boost/utility/string_ref.hpp>
#include <cstddef>
#include <string>
#include <type_traits>
#include <utility>
#include <vector>

#include "wire/field.h"
#include "wire/msgpack/base.h"
#include "wire/read.h"
#include "wire/traits.h"

namespace wire
{
  //! Reads MSGPACK tokens one-at-a-time for DOMless parsing
  class msgpack_reader : public reader
  {
    epee::byte_slice source_;
    std::size_t remaining_; //!< Expected number of elements remaining

    //! \throw std::logic_error
    [[noreturn]] void throw_logic_error();
    //! Decrement remaining_ if not zero, \throw std::logic_error when `remaining_ == 0`.
    void update_remaining()
    {
      if (remaining_)
        --remaining_;
      else
        throw_logic_error();
    }

    //! Skips next value. \throw wire::exception if invalid JSON syntax.
    void skip_value();

    //! \return Next tag but leave `source_` untouched.
    msgpack::tag peek_tag();
    //! \return Next tag and remove first byte from `source_`.
    msgpack::tag get_tag();

    //! \return Integer from `soure_` where positive fixed tag has been checked.
    std::intmax_t do_integer(msgpack::tag);
    //! \return Integer from `source_` where fixed tag has been checked.
    std::uintmax_t do_unsigned_integer(msgpack::tag);

    //! \return Number of items determined by `T` fixed tag and `U` tuple of tags.
    template<typename T, typename U>
    std::size_t read_count(error::schema);

  public:
    explicit msgpack_reader(epee::byte_slice&& source)
      : reader(), source_(std::move(source)), remaining_(1)
    {}

    //! \throw wire::exception if JSON parsing is incomplete.
    void check_complete() const override final;

    //! \throw wire::exception if next token not a boolean.
    bool boolean() override final;

    //! \throw wire::expception if next token not an integer.
    std::intmax_t integer() override final
    {
      update_remaining();
      const msgpack::tag next = get_tag();
      if (std::uint8_t(next) <= msgpack::ftag_unsigned::max())
        return std::uint8_t(next);
      return do_integer(next);
    }

    //! \throw wire::exception if next token not an unsigned integer.
    std::uintmax_t unsigned_integer() override final
    {
      update_remaining();
      const msgpack::tag next = get_tag();
      if (std::uint8_t(next) <= msgpack::ftag_unsigned::max())
        return std::uint8_t(next);
      return do_unsigned_integer(next);
    }

    //! \throw wire::exception if next token not a valid real number
    double real() override final;

    //! \throw wire::exception if next token not a string
    std::string string() override final;

    //! \throw wire::exception if next token cannot be read as hex
    std::vector<std::uint8_t> binary() override final;

    //! \throw wire::exception if next token cannot be read as hex into `dest`.
    void binary(epee::span<std::uint8_t> dest) override final;


    //! \throw wire::exception if next token not `[`.
    std::size_t start_array() override final;

    //! \return true when `count == 0`.
    bool is_array_end(const std::size_t count) override final;


    //! \throw wire::exception if next token not `{`.
    std::size_t start_object() override final;

    /*! \throw wire::exception if next token not key or `}`.
        \param[out] index of key match within `map`.
        \return True if another value to read. */
    bool key(epee::span<const key_map> map, std::size_t&, std::size_t& index) override final;
  };
} // wire