cpp-stateful-serializer/include/serializer/jsonizer.tpp

//
//  jsonizer.tpp
//  serializer
//
//  Created by Sam Jaffe on 3/15/23.
//

#pragma once

#include <fstream>
#include <iostream>
#include <stdexcept>

#include <expect/expect.hpp>
#include <json/json.h>
#include <magic_enum.hpp>
#include <string_utils/cast.h>

#include <serializer/jsonizer.h>
#include <serializer/shared_cache.h>
#include <serializer/strconv.h>
#include <serializer/traits.h>

namespace serializer {

Jsonizer::Jsonizer() : p_cache(std::make_shared<SharedCache>()) {}
/**
 * @brief Construct a jsonizer with an externally owned cache
 * @param cache A shared_ptr to a data cache. Cannot be null
 * @throws std::logic_error if cache == nullptr
 */
Jsonizer::Jsonizer(std::shared_ptr<SharedCache> cache) : p_cache(cache) {
  expects(p_cache != nullptr);
}

template <typename T, size_t... Is>
Json::Value Jsonizer::to_json(T & value, std::index_sequence<Is...>) const {
  Json::Value json;
  [[maybe_unused]] auto l = {
      ((json[int(Is)] = to_json(std::get<Is>(value))), 0)...};
  return json;
}

template <typename T> Json::Value Jsonizer::to_json(T const & value) const {
  if constexpr (detail::has_serial_type_v<T>) {
    return to_json(static_cast<typename T::serial_type>(value));
  } else if constexpr (std::is_enum_v<T>) {
    constexpr auto type =
        magic_enum::as_flags<magic_enum::detail::is_flags_v<T>>;
    return std::string(magic_enum::enum_name<type>(value));
  } else if constexpr (detail::is_tuple_v<T>) {
    return to_json(value, std::make_index_sequence<std::tuple_size_v<T>>());
  } else if constexpr (std::is_constructible_v<std::string, T>) {
    return std::string(value);
  } else if constexpr (std::is_floating_point_v<T>) {
    return static_cast<double>(value);
  } else if constexpr (std::is_same_v<bool, T>) {
    return value;
  } else if constexpr (std::is_arithmetic_v<T>) {
    return static_cast<int>(value);
  } else if constexpr (detail::is_associative_container_v<T>) {
    Json::Value rval;
    using K = std::decay_t<typename T::key_type>;
    if constexpr (std::is_same_v<std::string, K> || std::is_arithmetic_v<K>) {
      for (auto const & [k, v] : value) {
        rval[to_string(k)] = to_json(v);
      }
    } else {
      for (auto const & pair : value) {
        rval.append(to_json(pair));
      }
    }
    return rval;
  } else if constexpr (detail::is_container_v<T>) {
    Json::Value rval;
    for (auto const & elem : value) {
      rval.append(to_json(elem));
    }
    return rval;
  } else {
    return to_json_impl(value);
  }
}

template <typename T, size_t... Is>
void Jsonizer::from_json(T & value, Json::Value const & json,
                         std::index_sequence<Is...>) const {
  [[maybe_unused]] auto l = {
      ((std::get<Is>(value) =
            from_json<std::tuple_element_t<Is, T>>(json[int(Is)])),
       0)...};
}

template <typename T>
void Jsonizer::from_json(T & value, Json::Value const & json) const {
  if (json.isNull()) return;
  if constexpr (detail::has_serial_type_v<T>) {
    value = T(from_json<typename T::serial_type>(json));
  } else if constexpr (std::is_enum_v<T>) {
    if (!string_utils::cast(value, json.asString())) {
      throw std::invalid_argument("Cannot cast to enum: " + json.asString());
    }
  } else if constexpr (std::is_same_v<std::string, T>) {
    value = json.asString();
  } else if constexpr (detail::is_tuple_v<T>) {
    from_json(value, json, std::make_index_sequence<std::tuple_size_v<T>>());
  } else if constexpr (detail::is_associative_container_v<T>) {
    using K = std::decay_t<typename T::key_type>;
    using V = std::decay_t<typename T::mapped_type>;
    if (json.isArray()) {
      std::vector<std::pair<K, V>> tmp;
      from_json(tmp, json);
      value.insert(tmp.begin(), tmp.end());
    } else if (json.isObject()) {
      if constexpr (std::is_constructible_v<K, std::string>) {
        for (auto it = json.begin(), end = json.end(); it != end; ++it) {
          value.emplace(it.key().asString(), from_json<V>(*it));
        }
      } else {
        for (auto it = json.begin(), end = json.end(); it != end; ++it) {
          value.emplace(from_string<K>(it.key().asString()), from_json<V>(*it));
        }
      }
    } else {
      throw std::invalid_argument(
          "cannot construct container from non-container");
    }
  } else if constexpr (detail::is_container_v<T>) {
    using V = std::decay_t<typename T::value_type>;
    if (!json.isArray()) {
      throw std::invalid_argument("cannot construct container from non-array");
    }
    for (auto const & elem : json) {
      value.insert(value.end(), from_json<V>(elem));
    }
  } else if constexpr (std::is_floating_point_v<T>) {
    value = static_cast<T>(json.asDouble());
  } else if constexpr (std::is_same_v<bool, T>) {
    value = json.asBool();
  } else if constexpr (std::is_arithmetic_v<T>) {
    value = static_cast<T>(json.asInt());
  } else {
    from_json_impl(value, json);
  }
}

template <typename T, typename F>
T Jsonizer::from_cached_json(std::string const & key, Json::Value const & json,
                             F && fetch) const {
  std::shared_ptr<T const> ptr = p_cache->fetch<T>(json[key].asString());
  if (!ptr) {
    T value{};
    std::forward<F>(fetch)(value, json);
    ptr = p_cache->store(value.name, std::move(value));
  }
  return *ptr;
}

template <typename T>
void Jsonizer::from_json(std::shared_ptr<T const> & ptr,
                         Json::Value const & json) const {
  if (json.isString()) {
    ptr = p_cache->fetch<T>(json.asString());
  } else {
    T local{};
    from_json(local, json);
    ptr = p_cache->store(local.name, local);
  }
}

template <typename T> T Jsonizer::from_json(Json::Value const & json) const {
  std::decay_t<T> tmp;
  from_json(tmp, json);
  return tmp;
}

template <typename T> T Jsonizer::from_stream(std::istream & in) const {
  Json::Value root;
  in >> root;
  return from_json<T>(root);
}

template <typename T> T Jsonizer::from_string(std::string const & in) const {
  std::stringstream ss;
  ss << in;
  return from_stream<T>(ss);
}

template <typename T>
void Jsonizer::to_stream(T const & value, std::ostream & out) const {
  Json::Value root = to_json(value);
  out << root;
}

template <typename T> T Jsonizer::from_file(std::string const & file) const {
  std::ifstream in(file);
  return from_stream<T>(in);
}
}