MetaProcessors.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2023, the clio developers.
 
    Permission to use, copy, modify, and distribute this software for any
    purpose with or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
 
    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
 
#pragma once
 
#include "rpc/Errors.hpp"
#include "rpc/common/Concepts.hpp"
#include "rpc/common/Specs.hpp"
#include "rpc/common/Types.hpp"
 
#include <boost/json/value.hpp>
#include <fmt/format.h>
 
#include <cstddef>
#include <functional>
#include <initializer_list>
#include <optional>
#include <string_view>
#include <utility>
#include <vector>
 
namespace rpc::meta {

class Section final {
    std::vector<FieldSpec> specs_;
 
public:
    explicit Section(std::initializer_list<FieldSpec> specs) : specs_{specs}
    {
    }

    [[nodiscard]] MaybeError
    verify(boost::json::value& value, std::string_view key) const;
};

class ValidateArrayAt final {
    std::size_t idx_;
    std::vector<FieldSpec> specs_;
 
public:
    ValidateArrayAt(std::size_t idx, std::initializer_list<FieldSpec> specs)
        : idx_{idx}, specs_{specs}
    {
    }

    [[nodiscard]] MaybeError
    verify(boost::json::value& value, std::string_view key) const;
};

template <typename Type>
class IfType final {
public:
    template <SomeRequirement... Requirements>
    explicit IfType(Requirements&&... requirements)
        : processor_(
              [... r = std::forward<Requirements>(
                   requirements
               )](boost::json::value& j, std::string_view key) -> MaybeError {
                  std::optional<Status> firstFailure = std::nullopt;
 
                  // the check logic is the same as fieldspec
                  (
                      [&j, &key, &firstFailure, req = &r]() {
                          if (firstFailure)
                              return;
 
                          if (auto const res = req->verify(j, key); not res)
                              firstFailure = res.error();
                      }(),
                      ...
                  );
 
                  if (firstFailure)
                      return Error{firstFailure.value()};
 
                  return {};
              }
          )
    {
    }
 
    IfType(IfType const&) = default;
    IfType(IfType&&) = default;

    [[nodiscard]] MaybeError
    verify(boost::json::value& value, std::string_view key) const
    {
        if (not value.is_object() or not value.as_object().contains(key))
            return {};  // ignore. field does not exist, let 'required' fail instead
 
        if (not rpc::validation::checkType<Type>(value.as_object().at(key)))
            return {};  // ignore if type does not match
 
        return processor_(value, key);
    }
 
private:
    std::function<MaybeError(boost::json::value&, std::string_view)> processor_;
};

template <typename RequirementOrModifierType>
    requires SomeRequirement<RequirementOrModifierType> or SomeModifier<RequirementOrModifierType>
class WithCustomError final {
    RequirementOrModifierType reqOrModifier_;
    Status error_;
 
public:
    WithCustomError(RequirementOrModifierType reqOrModifier, Status err)
        : reqOrModifier_{std::move(reqOrModifier)}, error_{std::move(err)}
    {
    }

    [[nodiscard]] MaybeError
    verify(boost::json::value const& value, std::string_view key) const
        requires SomeRequirement<RequirementOrModifierType>
    {
        if (auto const res = reqOrModifier_.verify(value, key); not res)
            return Error{error_};
 
        return {};
    }

    [[nodiscard]] MaybeError
    verify(boost::json::value& value, std::string_view key) const
        requires SomeRequirement<RequirementOrModifierType>
    {
        if (auto const res = reqOrModifier_.verify(value, key); not res)
            return Error{error_};
 
        return {};
    }

    MaybeError
    modify(boost::json::value& value, std::string_view key) const
        requires SomeModifier<RequirementOrModifierType>
 
    {
        if (auto const res = reqOrModifier_.modify(value, key); not res)
            return Error{error_};
        return {};
    }
};
 
}  // namespace rpc::meta