ConfigValue.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2024, 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 "util/Assert.hpp"
#include "util/OverloadSet.hpp"
#include "util/newconfig/ConfigConstraints.hpp"
#include "util/newconfig/Error.hpp"
#include "util/newconfig/Types.hpp"
 
#include <fmt/core.h>
 
#include <cstddef>
#include <cstdint>
#include <functional>
#include <optional>
#include <ostream>
#include <string>
#include <string_view>
#include <utility>
#include <variant>
 
namespace util::config {
 
class ConfigValue {
public:
    constexpr ConfigValue(ConfigType type) : type_(type)
    {
    }
 
    [[nodiscard]] ConfigValue&
    defaultValue(Value value)
    {
        auto const err = checkTypeConsistency(type_, value);
        ASSERT(!err.has_value(), "{}", err->error);
        value_ = value;
        return *this;
    }
 
    [[nodiscard]] std::optional<Error>
    setValue(Value value, std::optional<std::string_view> key = std::nullopt)
    {
        if (std::holds_alternative<NullType>(value)) {
            if (hasValue()) {
                // Using default value
                return std::nullopt;
            }
            if (not isOptional()) {
                return Error{
                    key.value_or("Unknown_key"),
                    "Provided value is null but ConfigValue is not optional and doesn't have a default value."
                };
            }
            value_ = std::move(value);
            return std::nullopt;
        }
 
        auto err = checkTypeConsistency(type_, value);
        if (err.has_value()) {
            err->error = fmt::format("{} {}", key.value_or("Unknown_key"), err->error);
            return err;
        }
 
        if (cons_.has_value()) {
            auto constraintCheck = cons_->get().checkConstraint(value);
            if (constraintCheck.has_value()) {
                constraintCheck->error = fmt::format("{} {}", key.value_or("Unknown_key"), constraintCheck->error);
                return constraintCheck;
            }
        }
        value_ = value;
        return std::nullopt;
    }
 
    [[nodiscard]] constexpr ConfigValue&
    withConstraint(Constraint const& cons)
    {
        cons_ = std::reference_wrapper<Constraint const>(cons);
        ASSERT(cons_.has_value(), "Constraint must be defined");
 
        if (value_.has_value()) {
            auto const& temp = cons_.value().get();
            auto const& result = temp.checkConstraint(value_.value());
            if (result.has_value()) {
                // useful for specifying clear Error message
                std::string type;
                std::visit(
                    util::OverloadSet{
                        [&type](bool tmp) { type = fmt::format("bool {}", tmp); },
                        [&type](std::string const& tmp) { type = fmt::format("string {}", tmp); },
                        [&type](double tmp) { type = fmt::format("double {}", tmp); },
                        [&type](int64_t tmp) { type = fmt::format("int {}", tmp); },
                        [&type](NullType) { type = "null"; },
                    },
                    value_.value()
                );
                ASSERT(false, "Value {} ConfigValue does not satisfy the set Constraint", type);
            }
        }
        return *this;
    }
 
    [[nodiscard]] constexpr std::optional<std::reference_wrapper<Constraint const>>
    getConstraint() const
    {
        return cons_;
    }
 
    [[nodiscard]] constexpr ConfigType
    type() const
    {
        return type_;
    }
 
    [[nodiscard]] constexpr ConfigValue&
    optional()
    {
        optional_ = true;
        return *this;
    }
 
    [[nodiscard]] bool constexpr isOptional() const
    {
        return optional_;
    }
 
    [[nodiscard]] bool constexpr hasValue() const
    {
        return value_.has_value();
    }
 
    [[nodiscard]] Value const&
    getValue() const
    {
        ASSERT(value_.has_value(), "getValue() is called when there is no value set");
        return value_.value();
    }
 
    friend std::ostream&
    operator<<(std::ostream& stream, ConfigValue val)
    {
        stream << "- **Required**: " << (val.isOptional() ? "False" : "True") << "\n";
        stream << "- **Type**: " << val.type() << "\n";
        stream << "- **Default value**: " << (val.hasValue() ? *val.value_ : "None") << "\n";
        stream << "- **Constraints**: ";
 
        if (val.getConstraint().has_value()) {
            stream << val.getConstraint()->get() << "\n";
        } else {
            stream << "None" << "\n";
        }
        return stream;
    }
 
private:
    static std::optional<Error>
    checkTypeConsistency(ConfigType type, Value value)
    {
        if (type == ConfigType::String && !std::holds_alternative<std::string>(value)) {
            return Error{"value does not match type string"};
        }
        if (type == ConfigType::Boolean && !std::holds_alternative<bool>(value)) {
            return Error{"value does not match type boolean"};
        }
        if (type == ConfigType::Double && (!std::holds_alternative<double>(value))) {
            if (std::holds_alternative<int64_t>(value))
                return std::nullopt;
            return Error{"value does not match type double"};
        }
        if (type == ConfigType::Integer && !std::holds_alternative<int64_t>(value)) {
            return Error{"value does not match type integer"};
        }
        return std::nullopt;
    }
 
    ConfigType type_{};
    bool optional_{false};
    std::optional<Value> value_;
    std::optional<std::reference_wrapper<Constraint const>> cons_;
};
 
}  // namespace util::config