Taggable.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2022, 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/config/ConfigDefinition.hpp"
 
#include <boost/algorithm/string/predicate.hpp>
#include <boost/json.hpp>
#include <boost/json/conversion.hpp>
#include <boost/json/value.hpp>
#include <boost/uuid/uuid.hpp>
#include <boost/uuid/uuid_io.hpp>
 
#include <atomic>
#include <functional>
#include <memory>
#include <optional>
#include <ostream>
#include <string>
#include <string_view>
#include <utility>
 
namespace util {
namespace impl {

struct NullTagGenerator final {};

struct UIntTagGenerator final {
    using TagType = std::atomic_uint64_t;
 
    static TagType
    next();
};

struct UUIDTagGenerator final {
    using TagType = boost::uuids::uuid;
 
    static TagType
    next();
};
 
}  // namespace impl

class BaseTagDecorator {
public:
    virtual ~BaseTagDecorator() = default;

    virtual void
    decorate(std::ostream& os) const = 0;

    friend std::ostream&
    operator<<(std::ostream& os, BaseTagDecorator const& decorator)
    {
        decorator.decorate(os);
        return os;
    }

    std::string
    toString() const
    {
        std::ostringstream oss;
        decorate(oss);
        return std::move(oss).str();
    }
};

template <typename Generator>
class TagDecorator final : public BaseTagDecorator {
    using ParentType = std::optional<std::reference_wrapper<BaseTagDecorator const>>;
    using TagType = typename Generator::TagType;
 
    ParentType parent_ = std::nullopt;
    TagType tag_ = Generator::next();
 
public:
    explicit TagDecorator(ParentType parent = std::nullopt) : parent_{parent}
    {
    }

    void
    decorate(std::ostream& os) const override
    {
        os << "[";
 
        if (parent_.has_value())
            (*parent_).get().decorate(os);
 
        os << tag_ << "] ";
    }
};

template <>
class TagDecorator<impl::NullTagGenerator> final : public BaseTagDecorator {
public:
    void
    decorate([[maybe_unused]] std::ostream& os) const override
    {
        // nop
    }
};

class TagDecoratorFactory final {
    using ParentType = std::optional<std::reference_wrapper<BaseTagDecorator const>>;

    enum class Type {
        NONE, 
        UUID, 
        UINT  
    };
 
    Type type_;                        /*< The type of TagDecorator this factory produces */
    ParentType parent_ = std::nullopt; /*< The parent tag decorator to bind */
 
    static Type
    getLogTagType(std::string_view style)
    {
        if (boost::iequals(style, "int") || boost::iequals(style, "uint"))
            return TagDecoratorFactory::Type::UINT;
 
        if (boost::iequals(style, "null") || boost::iequals(style, "none"))
            return TagDecoratorFactory::Type::NONE;
 
        if (boost::iequals(style, "uuid"))
            return TagDecoratorFactory::Type::UUID;
 
        ASSERT(false, "log.tag_style does not have valid value");
        std::unreachable();
    }
 
public:
    ~TagDecoratorFactory() = default;

    explicit TagDecoratorFactory(util::config::ClioConfigDefinition const& config)
        : type_{getLogTagType(config.get<std::string>("log.tag_style"))}
    {
    }
 
private:
    TagDecoratorFactory(Type type, ParentType parent) noexcept : type_{type}, parent_{parent}
    {
    }
 
public:
    std::unique_ptr<BaseTagDecorator>
    make() const;

    TagDecoratorFactory
    with(ParentType parent) const noexcept;
};

class Taggable {
    using DecoratorType = std::unique_ptr<BaseTagDecorator>;
    DecoratorType tagDecorator_;
 
protected:
    explicit Taggable(util::TagDecoratorFactory const& tagFactory)
        : tagDecorator_{tagFactory.make()}
    {
    }
 
public:
    virtual ~Taggable() = default;
    Taggable(Taggable&&) = default;
 
    Taggable&
    operator=(Taggable&&) = default;

    BaseTagDecorator const&
    tag() const
    {
        return *tagDecorator_;
    }
};
 
}  // namespace util