ServiceManager.h

#pragma once
 
#include <type_traits>
 
#include "ll/api/event/EventBus.h"
#include "ll/api/event/MultiListener.h"
#include "ll/api/event/service/ServiceEvents.h"
#include "ll/api/mod/NativeMod.h"
#include "ll/api/service/Service.h"
#include "ll/api/service/ServiceId.h"
 
#include "ll/api/Expected.h"
 
namespace ll::service {
 
struct GetServiceError : ErrorInfoBase {
    enum class ErrorType : char {
        NotExist        = 0,
        VersionMismatch = 1,
    };
    using enum ErrorType;
 
    ErrorType code;
    size_t    version;
 
    GetServiceError(ErrorType code, size_t version = 0) : code(code), version(version) {}
 
    LLAPI std::string message() const noexcept override;
};
 
struct QueryServiceResult {
    std::string              name;
    size_t                   version;
    std::string              modName;
    std::shared_ptr<Service> service;
};
 
class ServiceManager {
public:
    LLNDAPI static ServiceManager& getInstance();
 
    template <IsService T>
    event::ListenerPtr subscribeService(std::function<void(std::shared_ptr<T> const&)> const& fn) {
        if (auto service = getService<T>(); service) {
            fn(*service);
        }
        auto listener =
            event::MultiListener<event::server::ServiceRegisterEvent, event::server::ServiceUnregisterEvent>::create(
                [fn](auto&& event) {
                    if (event.service()->getServiceId() == T::ServiceId) {
                        if constexpr (std::is_same_v<
                                          std::remove_cvref_t<decltype((event))>,
                                          event::server::ServiceUnregisterEvent>) {
                            fn(nullptr);
                        } else {
                            fn(std::static_pointer_cast<T>(event.service()));
                        }
                    }
                }
            );
        event::EventBus::getInstance().addListener(listener);
        return listener;
    }
 
    template <IsService T>
    Expected<std::shared_ptr<T>> getService() {
        auto res = getService(getServiceId<T>);
        if (!res) {
            return forwardError(res.error());
        }
        return std::static_pointer_cast<T>(*res);
    }
 
    LLNDAPI Expected<std::shared_ptr<Service>> getService(ServiceIdView const& id);
 
    LLNDAPI std::optional<QueryServiceResult> queryService(std::string_view name);
 
    LLAPI bool registerService(
        std::shared_ptr<Service> const&  service,
        std::shared_ptr<mod::Mod> const& mod = mod::NativeMod::current()
    );
 
    LLAPI bool unregisterService(ServiceIdView const& id);
 
    LLAPI void unregisterService(mod::Mod const& mod);
 
    ServiceManager(ServiceManager const&)            = delete;
    ServiceManager(ServiceManager&&)                 = delete;
    ServiceManager& operator=(ServiceManager const&) = delete;
    ServiceManager& operator=(ServiceManager&&)      = delete;
 
private:
    class Impl;
    std::unique_ptr<Impl> impl;
 
    ServiceManager();
    ~ServiceManager();
};
 
} // namespace ll::service