dusklight/include/mods/service.hpp

#pragma once

#include "mods/api.h"

#include <cstdint>
#include <cstdio>
#include <type_traits>
#include <vector>

namespace dusk::mods {

template <class Service>
struct ServiceTraits;

namespace detail {

inline std::vector<ServiceImport>& imports() {
    static std::vector<ServiceImport> entries;
    return entries;
}

inline std::vector<ServiceExport>& exports() {
    static std::vector<ServiceExport> entries;
    return entries;
}

inline int register_import(ServiceImport entry) {
    imports().push_back(entry);
    return 0;
}

inline int register_export(ServiceExport entry) {
    exports().push_back(entry);
    return 0;
}

inline const ModManifest* manifest() {
    static ModManifest manifest{
        sizeof(ModManifest),
        MOD_ABI_VERSION,
        nullptr,
        0,
        nullptr,
        0,
    };

    auto& importEntries = imports();
    auto& exportEntries = exports();
    manifest.imports = importEntries.data();
    manifest.import_count = importEntries.size();
    manifest.exports = exportEntries.data();
    manifest.export_count = exportEntries.size();
    return &manifest;
}

}  // namespace detail

inline ModResult set_error(ModError* outError, ModResult code, const char* message) {
    if (outError != nullptr && outError->struct_size >= sizeof(ModError)) {
        outError->code = code;
        outError->message[0] = '\0';
        if (message != nullptr) {
            std::snprintf(outError->message, sizeof(outError->message), "%s", message);
        }
    }
    return code;
}

}  // namespace dusk::mods

#define DEFINE_MOD()                                                                               \
    extern "C" {                                                                                   \
    MOD_EXPORT ModContext* mod_ctx = nullptr;                                                      \
    MOD_EXPORT const ModManifest* mod_get_manifest(void) {                                         \
        return ::dusk::mods::detail::manifest();                                                   \
    }                                                                                              \
    }

// Declares `static const service_type* variable`, filled in by the host before mod_initialize.
// Required imports are guaranteed non-null (the mod fails to load otherwise); optional imports
// must be checked against nullptr before use.
#define IMPORT_SERVICE_EX(                                                                         \
    service_type, variable, service_id_value, major_value, min_minor_value, flags_value)           \
    static const service_type* variable = nullptr;                                                 \
    [[maybe_unused]] static const int mod_import_registration_##variable =                         \
        ::dusk::mods::detail::register_import(ServiceImport{                                       \
            sizeof(ServiceImport),                                                                 \
            (service_id_value),                                                                    \
            static_cast<uint16_t>(major_value),                                                    \
            static_cast<uint16_t>(min_minor_value),                                                \
            static_cast<uint32_t>(flags_value),                                                    \
            &(variable),                                                                           \
        })

#define IMPORT_SERVICE_VERSION(service_type, variable, min_minor_value)                            \
    IMPORT_SERVICE_EX(service_type, variable, ::dusk::mods::ServiceTraits<service_type>::id,       \
        ::dusk::mods::ServiceTraits<service_type>::major_version, min_minor_value,                 \
        SERVICE_IMPORT_REQUIRED)

#define IMPORT_SERVICE(service_type, variable) IMPORT_SERVICE_VERSION(service_type, variable, 0)

#define IMPORT_OPTIONAL_SERVICE_VERSION(service_type, variable, min_minor_value)                   \
    IMPORT_SERVICE_EX(service_type, variable, ::dusk::mods::ServiceTraits<service_type>::id,       \
        ::dusk::mods::ServiceTraits<service_type>::major_version, min_minor_value,                 \
        SERVICE_IMPORT_OPTIONAL)

#define IMPORT_OPTIONAL_SERVICE(service_type, variable)                                            \
    IMPORT_OPTIONAL_SERVICE_VERSION(service_type, variable, 0)

#define EXPORT_SERVICE_AS(instance, service_id_value)                                              \
    namespace {                                                                                    \
    const int mod_export_registration_##instance =                                                 \
        ::dusk::mods::detail::register_export(ServiceExport{                                       \
            sizeof(ServiceExport),                                                                 \
            (service_id_value),                                                                    \
            (instance).header.major_version,                                                       \
            (instance).header.minor_version,                                                       \
            SERVICE_EXPORT_STATIC,                                                                 \
            &(instance),                                                                           \
        });                                                                                        \
    }

#define EXPORT_SERVICE(instance)                                                                   \
    EXPORT_SERVICE_AS(                                                                             \
        instance, ::dusk::mods::ServiceTraits<std::remove_cv_t<decltype(instance)> >::id)

#define EXPORT_DEFERRED_SERVICE(token, service_id_value, major_value, minor_value)                 \
    namespace {                                                                                    \
    const int mod_deferred_export_registration_##token =                                           \
        ::dusk::mods::detail::register_export(ServiceExport{                                       \
            sizeof(ServiceExport),                                                                 \
            (service_id_value),                                                                    \
            static_cast<uint16_t>(major_value),                                                    \
            static_cast<uint16_t>(minor_value),                                                    \
            SERVICE_EXPORT_DEFERRED,                                                               \
            nullptr,                                                                               \
        });                                                                                        \
    }