/* @file service_registry.hpp
 * @brief Name-versioned service registry for decoupled plugin communication.
 * 基于名称+版本的服务注册表，用于插件间解耦通信。
 * Copyright (c) 2026 dstalk contributors. GPLv3.
 */

#pragma once

#include <mutex>
#include <shared_mutex>
#include <string>
#include <unordered_map>
#include <vector>

namespace dstalk {

// 名称 + 最低版本服务目录 / Name + minimum-version service directory.
// 插件注册 vtable；消费者按名称和版本约束查询 /
// Plugins register vtables; consumers query by name and version constraint.
// 读取（query）使用 shared_lock；写入（register/unregister）使用 unique_lock /
// Reads (query) use shared_lock; writes (register/unregister) use unique_lock.
class ServiceRegistry {
public:
    ServiceRegistry() = default;
    ~ServiceRegistry() = default;

    // 注册服务 / Register a named service at a given version
    int register_service(const char* name, int version, void* vtable);

    // 查询服务（返回 vtable 指针，或 nullptr）/ Query a service by name and minimum version
    void* query_service(const char* name, int min_version) const;

    // 注销服务 / Unregister a named service
    void unregister_service(const char* name);

    // 列出所有已注册服务名称（用于 diff/遍历）/ List all currently registered service names (for diff / iteration)
    std::vector<std::string> list_service_names() const;

    // 清空所有注册服务 / Remove all registered services
    void clear();

private:
    struct ServiceEntry {
        std::string name;
        int version;
        void* vtable;
    };

    mutable std::shared_mutex mutex_;            // 读写锁：query 用 shared，register/unregister 用 unique / RW lock: shared for query, unique for register/unregister
    std::unordered_map<std::string, ServiceEntry> services_;
};

} // namespace dstalk