future code, homework, 4.1.1. Access Control

#include <string>
#include <unordered_map>
#include <unordered_set>

class AccessControl {
private:
    std::unordered_map<int, std::unordered_set<std::string>> userRoles;
    std::unordered_set<std::string> registeredRoles;

public:
    bool HasRole(int id, const std::string& roleName) const {
        auto userIt = userRoles.find(id);
        if (userIt != userRoles.end()) {
            return userIt->second.find(roleName) != userIt->second.end();
        }
        return false;
    }

    bool GrantRole(int id, const std::string& roleName) {
        if (registeredRoles.find(roleName) == registeredRoles.end()) {
            return false;
        }
        return userRoles[id].insert(roleName).second;
    }

    bool RemoveRole(int id, const std::string& roleName) {
        auto userIt = userRoles.find(id);
        if (userIt != userRoles.end() && userIt->second.find(roleName) != userIt->second.end()) {
            userIt->second.erase(roleName);
            return true;
        }
        return false;
    }

    void RegisterRole(const std::string& roleName) {
        registeredRoles.insert(roleName);
    }
};