#ifndef USER_DATA_HPP
#define USER_DATA_HPP

#include <string>
#include <vector>

// TODO: This is a so-called "POD" (Plain Old Data) type. It's a struct that only contains data members; it is essentially a named tuple.
// Define an operator< so it gets sorted by age, then by name length, then by name lexicographically.
struct UserData {
    std::string name;
    int age;
    double height;
};


// ------------------------------------------------------------------

enum class UserDataComparison {
    Name,
    Age,
    Height
};

// TODO: Define the UserDataComparator class so that it compares UserData objects by the field specified in the constructor.
class UserDataComparator {
public:
    UserDataComparator(UserDataComparison comparison) {} // TODO: reimplement this constructor
    bool operator()(const UserData& lhs, const UserData& rhs) const {
        return false; // TODO: reimplement this function
    }
};

// TODO: what is the meaning of the `inline` keyword here?
inline void sort_user_data(std::vector<UserData>& users, UserDataComparison comparison) {
    //  TODO: sort the users vector using the UserDataComparator
}

struct dummy_set {
    // pointers are technically iterators; but do not do this
    // this dummy set returns iterators representing an empty range (both are the iterator past the end)
    const UserData* begin() const {
        return nullptr;
    }

    const UserData* end() const {
        return nullptr;
    }

    void emplace(const std::string& name, int age, double height) {
        // do nothing
    }

    void emplace_back(std::string&& name, int age, double height) {
        // do nothing
    }
};

inline auto set_sorted_by_criterion(UserDataComparison comparison) {
    // TODO: create a set of UserData objects sorted by the specified criterion
    return dummy_set{};
}

// ------------------------------------------------------------------

#endif // USER_DATA_HPP