class Exception : public std::exception
{
public:
    enum class State { FILE_DOES_NOT_EXISTS = 1, FILE_IS_NOT_OPEN = 2 };

    explicit Exception(State state) : state(state) {}

    const char* what() const noexcept override { return state_to_string(); }

private:
    const char* state_to_string() const
    {
        switch (state)
        {
        case State::FILE_DOES_NOT_EXISTS:
            return "File does not exists";
        case State::FILE_IS_NOT_OPEN:
            return "File is not open";
        }
    }

private:
    State state;
};

list read_file(const fs::path& file_path)
{
    if(!fs::exists(file_path))
        throw Exception{Exception::State::FILE_DOES_NOT_EXISTS};

    std::ifstream infile{file_path.string()};

    if(!infile.is_open())
        throw Exception{Exception::State::FILE_IS_NOT_OPEN};

    list data{};

    std::string number{""};
    while(std::getline(infile, number, ','))
        data.push_back(std::stoi(number));

    return data;
}