struct list_node {
    train* data;
    list_node* next;
}

struct train {
    string destination;
    int number;
    unsigned int arrivalTime;
}

class TrainList {
    list_node *head;

public:
    TrainList() {head = NULL;}
    ~TrainList();

    bool checkTrainIdValid(int id);
    void add();
    void remove();
    void show();

    void save();
    void load();
}

TrainList::~TrainList() {
    while (head != NULL) {
        list_node *tmp = head->next;
        delete head;
        head = tmp;
    }
}

bool TrainList::checkTrainNumberValid(int number) {
    list_node *iter = head;
    while (iter != NULL) {
        if (iter->number == number) {
            cerr << "Train with such number already exists!!!" << endl;
            return false;
        }
    }

    return true;
}

int main() {
    TrainList trains;
    while(true) {
        cout << "Commands:" << endl;
        cout << "Enter 1 to add new train;" << endl;
        cout << "Enter 2 to modify one of the trains" << endl;
        cout << "Enter 3 to show existing trains" << endl;
        cout << "Enter 4 to modify one of the trains" << endl;
        cout << "Enter 5 to delete one of the trains" << endl;
        cout << "Enter 6 to save trains to file" << endl;
        cout << "Enter 7 to load trains from file" << endl;
        cout << "Enter 8 to exit" << endl;

        string command;
        cin >> command;

        if(command.size() > 1) {
            cerr << "Wrond command, try again!" << endl;
            continue;
        }

        switch(command[0]) {
            case '1':
                trains.add();
                break;
            case '2':
                trains.modify();
                break;
            case '3':
                trains.show();
                break;
            case '4':

                break;
            case '5':

                break;
            case '6':

                break;
            case '7':

                break;
            case '8':

                break;
            case '9':

                break;
            default:
                cerr << "Wrond command, try again!" << endl;
                continue;
        }
    }
}