main.cpp

#include <iostream>
#include <vector>
using namespace std;

/**
 * In the name of God
 * Homework 2
 * TODO: Complete this code using given TODO comments :). then remove TODOs
 * feel free to edit code as you want and make it better
 * Any questions? ask @devcom_support on telegram
 * Good luck!
 **/

enum UserType
{
    ADMIN,
    MEMBER
};

class UserNotFoundException : public exception {
    public:
    const char * what() {
        return  "couldn't login with given credentials.";
    }
};

class UserAlreadyExistsException : public exception {
    public:
    const char * what() {
        return "Error: username already exists";
    }

}; //TODO: Give exceptions a better structure. search google (optional)

class AbstractUser
{ // User structure
  public:
    virtual bool authenticate(string username, string password) = 0;
    virtual bool deleteAccount(vector<AbstractUser *> *users) = 0; //TODO: 1. implement this in User class. (You can't compile code and create instance of User until then). DON'T TOUCH ABSTRACT USER!
    string username;

  protected:
    string password;
    UserType type;
};

class User : public AbstractUser
{
  public:
    User(string username, string password, UserType type)
    {
        this->username = username;
        this->password = password;
        this->type = type;
    }

    bool authenticate(string username, string password)
    {
        return this->username == username && this->password == password;
    }

    static User *login(vector<AbstractUser *> *users, string username, string password)
    { //TODO: 2. handle user login errors with exceptions
        for (auto user = users->begin(); user != users->end(); user++)
        {
            if ((*user)->authenticate(username, password))
            {
                return (User *)*user;
            }
        }
        UserNotFoundException ex;
        throw ex;
        return nullptr;
    }

    static void signup(vector<AbstractUser *> *users, string username, string password)
    {

        //Check if user with that username exists and throw UserAlreadyExistsException in that case
        for (auto user = users->begin(); user != users->end(); user++)
        { //TODO: 3. this doesn't work. fix it!!
            if ((*user)->username == username)
            {
                UserAlreadyExistsException ex;
                throw ex;
            }
        }
        //Create user and add it to vector
        users->push_back(new User(username, password, UserType::MEMBER));
    }

    virtual bool deleteAccount(vector<AbstractUser *> *users){
        for (auto user = users->begin(); user != users->end(); user++)
        {
            if (this->username == (*user)->username)
            {
                users->erase(user);
                return true;
            }
        }
        
        return false;

    }
    // string username;
};

enum MenuState
{
    START,
    LOGGED_IN,
    END
};

class AppDatabase
{ //Just holds runtime data. doesn't save anything
  public:
    vector<AbstractUser *> appUsers;

    AppDatabase()
    { //Load initial data
        appUsers.push_back(new User("admin",
                                    "admin" /* password is unsafe! for test only */,
                                    UserType::ADMIN));
    }
};

int main()
{
    User *loggedInUser = nullptr;
    AppDatabase appDatabase;
    MenuState menuState = MenuState::START;

    char choice;
    cout << "Welcome!" << endl;

    while (menuState != MenuState::END)
    {
        switch (menuState)
        {
        case MenuState::START:
        {

            cout << "1. login\n2. signup\ne. exit\n";
            cin >> choice;
            switch (choice)
            {
            case '1':
            {
                string username, password;
                cout << "Enter Username" << endl;
                cin >> username;
                cout << "Enter Password" << endl;
                cin >> password;
                try {
                    loggedInUser = User::login(&appDatabase.appUsers, username, password);
                    menuState = MenuState::LOGGED_IN;
                } catch (UserNotFoundException e) {
                    cout << e.what() << endl;
                }
                break;
            }
            case '2':
            {
                string username, password;
                cout << "Enter Username" << endl;
                cin >> username;
                cout << "Enter Password" << endl;
                cin >> password;
                try
                {
                    User::signup(&appDatabase.appUsers, username, password);
                }
                catch (UserAlreadyExistsException e)
                {
                    cout << e.what() << endl;
                }
                break;
            }
            case 'e':
            {
                menuState = MenuState::END;
                break;
            }
            default:
            {
                cout << "Unknown Input" << endl;
            }
            }
            break;
        }
        case MenuState::LOGGED_IN:
        {
            cout << "d.delete account\nl. logout\ne. exit\n";
            cin >> choice;
            switch (choice)
            {
            case 'd':
            {
                loggedInUser->deleteAccount(&appDatabase.appUsers);
                cout << "Account successfully deleted";
                loggedInUser = nullptr;
                menuState = MenuState::START;
                break;
            }
            case 'l':
            {
                loggedInUser = nullptr;
                menuState = MenuState::START;
                break;
            }
            case 'e':
            {
                menuState = MenuState::END;
                break;
            }
            default:
            {
                cout << "Unknown Input" << endl;
            }
            }
            break;
        }
        }
    }

    return 0;
}