import java.util.Vector;

/**
 * Created by phann on 10/9/2016.
 */

class User{
    public String username;
    private String password;
    public Session session = null;

    User (String username, String password){
        this.username = username;
        this.password = password;
    }

    public boolean passwordOK(String password){
        if (password == null) return false;
        if (this.password.equals(password)){
            return true;
        }
        else return false;
    }
}



public class UserManager {
    private Vector<User> userlist = new Vector();

    private User getUser(String username){
        for (User i:userlist){
            if (i.username.equals(username))
                return i;
        }
        return null;
    }

    public boolean createUser(String newUsername, String newPassword){
        if (getUser(newUsername) != null){
            return false;
        }
        userlist.addElement(new User(newUsername,newPassword));
        //code them phan ghi username, password moi vao file user.txt
        return true;
    }

    public boolean login(String username,String password, Session session){
        if (username == null || password == null || session == null){
            return false;
        }
        User targetUser = getUser(username);
        if (targetUser.passwordOK(password)){
            targetUser.session = session;
            return true;
        }
        else{
            return false;
        }
    }

    public boolean logout(String username){
        if (username == null) return false;
        User target = getUser(username);
        if (target != null){
            target.session = null;
            return true;
        }
        else return false;
    }

    public Session getSession(String username){
        if (username == null) return null;
        User target = getUser(username);
        if (target != null)
            return target.session;
        else return null;
    }

    UserManager(){

    }
}