// vim:sts=2:sw=2:expandtab
public class MyLogin
{
  public void login(Request request,
    String login,
    String password)
  {
    if( login == null || password == null )
      respond(UNAUTHORIZED, "You should provide login and password");
    else
      doLogin(request, login, password);
  }

  private final void respond(int code, String description) {}

  private static final int UNAUTHORIZED = 1;
  private static final int FORBIDDEN = 2;

  private void doLogin(Request request, String login, String password)
  {
     UserInfo user = AccountsStorage.find(login);
     if( user == null )
        handleUnknownUserLogin();
     else
        (new KnownUserLoginHandler(request, login, password, user)).handle();
  }

  private void handleUnknownUserLogin()
  {
    respond(UNAUTHORIZED, "Unknown user");
  }

  private class KnownUserLoginHandler
  {
     Request request;
     String login;
     String password;
     UserInfo user;

     KnownUserLoginHandler(
           Request request,
           String login,
           String password,
           UserInfo user)
        {
           this.request = request;
           this.login = login;
           this.password = password;
           this.user = user;
        }

     public void handle()
     {
        if( user.inactive )
           handleInactiveUserLogin();
        else
           if( user.authScheme.equals( "PETRIVKA" ) )
              handlePetrivkaAuthSchemeLogin();
           else
              handleUsualAuthSchemeLogin();
     }

     private void handleInactiveUserLogin()
     {
        respond(UNAUTHORIZED, "Account is inactive");
     }

     private void handlePetrivkaAuthSchemeLogin()
     {
        if( user.passwordMatches(password) )
           setupSuccessfulAuthResult();
        else
           respond(UNAUTHORIZED, "Authentication failed");
     }

     private void handleUsualAuthSchemeLogin()
     {
        AuthScheme scheme = findAuthScheme();
        if( scheme == null )
           respond(FORBIDDEN, "Unknown authentication scheme: " + user.authScheme);
        else
        {
          int waitFor = 0;
          if( waitFor == 0 )
             setupSuccessfulAuthResult();
          else
             respond(UNAUTHORIZED, "Authentication within failed");
        }
     }

     private void setupSuccessfulAuthResult()
     {
        request.storeInSession("user", user );
     }

     private AuthScheme findAuthScheme()
     {
        return null;
     }
  }
}

class Request
{
  final void storeInSession(String key, Object what) {}
}

class AccountsStorage
{
   static UserInfo find(String name) { return null; }
}

class UserInfo
{
  boolean inactive;
  String authScheme;

  final boolean passwordMatches(String psw) { return false; }
}

class AccessStorage
{
  static AuthScheme find(String name) { return null; }
}

class AuthScheme
{
}