package com.nilhcem.fakesmtp.server;

 import org.subethamail.smtp.AuthenticationHandler;

 /**

  * Simulates an authentication handler to allow capturing emails that are set up with login authentication.

  *

  * @author jasonpenny

  * @since 1.2

  */

 /*package*/ final class SMTPAuthHandler implements AuthenticationHandler {

         private static final String USER_IDENTITY = "User";

         private static final String PROMPT_USERNAME = "334 VXNlcm5hbWU6"; // VXNlcm5hbWU6 is base64 for "Username:"

         private static final String PROMPT_PASSWORD = "334 UGFzc3dvcmQ6"; // UGFzc3dvcmQ6 is base64 for "Password:"

         private int pass = 0;

         /**

          * Simulates an authentication process.

          * <p>

          * <ul>

          *   <li>first prompts for username;</li>

          *   <li>then, prompts for password;</li>

          *   <li>finally, returns {@code null} to finish the authentication process;</li>

          * </ul>

          * </p>

          *

          * @return <code>null</code> if the authentication process is finished, otherwise a string to hand back to the client.

          * @param clientInput The client's input, eg "AUTH PLAIN dGVzdAB0ZXN0ADEyMzQ="

          */

         @Override

         public String auth(String clientInput) {

                 String prompt;

                 if (++pass == 1) {

                         prompt = SMTPAuthHandler.PROMPT_USERNAME;

                 } else if (pass == 2) {

                         prompt = SMTPAuthHandler.PROMPT_PASSWORD;

                 } else {

                         pass = 0;

                         prompt = null;

                 }

                 return prompt;

         }

         /**

          * If the authentication process was successful, this returns the identity

          * of the user. The type defining the identity can vary depending on the

          * authentication mechanism used, but typically this returns a String username.

          * If authentication was not successful, the return value is undefined.

          */

         @Override

         public Object getIdentity() {

                 return SMTPAuthHandler.USER_IDENTITY;

         }

 }