package com.atlassian.sal.api.auth;
   
   import com.atlassian.sal.api.message.Message;
   
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   import java.io.Serializable;
   import java.security.Principal;
   
  /**
   * Authenticates requests
   *
   * @since 2.0
   */
  public interface Authenticator {
      /**
       * Authenticates a request
       *
       * @param request  The request
       * @param response The response
       * @return The result of the authentication
       */
      Result authenticate(HttpServletRequest request, HttpServletResponse response);
  
      /**
       * Encapsulates the results of an authentication attempt.  Includes the result status, any problem that
       * occurred, and possibly the authenticated users {@link Principal}.
       */
      class Result {
          private final Result.Status status;
          private final Message message;
          private final Principal principal;
  
          Result(final Result.Status status, final Message message) {
              this(status, message, null);
          }
  
          Result(final Result.Status status, final Message message, final Principal principal) {
              if (status == null) {
                  throw new NullPointerException("status");
              }
              if (message == null) {
                  throw new NullPointerException("message");
              }
              this.status = status;
              this.message = message;
              this.principal = principal;
          }
  
          public Result.Status getStatus() {
              return status;
          }
  
          public String getMessage() {
              return message.toString();
          }
  
          public Principal getPrincipal() {
              return principal;
          }
  
          public enum Status {
              SUCCESS("success"),
              FAILED("failed"),
              ERROR("error"),
              NO_ATTEMPT("no attempt");
  
              private final String name;
  
              Status(final String name) {
                  this.name = name;
              }
  
              @Override
              public String toString() {
                  return name;
              }
          }
  
          private static final Message NO_ATTEMPT_MESSAGE = new Message() {
              public Serializable[] getArguments() {
                  return null;
              }
  
              public String getKey() {
                  return "No authentication attempted";
              }
          };
  
          private static final Message SUCCESS_MESSAGE = new Message() {
              public Serializable[] getArguments() {
                  return null;
              }
  
              public String getKey() {
                  return "Successful authentication";
              }
          };
  
         public static final class NoAttempt extends Result {
             public NoAttempt() {
                 super(Status.NO_ATTEMPT, NO_ATTEMPT_MESSAGE);
             }
         }
 
         public static final class Error extends Result {
             public Error(final Message message) {
                 super(Status.ERROR, message);
             }
         }
 
         public static final class Failure extends Result {
             public Failure(final Message message) {
                 super(Status.FAILED, message);
             }
         }
 
         public static final class Success extends Result {
             /**
              * Construct a success result for a particular principal.
              *
              * @param principal the successfully-authenticated principal
              * @deprecated since 2.0.10, use {@link Success#Success(Message, Principal)}
              */
             @Deprecated
             public Success(final Principal principal) {
                 this(SUCCESS_MESSAGE, principal);
             }
 
             /**
              * Construct a success result for a particular principal with a result message.
              *
              * @param message   a message indicating the success of this result
              * @param principal the successfully-authenticated principal
              * @since 2.0.7
              */
             public Success(final Message message, final Principal principal) {
                 super(Status.SUCCESS, message, principal);
             }
         }
     }
 }