/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */
package org.apache.http.auth;

import org.apache.http.Header;
import org.apache.http.HttpRequest;

This interface represents an abstract challenge-response oriented
authentication scheme.

An authentication scheme should be able to support the following
functions:

  
Parse and process the challenge sent by the target server
      in response to request for a protected resource
  
Provide its textual designation
  
Provide its parameters, if available
  
Provide the realm this authentication scheme is applicable to,
      if available
  
Generate authorization string for the given set of credentials
      and the HTTP request in response to the authorization challenge.


Authentication schemes may be stateful involving a series of
challenge-response exchanges.
 IMPORTANT: implementations of this interface MUST also implement ContextAwareAuthScheme interface in order to remain API compatible with newer versions of HttpClient. 
Since:
4.0/**
 * This interface represents an abstract challenge-response oriented
 * authentication scheme.
 * <p>
 * An authentication scheme should be able to support the following
 * functions:
 * <ul>
 *   <li>Parse and process the challenge sent by the target server
 *       in response to request for a protected resource
 *   <li>Provide its textual designation
 *   <li>Provide its parameters, if available
 *   <li>Provide the realm this authentication scheme is applicable to,
 *       if available
 *   <li>Generate authorization string for the given set of credentials
 *       and the HTTP request in response to the authorization challenge.
 * </ul>
 * <p>
 * Authentication schemes may be stateful involving a series of
 * challenge-response exchanges.
 * <p>
 * IMPORTANT: implementations of this interface MUST also implement {@link ContextAwareAuthScheme}
 * interface in order to remain API compatible with newer versions of HttpClient.
 *
 * @since 4.0
 */

public interface AuthScheme {

    
Processes the given challenge token. Some authentication schemes
may involve multiple challenge-response exchanges. Such schemes must be able
to maintain the state information when dealing with sequential challenges
Params:
header – the challenge header/**
     * Processes the given challenge token. Some authentication schemes
     * may involve multiple challenge-response exchanges. Such schemes must be able
     * to maintain the state information when dealing with sequential challenges
     *
     * @param header the challenge header
     */
    void processChallenge(final Header header) throws MalformedChallengeException;

    
Returns textual designation of the given authentication scheme.
Returns:
the name of the given authentication scheme/**
     * Returns textual designation of the given authentication scheme.
     *
     * @return the name of the given authentication scheme
     */
    String getSchemeName();

    
Returns authentication parameter with the given name, if available.
Params:
name – The name of the parameter to be returned
Returns:
the parameter with the given name/**
     * Returns authentication parameter with the given name, if available.
     *
     * @param name The name of the parameter to be returned
     *
     * @return the parameter with the given name
     */
    String getParameter(final String name);

    
Returns authentication realm. If the concept of an authentication realm is not applicable to the given authentication scheme, returns null. 
Returns:
the authentication realm/**
     * Returns authentication realm. If the concept of an authentication
     * realm is not applicable to the given authentication scheme, returns
     * {@code null}.
     *
     * @return the authentication realm
     */
    String getRealm();

    
Tests if the authentication scheme is provides authorization on a per
connection basis instead of usual per request basis
Returns:
true if the scheme is connection based, false if the scheme is request based./**
     * Tests if the authentication scheme is provides authorization on a per
     * connection basis instead of usual per request basis
     *
     * @return {@code true} if the scheme is connection based, {@code false}
     * if the scheme is request based.
     */
    boolean isConnectionBased();

    
Authentication process may involve a series of challenge-response exchanges.
This method tests if the authorization process has been completed, either
successfully or unsuccessfully, that is, all the required authorization
challenges have been processed in their entirety.
Returns:
true if the authentication process has been completed, false otherwise./**
     * Authentication process may involve a series of challenge-response exchanges.
     * This method tests if the authorization process has been completed, either
     * successfully or unsuccessfully, that is, all the required authorization
     * challenges have been processed in their entirety.
     *
     * @return {@code true} if the authentication process has been completed,
     * {@code false} otherwise.
     */
    boolean isComplete();

    
Produces an authorization string for the given set of Credentials. 
Params:
credentials – The set of credentials to be used for athentication
request – The request being authenticated
Throws:
AuthenticationException – if authorization string cannot
  be generated due to an authentication failure
Returns:
the authorization string
Deprecated:
(4.1) Use ContextAwareAuthScheme.authenticate(Credentials, HttpRequest, HttpContext)/**
     * Produces an authorization string for the given set of {@link Credentials}.
     *
     * @param credentials The set of credentials to be used for athentication
     * @param request The request being authenticated
     * @throws AuthenticationException if authorization string cannot
     *   be generated due to an authentication failure
     *
     * @return the authorization string
     *
     * @deprecated (4.1)  Use {@link ContextAwareAuthScheme#authenticate(Credentials, HttpRequest, org.apache.http.protocol.HttpContext)}
     */
    @Deprecated
    Header authenticate(Credentials credentials, HttpRequest request)
            throws AuthenticationException;

}