/*
    * ====================================================================
    * 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.impl.client;
  
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.http.FormattedHeader;
  import org.apache.http.Header;
  import org.apache.http.HttpResponse;
  import org.apache.http.annotation.Immutable;
  import org.apache.http.auth.AuthScheme;
  import org.apache.http.auth.AuthSchemeRegistry;
  import org.apache.http.auth.AuthenticationException;
  import org.apache.http.auth.MalformedChallengeException;
  import org.apache.http.client.AuthenticationHandler;
  import org.apache.http.client.AuthenticationStrategy;
  import org.apache.http.client.params.AuthPolicy;
  import org.apache.http.client.protocol.ClientContext;
  import org.apache.http.protocol.HTTP;
  import org.apache.http.protocol.HttpContext;
  import org.apache.http.util.Asserts;
  import org.apache.http.util.CharArrayBuffer;
  
  /**
   * Base class for {@link AuthenticationHandler} implementations.
   *
   * @since 4.0
   *
   * @deprecated (4.2)  use {@link AuthenticationStrategy}
   */
  @Deprecated
  @Immutable
  public abstract class AbstractAuthenticationHandler implements AuthenticationHandler {
  
      private final Log log = LogFactory.getLog(getClass());
  
      private static final List<String> DEFAULT_SCHEME_PRIORITY =
          Collections.unmodifiableList(Arrays.asList(new String[] {
                  AuthPolicy.SPNEGO,
                  AuthPolicy.NTLM,
                  AuthPolicy.DIGEST,
                  AuthPolicy.BASIC
      }));
  
      public AbstractAuthenticationHandler() {
          super();
      }
  
      protected Map<String, Header> parseChallenges(
              final Header[] headers) throws MalformedChallengeException {
  
          final Map<String, Header> map = new HashMap<String, Header>(headers.length);
          for (final Header header : headers) {
              CharArrayBuffer buffer;
              int pos;
              if (header instanceof FormattedHeader) {
                  buffer = ((FormattedHeader) header).getBuffer();
                  pos = ((FormattedHeader) header).getValuePos();
              } else {
                  final String s = header.getValue();
                  if (s == null) {
                      throw new MalformedChallengeException("Header value is null");
                  }
                  buffer = new CharArrayBuffer(s.length());
                  buffer.append(s);
                  pos = 0;
             }
             while (pos < buffer.length() && HTTP.isWhitespace(buffer.charAt(pos))) {
                 pos++;
             }
             final int beginIndex = pos;
             while (pos < buffer.length() && !HTTP.isWhitespace(buffer.charAt(pos))) {
                 pos++;
             }
             final int endIndex = pos;
             final String s = buffer.substring(beginIndex, endIndex);
             map.put(s.toLowerCase(Locale.US), header);
         }
         return map;
     }
 
     /**
      * Returns default list of auth scheme names in their order of preference.
      *
      * @return list of auth scheme names
      */
     protected List<String> getAuthPreferences() {
         return DEFAULT_SCHEME_PRIORITY;
     }
 
     /**
      * Returns default list of auth scheme names in their order of preference
      * based on the HTTP response and the current execution context.
      *
      * @param response HTTP response.
      * @param context HTTP execution context.
      *
      * @since 4.1
      */
     protected List<String> getAuthPreferences(
             final HttpResponse response,
             final HttpContext context) {
         return getAuthPreferences();
     }
 
     public AuthScheme selectScheme(
             final Map<String, Header> challenges,
             final HttpResponse response,
             final HttpContext context) throws AuthenticationException {
 
         final AuthSchemeRegistry registry = (AuthSchemeRegistry) context.getAttribute(
                 ClientContext.AUTHSCHEME_REGISTRY);
         Asserts.notNull(registry, "AuthScheme registry");
         Collection<String> authPrefs = getAuthPreferences(response, context);
         if (authPrefs == null) {
             authPrefs = DEFAULT_SCHEME_PRIORITY;
         }
 
         if (this.log.isDebugEnabled()) {
             this.log.debug("Authentication schemes in the order of preference: "
                 + authPrefs);
         }
 
         AuthScheme authScheme = null;
         for (final String id: authPrefs) {
             final Header challenge = challenges.get(id.toLowerCase(Locale.ENGLISH));
 
             if (challenge != null) {
                 if (this.log.isDebugEnabled()) {
                     this.log.debug(id + " authentication scheme selected");
                 }
                 try {
                     authScheme = registry.getAuthScheme(id, response.getParams());
                     break;
                 } catch (final IllegalStateException e) {
                     if (this.log.isWarnEnabled()) {
                         this.log.warn("Authentication scheme " + id + " not supported");
                         // Try again
                     }
                 }
             } else {
                 if (this.log.isDebugEnabled()) {
                     this.log.debug("Challenge for " + id + " authentication scheme not available");
                     // Try again
                 }
             }
         }
         if (authScheme == null) {
             // If none selected, something is wrong
             throw new AuthenticationException(
                 "Unable to respond to any of these challenges: "
                     + challenges);
         }
         return authScheme;
     }
 
 }