/*
    * ====================================================================
    * 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.hc.client5.http.impl.auth;
  
  import java.io.Serializable;
  import java.security.Principal;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  
  import org.apache.hc.client5.http.auth.AuthChallenge;
  import org.apache.hc.client5.http.auth.AuthScheme;
  import org.apache.hc.client5.http.auth.AuthScope;
  import org.apache.hc.client5.http.auth.AuthStateCacheable;
  import org.apache.hc.client5.http.auth.AuthenticationException;
  import org.apache.hc.client5.http.auth.BearerToken;
  import org.apache.hc.client5.http.auth.Credentials;
  import org.apache.hc.client5.http.auth.CredentialsProvider;
  import org.apache.hc.client5.http.auth.MalformedChallengeException;
  import org.apache.hc.client5.http.auth.StandardAuthScheme;
  import org.apache.hc.client5.http.impl.StateHolder;
  import org.apache.hc.client5.http.protocol.HttpClientContext;
  import org.apache.hc.core5.annotation.Internal;
  import org.apache.hc.core5.http.HttpHost;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.NameValuePair;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.Asserts;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Bearer authentication scheme.
   *
   * @since 5.3
   */
  @AuthStateCacheable
  public class BearerScheme implements AuthScheme, StateHolder<BearerScheme.State>, Serializable {
  
      private static final Logger LOG = LoggerFactory.getLogger(BearerScheme.class);
  
      private final Map<String, String> paramMap;
      private boolean complete;
  
      private BearerToken bearerToken;
  
      public BearerScheme() {
          this.paramMap = new HashMap<>();
          this.complete = false;
      }
  
      @Override
      public String getName() {
          return StandardAuthScheme.BEARER;
      }
  
      @Override
      public boolean isConnectionBased() {
          return false;
      }
  
      @Override
      public String getRealm() {
          return this.paramMap.get("realm");
      }
  
      @Override
      public void processChallenge(
              final AuthChallenge authChallenge,
              final HttpContext context) throws MalformedChallengeException {
          this.paramMap.clear();
          final List<NameValuePair> params = authChallenge.getParams();
          if (params != null) {
             for (final NameValuePair param: params) {
                 this.paramMap.put(param.getName().toLowerCase(Locale.ROOT), param.getValue());
             }
             if (LOG.isDebugEnabled()) {
                 final String error = paramMap.get("error");
                 if (error != null) {
                     final StringBuilder buf = new StringBuilder();
                     buf.append(error);
                     final String desc = paramMap.get("error_description");
                     final String uri = paramMap.get("error_uri");
                     if (desc != null || uri != null) {
                         buf.append(" (");
                         buf.append(desc).append("; ").append(uri);
                         buf.append(")");
                     }
                     LOG.debug(buf.toString());
                 }
             }
         }
         this.complete = true;
     }
 
     @Override
     public boolean isChallengeComplete() {
         return this.complete;
     }
 
     @Override
     public boolean isResponseReady(
             final HttpHost host,
             final CredentialsProvider credentialsProvider,
             final HttpContext context) throws AuthenticationException {
 
         Args.notNull(host, "Auth host");
         Args.notNull(credentialsProvider, "Credentials provider");
 
         final AuthScope authScope = new AuthScope(host, getRealm(), getName());
         final Credentials credentials = credentialsProvider.getCredentials(authScope, context);
         if (credentials instanceof BearerToken) {
             this.bearerToken = (BearerToken) credentials;
             return true;
         }
 
         if (LOG.isDebugEnabled()) {
             final HttpClientContext clientContext = HttpClientContext.cast(context);
             final String exchangeId = clientContext.getExchangeId();
             LOG.debug("{} No credentials found for auth scope [{}]", exchangeId, authScope);
         }
         this.bearerToken = null;
         return false;
     }
 
     @Override
     public Principal getPrincipal() {
         return null;
     }
 
     @Override
     public String generateAuthResponse(
             final HttpHost host,
             final HttpRequest request,
             final HttpContext context) throws AuthenticationException {
         Asserts.notNull(bearerToken, "Bearer token");
         return StandardAuthScheme.BEARER + " " + bearerToken.getToken();
     }
 
     @Override
     public State store() {
         if (complete) {
             return new State(new HashMap<>(paramMap), bearerToken);
         } else {
             return null;
         }
     }
 
     @Override
     public void restore(final State state) {
         if (state != null) {
             paramMap.clear();
             paramMap.putAll(state.params);
             bearerToken = state.bearerToken;
             complete = true;
         }
     }
 
     @Override
     public String toString() {
         return getName() + this.paramMap;
     }
 
     @Internal
     public static class State {
 
         final Map<String, String> params;
         final BearerToken bearerToken;
 
         State(final Map<String, String> params, final BearerToken bearerToken) {
             this.params = params;
             this.bearerToken = bearerToken;
         }
 
         @Override
         public String toString() {
             return "State{" +
                     "params=" + params +
                     ", bearerToken=" + bearerToken +
                     '}';
         }
 
     }
 
 }