/*
    * ====================================================================
    * 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.security.Principal;
  
  import org.apache.hc.client5.http.auth.AuthChallenge;
  import org.apache.hc.client5.http.auth.AuthScheme;
  import org.apache.hc.client5.http.auth.StandardAuthScheme;
  import org.apache.hc.client5.http.auth.AuthScope;
  import org.apache.hc.client5.http.auth.AuthenticationException;
  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.NTCredentials;
  import org.apache.hc.client5.http.protocol.HttpClientContext;
  import org.apache.hc.core5.http.HttpHost;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.util.Args;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * NTLM is a proprietary authentication scheme developed by Microsoft
   * and optimized for Windows platforms.
   *
   * @since 4.0
   */
  public final class NTLMScheme implements AuthScheme {
  
      private static final Logger LOG = LoggerFactory.getLogger(NTLMScheme.class);
  
      enum State {
          UNINITIATED,
          CHALLENGE_RECEIVED,
          MSG_TYPE1_GENERATED,
          MSG_TYPE2_RECEIVED,
          MSG_TYPE3_GENERATED,
          FAILED,
      }
  
      private final NTLMEngine engine;
  
      private State state;
      private String challenge;
      private NTCredentials credentials;
  
      public NTLMScheme(final NTLMEngine engine) {
          super();
          Args.notNull(engine, "NTLM engine");
          this.engine = engine;
          this.state = State.UNINITIATED;
      }
  
      /**
       * @since 4.3
       */
      public NTLMScheme() {
          this(new NTLMEngineImpl());
      }
  
      @Override
      public String getName() {
          return StandardAuthScheme.NTLM;
      }
  
      @Override
      public boolean isConnectionBased() {
          return true;
      }
  
      @Override
      public String getRealm() {
          return null;
     }
 
     @Override
     public void processChallenge(
             final AuthChallenge authChallenge,
             final HttpContext context) throws MalformedChallengeException {
         Args.notNull(authChallenge, "AuthChallenge");
 
         this.challenge = authChallenge.getValue();
         if (this.challenge == null || this.challenge.isEmpty()) {
             if (this.state == State.UNINITIATED) {
                 this.state = State.CHALLENGE_RECEIVED;
             } else {
                 this.state = State.FAILED;
             }
         } else {
             if (this.state.compareTo(State.MSG_TYPE1_GENERATED) < 0) {
                 this.state = State.FAILED;
                 throw new MalformedChallengeException("Out of sequence NTLM response message");
             } else if (this.state == State.MSG_TYPE1_GENERATED) {
                 this.state = State.MSG_TYPE2_RECEIVED;
             }
         }
     }
 
     @Override
     public boolean isResponseReady(
             final HttpHost host,
             final CredentialsProvider credentialsProvider,
             final HttpContext context) throws AuthenticationException {
 
         Args.notNull(host, "Auth host");
         Args.notNull(credentialsProvider, "CredentialsProvider");
 
         final AuthScope authScope = new AuthScope(host, null, getName());
         final Credentials credentials = credentialsProvider.getCredentials(
                 authScope, context);
         if (credentials instanceof NTCredentials) {
             this.credentials = (NTCredentials) credentials;
             return true;
         }
 
         if (LOG.isDebugEnabled()) {
             final HttpClientContext clientContext = HttpClientContext.adapt(context);
             final String exchangeId = clientContext.getExchangeId();
             LOG.debug("{} No credentials found for auth scope [{}]", exchangeId, authScope);
         }
         return false;
     }
 
     @Override
     public Principal getPrincipal() {
         return this.credentials != null ? this.credentials.getUserPrincipal() : null;
     }
 
     @Override
     public String generateAuthResponse(
             final HttpHost host,
             final HttpRequest request,
             final HttpContext context) throws AuthenticationException {
         if (this.credentials == null) {
             throw new AuthenticationException("NT credentials not available");
         }
         final String response;
         if (this.state == State.FAILED) {
             throw new AuthenticationException("NTLM authentication failed");
         } else if (this.state == State.CHALLENGE_RECEIVED) {
             response = this.engine.generateType1Msg(
                     this.credentials.getNetbiosDomain(),
                     this.credentials.getWorkstation());
             this.state = State.MSG_TYPE1_GENERATED;
         } else if (this.state == State.MSG_TYPE2_RECEIVED) {
             response = this.engine.generateType3Msg(
                     this.credentials.getUserName(),
                     this.credentials.getPassword(),
                     this.credentials.getNetbiosDomain(),
                     this.credentials.getWorkstation(),
                     this.challenge);
             this.state = State.MSG_TYPE3_GENERATED;
         } else {
             throw new AuthenticationException("Unexpected state: " + this.state);
         }
         return StandardAuthScheme.NTLM + " " + response;
     }
 
     @Override
     public boolean isChallengeComplete() {
         return this.state == State.MSG_TYPE3_GENERATED || this.state == State.FAILED;
     }
 
     @Override
     public String toString() {
         return getName() + "{" + this.state + " " + challenge + '}';
     }
 
 }