/*
    * ====================================================================
    * 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.testing.classic;
  
  import java.io.IOException;
  import java.nio.charset.StandardCharsets;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.hc.client5.testing.auth.AuthResult;
  import org.apache.hc.client5.testing.auth.AuthenticationHandler;
  import org.apache.hc.client5.testing.auth.Authenticator;
  import org.apache.hc.client5.testing.auth.BasicAuthenticationHandler;
  import org.apache.hc.core5.http.ClassicHttpRequest;
  import org.apache.hc.core5.http.ClassicHttpResponse;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.HttpHeaders;
  import org.apache.hc.core5.http.HttpStatus;
  import org.apache.hc.core5.http.NameValuePair;
  import org.apache.hc.core5.http.io.HttpServerRequestHandler;
  import org.apache.hc.core5.http.io.entity.EntityUtils;
  import org.apache.hc.core5.http.io.entity.StringEntity;
  import org.apache.hc.core5.http.message.BasicClassicHttpResponse;
  import org.apache.hc.core5.http.message.BasicNameValuePair;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.net.URIAuthority;
  import org.apache.hc.core5.util.Args;
  
  public class AuthenticatingDecorator implements HttpServerRequestHandler {
  
      private final HttpServerRequestHandler requestHandler;
      private final AuthenticationHandler<String> authenticationHandler;
      private final Authenticator authenticator;
  
      /**
       * @since 5.3
       */
      public AuthenticatingDecorator(final HttpServerRequestHandler requestHandler,
                                     final AuthenticationHandler<String> authenticationHandler,
                                     final Authenticator authenticator) {
          this.requestHandler = Args.notNull(requestHandler, "Request handler");
          this.authenticationHandler = Args.notNull(authenticationHandler, "Authentication handler");
          this.authenticator = Args.notNull(authenticator, "Authenticator");
      }
  
      public AuthenticatingDecorator(final HttpServerRequestHandler requestHandler,
                                     final Authenticator authenticator) {
          this(requestHandler, new BasicAuthenticationHandler(StandardCharsets.US_ASCII), authenticator);
      }
  
      protected void customizeUnauthorizedResponse(final ClassicHttpResponse unauthorized) {
      }
  
      @Override
      public void handle(
              final ClassicHttpRequest request,
              final ResponseTrigger responseTrigger,
              final HttpContext context) throws HttpException, IOException {
          final Header h = request.getFirstHeader(HttpHeaders.AUTHORIZATION);
          final String challengeResponse = h != null ? authenticationHandler.extractAuthToken(h.getValue()) : null;
  
          final URIAuthority authority = request.getAuthority();
          final String requestUri = request.getRequestUri();
  
          final AuthResult authResult = authenticator.perform(authority, requestUri, challengeResponse);
          final Header expect = request.getFirstHeader(HttpHeaders.EXPECT);
          final boolean expectContinue = expect != null && "100-continue".equalsIgnoreCase(expect.getValue());
  
          if (authResult.isSuccess()) {
              if (expectContinue) {
                  responseTrigger.sendInformation(new BasicClassicHttpResponse(HttpStatus.SC_CONTINUE));
              }
              requestHandler.handle(request, responseTrigger, context);
         } else {
             final ClassicHttpResponse unauthorized = new BasicClassicHttpResponse(HttpStatus.SC_UNAUTHORIZED);
             final List<NameValuePair> challengeParams = new ArrayList<>();
             final String realm = authenticator.getRealm(authority, requestUri);
             if (realm != null) {
                 challengeParams.add(new BasicNameValuePair("realm", realm));
             }
             if (authResult.hasParams()) {
                 challengeParams.addAll(authResult.getParams());
             }
             final String challenge = authenticationHandler.challenge(challengeParams);
             unauthorized.addHeader(HttpHeaders.WWW_AUTHENTICATE, challenge);
             customizeUnauthorizedResponse(unauthorized);
             if (unauthorized.getEntity() == null) {
                 unauthorized.setEntity(new StringEntity("Unauthorized"));
             }
             if (expectContinue || request.getEntity() == null) {
                 // Respond immediately
                 responseTrigger.submitResponse(unauthorized);
                 // Consume request body later
                 EntityUtils.consume(request.getEntity());
             } else {
                 // Consume request body first
                 EntityUtils.consume(request.getEntity());
                 // Respond later
                 responseTrigger.submitResponse(unauthorized);
             }
         }
     }
 
 }