/*
    * ====================================================================
    * 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.core5.http.impl.io;
  
  import java.io.IOException;
  
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.http.ClassicHttpRequest;
  import org.apache.hc.core5.http.ClassicHttpResponse;
  import org.apache.hc.core5.http.ConnectionReuseStrategy;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HeaderElements;
  import org.apache.hc.core5.http.HttpEntity;
  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.HttpVersion;
  import org.apache.hc.core5.http.ProtocolException;
  import org.apache.hc.core5.http.ProtocolVersion;
  import org.apache.hc.core5.http.UnsupportedHttpVersionException;
  import org.apache.hc.core5.http.impl.DefaultConnectionReuseStrategy;
  import org.apache.hc.core5.http.impl.Http1StreamListener;
  import org.apache.hc.core5.http.io.HttpClientConnection;
  import org.apache.hc.core5.http.io.HttpResponseInformationCallback;
  import org.apache.hc.core5.http.message.MessageSupport;
  import org.apache.hc.core5.http.message.StatusLine;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.http.protocol.HttpCoreContext;
  import org.apache.hc.core5.http.protocol.HttpProcessor;
  import org.apache.hc.core5.io.Closer;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.Timeout;
  
  /**
   * {@code HttpRequestExecutor} is a client side HTTP protocol handler based
   * on the blocking (classic) I/O model.
   * <p>
   * {@code HttpRequestExecutor} relies on {@link HttpProcessor} to generate
   * mandatory protocol headers for all outgoing messages and apply common,
   * cross-cutting message transformations to all incoming and outgoing messages.
   * Application specific processing can be implemented outside
   * {@code HttpRequestExecutor} once the request has been executed and
   * a response has been received.
   *
   * @since 4.0
   */
  @Contract(threading = ThreadingBehavior.IMMUTABLE)
  public class HttpRequestExecutor {
  
      public static final Timeout DEFAULT_WAIT_FOR_CONTINUE = Timeout.ofSeconds(3);
  
      private final Timeout waitForContinue;
      private final ConnectionReuseStrategy connReuseStrategy;
      private final Http1StreamListener streamListener;
  
      /**
       * Creates new instance of HttpRequestExecutor.
       *
       * @since 4.3
       */
      public HttpRequestExecutor(
              final Timeout waitForContinue,
              final ConnectionReuseStrategy connReuseStrategy,
              final Http1StreamListener streamListener) {
          super();
          this.waitForContinue = Args.positive(waitForContinue, "Wait for continue time");
          this.connReuseStrategy = connReuseStrategy != null ? connReuseStrategy : DefaultConnectionReuseStrategy.INSTANCE;
          this.streamListener = streamListener;
      }
  
      public HttpRequestExecutor(final ConnectionReuseStrategy connReuseStrategy) {
          this(DEFAULT_WAIT_FOR_CONTINUE, connReuseStrategy, null);
      }
 
     public HttpRequestExecutor() {
         this(DEFAULT_WAIT_FOR_CONTINUE, null, null);
     }
 
     /**
      * Sends the request and obtain a response.
      *
      * @param request   the request to execute.
      * @param conn      the connection over which to execute the request.
      * @param informationCallback   callback to execute upon receipt of information status (1xx).
      *                              May be null.
      * @param context the context
      * @return  the response to the request.
      *
      * @throws IOException in case of an I/O error.
      * @throws HttpException in case of HTTP protocol violation or a processing
      *   problem.
      */
     public ClassicHttpResponse execute(
             final ClassicHttpRequest request,
             final HttpClientConnection conn,
             final HttpResponseInformationCallback informationCallback,
             final HttpContext context) throws IOException, HttpException {
         Args.notNull(request, "HTTP request");
         Args.notNull(conn, "Client connection");
         Args.notNull(context, "HTTP context");
         try {
             context.setAttribute(HttpCoreContext.SSL_SESSION, conn.getSSLSession());
             context.setAttribute(HttpCoreContext.CONNECTION_ENDPOINT, conn.getEndpointDetails());
 
             conn.sendRequestHeader(request);
             if (streamListener != null) {
                 streamListener.onRequestHead(conn, request);
             }
             boolean expectContinue = false;
             final HttpEntity entity = request.getEntity();
             if (entity != null) {
                 final Header expect = request.getFirstHeader(HttpHeaders.EXPECT);
                 expectContinue = expect != null && HeaderElements.CONTINUE.equalsIgnoreCase(expect.getValue());
                 if (!expectContinue) {
                     conn.sendRequestEntity(request);
                 }
             }
             conn.flush();
             ClassicHttpResponse response = null;
             while (response == null) {
                 if (expectContinue) {
                     if (conn.isDataAvailable(this.waitForContinue)) {
                         response = conn.receiveResponseHeader();
                         if (streamListener != null) {
                             streamListener.onResponseHead(conn, response);
                         }
                         final int status = response.getCode();
                         if (status == HttpStatus.SC_CONTINUE) {
                             // discard 100-continue
                             response = null;
                             conn.sendRequestEntity(request);
                         } else if (status < HttpStatus.SC_SUCCESS) {
                             if (informationCallback != null) {
                                 informationCallback.execute(response, conn, context);
                             }
                             response = null;
                             continue;
                         } else if (status >= HttpStatus.SC_CLIENT_ERROR){
                             conn.terminateRequest(request);
                         } else {
                             conn.sendRequestEntity(request);
                         }
                     } else {
                         conn.sendRequestEntity(request);
                     }
                     conn.flush();
                     expectContinue = false;
                 } else {
                     response = conn.receiveResponseHeader();
                     if (streamListener != null) {
                         streamListener.onResponseHead(conn, response);
                     }
                     final int status = response.getCode();
                     if (status < HttpStatus.SC_INFORMATIONAL) {
                         throw new ProtocolException("Invalid response: " + new StatusLine(response));
                     }
                     if (status < HttpStatus.SC_SUCCESS) {
                         if (informationCallback != null && status != HttpStatus.SC_CONTINUE) {
                             informationCallback.execute(response, conn, context);
                         }
                         response = null;
                     }
                 }
             }
             if (MessageSupport.canResponseHaveBody(request.getMethod(), response)) {
                 conn.receiveResponseEntity(response);
             }
             return response;
 
         } catch (final HttpException | IOException | RuntimeException ex) {
             Closer.closeQuietly(conn);
             throw ex;
         }
     }
 
     /**
      * Sends the request and obtain a response.
      *
      * @param request   the request to execute.
      * @param conn      the connection over which to execute the request.
      * @param context the context
      * @return  the response to the request.
      *
      * @throws IOException in case of an I/O error.
      * @throws HttpException in case of HTTP protocol violation or a processing
      *   problem.
      */
     public ClassicHttpResponse execute(
             final ClassicHttpRequest request,
             final HttpClientConnection conn,
             final HttpContext context) throws IOException, HttpException {
         return execute(request, conn, null, context);
     }
 
     /**
      * Pre-process the given request using the given protocol processor and
      * initiates the process of request execution.
      *
      * @param request   the request to prepare
      * @param processor the processor to use
      * @param context   the context for sending the request
      *
      * @throws IOException in case of an I/O error.
      * @throws HttpException in case of HTTP protocol violation or a processing
      *   problem.
      */
     public void preProcess(
             final ClassicHttpRequest request,
             final HttpProcessor processor,
             final HttpContext context) throws HttpException, IOException {
         Args.notNull(request, "HTTP request");
         Args.notNull(processor, "HTTP processor");
         Args.notNull(context, "HTTP context");
         final ProtocolVersion transportVersion = request.getVersion();
         if (transportVersion != null && transportVersion.greaterEquals(HttpVersion.HTTP_2)) {
             throw new UnsupportedHttpVersionException(transportVersion);
         }
         context.setProtocolVersion(transportVersion != null ? transportVersion : HttpVersion.HTTP_1_1);
         context.setAttribute(HttpCoreContext.HTTP_REQUEST, request);
         processor.process(request, request.getEntity(), context);
     }
 
     /**
      * Post-processes the given response using the given protocol processor and
      * completes the process of request execution.
      * <p>
      * This method does <i>not</i> read the response entity, if any.
      * The connection over which content of the response entity is being
      * streamed from cannot be reused until the response entity has been
      * fully consumed.
      *
      * @param response  the response object to post-process
      * @param processor the processor to use
      * @param context   the context for post-processing the response
      *
      * @throws IOException in case of an I/O error.
      * @throws HttpException in case of HTTP protocol violation or a processing
      *   problem.
      */
     public void postProcess(
             final ClassicHttpResponse response,
             final HttpProcessor processor,
             final HttpContext context) throws HttpException, IOException {
         Args.notNull(response, "HTTP response");
         Args.notNull(processor, "HTTP processor");
         Args.notNull(context, "HTTP context");
         final ProtocolVersion transportVersion = response.getVersion();
         context.setProtocolVersion(transportVersion != null ? transportVersion : HttpVersion.HTTP_1_1);
         context.setAttribute(HttpCoreContext.HTTP_RESPONSE, response);
         processor.process(response, response.getEntity(), context);
     }
 
     /**
      * Determines whether the connection can be kept alive and is safe to be re-used for subsequent message exchanges.
      *
      * @param request current request object.
      * @param response  current response object.
      * @param connection actual connection.
      * @param context current context.
      * @return {@code true} is the connection can be kept-alive and re-used.
      * @throws IOException in case of an I/O error.
      */
     public boolean keepAlive(
             final ClassicHttpRequest request,
             final ClassicHttpResponse response,
             final HttpClientConnection connection,
             final HttpContext context) throws IOException {
         Args.notNull(connection, "HTTP connection");
         Args.notNull(request, "HTTP request");
         Args.notNull(response, "HTTP response");
         Args.notNull(context, "HTTP context");
         final boolean keepAlive = connection.isConsistent() && connReuseStrategy.keepAlive(request, response, context);
         if (streamListener != null) {
             streamListener.onExchangeComplete(connection, keepAlive);
         }
         return keepAlive;
     }
 
 }