/*
    * ====================================================================
    * 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.protocol;
  
  import java.io.IOException;
  
  import org.apache.http.ConnectionReuseStrategy;
  import org.apache.http.HttpEntity;
  import org.apache.http.HttpEntityEnclosingRequest;
  import org.apache.http.HttpException;
  import org.apache.http.HttpRequest;
  import org.apache.http.HttpResponse;
  import org.apache.http.HttpResponseFactory;
  import org.apache.http.HttpServerConnection;
  import org.apache.http.HttpStatus;
  import org.apache.http.HttpVersion;
  import org.apache.http.MethodNotSupportedException;
  import org.apache.http.ProtocolException;
  import org.apache.http.UnsupportedHttpVersionException;
  import org.apache.http.annotation.Immutable;
  import org.apache.http.entity.ByteArrayEntity;
  import org.apache.http.params.HttpParams;
  import org.apache.http.params.DefaultedHttpParams;
  import org.apache.http.util.EncodingUtils;
  import org.apache.http.util.EntityUtils;
  
  /**
   * <tt>HttpService</tt> is a server side HTTP protocol handler based on
   * the classic (blocking) I/O model.
   * <p/>
   * <tt>HttpService</tt> 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, whereas
   * individual {@link HttpRequestHandler}s are expected to implement
   * application specific content generation and processing.
   * <p/>
   * <tt>HttpService</tt> uses {@link HttpRequestHandlerResolver} to resolve
   * matching request handler for a particular request URI of an incoming HTTP
   * request.
   * <p/>
   * <tt>HttpService</tt> can use optional {@link HttpExpectationVerifier}
   * to ensure that incoming requests meet server's expectations.
   *
   * @since 4.0
   */
  @Immutable // provided injected dependencies are immutable and deprecated methods are not used
  public class HttpService {
  
      /**
       * TODO: make all variables final in the next major version
       */
      private volatile HttpParams params = null;
      private volatile HttpProcessor processor = null;
      private volatile HttpRequestHandlerResolver handlerResolver = null;
      private volatile ConnectionReuseStrategy connStrategy = null;
      private volatile HttpResponseFactory responseFactory = null;
      private volatile HttpExpectationVerifier expectationVerifier = null;
  
      /**
       * Create a new HTTP service.
       *
       * @param processor            the processor to use on requests and responses
       * @param connStrategy         the connection reuse strategy
       * @param responseFactory      the response factory
       * @param handlerResolver      the handler resolver. May be null.
       * @param expectationVerifier  the expectation verifier. May be null.
       * @param params               the HTTP parameters
       *
       * @since 4.1
       */
      public HttpService(
              final HttpProcessor processor,
              final ConnectionReuseStrategy connStrategy,
              final HttpResponseFactory responseFactory,
             final HttpRequestHandlerResolver handlerResolver,
             final HttpExpectationVerifier expectationVerifier,
             final HttpParams params) {
         super();
         if (processor == null) {
             throw new IllegalArgumentException("HTTP processor may not be null");
         }
         if (connStrategy == null) {
             throw new IllegalArgumentException("Connection reuse strategy may not be null");
         }
         if (responseFactory == null) {
             throw new IllegalArgumentException("Response factory may not be null");
         }
         if (params == null) {
             throw new IllegalArgumentException("HTTP parameters may not be null");
         }
         this.processor = processor;
         this.connStrategy = connStrategy;
         this.responseFactory = responseFactory;
         this.handlerResolver = handlerResolver;
         this.expectationVerifier = expectationVerifier;
         this.params = params;
     }
 
     /**
      * Create a new HTTP service.
      *
      * @param processor            the processor to use on requests and responses
      * @param connStrategy         the connection reuse strategy
      * @param responseFactory      the response factory
      * @param handlerResolver      the handler resolver. May be null.
      * @param params               the HTTP parameters
      *
      * @since 4.1
      */
     public HttpService(
             final HttpProcessor processor,
             final ConnectionReuseStrategy connStrategy,
             final HttpResponseFactory responseFactory,
             final HttpRequestHandlerResolver handlerResolver,
             final HttpParams params) {
         this(processor, connStrategy, responseFactory, handlerResolver, null, params);
     }
 
     /**
      * Create a new HTTP service.
      *
      * @param proc             the processor to use on requests and responses
      * @param connStrategy     the connection reuse strategy
      * @param responseFactory  the response factory
      *
      * @deprecated (4.1) use {@link HttpService#HttpService(HttpProcessor,
      *  ConnectionReuseStrategy, HttpResponseFactory, HttpRequestHandlerResolver, HttpParams)}
      */
     @Deprecated
     public HttpService(
             final HttpProcessor proc,
             final ConnectionReuseStrategy connStrategy,
             final HttpResponseFactory responseFactory) {
         super();
         setHttpProcessor(proc);
         setConnReuseStrategy(connStrategy);
         setResponseFactory(responseFactory);
     }
 
     /**
      * @deprecated (4.1) set {@link HttpProcessor} using constructor
      */
     @Deprecated
     public void setHttpProcessor(final HttpProcessor processor) {
         if (processor == null) {
             throw new IllegalArgumentException("HTTP processor may not be null");
         }
         this.processor = processor;
     }
 
     /**
      * @deprecated (4.1) set {@link ConnectionReuseStrategy} using constructor
      */
     @Deprecated
     public void setConnReuseStrategy(final ConnectionReuseStrategy connStrategy) {
         if (connStrategy == null) {
             throw new IllegalArgumentException("Connection reuse strategy may not be null");
         }
         this.connStrategy = connStrategy;
     }
 
     /**
      * @deprecated (4.1) set {@link HttpResponseFactory} using constructor
      */
     @Deprecated
     public void setResponseFactory(final HttpResponseFactory responseFactory) {
         if (responseFactory == null) {
             throw new IllegalArgumentException("Response factory may not be null");
         }
         this.responseFactory = responseFactory;
     }
 
     /**
      * @deprecated (4.1) set {@link HttpResponseFactory} using constructor
      */
     @Deprecated
     public void setParams(final HttpParams params) {
         this.params = params;
     }
 
     /**
      * @deprecated (4.1) set {@link HttpRequestHandlerResolver} using constructor
      */
     @Deprecated
     public void setHandlerResolver(final HttpRequestHandlerResolver handlerResolver) {
         this.handlerResolver = handlerResolver;
     }
 
     /**
      * @deprecated (4.1) set {@link HttpExpectationVerifier} using constructor
      */
     @Deprecated
     public void setExpectationVerifier(final HttpExpectationVerifier expectationVerifier) {
         this.expectationVerifier = expectationVerifier;
     }
 
     public HttpParams getParams() {
         return this.params;
     }
 
     /**
      * Handles receives one HTTP request over the given connection within the
      * given execution context and sends a response back to the client.
      *
      * @param conn the active connection to the client
      * @param context the actual execution context.
      * @throws IOException in case of an I/O error.
      * @throws HttpException in case of HTTP protocol violation or a processing
      *   problem.
      */
     public void handleRequest(
             final HttpServerConnection conn,
             final HttpContext context) throws IOException, HttpException {
 
         context.setAttribute(ExecutionContext.HTTP_CONNECTION, conn);
 
         HttpResponse response = null;
 
         try {
 
             HttpRequest request = conn.receiveRequestHeader();
             request.setParams(
                     new DefaultedHttpParams(request.getParams(), this.params));
 
             if (request instanceof HttpEntityEnclosingRequest) {
 
                 if (((HttpEntityEnclosingRequest) request).expectContinue()) {
                     response = this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_1,
                             HttpStatus.SC_CONTINUE, context);
                     response.setParams(
                             new DefaultedHttpParams(response.getParams(), this.params));
 
                     if (this.expectationVerifier != null) {
                         try {
                             this.expectationVerifier.verify(request, response, context);
                         } catch (HttpException ex) {
                             response = this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_0,
                                     HttpStatus.SC_INTERNAL_SERVER_ERROR, context);
                             response.setParams(
                                     new DefaultedHttpParams(response.getParams(), this.params));
                             handleException(ex, response);
                         }
                     }
                     if (response.getStatusLine().getStatusCode() < 200) {
                         // Send 1xx response indicating the server expections
                         // have been met
                         conn.sendResponseHeader(response);
                         conn.flush();
                         response = null;
                         conn.receiveRequestEntity((HttpEntityEnclosingRequest) request);
                     }
                 } else {
                     conn.receiveRequestEntity((HttpEntityEnclosingRequest) request);
                 }
             }
 
             context.setAttribute(ExecutionContext.HTTP_REQUEST, request);
 
             if (response == null) {
                 response = this.responseFactory.newHttpResponse(HttpVersion.HTTP_1_1,
                         HttpStatus.SC_OK, context);
                 response.setParams(
                         new DefaultedHttpParams(response.getParams(), this.params));
                 this.processor.process(request, context);
                 doService(request, response, context);
             }
 
             // Make sure the request content is fully consumed
             if (request instanceof HttpEntityEnclosingRequest) {
                 HttpEntity entity = ((HttpEntityEnclosingRequest)request).getEntity();
                 EntityUtils.consume(entity);
             }
 
         } catch (HttpException ex) {
             response = this.responseFactory.newHttpResponse
                 (HttpVersion.HTTP_1_0, HttpStatus.SC_INTERNAL_SERVER_ERROR,
                  context);
             response.setParams(
                     new DefaultedHttpParams(response.getParams(), this.params));
             handleException(ex, response);
         }
 
         context.setAttribute(ExecutionContext.HTTP_RESPONSE, response);
 
         this.processor.process(response, context);
         conn.sendResponseHeader(response);
         conn.sendResponseEntity(response);
         conn.flush();
 
         if (!this.connStrategy.keepAlive(response, context)) {
             conn.close();
         }
     }
 
     /**
      * Handles the given exception and generates an HTTP response to be sent
      * back to the client to inform about the exceptional condition encountered
      * in the course of the request processing.
      *
      * @param ex the exception.
      * @param response the HTTP response.
      */
     protected void handleException(final HttpException ex, final HttpResponse response) {
         if (ex instanceof MethodNotSupportedException) {
             response.setStatusCode(HttpStatus.SC_NOT_IMPLEMENTED);
         } else if (ex instanceof UnsupportedHttpVersionException) {
             response.setStatusCode(HttpStatus.SC_HTTP_VERSION_NOT_SUPPORTED);
         } else if (ex instanceof ProtocolException) {
             response.setStatusCode(HttpStatus.SC_BAD_REQUEST);
         } else {
             response.setStatusCode(HttpStatus.SC_INTERNAL_SERVER_ERROR);
         }
         String message = ex.getMessage();
         if (message == null) {
             message = ex.toString();
         }
         byte[] msg = EncodingUtils.getAsciiBytes(message);
         ByteArrayEntity entity = new ByteArrayEntity(msg);
         entity.setContentType("text/plain; charset=US-ASCII");
         response.setEntity(entity);
     }
 
     /**
      * The default implementation of this method attempts to resolve an
      * {@link HttpRequestHandler} for the request URI of the given request
      * and, if found, executes its
      * {@link HttpRequestHandler#handle(HttpRequest, HttpResponse, HttpContext)}
      * method.
      * <p>
      * Super-classes can override this method in order to provide a custom
      * implementation of the request processing logic.
      *
      * @param request the HTTP request.
      * @param response the HTTP response.
      * @param context the execution context.
      * @throws IOException in case of an I/O error.
      * @throws HttpException in case of HTTP protocol violation or a processing
      *   problem.
      */
     protected void doService(
             final HttpRequest request,
             final HttpResponse response,
             final HttpContext context) throws HttpException, IOException {
         HttpRequestHandler handler = null;
         if (this.handlerResolver != null) {
             String requestURI = request.getRequestLine().getUri();
             handler = this.handlerResolver.lookup(requestURI);
         }
         if (handler != null) {
             handler.handle(request, response, context);
         } else {
             response.setStatusCode(HttpStatus.SC_NOT_IMPLEMENTED);
         }
     }
 
 }