/*
    * ====================================================================
    * 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.classic;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.net.SocketException;
  import java.util.Arrays;
  import java.util.List;
  
  import org.apache.hc.client5.http.classic.ExecRuntime;
  import org.apache.hc.core5.function.Supplier;
  import org.apache.hc.core5.http.ClassicHttpResponse;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HttpEntity;
  import org.apache.hc.core5.http.impl.io.ChunkedInputStream;
  import org.apache.hc.core5.http.io.EofSensorInputStream;
  import org.apache.hc.core5.http.io.EofSensorWatcher;
  import org.apache.hc.core5.http.io.entity.HttpEntityWrapper;
  
  class ResponseEntityProxy extends HttpEntityWrapper implements EofSensorWatcher {
  
      private final ExecRuntime execRuntime;
  
      public static void enhance(final ClassicHttpResponse response, final ExecRuntime execRuntime) {
          final HttpEntity entity = response.getEntity();
          if (entity != null && entity.isStreaming() && execRuntime != null) {
              response.setEntity(new ResponseEntityProxy(entity, execRuntime));
          }
      }
  
      ResponseEntityProxy(final HttpEntity entity, final ExecRuntime execRuntime) {
          super(entity);
          this.execRuntime = execRuntime;
      }
  
      private void cleanup() throws IOException {
          if (this.execRuntime != null) {
              if (this.execRuntime.isEndpointConnected()) {
                  this.execRuntime.disconnectEndpoint();
              }
              this.execRuntime.discardEndpoint();
          }
      }
  
      private void discardConnection() {
          if (this.execRuntime != null) {
              this.execRuntime.discardEndpoint();
          }
      }
  
      public void releaseConnection() {
          if (this.execRuntime != null) {
              this.execRuntime.releaseEndpoint();
          }
      }
  
      @Override
      public boolean isRepeatable() {
          return false;
      }
  
      @Override
      public InputStream getContent() throws IOException {
          return new EofSensorInputStream(super.getContent(), this);
      }
  
      @Override
      public void writeTo(final OutputStream outStream) throws IOException {
          try {
              super.writeTo(outStream != null ? outStream : NullOutputStream.INSTANCE);
              releaseConnection();
          } catch (final IOException | RuntimeException ex) {
             discardConnection();
             throw ex;
         } finally {
             cleanup();
         }
     }
 
     @Override
     public boolean eofDetected(final InputStream wrapped) throws IOException {
         try {
             // there may be some cleanup required, such as
             // reading trailers after the response body:
             if (wrapped != null) {
                 wrapped.close();
             }
             releaseConnection();
         } catch (final IOException | RuntimeException ex) {
             discardConnection();
             throw ex;
         } finally {
             cleanup();
         }
         return false;
     }
 
     @Override
     public boolean streamClosed(final InputStream wrapped) throws IOException {
         try {
             final boolean open = execRuntime != null && execRuntime.isEndpointAcquired();
             // this assumes that closing the stream will
             // consume the remainder of the response body:
             try {
                 if (wrapped != null) {
                     wrapped.close();
                 }
                 releaseConnection();
             } catch (final SocketException ex) {
                 if (open) {
                     throw ex;
                 }
             }
         } catch (final IOException | RuntimeException ex) {
             discardConnection();
             throw ex;
         } finally {
             cleanup();
         }
         return false;
     }
 
     @Override
     public boolean streamAbort(final InputStream wrapped) throws IOException {
         cleanup();
         return false;
     }
 
     @Override
     public Supplier<List<? extends Header>> getTrailers() {
             try {
                 final InputStream underlyingStream = super.getContent();
                 return () -> {
                     final Header[] footers;
                     if (underlyingStream instanceof ChunkedInputStream) {
                         final ChunkedInputStream chunkedInputStream = (ChunkedInputStream) underlyingStream;
                         footers = chunkedInputStream.getFooters();
                     } else {
                         footers = new Header[0];
                     }
                     return Arrays.asList(footers);
                 };
             } catch (final IOException e) {
                 throw new IllegalStateException("Unable to retrieve input stream", e);
             }
     }
 
     @Override
     public void close() throws IOException {
         try {
             // HttpEntity.close will close the underlying resource. Closing a reusable request stream results in
             // draining remaining data, allowing for connection reuse.
             super.close();
             releaseConnection();
         } catch (final IOException | RuntimeException ex) {
             discardConnection();
             throw ex;
         } finally {
             cleanup();
         }
     }
 
     private static final class NullOutputStream extends OutputStream {
         private static final NullOutputStream INSTANCE = new NullOutputStream();
 
         private NullOutputStream() {}
 
         @Override
         public void write(@SuppressWarnings("unused") final int byteValue) {
             // no-op
         }
 
         @Override
         public void write(@SuppressWarnings("unused") final byte[] buffer) {
             // no-op
         }
 
         @Override
         public void write(
                 @SuppressWarnings("unused") final byte[] buffer,
                 @SuppressWarnings("unused") final int off,
                 @SuppressWarnings("unused") final int len) {
             // no-op
         }
 
         @Override
         public void flush() {
             // no-op
         }
 
         @Override
         public void close() {
             // no-op
         }
 
         @Override
         public String toString() {
             return "NullOutputStream{}";
         }
     }
 }