/*
    * ====================================================================
    * 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.compat;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.io.OutputStream;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.atomic.AtomicReference;
  
  import org.apache.hc.core5.annotation.Experimental;
  import org.apache.hc.core5.annotation.Internal;
  import org.apache.hc.core5.http.ClassicHttpRequest;
  import org.apache.hc.core5.http.HttpEntity;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.nio.AsyncRequestProducer;
  import org.apache.hc.core5.http.nio.DataStreamChannel;
  import org.apache.hc.core5.http.nio.RequestChannel;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.Asserts;
  import org.apache.hc.core5.util.Timeout;
  
  /**
   * TODO: to be replaced by core functionality
   */
  @Experimental
  @Internal
  class ClassicToAsyncRequestProducer implements AsyncRequestProducer {
  
      private final ClassicHttpRequest request;
      private final int initialBufferSize;
      private final Timeout timeout;
      private final CountDownLatch countDownLatch;
      private final AtomicReference<SharedOutputBuffer> bufferRef;
      private final AtomicReference<Exception> exceptionRef;
  
      private volatile boolean repeatable;
  
      public interface IORunnable {
  
          void execute() throws IOException;
  
      }
  
      public ClassicToAsyncRequestProducer(final ClassicHttpRequest request, final int initialBufferSize, final Timeout timeout) {
          this.request = Args.notNull(request, "HTTP request");
          this.initialBufferSize = Args.positive(initialBufferSize, "Initial buffer size");
          this.timeout = timeout;
          this.countDownLatch = new CountDownLatch(1);
          this.bufferRef = new AtomicReference<>();
          this.exceptionRef = new AtomicReference<>();
      }
  
      public ClassicToAsyncRequestProducer(final ClassicHttpRequest request, final Timeout timeout) {
          this(request, ClassicToAsyncSupport.INITIAL_BUF_SIZE, timeout);
      }
  
      void propagateException() throws IOException {
          final Exception ex = exceptionRef.getAndSet(null);
          if (ex != null) {
              ClassicToAsyncSupport.rethrow(ex);
          }
      }
  
      public IORunnable blockWaiting() throws IOException, InterruptedException {
          if (timeout == null) {
              countDownLatch.await();
          } else {
              if (!countDownLatch.await(timeout.getDuration(), timeout.getTimeUnit())) {
                  throw new InterruptedIOException("Timeout blocked waiting for output (" + timeout + ")");
              }
          }
          propagateException();
          final SharedOutputBuffer outputBuffer = bufferRef.get();
         return () -> {
             final HttpEntity requestEntity = request.getEntity();
             if (requestEntity != null) {
                 try (final InternalOutputStream outputStream = new InternalOutputStream(outputBuffer)) {
                     requestEntity.writeTo(outputStream);
                 }
             }
         };
     }
 
     @Override
     public void sendRequest(final RequestChannel channel, final HttpContext context) throws HttpException, IOException {
         final HttpEntity requestEntity = request.getEntity();
         final SharedOutputBuffer buffer = requestEntity != null ? new SharedOutputBuffer(initialBufferSize) : null;
         bufferRef.set(buffer);
         repeatable = requestEntity == null || requestEntity.isRepeatable();
         channel.sendRequest(request, requestEntity, null);
         countDownLatch.countDown();
     }
 
     @Override
     public boolean isRepeatable() {
         return repeatable;
     }
 
     @Override
     public int available() {
         final SharedOutputBuffer buffer = bufferRef.get();
         if (buffer != null) {
             return buffer.length();
         }
         return 0;
     }
 
     @Override
     public void produce(final DataStreamChannel channel) throws IOException {
         final SharedOutputBuffer buffer = bufferRef.get();
         if (buffer != null) {
             buffer.flush(channel);
         }
     }
 
     @Override
     public void failed(final Exception cause) {
         try {
             exceptionRef.set(cause);
         } finally {
             countDownLatch.countDown();
         }
     }
 
     @Override
     public void releaseResources() {
     }
 
     class InternalOutputStream extends OutputStream {
 
         private final SharedOutputBuffer buffer;
 
         public InternalOutputStream(final SharedOutputBuffer buffer) {
             Asserts.notNull(buffer, "Shared buffer");
             this.buffer = buffer;
         }
 
         @Override
         public void close() throws IOException {
             propagateException();
             this.buffer.writeCompleted(timeout);
         }
 
         @Override
         public void flush() throws IOException {
             propagateException();
         }
 
         @Override
         public void write(final byte[] b, final int off, final int len) throws IOException {
             propagateException();
             this.buffer.write(b, off, len, timeout);
         }
 
         @Override
         public void write(final byte[] b) throws IOException {
             propagateException();
             if (b == null) {
                 return;
             }
             this.buffer.write(b, 0, b.length, timeout);
         }
 
         @Override
         public void write(final int b) throws IOException {
             propagateException();
             this.buffer.write(b, timeout);
         }
 
     }
 
 }