/*
    * ====================================================================
    * 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.nio.util;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.util.concurrent.locks.Condition;
  import java.util.concurrent.locks.ReentrantLock;
  
  import org.apache.http.annotation.ThreadSafe;
  import org.apache.http.nio.ContentDecoder;
  import org.apache.http.nio.IOControl;
  
  /**
   * Implementation of the {@link ContentInputBuffer} interface that can be
   * shared by multiple threads, usually the I/O dispatch of an I/O reactor and
   * a worker thread.
   * <p>
   * The I/O dispatch thread is expect to transfer data from {@link ContentDecoder} to the buffer
   *   by calling {@link #consumeContent(ContentDecoder)}.
   * <p>
   * The worker thread is expected to read the data from the buffer by calling
   *   {@link #read()} or {@link #read(byte[], int, int)} methods.
   * <p>
   * In case of an abnormal situation or when no longer needed the buffer must be shut down
   * using {@link #shutdown()} method.
   *
   * @since 4.0
   */
  @ThreadSafe
  public class SharedInputBuffer extends ExpandableBuffer implements ContentInputBuffer {
  
      private final IOControl ioctrl;
      private final ReentrantLock lock;
      private final Condition condition;
  
      private volatile boolean shutdown = false;
      private volatile boolean endOfStream = false;
  
      public SharedInputBuffer(int buffersize, final IOControl ioctrl, final ByteBufferAllocator allocator) {
          super(buffersize, allocator);
          if (ioctrl == null) {
              throw new IllegalArgumentException("I/O content control may not be null");
          }
          this.ioctrl = ioctrl;
          this.lock = new ReentrantLock();
          this.condition = this.lock.newCondition();
      }
  
      public void reset() {
          if (this.shutdown) {
              return;
          }
          this.lock.lock();
          try {
              clear();
              this.endOfStream = false;
          } finally {
              this.lock.unlock();
          }
      }
  
      public int consumeContent(final ContentDecoder decoder) throws IOException {
          if (this.shutdown) {
              return -1;
          }
          this.lock.lock();
          try {
              setInputMode();
              int totalRead = 0;
              int bytesRead;
              while ((bytesRead = decoder.read(this.buffer)) > 0) {
                  totalRead += bytesRead;
              }
              if (bytesRead == -1 || decoder.isCompleted()) {
                 this.endOfStream = true;
             }
             if (!this.buffer.hasRemaining()) {
                 this.ioctrl.suspendInput();
             }
             this.condition.signalAll();
 
             if (totalRead > 0) {
                 return totalRead;
             } else {
                 if (this.endOfStream) {
                     return -1;
                 } else {
                     return 0;
                 }
             }
         } finally {
             this.lock.unlock();
         }
     }
 
     @Override
     public boolean hasData() {
         this.lock.lock();
         try {
             return super.hasData();
         } finally {
             this.lock.unlock();
         }
     }
 
     @Override
     public int available() {
         this.lock.lock();
         try {
             return super.available();
         } finally {
             this.lock.unlock();
         }
     }
 
     @Override
     public int capacity() {
         this.lock.lock();
         try {
             return super.capacity();
         } finally {
             this.lock.unlock();
         }
     }
 
     @Override
     public int length() {
         this.lock.lock();
         try {
             return super.length();
         } finally {
             this.lock.unlock();
         }
     }
 
     protected void waitForData() throws IOException {
         this.lock.lock();
         try {
             try {
                 while (!super.hasData() && !this.endOfStream) {
                     if (this.shutdown) {
                         throw new InterruptedIOException("Input operation aborted");
                     }
                     this.ioctrl.requestInput();
                     this.condition.await();
                 }
             } catch (InterruptedException ex) {
                 throw new IOException("Interrupted while waiting for more data");
             }
         } finally {
             this.lock.unlock();
         }
     }
 
     public void close() {
         if (this.shutdown) {
             return;
         }
         this.endOfStream = true;
         this.lock.lock();
         try {
             this.condition.signalAll();
         } finally {
             this.lock.unlock();
         }
     }
 
     public void shutdown() {
         if (this.shutdown) {
             return;
         }
         this.shutdown = true;
         this.lock.lock();
         try {
             this.condition.signalAll();
         } finally {
             this.lock.unlock();
         }
     }
 
     protected boolean isShutdown() {
         return this.shutdown;
     }
 
     protected boolean isEndOfStream() {
         return this.shutdown || (!hasData() && this.endOfStream);
     }
 
     public int read() throws IOException {
         if (this.shutdown) {
             return -1;
         }
         this.lock.lock();
         try {
             if (!hasData()) {
                 waitForData();
             }
             if (isEndOfStream()) {
                 return -1;
             }
             return this.buffer.get() & 0xff;
         } finally {
             this.lock.unlock();
         }
     }
 
     public int read(final byte[] b, int off, int len) throws IOException {
         if (this.shutdown) {
             return -1;
         }
         if (b == null) {
             return 0;
         }
         this.lock.lock();
         try {
             if (!hasData()) {
                 waitForData();
             }
             if (isEndOfStream()) {
                 return -1;
             }
             setOutputMode();
             int chunk = len;
             if (chunk > this.buffer.remaining()) {
                 chunk = this.buffer.remaining();
             }
             this.buffer.get(b, off, chunk);
             return chunk;
         } finally {
             this.lock.unlock();
         }
     }
 
     public int read(final byte[] b) throws IOException {
         if (this.shutdown) {
             return -1;
         }
         if (b == null) {
             return 0;
         }
         return read(b, 0, b.length);
     }
 
 }