/*

  * 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.

  */

 package org.apache.commons.flatfile.util;

 import java.io.IOException;

 import java.io.InputStream;

 import org.apache.commons.io.input.CountingInputStream;

 /**

  * FilterInputStream that limits the data returned from the proxy.

  * @version $Revision: 1301244 $ $Date: 2012-03-15 17:16:23 -0500 (Thu, 15 Mar 2012) $

  */

 public class ThresholdingInputStream extends CountingInputStream {

     private static final int EOF = -1;

     private final int maximum;

     private boolean closed;

     /**

      * Create a new ThresholdingInputStream.

      * @param in the filtered stream

      * @param maximum length

      */

     public ThresholdingInputStream(InputStream in, int maximum) {

         super(in);

         this.maximum = maximum;

     }

     /*

      * NOTICE: implementing all three read(...) methods such that corresponding

      * super methods are called

      */

     /**

      * {@inheritDoc}

      */

     public synchronized int read() throws IOException {

         assertNotClosed();

         if (getCount() >= maximum) {

             return EOF;

         }

         return super.read();

     }

     /**

      * {@inheritDoc}

      */

     public synchronized int read(byte[] b, int off, int len) throws IOException {

         assertNotClosed();

         int n = maximum - getCount();

         return n == 0 ? EOF : super.read(b, off, n < len ? n : len);

     }

     /**

      * {@inheritDoc}

      */

     public synchronized int read(byte[] b) throws IOException {

         assertNotClosed();

         int n = maximum - getCount();

         if (n == 0) {

             return EOF;

         }

         if (n < b.length) {

             byte[] buf = new byte[n];

             System.arraycopy(b, 0, buf, 0, n);

             try {

                 return super.read(buf);

             } finally {

                 System.arraycopy(buf, 0, b, 0, n);

             }

         }

         return super.read(b);

     }

     /**

      * {@inheritDoc}

      */

     public synchronized void close() throws IOException {

         this.closed = true;

         super.close();

     }

     /**

      * Make sure the stream is not closed.

      * @throws IOException if stream has been closed.

      */

     private synchronized void assertNotClosed() throws IOException {

         if (closed) {

             throw new IOException("Stream closed");

         }

     }

 }