/*
    * 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.chemistry.opencmis.server.shared;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.UnsupportedEncodingException;
  
  import org.apache.chemistry.opencmis.commons.exceptions.CmisInvalidArgumentException;
  
  /**
   * A stream that counts bytes and throws an exception if the given maximum is
   * reached. Counted bytes can be deducted to excludes parts of stream from the
   * length limitation.
   */
  public class CappedInputStream extends InputStream {
  
      private InputStream stream;
      private long max;
      private long counter;
  
      public CappedInputStream(InputStream stream, long max) {
          this.stream = stream;
          this.max = max;
          this.counter = 0;
      }
  
      /**
       * Returns the counter.
       */
      public long getCounter() {
          return counter;
      }
  
      /**
       * Deducts the byte counter.
       */
      public void deductBytes(int byteCount) {
          counter -= byteCount;
      }
  
      /**
       * Deducts the byte counter.
       */
      public void deductString(String s, String encoding) throws UnsupportedEncodingException {
          if (encoding == null) {
              counter -= s.getBytes("UTF-8").length;
          } else {
              counter -= s.getBytes(encoding).length;
          }
      }
  
      private void checkLength() throws IOException {
          if (counter > max) {
              throw new CmisInvalidArgumentException("Limit exceeded!");
          }
      }
  
      @Override
      public int available() throws IOException {
          return stream.available();
      }
  
      @Override
      public synchronized void mark(int readlimit) {
      }
  
      @Override
      public synchronized void reset() throws IOException {
      }
  
      @Override
      public boolean markSupported() {
          return false;
      }
  
      @Override
      public int read() throws IOException {
          checkLength();
  
          int b = stream.read();
          if (b > -1) {
              counter++;
         }
 
         return b;
     }
 
     @Override
     public int read(byte[] b, int off, int len) throws IOException {
         checkLength();
 
         int l = stream.read(b, off, len);
         counter += l;
 
         return l;
     }
 
     @Override
     public int read(byte[] b) throws IOException {
         checkLength();
 
         int l = stream.read(b);
         counter += l;
 
         return l;
     }
 
     @Override
     public long skip(long n) throws IOException {
         checkLength();
 
         long l = stream.skip(n);
         counter += l;
 
         return l;
     }
 
     @Override
     public void close() throws IOException {
         stream.close();
     }
 }