/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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.jboss.netty.handler.codec.marshalling;
  
  import java.io.IOException;
  
  import org.jboss.marshalling.ByteInput;
  
  /**
   * {@link ByteInput} implementation which wraps another {@link ByteInput} and throws a {@link TooBigObjectException}
   * if the read limit was reached.
   *
   *
   */
  class LimitingByteInput implements ByteInput {
  
      // Use a static instance here to remove the overhead of fillStacktrace
      private static final TooBigObjectException EXCEPTION = new TooBigObjectException();
  
      private final ByteInput input;
      private final long limit;
      private long read;
  
      public LimitingByteInput(ByteInput input, long limit) {
          if (limit <= 0) {
              throw new IllegalArgumentException("The limit MUST be > 0");
          }
          this.input = input;
          this.limit = limit;
      }
  
      public void close() throws IOException {
          // Nothing todo
      }
  
      public int available() throws IOException {
          int available = input.available();
          int readable = readable(available);
          return readable;
      }
  
      public int read() throws IOException {
          int readable = readable(1);
          if (readable > 0) {
              int b = input.read();
              read++;
              return b;
          } else {
              throw EXCEPTION;
          }
      }
  
      public int read(byte[] array) throws IOException {
          return read(array, 0, array.length);
      }
  
      public int read(byte[] array, int offset, int length) throws IOException {
          int readable = readable(length);
          if (readable > 0) {
              int i = input.read(array, offset, readable);
              read += i;
              return i;
          } else {
              throw EXCEPTION;
          }
      }
  
      public long skip(long bytes) throws IOException {
          int readable = readable((int) bytes);
          if (readable > 0) {
              long i = input.skip(readable);
              read += i;
              return i;
          } else {
              throw EXCEPTION;
          }
      }
  
      private int readable(int length) {
          return (int) Math.min(length, limit - read);
      }
  
      /**
       * Exception that will get thrown if the {@link Object} is to big to unmarshall
       *
       */
     static final class TooBigObjectException extends IOException {
 
         /**
          *
          */
         private static final long serialVersionUID = 1L;
 
     }
 }