/*

   Derby - Class org.apache.derby.iapi.services.io.CloseFilterInputStream

   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.derby.iapi.services.io;

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.derby.shared.common.reference.MessageId;
import org.apache.derby.shared.common.i18n.MessageService;

/**
 * A stream that will throw an exception if its methods are invoked after it
 * has been closed.
 */
public class CloseFilterInputStream
        extends FilterInputStream {

    /** Message, modeled after CloseFilterInputStream in the client. */
    private static final String MESSAGE =
            MessageService.getTextMessage(MessageId.OBJECT_CLOSED); 
    
    /** Tells if this stream has been closed. */
    private boolean closed;

    public CloseFilterInputStream(InputStream in) {
        super(in);
    }

    public void close() throws IOException {
        closed = true;        
        super.close();
    }

    public int available() throws IOException {
        checkIfClosed();
        return super.available();
    }

    public int read() throws IOException {
        checkIfClosed();
        return super.read();
    }

    public int read(byte[] b) throws IOException {
        checkIfClosed();
        return super.read(b);
    }

    public int read(byte[] b, int off, int len) throws IOException {
        checkIfClosed();
        return super.read(b, off, len);
    }

    public long skip(long n) throws IOException {
        checkIfClosed();
        return super.skip(n);
    }
    
    /** Throws exception if this stream has been closed. */
    private void checkIfClosed() throws IOException {
        if (closed) {
            throw new IOException(MESSAGE);
        }
    }
}
