/*
Copyright (c) 2012, Adam Retter
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of Adam Retter Consulting nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL Adam Retter BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.exist.util.io;

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

/**
 * Implementation of an InputStream which reads from a ByteBuffer
 *
 * @version 1.0
 *
 * @author Adam Retter <adam.retter@googlemail.com>
 */
public class ByteBufferInputStream extends InputStream {

    private final ByteBufferAccessor bufAccessor;
    private boolean closed = false;
    private final static int END_OF_STREAM = -1;

    public ByteBufferInputStream(final ByteBufferAccessor bufAccessor) {
        this.bufAccessor = bufAccessor;
    }

    @Override
    public int available() throws IOException {
        int available = 0;

        if(!closed) {
            available = bufAccessor.getBuffer().capacity() - bufAccessor.getBuffer().position();
        }

        return available;
    }
    
    @Override
    public int read() throws IOException {
        isClosed();
        
        if(available() == 0) {
            return END_OF_STREAM;
        }

        return bufAccessor.getBuffer().get();
    }

    @Override
    public int read(final byte[] b) throws IOException {
        isClosed();

        if(available() == 0) {
            return END_OF_STREAM;
        } else if(b.length > available()) {
            return read(b, 0, available());
        } else {
            final int currentPosition = bufAccessor.getBuffer().position();
            return bufAccessor.getBuffer().get(b).position() - currentPosition;
        }
    }

    @Override
    public int read(final byte[] b, final int off, int len) throws IOException {
        isClosed();

        if(available() == 0) {
            return END_OF_STREAM;
        }
        
        if(len > available()) {
            len = available();
        }

        final int currentPosition = bufAccessor.getBuffer().position();
        return bufAccessor.getBuffer().get(b, off, len).position() - currentPosition;
    }

    @Override
    public boolean markSupported() {
        return true;
    }

    @Override
    public synchronized void mark(final int i) {
        bufAccessor.getBuffer().mark();
    }

    @Override
    public synchronized void reset() throws IOException {
        bufAccessor.getBuffer().reset();
    }

    @Override
    public long skip(long l) throws IOException {

        if(l > available()) {
            l = available();
        }

        long newPosition = bufAccessor.getBuffer().position();
        newPosition += l;
        try {
            bufAccessor.getBuffer().position((int)newPosition);
        } catch(final IllegalArgumentException iae) {
            throw new IOException("Unable to skip " + l + " bytes", iae);
        }

        return l;
    }

    @Override
    public void close() throws IOException {

        isClosed();

        bufAccessor.getBuffer().clear();
        closed = true;
    }

    private void isClosed() throws IOException {
        if(closed) {
            throw new IOException("The stream was previously closed");
        }
    }

}