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 * #%L
 * SciJava Common shared library for SciJava software.
 * %%
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 * Wisconsin-Madison, Broad Institute of MIT and Harvard, Max Planck
 * Institute of Molecular Cell Biology and Genetics, University of
 * Konstanz, and KNIME GmbH.
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 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
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package org.scijava.io.handle;

import java.io.IOException;
import java.util.Arrays;

import org.scijava.io.location.DummyLocation;
import org.scijava.plugin.Plugin;

/**
 * A {@link DataHandle} which reads all zeroes, and writes no actual data.
 *
 * @author Curtis Rueden
 */
@Plugin(type = DataHandle.class)
public class DummyHandle extends AbstractDataHandle {

	// -- Fields --

	private long offset;
	private long length;

	// -- DataHandle methods --

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

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

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

	@Override
	public long offset() {
		return offset;
	}

	@Override
	public void seek(final long pos) {
		if (pos > length()) setLength(pos);
		offset = pos;
	}

	@Override
	public long length() {
		return length;
	}

	@Override
	public void setLength(final long length) {
		this.length = length;
	}

	// -- DataInput methods --

	@Override
	public byte readByte() throws IOException {
		final long r = available(1);
		if (r <= 0) return -1;
		offset++;
		return 0;
	}

	@Override
	public int read(final byte[] b, final int off, final int len)
		throws IOException
	{
		final int r = (int) available(len);
		offset += r;
		Arrays.fill(b, off, off + r, (byte) 0);
		return r;
	}

	// -- DataOutput methods --

	@Override
	public void write(final int v) throws IOException {
		ensureWritable(1);
		offset++;
	}

	@Override
	public void write(final byte[] b, final int off, final int len)
		throws IOException
	{
		ensureWritable(len);
		offset += len;
	}

	// -- Closeable methods --

	@Override
	public void close() {
		// NB: No action needed.
	}

	// -- Typed methods --

	@Override
	public Class getType() {
		return DummyLocation.class;
	}
}