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 * Institute of Molecular Cell Biology and Genetics, University of
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package org.scijava.io.handle;

import java.io.EOFException;
import java.io.IOException;

import org.scijava.io.ByteBank;
import org.scijava.io.location.BytesLocation;
import org.scijava.plugin.Plugin;

/**
 * {@link DataHandle} for a {@link BytesLocation}.
 *
 * @author Curtis Rueden
 * @author Melissa Linkert
 * @author Gabriel Einsdorf
 */
@Plugin(type = DataHandle.class)
public class BytesHandle extends AbstractDataHandle {

	private long offset = 0;

	// -- DataHandle methods --

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

	@Override
	public boolean isWritable() {
		return !bytes().isReadOnly();
	}

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

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

	@Override
	public long length() {
		return bytes().size();
	}

	@Override
	public void setLength(final long length) throws IOException {
		// check if new length is legal
		bytes().basicRangeCheck(0, length);
		// TODO update the maxLength?
	}

	@Override
	public int read(final byte[] b, final int off, int len) throws IOException {
		if (offset + len > length()) {
			len = (int) (length() - offset);
		}
		bytes().getBytes(offset, b, off, len);
		offset += len;
		return len;
	}

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

	// -- DataInput methods --

	@Override
	public byte readByte() throws IOException {
		ensureReadable(1);
		try {
			// we need to convert the bytes into the range 0-255
			return bytes().getByte(offset++);
		}
		catch (final Exception e) {
			throw eofException(e);
		}
	}

	@Override
	public void readFully(final byte[] b, final int off, final int len)
		throws IOException
	{
		ensureReadable(len);
		try {
			bytes().getBytes(offset, b, off, len);
			offset += len;
		}
		catch (final Exception e) {
			throw eofException(e);
		}
	}

	// -- DataOutput methods --

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

	@Override
	public void write(final int b) throws IOException {
		ensureWritable(1);
		bytes().setByte(offset, (byte) b);
		offset++;
	}

	// -- Closeable methods --

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

	// -- Typed methods --

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

	// -- Helper methods --

	private ByteBank bytes() {
		return get().getByteBank();
	}

	private EOFException eofException(final Throwable cause) {
		final EOFException eof = new EOFException();
		eof.initCause(cause);
		return eof;
	}

}