/*
 * Copyright (C) 2010, 2013 Google Inc. and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.util.io;

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

Input stream that copies data read to another output stream. This stream is primarily useful with a TemporaryBuffer, where any data read or skipped by the caller is also duplicated into the temporary buffer. Later the temporary buffer can then be used instead of the original source stream. During close this stream copies any remaining data from the source stream into the destination stream. /**
 * Input stream that copies data read to another output stream.
 *
 * This stream is primarily useful with a
 * {@link org.eclipse.jgit.util.TemporaryBuffer}, where any data read or skipped
 * by the caller is also duplicated into the temporary buffer. Later the
 * temporary buffer can then be used instead of the original source stream.
 *
 * During close this stream copies any remaining data from the source stream
 * into the destination stream.
 */
public class TeeInputStream extends InputStream {
	private byte[] skipBuffer;

	private InputStream src;

	private OutputStream dst;

	
Initialize a tee input stream.
Params:
src – 
           source stream to consume.
dst –  destination to copy the source to as it is consumed. Typically this is a TemporaryBuffer./**
	 * Initialize a tee input stream.
	 *
	 * @param src
	 *            source stream to consume.
	 * @param dst
	 *            destination to copy the source to as it is consumed. Typically
	 *            this is a {@link org.eclipse.jgit.util.TemporaryBuffer}.
	 */
	public TeeInputStream(InputStream src, OutputStream dst) {
		this.src = src;
		this.dst = dst;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public int read() throws IOException {
		byte[] b = skipBuffer();
		int n = read(b, 0, 1);
		return n == 1 ? b[0] & 0xff : -1;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public long skip(long count) throws IOException {
		long skipped = 0;
		long cnt = count;
		final byte[] b = skipBuffer();
		while (0 < cnt) {
			final int n = src.read(b, 0, (int) Math.min(b.length, cnt));
			if (n <= 0)
				break;
			dst.write(b, 0, n);
			skipped += n;
			cnt -= n;
		}
		return skipped;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public int read(byte[] b, int off, int len) throws IOException {
		if (len == 0)
			return 0;

		int n = src.read(b, off, len);
		if (0 < n)
			dst.write(b, off, n);
		return n;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public void close() throws IOException {
		byte[] b = skipBuffer();
		for (;;) {
			int n = src.read(b);
			if (n <= 0)
				break;
			dst.write(b, 0, n);
		}
		dst.close();
		src.close();
	}

	private byte[] skipBuffer() {
		if (skipBuffer == null)
			skipBuffer = new byte[2048];
		return skipBuffer;
	}
}