/*
    * Copyright (C) 2015, Ivan Motsch <ivan.motsch@bsiag.com>
    *
    * This program and the accompanying materials are made available
    * under the terms of the Eclipse Distribution License v1.0 which
    * accompanies this distribution, is reproduced below, and is
    * available at http://www.eclipse.org/org/documents/edl-v10.php
    *
    * 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 the Eclipse Foundation, Inc. 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 THE COPYRIGHT OWNER OR
   * CONTRIBUTORS 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.eclipse.jgit.util.io;
  
  import java.io.IOException;
  import java.io.OutputStream;
  
  import org.eclipse.jgit.diff.RawText;
  
  /**
   * An OutputStream that reduces CRLF to LF.
   *
   * Existing single CR are not changed to LF, but retained as is.
   *
   * A binary check on the first 8000 bytes is performed and in case of binary
   * files, canonicalization is turned off (for the complete file).
   *
   * @since 4.3
   */
  public class AutoLFOutputStream extends OutputStream {
  
  	static final int BUFFER_SIZE = 8000;
  
  	private final OutputStream out;
  
  	private int buf = -1;
  
  	private byte[] binbuf = new byte[BUFFER_SIZE];
  
  	private byte[] onebytebuf = new byte[1];
  
  	private int binbufcnt = 0;
  
  	private boolean detectBinary;
  
  	private boolean isBinary;
  
  	/**
  	 * @param out
  	 */
  	public AutoLFOutputStream(OutputStream out) {
  		this(out, true);
  	}
  
  	/**
  	 * @param out
  	 * @param detectBinary
  	 *            whether binaries should be detected
  	 */
  	public AutoLFOutputStream(OutputStream out, boolean detectBinary) {
  		this.out = out;
  		this.detectBinary = detectBinary;
  	}
  
  	@Override
  	public void write(int b) throws IOException {
  		onebytebuf[0] = (byte) b;
  		write(onebytebuf, 0, 1);
  	}
 
 	@Override
 	public void write(byte[] b) throws IOException {
 		int overflow = buffer(b, 0, b.length);
 		if (overflow > 0) {
 			write(b, b.length - overflow, overflow);
 		}
 	}
 
 	@Override
 	public void write(byte[] b, final int startOff, final int startLen)
 			throws IOException {
 		final int overflow = buffer(b, startOff, startLen);
 		if (overflow < 0) {
 			return;
 		}
 		final int off = startOff + startLen - overflow;
 		final int len = overflow;
 		if (len == 0) {
 			return;
 		}
 		int lastw = off;
 		if (isBinary) {
 			out.write(b, off, len);
 			return;
 		}
 		for (int i = off; i < off + len; ++i) {
 			final byte c = b[i];
 			if (c == '\r') {
 				// skip write r but backlog r
 				if (lastw < i) {
 					out.write(b, lastw, i - lastw);
 				}
 				lastw = i + 1;
 				buf = '\r';
 			} else if (c == '\n') {
 				if (buf == '\r') {
 					out.write('\n');
 					lastw = i + 1;
 					buf = -1;
 				} else {
 					if (lastw < i + 1) {
 						out.write(b, lastw, i + 1 - lastw);
 					}
 					lastw = i + 1;
 				}
 			} else {
 				if (buf == '\r') {
 					out.write('\r');
 					lastw = i;
 				}
 				buf = -1;
 			}
 		}
 		if (lastw < off + len) {
 			out.write(b, lastw, off + len - lastw);
 		}
 	}
 
 	private int buffer(byte[] b, int off, int len) throws IOException {
 		if (binbufcnt > binbuf.length) {
 			return len;
 		}
 		int copy = Math.min(binbuf.length - binbufcnt, len);
 		System.arraycopy(b, off, binbuf, binbufcnt, copy);
 		binbufcnt += copy;
 		int remaining = len - copy;
 		if (remaining > 0) {
 			decideMode();
 		}
 		return remaining;
 	}
 
 	private void decideMode() throws IOException {
 		if (detectBinary) {
 			isBinary = RawText.isBinary(binbuf, binbufcnt);
 			detectBinary = false;
 		}
 		int cachedLen = binbufcnt;
 		binbufcnt = binbuf.length + 1; // full!
 		write(binbuf, 0, cachedLen);
 	}
 
 	@Override
 	public void flush() throws IOException {
 		if (binbufcnt <= binbuf.length) {
 			decideMode();
 		}
 		out.flush();
 	}
 
 	@Override
 	public void close() throws IOException {
 		flush();
 		if (buf == '\r') {
 			out.write(buf);
 			buf = -1;
 		}
 		out.close();
 	}
 }