/*
    * Copyright (C) 2011, 2013 Robin Rosenberg 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.BufferedOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  
  import org.eclipse.jgit.diff.RawText;
  
  /**
   * An OutputStream that expands LF to CRLF.
   *
   * Existing CRLF are not expanded to CRCRLF, but retained as is.
   *
   * A binary check on the first {@link RawText#getBufferSize()} bytes is
   * performed and in case of binary files, canonicalization is turned off (for
   * the complete file).
   */
  public class AutoCRLFOutputStream extends OutputStream {
  
  	private final OutputStream out;
  
  	private int buf = -1;
  
  	private byte[] binbuf = new byte[RawText.getBufferSize()];
  
  	private byte[] onebytebuf = new byte[1];
  
  	private int binbufcnt = 0;
  
  	private boolean detectBinary;
  
  	private boolean isBinary;
  
  	/**
  	 * <p>Constructor for AutoCRLFOutputStream.</p>
  	 *
  	 * @param out a {@link java.io.OutputStream} object.
  	 */
  	public AutoCRLFOutputStream(OutputStream out) {
  		this(out, true);
  	}
  
  	/**
  	 * <p>Constructor for AutoCRLFOutputStream.</p>
  	 *
  	 * @param out a {@link java.io.OutputStream} object.
  	 * @param detectBinary
  	 *            whether binaries should be detected
  	 * @since 4.3
  	 */
  	public AutoCRLFOutputStream(OutputStream out, boolean detectBinary) {
  		// avoid to write single lines directly to FileOutputStream:
  		this.out = out instanceof BufferedOutputStream ? out
  				: new BufferedOutputStream(out);
  		this.detectBinary = detectBinary;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public void write(int b) throws IOException {
  		onebytebuf[0] = (byte) b;
  		write(onebytebuf, 0, 1);
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public void write(byte[] b) throws IOException {
  		int overflow = buffer(b, 0, b.length);
  		if (overflow > 0)
  			write(b, b.length - overflow, overflow);
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public void write(byte[] b, int startOff, 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];
 			switch (c) {
 			case '\r':
 				buf = '\r';
 				break;
 			case '\n':
 				if (buf != '\r') {
 					if (lastw < i) {
 						out.write(b, lastw, i - lastw);
 					}
 					out.write('\r');
 					lastw = i;
 				}
 				buf = -1;
 				break;
 			default:
 				buf = -1;
 				break;
 			}
 		}
 		if (lastw < off + len) {
 			out.write(b, lastw, off + len - lastw);
 		}
 		if (b[off + len - 1] == '\r')
 			buf = '\r';
 	}
 
 	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(false);
 		}
 		return remaining;
 	}
 
 	private void decideMode(boolean complete) throws IOException {
 		if (detectBinary) {
 			isBinary = RawText.isBinary(binbuf, binbufcnt, complete);
 			if (!isBinary) {
 				isBinary = RawText.isCrLfText(binbuf, binbufcnt, complete);
 			}
 			detectBinary = false;
 		}
 		int cachedLen = binbufcnt;
 		binbufcnt = binbuf.length + 1; // full!
 		write(binbuf, 0, cachedLen);
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public void flush() throws IOException {
 		if (binbufcnt <= binbuf.length) {
 			decideMode(true);
 		}
 		buf = -1;
 		out.flush();
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public void close() throws IOException {
 		flush();
 		out.close();
 	}
 }