kitaev@213: /*
kitaev@213:  * Copyright (c) 2010-2011 TMate Software Ltd
kitaev@213:  *  
kitaev@213:  * This program is free software; you can redistribute it and/or modify
kitaev@213:  * it under the terms of the GNU General Public License as published by
kitaev@213:  * the Free Software Foundation; version 2 of the License.
kitaev@213:  *
kitaev@213:  * This program is distributed in the hope that it will be useful,
kitaev@213:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
kitaev@213:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
kitaev@213:  * GNU General Public License for more details.
kitaev@213:  *
kitaev@213:  * For information on how to redistribute this software under
kitaev@213:  * the terms of a license other than GNU General Public License
kitaev@213:  * contact TMate Software at support@hg4j.com
kitaev@213:  */
kitaev@213: package org.tmatesoft.hg.internal;
kitaev@213: 
kitaev@213: import java.io.IOException;
kitaev@213: import java.io.InputStream;
kitaev@213: import java.security.MessageDigest;
kitaev@213: import java.security.NoSuchAlgorithmException;
kitaev@213: 
kitaev@213: import org.tmatesoft.hg.core.Nodeid;
kitaev@213: 
kitaev@213: 
kitaev@213: /**
kitaev@213:  * <pre>
kitaev@213:  * DigestHelper dh;
kitaev@213:  * dh.sha1(...).asHexString();
kitaev@213:  *  or 
kitaev@213:  * dh = dh.sha1(...);
kitaev@213:  * nodeid.equalsTo(dh.asBinary());
kitaev@213:  * </pre>
kitaev@213:  *
kitaev@213:  * @author Artem Tikhomirov
kitaev@213:  * @author TMate Software Ltd.
kitaev@213:  */
kitaev@213: public class DigestHelper {
kitaev@213: 	private MessageDigest sha1;
kitaev@213: 	private byte[] digest;
kitaev@213: 
kitaev@213: 	public DigestHelper() {
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	private MessageDigest getSHA1() {
kitaev@213: 		if (sha1 == null) {
kitaev@213: 			try {
kitaev@213: 				sha1 = MessageDigest.getInstance("SHA-1");
kitaev@213: 			} catch (NoSuchAlgorithmException ex) {
kitaev@213: 				// could hardly happen, JDK from Sun always has sha1.
kitaev@213: 				ex.printStackTrace(); // FIXME log error
kitaev@213: 			}
kitaev@213: 		}
kitaev@213: 		return sha1;
kitaev@213: 	}
kitaev@213: 
kitaev@213: 
kitaev@213: 	public DigestHelper sha1(Nodeid nodeid1, Nodeid nodeid2, byte[] data) {
kitaev@213: 		return sha1(nodeid1.toByteArray(), nodeid2.toByteArray(), data);
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	//  sha1_digest(min(p1,p2) ++ max(p1,p2) ++ final_text)
kitaev@213: 	public DigestHelper sha1(byte[] nodeidParent1, byte[] nodeidParent2, byte[] data) {
kitaev@213: 		MessageDigest alg = getSHA1();
kitaev@213: 		if ((nodeidParent1[0] & 0x00FF) < (nodeidParent2[0] & 0x00FF)) { 
kitaev@213: 			alg.update(nodeidParent1);
kitaev@213: 			alg.update(nodeidParent2);
kitaev@213: 		} else {
kitaev@213: 			alg.update(nodeidParent2);
kitaev@213: 			alg.update(nodeidParent1);
kitaev@213: 		}
kitaev@213: 		digest = alg.digest(data);
kitaev@213: 		assert digest.length == 20;
kitaev@213: 		return this;
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	public String asHexString() {
kitaev@213: 		if (digest == null) {
kitaev@213: 			throw new IllegalStateException("Shall init with sha1() call first");
kitaev@213: 		}
kitaev@213: 		return toHexString(digest, 0, digest.length);
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	// by reference, be careful not to modify (or #clone() if needed)
kitaev@213: 	public byte[] asBinary() {
kitaev@213: 		if (digest == null) {
kitaev@213: 			throw new IllegalStateException("Shall init with sha1() call first");
kitaev@213: 		}
kitaev@213: 		return digest; 
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	// XXX perhaps, digest functions should throw an exception, as it's caller responsibility to deal with eof, etc
kitaev@213: 	public DigestHelper sha1(InputStream is /*ByteBuffer*/) throws IOException {
kitaev@213: 		MessageDigest alg = getSHA1();
kitaev@213: 		byte[] buf = new byte[1024];
kitaev@213: 		int c;
kitaev@213: 		while ((c = is.read(buf)) != -1) {
kitaev@213: 			alg.update(buf, 0, c);
kitaev@213: 		}
kitaev@213: 		digest = alg.digest();
kitaev@213: 		return this;
kitaev@213: 	}
kitaev@213: 	
kitaev@213: 	public DigestHelper sha1(CharSequence... seq) {
kitaev@213: 		MessageDigest alg = getSHA1();
kitaev@213: 		for (CharSequence s : seq) {
kitaev@213: 			byte[] b = s.toString().getBytes();
kitaev@213: 			alg.update(b);
kitaev@213: 		}
kitaev@213: 		digest = alg.digest();
kitaev@213: 		return this;
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	public static String toHexString(byte[] data, final int offset, final int count) {
kitaev@213: 		char[] result = new char[count << 1];
kitaev@213: 		final String hexDigits = "0123456789abcdef";
kitaev@213: 		final int end = offset+count;
kitaev@213: 		for (int i = offset, j = 0; i < end; i++) {
kitaev@213: 			result[j++] = hexDigits.charAt((data[i] >>> 4) & 0x0F);
kitaev@213: 			result[j++] = hexDigits.charAt(data[i] & 0x0F);
kitaev@213: 		}
kitaev@213: 		return new String(result);
kitaev@213: 	}
kitaev@213: }