package org.gcube.dataanalysis.ecoengine.utils;

import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Sha1 {

	static String fixedCachePrefix = "cache_";

	private static String convertToHex(byte[] data) {
		StringBuffer buf = new StringBuffer();
		for (int i = 0; i < data.length; i++) {
			int halfbyte = (data[i] >>> 4) & 0x0F;
			int two_halfs = 0;
			do {
				if ((0 <= halfbyte) && (halfbyte <= 9))
					buf.append((char) ('0' + halfbyte));
				else
					buf.append((char) ('a' + (halfbyte - 10)));
				halfbyte = data[i] & 0x0F;
			} while (two_halfs++ < 1);
		}
		return buf.toString();
	}

	public static String SHA1(String text) throws NoSuchAlgorithmException, UnsupportedEncodingException {
		MessageDigest md;
		md = MessageDigest.getInstance("SHA-1");
		byte[] sha1hash = new byte[40];
		md.update(text.getBytes("iso-8859-1"), 0, text.length());
		sha1hash = md.digest();
		return convertToHex(sha1hash);
	}

	public static String calcFilePrefix(String filestring) {
		try {
			// prendo i primi 3 caratteri del file
			int len = filestring.length();
			int counter = 0;
			String cacheDir = "";

			// Bug
			//
			// RE regex = new RE("[a-z]");
			// for (int i = 0; i < len; i++) {
			// String chars = "" + filestring.charAt(i);
			// boolean optioned = regex.match(chars);

			// Fix
			Pattern p = Pattern.compile("[a-z]");

			for (int i = 0; i < len; i++) {
				String chars = "" + filestring.charAt(i);
				Matcher m = p.matcher(chars);
				boolean optioned = m.matches();

				if (optioned) {
					counter++;
					cacheDir += chars;
				}
				if (counter > 2)
					break;
			}

			return cacheDir + "/";
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		return null;
	}

	public static String calculateDigestMD5(String plainText)

	{

		String hashText = "";
		try {
			MessageDigest m = MessageDigest.getInstance("MD5");
			m.reset();
			m.update(plainText.getBytes("UTF-8"));

			byte[] digestBytes = m.digest();
			BigInteger digestValue = new BigInteger(1, digestBytes);

			hashText = digestValue.toString(16);

			// filling
			int remain = 32 - hashText.length();

			for (int i = 0; i < remain; i++)
				hashText = "0" + hashText;

		} catch (Exception e) {
			// TTSLogger.getLogger().debug("Exception: " + e.getMessage());

		}
		return hashText;
	}
}