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/**
 * Copyright (c) 2000-2009 Liferay, Inc. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.liferay.portal.kernel.util;

import com.liferay.portal.kernel.log.Log;
import com.liferay.portal.kernel.log.LogFactoryUtil;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

/**
 * View Source
 *
 * @author Brian Wing Shun Chan
 *
 */
public class Base64 {

	protected static char getChar(int sixbit) {
		if (sixbit >= 0 && sixbit <= 25) {
			return (char)(65 + sixbit);
		}

		if (sixbit >= 26 && sixbit <= 51) {
			return (char)(97 + (sixbit - 26));
		}

		if (sixbit >= 52 && sixbit <= 61) {
			return (char)(48 + (sixbit - 52));
		}

		if (sixbit == 62) {
			return '+';
		}

		return sixbit != 63 ? '?' : '/';
	}

	protected static int getValue(char c) {
		if (c >= 'A' && c <= 'Z') {
			return c - 65;
		}

		if (c >= 'a' && c <= 'z') {
			return (c - 97) + 26;
		}

		if (c >= '0' && c <= '9') {
			return (c - 48) + 52;
		}

		if (c == '+') {
			return 62;
		}

		if (c == '/') {
			return 63;
		}

		return c != '=' ? -1 : 0;
	}

	public static String encode(byte raw[]) {
		StringBuilder encoded = new StringBuilder();

		for (int i = 0; i < raw.length; i += 3) {
			encoded.append(encodeBlock(raw, i));
		}

		return encoded.toString();
	}

	protected static char[] encodeBlock(byte raw[], int offset) {
		int block = 0;
		int slack = raw.length - offset - 1;
		int end = slack < 2 ? slack : 2;

		for (int i = 0; i <= end; i++) {
			byte b = raw[offset + i];

			int neuter = b >= 0 ? ((int) (b)) : b + 256;
			block += neuter << 8 * (2 - i);
		}

		char base64[] = new char[4];

		for (int i = 0; i < 4; i++) {
			int sixbit = block >>> 6 * (3 - i) & 0x3f;
			base64[i] = getChar(sixbit);
		}

		if (slack < 1) {
			base64[2] = '=';
		}

		if (slack < 2) {
			base64[3] = '=';
		}

		return base64;
	}

	public static byte[] decode(String base64) {
		if (Validator.isNull(base64)) {
			return new byte[0];
		}

		int pad = 0;

		for (int i = base64.length() - 1; base64.charAt(i) == '='; i--) {
			pad++;
		}

		int length = (base64.length() * 6) / 8 - pad;
		byte raw[] = new byte[length];
		int rawindex = 0;

		for (int i = 0; i < base64.length(); i += 4) {
			int block = (getValue(base64.charAt(i)) << 18) +
						(getValue(base64.charAt(i + 1)) << 12) +
						(getValue(base64.charAt(i + 2)) << 6) +
						getValue(base64.charAt(i + 3));

			for (int j = 0; j < 3 && rawindex + j < raw.length; j++) {
				raw[rawindex + j] = (byte)(block >> 8 * (2 - j) & 0xff);
			}

			rawindex += 3;
		}

		return raw;
	}

	public static String objectToString(Object o) {
		if (o == null) {
			return null;
		}

		ByteArrayMaker bam = new ByteArrayMaker(32000);

		try {
			ObjectOutputStream os = new ObjectOutputStream(
				new BufferedOutputStream(bam));

			os.flush();
			os.writeObject(o);
			os.flush();
		}
		catch (IOException e) {
			_log.error(e.getMessage());
		}

		return encode(bam.toByteArray());
	}

	public static Object stringToObject(String s) {
		if (s == null) {
			return null;
		}

		byte bytes[] = decode(s);

		ByteArrayInputStream bais = new ByteArrayInputStream(bytes);

		try {
			ObjectInputStream is = new ObjectInputStream(
				new BufferedInputStream(bais));

			return is.readObject();
		}
		catch (Exception e) {
			_log.error(e.getMessage());
		}

		return null;
	}

	private static Log _log = LogFactoryUtil.getLog(Base64.class);

}