/* ========================================================================
 * PlantUML : a free UML diagram generator
 * ========================================================================
 *
 * (C) Copyright 2009-2020, Arnaud Roques
 *
 * Project Info:  http://plantuml.com
 * 
 * If you like this project or if you find it useful, you can support us at:
 * 
 * http://plantuml.com/patreon (only 1$ per month!)
 * http://plantuml.com/paypal
 * 
 * This file is part of PlantUML.
 *
 * PlantUML is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * PlantUML distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
 * License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 *
 * Original Author:  Arnaud Roques
 *
 *
 */
// Copyright 2003-2010 Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland
// www.source-code.biz, www.inventec.ch/chdh
//
// This module is multi-licensed and may be used under the terms
// of any of the following licenses:
//
//  EPL, Eclipse Public License, V1.0 or later, http://www.eclipse.org/legal
//  LGPL, GNU Lesser General Public License, V2.1 or later, http://www.gnu.org/licenses/lgpl.html
//  GPL, GNU General Public License, V2 or later, http://www.gnu.org/licenses/gpl.html
//  AGPL, GNU Affero General Public License V3 or later, http://www.gnu.org/licenses/agpl.html
//  AL, Apache License, V2.0 or later, http://www.apache.org/licenses
//  BSD, BSD License, http://www.opensource.org/licenses/bsd-license.php
//  MIT, MIT License, http://www.opensource.org/licenses/MIT
//
// Please contact the author if you need another license.
// This module is provided "as is", without warranties of any kind.
//
// Project home page: www.source-code.biz/base64coder/java

package net.sourceforge.plantuml.code;

/**
 * A Base64 encoder/decoder.
 * 
 * <p>
 * This class is used to encode and decode data in Base64 format as described in RFC 1521.
 * <p>
 * Project home page: <a href="http://www.source-code.biz/base64coder/java/">www.source-code.biz/base64coder/java</a><br>
 * Author: Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland<br>
 * Multi-licensed: EPL / LGPL / GPL / AL / BSD / MIT.
 * 
 * @author Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland, www.source-code.biz
 */
public class Base64Coder {

	// The line separator string of the operating system.
	private static final String systemLineSeparator = System.getProperty("line.separator");

	// Mapping table from 6-bit nibbles to Base64 characters.
	private static final char[] map1 = new char[64];
	static {
		int i = 0;
		for (char c = 'A'; c <= 'Z'; c++)
			map1[i++] = c;
		for (char c = 'a'; c <= 'z'; c++)
			map1[i++] = c;
		for (char c = '0'; c <= '9'; c++)
			map1[i++] = c;
		map1[i++] = '+';
		map1[i++] = '/';
	}

	// Mapping table from Base64 characters to 6-bit nibbles.
	private static final byte[] map2 = new byte[128];
	static {
		for (int i = 0; i < map2.length; i++)
			map2[i] = -1;
		for (int i = 0; i < 64; i++)
			map2[map1[i]] = (byte) i;
	}

	/**
	 * Encodes a string into Base64 format. No blanks or line breaks are inserted.
	 * 
	 * @param s
	 *            A String to be encoded.
	 * @return A String containing the Base64 encoded data.
	 */
	public static String encodeString(String s) {
		return new String(encode(s.getBytes()));
	}

	/**
	 * Encodes a byte array into Base 64 format and breaks the output into lines of 76 characters. This method is
	 * compatible with <code>sun.misc.BASE64Encoder.encodeBuffer(byte[])</code>.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @return A String containing the Base64 encoded data, broken into lines.
	 */
	public static String encodeLines(byte[] in) {
		return encodeLines(in, 0, in.length, 76, systemLineSeparator);
	}

	/**
	 * Encodes a byte array into Base 64 format and breaks the output into lines.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @param iOff
	 *            Offset of the first byte in <code>in</code> to be processed.
	 * @param iLen
	 *            Number of bytes to be processed in <code>in</code>, starting at <code>iOff</code>.
	 * @param lineLen
	 *            Line length for the output data. Should be a multiple of 4.
	 * @param lineSeparator
	 *            The line separator to be used to separate the output lines.
	 * @return A String containing the Base64 encoded data, broken into lines.
	 */
	public static String encodeLines(byte[] in, int iOff, int iLen, int lineLen, String lineSeparator) {
		int blockLen = (lineLen * 3) / 4;
		if (blockLen <= 0)
			throw new IllegalArgumentException();
		int lines = (iLen + blockLen - 1) / blockLen;
		int bufLen = ((iLen + 2) / 3) * 4 + lines * lineSeparator.length();
		StringBuilder buf = new StringBuilder(bufLen);
		int ip = 0;
		while (ip < iLen) {
			int l = Math.min(iLen - ip, blockLen);
			buf.append(encode(in, iOff + ip, l));
			buf.append(lineSeparator);
			ip += l;
		}
		return buf.toString();
	}

	/**
	 * Encodes a byte array into Base64 format. No blanks or line breaks are inserted in the output.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @return A character array containing the Base64 encoded data.
	 */
	public static char[] encode(byte[] in) {
		return encode(in, 0, in.length);
	}

	/**
	 * Encodes a byte array into Base64 format. No blanks or line breaks are inserted in the output.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @param iLen
	 *            Number of bytes to process in <code>in</code>.
	 * @return A character array containing the Base64 encoded data.
	 */
	public static char[] encode(byte[] in, int iLen) {
		return encode(in, 0, iLen);
	}

	/**
	 * Encodes a byte array into Base64 format. No blanks or line breaks are inserted in the output.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @param iOff
	 *            Offset of the first byte in <code>in</code> to be processed.
	 * @param iLen
	 *            Number of bytes to process in <code>in</code>, starting at <code>iOff</code>.
	 * @return A character array containing the Base64 encoded data.
	 */
	public static char[] encode(byte[] in, int iOff, int iLen) {
		int oDataLen = (iLen * 4 + 2) / 3; // output length without padding
		int oLen = ((iLen + 2) / 3) * 4; // output length including padding
		char[] out = new char[oLen];
		int ip = iOff;
		int iEnd = iOff + iLen;
		int op = 0;
		while (ip < iEnd) {
			int i0 = in[ip++] & 0xff;
			int i1 = ip < iEnd ? in[ip++] & 0xff : 0;
			int i2 = ip < iEnd ? in[ip++] & 0xff : 0;
			int o0 = i0 >>> 2;
			int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
			int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
			int o3 = i2 & 0x3F;
			out[op++] = map1[o0];
			out[op++] = map1[o1];
			out[op] = op < oDataLen ? map1[o2] : '=';
			op++;
			out[op] = op < oDataLen ? map1[o3] : '=';
			op++;
		}
		return out;
	}

	/**
	 * Decodes a string from Base64 format. No blanks or line breaks are allowed within the Base64 encoded input data.
	 * 
	 * @param s
	 *            A Base64 String to be decoded.
	 * @return A String containing the decoded data.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static String decodeString(String s) {
		return new String(decode(s));
	}

	/**
	 * Decodes a byte array from Base64 format and ignores line separators, tabs and blanks. CR, LF, Tab and Space
	 * characters are ignored in the input data. This method is compatible with
	 * <code>sun.misc.BASE64Decoder.decodeBuffer(String)</code>.
	 * 
	 * @param s
	 *            A Base64 String to be decoded.
	 * @return An array containing the decoded data bytes.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static byte[] decodeLines(String s) {
		char[] buf = new char[s.length()];
		int p = 0;
		for (int ip = 0; ip < s.length(); ip++) {
			char c = s.charAt(ip);
			if (c != ' ' && c != '\r' && c != '\n' && c != '\t')
				buf[p++] = c;
		}
		return decode(buf, 0, p);
	}

	/**
	 * Decodes a byte array from Base64 format. No blanks or line breaks are allowed within the Base64 encoded input
	 * data.
	 * 
	 * @param s
	 *            A Base64 String to be decoded.
	 * @return An array containing the decoded data bytes.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static byte[] decode(String s) {
		return decode(s.toCharArray());
	}

	/**
	 * Decodes a byte array from Base64 format. No blanks or line breaks are allowed within the Base64 encoded input
	 * data.
	 * 
	 * @param in
	 *            A character array containing the Base64 encoded data.
	 * @return An array containing the decoded data bytes.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static byte[] decode(char[] in) {
		return decode(in, 0, in.length);
	}

	/**
	 * Decodes a byte array from Base64 format. No blanks or line breaks are allowed within the Base64 encoded input
	 * data.
	 * 
	 * @param in
	 *            A character array containing the Base64 encoded data.
	 * @param iOff
	 *            Offset of the first character in <code>in</code> to be processed.
	 * @param iLen
	 *            Number of characters to process in <code>in</code>, starting at <code>iOff</code>.
	 * @return An array containing the decoded data bytes.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static byte[] decode(char[] in, int iOff, int iLen) {
		if (iLen % 4 != 0)
			throw new IllegalArgumentException("Length of Base64 encoded input string is not a multiple of 4.");
		while (iLen > 0 && in[iOff + iLen - 1] == '=')
			iLen--;
		int oLen = (iLen * 3) / 4;
		byte[] out = new byte[oLen];
		int ip = iOff;
		int iEnd = iOff + iLen;
		int op = 0;
		while (ip < iEnd) {
			int i0 = in[ip++];
			int i1 = in[ip++];
			int i2 = ip < iEnd ? in[ip++] : 'A';
			int i3 = ip < iEnd ? in[ip++] : 'A';
			if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
				throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
			int b0 = map2[i0];
			int b1 = map2[i1];
			int b2 = map2[i2];
			int b3 = map2[i3];
			if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
				throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
			int o0 = (b0 << 2) | (b1 >>> 4);
			int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
			int o2 = ((b2 & 3) << 6) | b3;
			out[op++] = (byte) o0;
			if (op < oLen)
				out[op++] = (byte) o1;
			if (op < oLen)
				out[op++] = (byte) o2;
		}
		return out;
	}

	// Dummy constructor.
	private Base64Coder() {
	}

} // end class Base64Coder
