/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.commons.net.util;
  
  import java.math.BigInteger;
  import java.nio.charset.StandardCharsets;
  import java.util.Objects;
  
  /**
   * Provides Base64 encoding and decoding as defined by RFC 2045.
   *
   * <p>
   * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose Internet Mail Extensions (MIME) Part One:
   * Format of Internet Message Bodies</cite> by Freed and Borenstein.
   * </p>
   * <p>
   * The class can be parameterized in the following manner with various constructors:
   * <ul>
   * <li>URL-safe mode: Default off.</li>
   * <li>Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
   * <li>Line separator: Default is CRLF ("\r\n")</li>
   * </ul>
   * <p>
   * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode character encodings which are
   * compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
   * </p>
   *
   * @deprecated Use {@link java.util.Base64}.
   * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
   * @since 2.2
   */
  @Deprecated
  public class Base64 {
      private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;
  
      private static final int DEFAULT_BUFFER_SIZE = 8192;
  
      /**
       * Chunk size per RFC 2045 section 6.8.
       *
       * <p>
       * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any equal signs.
       * </p>
       *
       * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
       */
      static final int CHUNK_SIZE = 76;
  
      /**
       * Chunk separator per RFC 2045 section 2.1.
       *
       * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
       */
      private static final byte[] CHUNK_SEPARATOR = { '\r', '\n' };
  
      /**
       * This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet" equivalents as specified in Table 1 of RFC
       * 2045.
       *
       * Thanks to "commons" project in ws.apache.org for <a href="http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/">this code</a>.
       */
      private static final byte[] STANDARD_ENCODE_TABLE = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
              'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w',
              'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };
  
      /**
       * This is a copy of the STANDARD_ENCODE_TABLE above, but with + and / changed to - and _ to make the encoded Base64 results more URL-SAFE. This table is
       * only used when the Base64's mode is set to URL-SAFE.
       */
      private static final byte[] URL_SAFE_ENCODE_TABLE = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
              'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w',
              'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_' };
  
      /**
       * Byte used to pad output.
       */
      private static final byte PAD = '=';
  
      /**
       * This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in Table 1 of RFC 2045) into their 6-bit
       * positive integer equivalents. Characters that are not in the Base64 alphabet but fall within the bounds of the array are translated to -1.
       *
       * Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles both URL_SAFE and STANDARD base64. (The
       * encoder, on the other hand, needs to know ahead of time what to emit).
      *
      * Thanks to "commons" project in ws.apache.org for <a href="http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/">this code</a>
      */
     private static final byte[] DECODE_TABLE = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1,
             0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29, 30, 31, 32,
             33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 };
 
     /** Mask used to extract 6 bits, used when encoding */
     private static final int MASK_6BITS = 0x3f;
 
     /** Mask used to extract 8 bits, used in decoding base64 bytes */
     private static final int MASK_8BITS = 0xff;
 
     // The static final fields above are used for the original static byte[] methods on Base64.
     // The private member fields below are used with the new streaming approach, which requires
     // some state be preserved between calls of encode() and decode().
 
     /**
      * Tests a given byte array to see if it contains any valid character within the Base64 alphabet.
      *
      * @param arrayOctet byte array to test
      * @return {@code true} if any byte is a valid character in the Base64 alphabet; {@code false} otherwise
      */
     private static boolean containsBase64Byte(final byte[] arrayOctet) {
         for (final byte element : arrayOctet) {
             if (isBase64(element)) {
                 return true;
             }
         }
         return false;
     }
 
     /**
      * Decodes Base64 data into octets.
      *
      * @param base64Data Byte array containing Base64 data
      * @return Array containing decoded data.
      */
     public static byte[] decodeBase64(final byte[] base64Data) {
         return new Base64().decode(base64Data);
     }
 
     /**
      * Decodes a Base64 String into octets.
      *
      * @param base64String String containing Base64 data
      * @return Array containing decoded data.
      * @since 1.4
      */
     public static byte[] decodeBase64(final String base64String) {
         return new Base64().decode(base64String);
     }
 
     // Implementation of integer encoding used for crypto
     /**
      * Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
      *
      * @param pArray a byte array containing base64 character data
      * @return A BigInteger
      * @since 1.4
      */
     public static BigInteger decodeInteger(final byte[] pArray) {
         return new BigInteger(1, decodeBase64(pArray));
     }
 
     /**
      * Encodes binary data using the base64 algorithm but does not chunk the output.
      *
      * @param binaryData binary data to encode
      * @return byte[] containing Base64 characters in their UTF-8 representation.
      */
     public static byte[] encodeBase64(final byte[] binaryData) {
         return encodeBase64(binaryData, false);
     }
 
     /**
      * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
      *
      * @param binaryData Array containing binary data to encode.
      * @param isChunked  if {@code true} this encoder will chunk the base64 output into 76 character blocks
      * @return Base64-encoded data.
      * @throws IllegalArgumentException Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
      */
     public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked) {
         return encodeBase64(binaryData, isChunked, false);
     }
 
     /**
      * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
      *
      * @param binaryData Array containing binary data to encode.
      * @param isChunked  if {@code true} this encoder will chunk the base64 output into 76 character blocks
      * @param urlSafe    if {@code true} this encoder will emit - and _ instead of the usual + and / characters.
      * @return Base64-encoded data.
      * @throws IllegalArgumentException Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
      * @since 1.4
      */
     public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked, final boolean urlSafe) {
         return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
     }
 
     /**
      * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
      *
      * @param binaryData    Array containing binary data to encode.
      * @param isChunked     if {@code true} this encoder will chunk the base64 output into 76 character blocks
      * @param urlSafe       if {@code true} this encoder will emit - and _ instead of the usual + and / characters.
      * @param maxResultSize The maximum result size to accept.
      * @return Base64-encoded data.
      * @throws IllegalArgumentException Thrown when the input array needs an output array bigger than maxResultSize
      * @since 1.4
      */
     public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked, final boolean urlSafe, final int maxResultSize) {
         if (binaryData == null || binaryData.length == 0) {
             return binaryData;
         }
 
         final long len = getEncodeLength(binaryData, isChunked ? CHUNK_SIZE : 0, isChunked ? CHUNK_SEPARATOR : NetConstants.EMPTY_BTYE_ARRAY);
         if (len > maxResultSize) {
             throw new IllegalArgumentException(
                     "Input array too big, the output array would be bigger (" + len + ") than the specified maxium size of " + maxResultSize);
         }
 
         final Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
         return b64.encode(binaryData);
     }
 
     /**
      * Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
      *
      * @param binaryData binary data to encode
      * @return Base64 characters chunked in 76 character blocks
      */
     public static byte[] encodeBase64Chunked(final byte[] binaryData) {
         return encodeBase64(binaryData, true);
     }
 
     /**
      * Encodes binary data using the base64 algorithm into 76 character blocks separated by CRLF.
      * <p>
      * For a non-chunking version, see {@link #encodeBase64StringUnChunked(byte[])}.
      *
      * @param binaryData binary data to encode
      * @return String containing Base64 characters.
      * @since 1.4
      */
     public static String encodeBase64String(final byte[] binaryData) {
         return newStringUtf8(encodeBase64(binaryData, true));
     }
 
     /**
      * Encodes binary data using the base64 algorithm.
      *
      * @param binaryData  binary data to encode
      * @param useChunking whether to split the output into chunks
      * @return String containing Base64 characters.
      * @since 3.2
      */
     public static String encodeBase64String(final byte[] binaryData, final boolean useChunking) {
         return newStringUtf8(encodeBase64(binaryData, useChunking));
     }
 
     /**
      * Encodes binary data using the base64 algorithm, without using chunking.
      * <p>
      * For a chunking version, see {@link #encodeBase64String(byte[])}.
      *
      * @param binaryData binary data to encode
      * @return String containing Base64 characters.
      * @since 3.2
      */
     public static String encodeBase64StringUnChunked(final byte[] binaryData) {
         return newStringUtf8(encodeBase64(binaryData, false));
     }
 
     /**
      * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The url-safe variation emits - and _ instead of +
      * and / characters.
      *
      * @param binaryData binary data to encode
      * @return byte[] containing Base64 characters in their UTF-8 representation.
      * @since 1.4
      */
     public static byte[] encodeBase64URLSafe(final byte[] binaryData) {
         return encodeBase64(binaryData, false, true);
     }
 
     /**
      * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The url-safe variation emits - and _ instead of +
      * and / characters.
      *
      * @param binaryData binary data to encode
      * @return String containing Base64 characters
      * @since 1.4
      */
     public static String encodeBase64URLSafeString(final byte[] binaryData) {
         return newStringUtf8(encodeBase64(binaryData, false, true));
     }
 
     /**
      * Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
      *
      * @param bigInt a BigInteger
      * @return A byte array containing base64 character data
      * @throws NullPointerException if null is passed in
      * @since 1.4
      */
     public static byte[] encodeInteger(final BigInteger bigInt) {
         return encodeBase64(toIntegerBytes(bigInt), false);
     }
 
     /**
      * Pre-calculates the amount of space needed to base64-encode the supplied array.
      *
      * @param pArray         byte[] array which will later be encoded
      * @param chunkSize      line-length of the output (<= 0 means no chunking) between each chunkSeparator (e.g. CRLF).
      * @param chunkSeparator the sequence of bytes used to separate chunks of output (e.g. CRLF).
      *
      * @return amount of space needed to encode the supplied array. Returns a long since a max-len array will require Integer.MAX_VALUE + 33%.
      */
     private static long getEncodeLength(final byte[] pArray, int chunkSize, final byte[] chunkSeparator) {
         // base64 always encodes to multiples of 4.
         chunkSize = chunkSize / 4 * 4;
 
         long len = pArray.length * 4 / 3;
         final long mod = len % 4;
         if (mod != 0) {
             len += 4 - mod;
         }
         if (chunkSize > 0) {
             final boolean lenChunksPerfectly = len % chunkSize == 0;
             len += len / chunkSize * chunkSeparator.length;
             if (!lenChunksPerfectly) {
                 len += chunkSeparator.length;
             }
         }
         return len;
     }
 
     /**
      * Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently, the method treats whitespace as valid.
      *
      * @param arrayOctet byte array to test
      * @return {@code true} if all bytes are valid characters in the Base64 alphabet or if the byte array is empty; false, otherwise
      */
     public static boolean isArrayByteBase64(final byte[] arrayOctet) {
         for (final byte element : arrayOctet) {
             if (!isBase64(element) && !isWhiteSpace(element)) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Returns whether or not the <code>octet</code> is in the base 64 alphabet.
      *
      * @param octet The value to test
      * @return {@code true} if the value is defined in the base 64 alphabet, {@code false} otherwise.
      * @since 1.4
      */
     public static boolean isBase64(final byte octet) {
         return octet == PAD || octet >= 0 && octet < DECODE_TABLE.length && DECODE_TABLE[octet] != -1;
     }
 
     /**
      * Checks if a byte value is whitespace or not.
      *
      * @param byteToCheck the byte to check
      * @return true if byte is whitespace, false otherwise
      */
     private static boolean isWhiteSpace(final byte byteToCheck) {
         switch (byteToCheck) {
         case ' ':
         case '\n':
         case '\r':
         case '\t':
             return true;
         default:
             return false;
         }
     }
 
     private static String newStringUtf8(final byte[] encode) {
         return new String(encode, StandardCharsets.UTF_8);
     }
 
     /**
      * Returns a byte-array representation of a <code>BigInteger</code> without sign bit.
      *
      * @param bigInt <code>BigInteger</code> to be converted
      * @return a byte array representation of the BigInteger parameter
      */
     static byte[] toIntegerBytes(final BigInteger bigInt) {
         Objects.requireNonNull(bigInt, "bigInt");
         int bitlen = bigInt.bitLength();
         // round bitlen
         bitlen = bitlen + 7 >> 3 << 3;
         final byte[] bigBytes = bigInt.toByteArray();
 
         if (bigInt.bitLength() % 8 != 0 && bigInt.bitLength() / 8 + 1 == bitlen / 8) {
             return bigBytes;
         }
         // set up params for copying everything but sign bit
         int startSrc = 0;
         int len = bigBytes.length;
 
         // if bigInt is exactly byte-aligned, just skip signbit in copy
         if (bigInt.bitLength() % 8 == 0) {
             startSrc = 1;
             len--;
         }
         final int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
         final byte[] resizedBytes = new byte[bitlen / 8];
         System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
         return resizedBytes;
     }
 
     /**
      * Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static because it is able to decode both STANDARD and URL_SAFE
      * streams, but the encodeTable must be a member variable, so we can switch between the two modes.
      */
     private final byte[] encodeTable;
 
     /**
      * Line length for encoding. Not used when decoding. A value of zero or less implies no chunking of the base64 encoded data.
      */
     private final int lineLength;
 
     /**
      * Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
      */
     private final byte[] lineSeparator;
 
     /**
      * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
      * <code>decodeSize = 3 + lineSeparator.length;</code>
      */
     private final int decodeSize;
 
     /**
      * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
      * <code>encodeSize = 4 + lineSeparator.length;</code>
      */
     private final int encodeSize;
 
     /**
      * Buffer for streaming.
      */
     private byte[] buffer;
 
     /**
      * Position where next character should be written in the buffer.
      */
     private int pos;
 
     /**
      * Position where next character should be read from the buffer.
      */
     private int readPos;
 
     /**
      * Variable tracks how many characters have been written to the current line. Only used when encoding. We use it to make sure each encoded line never goes
      * beyond lineLength (if lineLength > 0).
      */
     private int currentLinePos;
 
     /**
      * Writes to the buffer only occur after every 3 reads when encoding, an every 4 reads when decoding. This variable helps track that.
      */
     private int modulus;
 
     /**
      * Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this Base64 object becomes useless, and must be thrown away.
      */
     private boolean eof;
 
     /**
      * Placeholder for the 3 bytes we're dealing with for our base64 logic. Bitwise operations store and extract the base64 encoding or decoding from this
      * variable.
      */
     private int x;
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      * <p>
      * When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
      * </p>
      *
      * <p>
      * When decoding all variants are supported.
      * </p>
      */
     public Base64() {
         this(false);
     }
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
      * <p>
      * When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
      * </p>
      *
      * <p>
      * When decoding all variants are supported.
      * </p>
      *
      * @param urlSafe if {@code true}, URL-safe encoding is used. In most cases this should be set to {@code false}.
      * @since 1.4
      */
     public Base64(final boolean urlSafe) {
         this(CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
     }
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      * <p>
      * When encoding the line length is given in the constructor, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
      * </p>
      * <p>
      * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
      * </p>
      * <p>
      * When decoding all variants are supported.
      * </p>
      *
      * @param lineLength Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4).
      *                   If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored when decoding.
      * @since 1.4
      */
     public Base64(final int lineLength) {
         this(lineLength, CHUNK_SEPARATOR);
     }
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      * <p>
      * When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.
      * </p>
      * <p>
      * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
      * </p>
      * <p>
      * When decoding all variants are supported.
      * </p>
      *
      * @param lineLength    Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4).
      *                      If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored when decoding.
      * @param lineSeparator Each line of encoded data will end with this sequence of bytes.
      * @throws IllegalArgumentException Thrown when the provided lineSeparator included some base64 characters.
      * @since 1.4
      */
     public Base64(final int lineLength, final byte[] lineSeparator) {
         this(lineLength, lineSeparator, false);
     }
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      * <p>
      * When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.
      * </p>
      * <p>
      * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
      * </p>
      * <p>
      * When decoding all variants are supported.
      * </p>
      *
      * @param lineLength    Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 4).
      *                      If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored when decoding.
      * @param lineSeparator Each line of encoded data will end with this sequence of bytes.
      * @param urlSafe       Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode operations. Decoding seamlessly
      *                      handles both modes.
      * @throws IllegalArgumentException The provided lineSeparator included some base64 characters. That's not going to work!
      * @since 1.4
      */
     public Base64(int lineLength, byte[] lineSeparator, final boolean urlSafe) {
         if (lineSeparator == null) {
             lineLength = 0; // disable chunk-separating
             lineSeparator = NetConstants.EMPTY_BTYE_ARRAY; // this just gets ignored
         }
         this.lineLength = lineLength > 0 ? lineLength / 4 * 4 : 0;
         this.lineSeparator = new byte[lineSeparator.length];
         System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
         if (lineLength > 0) {
             this.encodeSize = 4 + lineSeparator.length;
         } else {
             this.encodeSize = 4;
         }
         this.decodeSize = this.encodeSize - 1;
         if (containsBase64Byte(lineSeparator)) {
             final String sep = newStringUtf8(lineSeparator);
             throw new IllegalArgumentException("lineSeperator must not contain base64 characters: [" + sep + "]");
         }
         this.encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
     }
 
     /**
      * Returns the amount of buffered data available for reading.
      *
      * @return The amount of buffered data available for reading.
      */
     int avail() {
         return buffer != null ? pos - readPos : 0;
     }
 
     /**
      * Decodes a byte array containing characters in the Base64 alphabet.
      *
      * @param pArray A byte array containing Base64 character data
      * @return a byte array containing binary data; will return {@code null} if provided byte array is {@code null}.
      */
     public byte[] decode(final byte[] pArray) {
         reset();
         if (pArray == null || pArray.length == 0) {
             return pArray;
         }
         final long len = pArray.length * 3 / 4;
         final byte[] buf = new byte[(int) len];
         setInitialBuffer(buf, 0, buf.length);
         decode(pArray, 0, pArray.length);
         decode(pArray, 0, -1); // Notify decoder of EOF.
 
         // Would be nice to just return buf (like we sometimes do in the encode
         // logic), but we have no idea what the line-length was (could even be
         // variable). So we cannot determine ahead of time exactly how big an
         // array is necessary. Hence, the need to construct a 2nd byte array to
         // hold the final result:
 
         final byte[] result = new byte[pos];
         readResults(result, 0, result.length);
         return result;
     }
 
     /**
      * <p>
      * Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once with the data to decode, and once with
      * inAvail set to "-1" to alert decoder that EOF has been reached. The "-1" call is not necessary when decoding, but it doesn't hurt, either.
      * </p>
      * <p>
      * Ignores all non-base64 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are silently ignored, but has implications
      * for other bytes, too. This method subscribes to the garbage-in, garbage-out philosophy: it will not check the provided data for validity.
      * </p>
      * <p>
      * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
      * <p>
      * See: <a href="http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/">
      * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
      * </a>
      *
      * </p>
      *
      * @param in      byte[] array of ascii data to base64 decode.
      * @param inPos   Position to start reading data from.
      * @param inAvail Amount of bytes available from input for encoding.
      */
     void decode(final byte[] in, int inPos, final int inAvail) {
         if (eof) {
             return;
         }
         if (inAvail < 0) {
             eof = true;
         }
         for (int i = 0; i < inAvail; i++) {
             if (buffer == null || buffer.length - pos < decodeSize) {
                 resizeBuffer();
             }
             final byte b = in[inPos++];
             if (b == PAD) {
                 // We're done.
                 eof = true;
                 break;
             }
             if (b >= 0 && b < DECODE_TABLE.length) {
                 final int result = DECODE_TABLE[b];
                 if (result >= 0) {
                     modulus = ++modulus % 4;
                     x = (x << 6) + result;
                     if (modulus == 0) {
                         buffer[pos++] = (byte) (x >> 16 & MASK_8BITS);
                         buffer[pos++] = (byte) (x >> 8 & MASK_8BITS);
                         buffer[pos++] = (byte) (x & MASK_8BITS);
                     }
                 }
             }
         }
 
         // Two forms of EOF as far as base64 decoder is concerned: actual
         // EOF (-1) and first time '=' character is encountered in stream.
         // This approach makes the '=' padding characters completely optional.
         if (eof && modulus != 0) {
             x = x << 6;
             switch (modulus) {
             case 2:
                 x = x << 6;
                 buffer[pos++] = (byte) (x >> 16 & MASK_8BITS);
                 break;
             case 3:
                 buffer[pos++] = (byte) (x >> 16 & MASK_8BITS);
                 buffer[pos++] = (byte) (x >> 8 & MASK_8BITS);
                 break;
             default:
                 break; // other values ignored
             }
         }
     }
 
     /**
      * Decodes a String containing characters in the Base64 alphabet.
      *
      * @param pArray A String containing Base64 character data, must not be {@code null}
      * @return a byte array containing binary data
      * @since 1.4
      */
     public byte[] decode(final String pArray) {
         return decode(getBytesUtf8(pArray));
     }
 
     /**
      * Encodes a byte[] containing binary data, into a byte[] containing characters in the Base64 alphabet.
      *
      * @param pArray a byte array containing binary data
      * @return A byte array containing only Base64 character data
      */
     public byte[] encode(final byte[] pArray) {
         reset();
         if (pArray == null || pArray.length == 0) {
             return pArray;
         }
         final long len = getEncodeLength(pArray, lineLength, lineSeparator);
         byte[] buf = new byte[(int) len];
         setInitialBuffer(buf, 0, buf.length);
         encode(pArray, 0, pArray.length);
         encode(pArray, 0, -1); // Notify encoder of EOF.
         // Encoder might have resized, even though it was unnecessary.
         if (buffer != buf) {
             readResults(buf, 0, buf.length);
         }
         // In URL-SAFE mode we skip the padding characters, so sometimes our
         // final length is a bit smaller.
         if (isUrlSafe() && pos < buf.length) {
             final byte[] smallerBuf = new byte[pos];
             System.arraycopy(buf, 0, smallerBuf, 0, pos);
             buf = smallerBuf;
         }
         return buf;
     }
 
     /**
      * <p>
      * Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with the data to encode, and once with
      * inAvail set to "-1" to alert encoder that EOF has been reached, so flush last remaining bytes (if not multiple of 3).
      * </p>
      * <p>
      * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
      * <p>
      * See: <a href="http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/">
      * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
      * </a>
      * </p>
      *
      * @param in      byte[] array of binary data to base64 encode.
      * @param inPos   Position to start reading data from.
      * @param inAvail Amount of bytes available from input for encoding.
      */
     void encode(final byte[] in, int inPos, final int inAvail) {
         if (eof) {
             return;
         }
         // inAvail < 0 is how we're informed of EOF in the underlying data we're
         // encoding.
         if (inAvail < 0) {
             eof = true;
             if (buffer == null || buffer.length - pos < encodeSize) {
                 resizeBuffer();
             }
             switch (modulus) {
             case 1:
                 buffer[pos++] = encodeTable[x >> 2 & MASK_6BITS];
                 buffer[pos++] = encodeTable[x << 4 & MASK_6BITS];
                 // URL-SAFE skips the padding to further reduce size.
                 if (encodeTable == STANDARD_ENCODE_TABLE) {
                     buffer[pos++] = PAD;
                     buffer[pos++] = PAD;
                 }
                 break;
 
             case 2:
                 buffer[pos++] = encodeTable[x >> 10 & MASK_6BITS];
                 buffer[pos++] = encodeTable[x >> 4 & MASK_6BITS];
                 buffer[pos++] = encodeTable[x << 2 & MASK_6BITS];
                 // URL-SAFE skips the padding to further reduce size.
                 if (encodeTable == STANDARD_ENCODE_TABLE) {
                     buffer[pos++] = PAD;
                 }
                 break;
             default:
                 break; // other values ignored
             }
             if (lineLength > 0 && pos > 0) {
                 System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
                 pos += lineSeparator.length;
             }
         } else {
             for (int i = 0; i < inAvail; i++) {
                 if (buffer == null || buffer.length - pos < encodeSize) {
                     resizeBuffer();
                 }
                 modulus = ++modulus % 3;
                 int b = in[inPos++];
                 if (b < 0) {
                     b += 256;
                 }
                 x = (x << 8) + b;
                 if (0 == modulus) {
                     buffer[pos++] = encodeTable[x >> 18 & MASK_6BITS];
                     buffer[pos++] = encodeTable[x >> 12 & MASK_6BITS];
                     buffer[pos++] = encodeTable[x >> 6 & MASK_6BITS];
                     buffer[pos++] = encodeTable[x & MASK_6BITS];
                     currentLinePos += 4;
                     if (lineLength > 0 && lineLength <= currentLinePos) {
                         System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
                         pos += lineSeparator.length;
                         currentLinePos = 0;
                     }
                 }
             }
         }
     }
 
     /**
      * Encodes a byte[] containing binary data, into a String containing characters in the Base64 alphabet.
      *
      * @param pArray a byte array containing binary data
      * @return A String containing only Base64 character data
      * @since 1.4
      */
     public String encodeToString(final byte[] pArray) {
         return newStringUtf8(encode(pArray));
     }
 
     private byte[] getBytesUtf8(final String pArray) {
         return pArray.getBytes(StandardCharsets.UTF_8);
     }
 
     int getLineLength() {
         return lineLength;
     }
 
     byte[] getLineSeparator() {
         return lineSeparator.clone();
     }
 
     /**
      * Returns true if this Base64 object has buffered data for reading.
      *
      * @return true if there is Base64 object still available for reading.
      */
     boolean hasData() {
         return this.buffer != null;
     }
 
     /**
      * Returns our current encode mode. True if we're URL-SAFE, false otherwise.
      *
      * @return true if we're in URL-SAFE mode, false otherwise.
      * @since 1.4
      */
     public boolean isUrlSafe() {
         return this.encodeTable == URL_SAFE_ENCODE_TABLE;
     }
 
     /**
      * Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail bytes. Returns how many bytes were actually
      * extracted.
      *
      * @param b      byte[] array to extract the buffered data into.
      * @param bPos   position in byte[] array to start extraction at.
      * @param bAvail amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
      * @return The number of bytes successfully extracted into the provided byte[] array.
      */
     int readResults(final byte[] b, final int bPos, final int bAvail) {
         if (buffer != null) {
             final int len = Math.min(avail(), bAvail);
             if (buffer != b) {
                 System.arraycopy(buffer, readPos, b, bPos, len);
                 readPos += len;
                 if (readPos >= pos) {
                     buffer = null;
                 }
             } else {
                 // Re-using the original consumer's output array is only
                 // allowed for one round.
                 buffer = null;
             }
             return len;
         }
         return eof ? -1 : 0;
     }
 
     /**
      * Resets this Base64 object to its initial newly constructed state.
      */
     private void reset() {
         buffer = null;
         pos = 0;
         readPos = 0;
         currentLinePos = 0;
         modulus = 0;
         eof = false;
     }
 
     // Getters for use in testing
 
     /** Doubles our buffer. */
     private void resizeBuffer() {
         if (buffer == null) {
             buffer = new byte[DEFAULT_BUFFER_SIZE];
             pos = 0;
             readPos = 0;
         } else {
             final byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
             System.arraycopy(buffer, 0, b, 0, buffer.length);
             buffer = b;
         }
     }
 
     /**
      * Sets the streaming buffer. This is a small optimization where we try to buffer directly to the consumer's output array for one round (if the consumer
      * calls this method first) instead of starting our own buffer.
      *
      * @param out      byte[] array to buffer directly to.
      * @param outPos   Position to start buffering into.
      * @param outAvail Amount of bytes available for direct buffering.
      */
     void setInitialBuffer(final byte[] out, final int outPos, final int outAvail) {
         // We can re-use consumer's original output array under
         // special circumstances, saving on some System.arraycopy().
         if (out != null && out.length == outAvail) {
             buffer = out;
             pos = outPos;
             readPos = outPos;
         }
     }
 }