<?php

/*
 * This file is part of SwiftMailer.
 * (c) 2004-2009 Chris Corbyn
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

//@require 'Swift/Encoder.php';
//@require 'Swift/CharacterStream.php';

/**
 * Handles Quoted Printable (QP) Encoding in Swift Mailer.
 * Possibly the most accurate RFC 2045 QP implementation found in PHP.
 * @package Swift
 * @subpackage Encoder
 * @author Chris Corbyn
 */
class Swift_Encoder_QpEncoder implements Swift_Encoder
{

  /**
   * The CharacterStream used for reading characters (as opposed to bytes).
   * @var Swift_CharacterStream
   * @access protected
   */
  protected $_charStream;

  /**
   * A filter used if input should be canonicalized.
   * @var Swift_StreamFilter
   * @access protected
   */
  protected $_filter;

  /**
   * Pre-computed QP for HUGE optmization.
   * @var string[]
   * @access protected
   */
  protected static $_qpMap = array(
    0   => '=00', 1   => '=01', 2   => '=02', 3   => '=03', 4   => '=04',
    5   => '=05', 6   => '=06', 7   => '=07', 8   => '=08', 9   => '=09',
    10  => '=0A', 11  => '=0B', 12  => '=0C', 13  => '=0D', 14  => '=0E',
    15  => '=0F', 16  => '=10', 17  => '=11', 18  => '=12', 19  => '=13',
    20  => '=14', 21  => '=15', 22  => '=16', 23  => '=17', 24  => '=18',
    25  => '=19', 26  => '=1A', 27  => '=1B', 28  => '=1C', 29  => '=1D',
    30  => '=1E', 31  => '=1F', 32  => '=20', 33  => '=21', 34  => '=22',
    35  => '=23', 36  => '=24', 37  => '=25', 38  => '=26', 39  => '=27',
    40  => '=28', 41  => '=29', 42  => '=2A', 43  => '=2B', 44  => '=2C',
    45  => '=2D', 46  => '=2E', 47  => '=2F', 48  => '=30', 49  => '=31',
    50  => '=32', 51  => '=33', 52  => '=34', 53  => '=35', 54  => '=36',
    55  => '=37', 56  => '=38', 57  => '=39', 58  => '=3A', 59  => '=3B',
    60  => '=3C', 61  => '=3D', 62  => '=3E', 63  => '=3F', 64  => '=40',
    65  => '=41', 66  => '=42', 67  => '=43', 68  => '=44', 69  => '=45',
    70  => '=46', 71  => '=47', 72  => '=48', 73  => '=49', 74  => '=4A',
    75  => '=4B', 76  => '=4C', 77  => '=4D', 78  => '=4E', 79  => '=4F',
    80  => '=50', 81  => '=51', 82  => '=52', 83  => '=53', 84  => '=54',
    85  => '=55', 86  => '=56', 87  => '=57', 88  => '=58', 89  => '=59',
    90  => '=5A', 91  => '=5B', 92  => '=5C', 93  => '=5D', 94  => '=5E',
    95  => '=5F', 96  => '=60', 97  => '=61', 98  => '=62', 99  => '=63',
    100 => '=64', 101 => '=65', 102 => '=66', 103 => '=67', 104 => '=68',
    105 => '=69', 106 => '=6A', 107 => '=6B', 108 => '=6C', 109 => '=6D',
    110 => '=6E', 111 => '=6F', 112 => '=70', 113 => '=71', 114 => '=72',
    115 => '=73', 116 => '=74', 117 => '=75', 118 => '=76', 119 => '=77',
    120 => '=78', 121 => '=79', 122 => '=7A', 123 => '=7B', 124 => '=7C',
    125 => '=7D', 126 => '=7E', 127 => '=7F', 128 => '=80', 129 => '=81',
    130 => '=82', 131 => '=83', 132 => '=84', 133 => '=85', 134 => '=86',
    135 => '=87', 136 => '=88', 137 => '=89', 138 => '=8A', 139 => '=8B',
    140 => '=8C', 141 => '=8D', 142 => '=8E', 143 => '=8F', 144 => '=90',
    145 => '=91', 146 => '=92', 147 => '=93', 148 => '=94', 149 => '=95',
    150 => '=96', 151 => '=97', 152 => '=98', 153 => '=99', 154 => '=9A',
    155 => '=9B', 156 => '=9C', 157 => '=9D', 158 => '=9E', 159 => '=9F',
    160 => '=A0', 161 => '=A1', 162 => '=A2', 163 => '=A3', 164 => '=A4',
    165 => '=A5', 166 => '=A6', 167 => '=A7', 168 => '=A8', 169 => '=A9',
    170 => '=AA', 171 => '=AB', 172 => '=AC', 173 => '=AD', 174 => '=AE',
    175 => '=AF', 176 => '=B0', 177 => '=B1', 178 => '=B2', 179 => '=B3',
    180 => '=B4', 181 => '=B5', 182 => '=B6', 183 => '=B7', 184 => '=B8',
    185 => '=B9', 186 => '=BA', 187 => '=BB', 188 => '=BC', 189 => '=BD',
    190 => '=BE', 191 => '=BF', 192 => '=C0', 193 => '=C1', 194 => '=C2',
    195 => '=C3', 196 => '=C4', 197 => '=C5', 198 => '=C6', 199 => '=C7',
    200 => '=C8', 201 => '=C9', 202 => '=CA', 203 => '=CB', 204 => '=CC',
    205 => '=CD', 206 => '=CE', 207 => '=CF', 208 => '=D0', 209 => '=D1',
    210 => '=D2', 211 => '=D3', 212 => '=D4', 213 => '=D5', 214 => '=D6',
    215 => '=D7', 216 => '=D8', 217 => '=D9', 218 => '=DA', 219 => '=DB',
    220 => '=DC', 221 => '=DD', 222 => '=DE', 223 => '=DF', 224 => '=E0',
    225 => '=E1', 226 => '=E2', 227 => '=E3', 228 => '=E4', 229 => '=E5',
    230 => '=E6', 231 => '=E7', 232 => '=E8', 233 => '=E9', 234 => '=EA',
    235 => '=EB', 236 => '=EC', 237 => '=ED', 238 => '=EE', 239 => '=EF',
    240 => '=F0', 241 => '=F1', 242 => '=F2', 243 => '=F3', 244 => '=F4',
    245 => '=F5', 246 => '=F6', 247 => '=F7', 248 => '=F8', 249 => '=F9',
    250 => '=FA', 251 => '=FB', 252 => '=FC', 253 => '=FD', 254 => '=FE',
    255 => '=FF'
    );

  /**
   * A map of non-encoded ascii characters.
   * @var string[]
   * @access protected
   */
  protected static $_safeMap = array();

  /**
   * Creates a new QpEncoder for the given CharacterStream.
   * @param Swift_CharacterStream $charStream to use for reading characters
   * @param Swift_StreamFilter $filter if input should be canonicalized
   */
  public function __construct(Swift_CharacterStream $charStream,
    Swift_StreamFilter $filter = null)
  {
    $this->_charStream = $charStream;
    if (empty(self::$_safeMap))
    {
      foreach (array_merge(
        array(0x09, 0x20), range(0x21, 0x3C), range(0x3E, 0x7E)) as $byte)
      {
        self::$_safeMap[$byte] = chr($byte);
      }
    }
    $this->_filter = $filter;
  }

  /**
   * Takes an unencoded string and produces a QP encoded string from it.
   * QP encoded strings have a maximum line length of 76 characters.
   * If the first line needs to be shorter, indicate the difference with
   * $firstLineOffset.
   * @param string $string to encode
   * @param int $firstLineOffset, optional
   * @param int $maxLineLength, optional, 0 indicates the default of 76 chars
   * @return string
   */
  public function encodeString($string, $firstLineOffset = 0,
    $maxLineLength = 0)
  {
    if ($maxLineLength > 76 || $maxLineLength <= 0)
    {
      $maxLineLength = 76;
    }

    $thisLineLength = $maxLineLength - $firstLineOffset;

    $lines = array();
    $lNo = 0;
    $lines[$lNo] = '';
    $currentLine =& $lines[$lNo++];
    $size=$lineLen=0;

    $this->_charStream->flushContents();
    $this->_charStream->importString($string);

    //Fetching more than 4 chars at one is slower, as is fetching fewer bytes
    // Conveniently 4 chars is the UTF-8 safe number since UTF-8 has up to 6
    // bytes per char and (6 * 4 * 3 = 72 chars per line) * =NN is 3 bytes
    while (false !== $bytes = $this->_nextSequence())
    {
      //If we're filtering the input
      if (isset($this->_filter))
      {
        //If we can't filter because we need more bytes
        while ($this->_filter->shouldBuffer($bytes))
        {
          //Then collect bytes into the buffer
          if (false === $moreBytes = $this->_nextSequence(1))
          {
            break;
          }

          foreach ($moreBytes as $b)
          {
            $bytes[] = $b;
          }
        }
        //And filter them
        $bytes = $this->_filter->filter($bytes);
      }

      $enc = $this->_encodeByteSequence($bytes, $size);
      if ($currentLine && $lineLen+$size >= $thisLineLength)
      {
        $lines[$lNo] = '';
        $currentLine =& $lines[$lNo++];
        $thisLineLength = $maxLineLength;
        $lineLen=0;
      }
      $lineLen+=$size;
      $currentLine .= $enc;
    }

    return $this->_standardize(implode("=\r\n", $lines));
  }

  /**
   * Updates the charset used.
   * @param string $charset
   */
  public function charsetChanged($charset)
  {
    $this->_charStream->setCharacterSet($charset);
  }

  // -- Protected methods

  /**
   * Encode the given byte array into a verbatim QP form.
   * @param int[] $bytes
   * @return string
   * @access protected
   */
  protected function _encodeByteSequence(array $bytes, &$size)
  {
    $ret = '';
    $size=0;
    foreach ($bytes as $b)
    {
      if (isset(self::$_safeMap[$b]))
      {
        $ret .= self::$_safeMap[$b];
        ++$size;
      }
      else
      {
        $ret .= self::$_qpMap[$b];
        $size+=3;
      }
    }
    return $ret;
  }

  /**
   * Get the next sequence of bytes to read from the char stream.
   * @param int $size number of bytes to read
   * @return int[]
   * @access protected
   */
  protected function _nextSequence($size = 4)
  {
    return $this->_charStream->readBytes($size);
  }

  /**
   * Make sure CRLF is correct and HT/SPACE are in valid places.
   * @param string $string
   * @return string
   * @access protected
   */
  protected function _standardize($string)
  {
    $string = str_replace(array("\t=0D=0A", " =0D=0A", "=0D=0A"),
      array("=09\r\n", "=20\r\n", "\r\n"), $string
      );
    switch ($end = ord(substr($string, -1)))
    {
      case 0x09:
      case 0x20:
        $string = substr_replace($string, self::$_qpMap[$end], -1);
    }
    return $string;
  }

}
