<?php
/****************************************************************************************\
**   JoomGallery 3                                                                      **
**   By: JoomGallery::ProjectTeam                                                       **
**   Copyright (C) 2008 - 2021  JoomGallery::ProjectTeam                                **
**   Based on: JoomGallery 1.0.0 by JoomGallery::ProjectTeam                            **
**   Released under GNU GPL Public License                                              **
**   License: http://www.gnu.org/copyleft/gpl.html or have a look                       **
**   at administrator/components/com_joomgallery/LICENSE.TXT                            **
\****************************************************************************************/

defined('_JEXEC') or die('Direct Access to this location is not allowed.');

/**
 * Create an animated GIF from multiple images
 *
 * @version   1.0
 * @link      https://github.com/Sybio/GifCreator
 * @author    Sybio (Clément Guillemain  / @Sybio01)
 * @license   http://opensource.org/licenses/gpl-license.php GNU Public License
 * @copyright Clément Guillemain, modified by JoomGallery::ProjectTeam
 */
class GifCreator
{
  /**
   * @var string The gif string source (old: this->GIF)
   */
  private $gif;

  /**
   * @var string Encoder version (old: this->VER)
   */
  private $version;

  /**
   * @var boolean Check the image is build or not (old: this->IMG)
   */
  private $imgBuilt;

  /**
   * @var array Frames string sources (old: this->BUF)
   */
  private $frameSources;

  /**
   * @var integer Gif loop (old: this->LOP)
   */
  private $loop;

  /**
   * @var integer Gif dis (old: this->DIS)
   */
  private $dis;

  /**
   * @var integer Gif color (old: this->COL)
   */
  private $colour;

  /**
   * @var array (old: this->ERR)
   */
  private $errors;

  // Methods
  // ===================================================================================

  /**
   * Constructor
   */
  public function __construct()
  {
    $this->reset();

    // Static data
    $this->version = 'GifCreator: v1.0.0';
    $this->errors  = array(
      'ERR00' => 'Does not supported function for only one image.',
      'ERR01' => 'Source is not a GIF image.',
      'ERR02' => 'You have to give resource image variables, image URL or image binary sources in $frames array.',
      'ERR03' => 'Does not make animation from animated GIF source.',
    );
  }

  /**
   * Create the GIF string (old: GIFEncoder)
   *
   * @param array   $dst_frames An array of frames and durations: frames can be file paths, resource image variables, binary sources or image URLs
   * @param integer $loop       Number of GIF loops before stopping animation (Set 0 to get an infinite loop)
   *
   * @return string The GIF string source
   */
  public function create($dst_frames = array(), $loop = 0)
  {
    if(!is_array($dst_frames))
    {
      throw new \Exception($this->version.': '.$this->errors['ERR00']);
    }

    $frames    = array();
    $durations = array();

    foreach($dst_frames as $key => $frame)
    {
        $frames[$key]    = $dst_frames[$key]['image'];
        $durations[$key] = $dst_frames[$key]['duration'];
    }

    $this->loop = ($loop > -1) ? $loop : 0;
    $this->dis  = 2;

    for($i = 0; $i < count($frames); $i++)
    {
      if(is_resource($frames[$i]))
      {
        // Resource var
        $resourceImg = $frames[$i];

        ob_start();
        imagegif($frames[$i]);
        $this->frameSources[] = ob_get_contents();
        ob_end_clean();
      }
      elseif(is_string($frames[$i]))
      {
        // File path or URL or Binary source code
        if(file_exists($frames[$i]) || filter_var($frames[$i], FILTER_VALIDATE_URL))
        {
          // File path
          $frames[$i] = file_get_contents($frames[$i]);
        }

        $resourceImg = imagecreatefromstring($frames[$i]);

        ob_start();
        imagegif($resourceImg);
        $this->frameSources[] = ob_get_contents();
        ob_end_clean();
      }
      else
      {
        // Fail
        throw new \Exception($this->version.': '.$this->errors['ERR02'].' ('.$mode.')');
      }

      if($i == 0)
      {
        $colour = imagecolortransparent($resourceImg);
      }

      if(substr($this->frameSources[$i], 0, 6) != 'GIF87a' && substr($this->frameSources[$i], 0, 6) != 'GIF89a')
      {
        throw new \Exception($this->version.': '.$i.' '.$this->errors['ERR01']);
      }

      for($j = (13 + 3 * (2 << (ord($this->frameSources[$i][10]) & 0x07))), $k = TRUE; $k; $j++)
      {
        switch($this->frameSources[$i][$j]) {
          case '!':
            if((substr($this->frameSources[$i], ($j + 3), 8)) == 'NETSCAPE')
            {
              throw new \Exception($this->version.': '.$this->errors['ERR03'].' ('.($i + 1).' source).');
            }
            break;
          case ';':
              $k = false;
            break;
        }
      }

      unset($resourceImg);
    }

    if(isset($colour))
    {
      $this->colour = $colour;
    }
    else
    {
      $red = $green = $blue = 0;
      $this->colour = ($red > -1 && $green > -1 && $blue > -1) ? ($red | ($green << 8) | ($blue << 16)) : -1;
    }

    $this->gifAddHeader();

    for($i = 0; $i < count($this->frameSources); $i++)
    {
      $this->addGifFrames($i, $durations[$i]);
    }

    $this->gifAddFooter();

    return $this->gif;
  }

  // Internals
  // ===================================================================================

  /**
   * Add the header gif string in its source (old: GIFAddHeader)
   */
  public function gifAddHeader()
  {
    $cmap = 0;

    if(ord($this->frameSources[0][10]) & 0x80)
    {
      $cmap = 3 * (2 << (ord($this->frameSources[0][10]) & 0x07));

      $this->gif .= substr($this->frameSources[0], 6, 7);
      $this->gif .= substr($this->frameSources[0], 13, $cmap);
      $this->gif .= "!\377\13NETSCAPE2.0\3\1".$this->encodeAsciiToChar($this->loop)."\0";
    }
  }

  /**
   * Add the frame sources to the GIF string (old: GIFAddFrames)
   *
   * @param integer $i
   * @param integer $d
   */
  public function addGifFrames($i, $d)
  {
    $Locals_str = 13 + 3 * (2 << (ord($this->frameSources[ $i ][10]) & 0x07));

    $Locals_end = strlen($this->frameSources[$i]) - $Locals_str - 1;
    $Locals_tmp = substr($this->frameSources[$i], $Locals_str, $Locals_end);

    $Global_len = 2 << (ord($this->frameSources[0 ][10]) & 0x07);
    $Locals_len = 2 << (ord($this->frameSources[$i][10]) & 0x07);

    $Global_rgb = substr($this->frameSources[0], 13, 3 * (2 << (ord($this->frameSources[0][10]) & 0x07)));
    $Locals_rgb = substr($this->frameSources[$i], 13, 3 * (2 << (ord($this->frameSources[$i][10]) & 0x07)));

    $Locals_ext = "!\xF9\x04".chr(($this->dis << 2) + 0).chr(($d >> 0 ) & 0xFF).chr(($d >> 8) & 0xFF)."\x0\x0";

    if($this->colour > -1 && ord($this->frameSources[$i][10]) & 0x80)
    {
      for($j = 0; $j < (2 << (ord($this->frameSources[$i][10]) & 0x07)); $j++)
      {
        if(    ord($Locals_rgb[3 * $j + 0]) == (($this->colour >> 16) & 0xFF)
            && ord($Locals_rgb[3 * $j + 1]) == (($this->colour >> 8) & 0xFF)
            && ord($Locals_rgb[3 * $j + 2]) == (($this->colour >> 0) & 0xFF)
          )
        {
          $Locals_ext = "!\xF9\x04".chr(($this->dis << 2) + 1).chr(($d >> 0) & 0xFF).chr(($d >> 8) & 0xFF).chr($j)."\x0";
          break;
        }
      }
    }

    switch($Locals_tmp[0])
    {
      case '!':
         $Locals_img = substr($Locals_tmp, 8, 10);
         $Locals_tmp = substr($Locals_tmp, 18, strlen($Locals_tmp) - 18);
        break;
      case ',':
         $Locals_img = substr($Locals_tmp, 0, 10);
         $Locals_tmp = substr($Locals_tmp, 10, strlen($Locals_tmp) - 10);
        break;
    }

    if(ord($this->frameSources[$i][10]) & 0x80 && $this->imgBuilt)
    {
      if($Global_len == $Locals_len)
      {
        if($this->gifBlockCompare($Global_rgb, $Locals_rgb, $Global_len))
        {
          $this->gif .= $Locals_ext.$Locals_img.$Locals_tmp;
        }
        else
        {
          $byte              = ord($Locals_img[9]);
          $byte             |= 0x80;
          $byte             &= 0xF8;
          $byte             |= (ord($this->frameSources[0][10]) & 0x07);
          $Locals_img[9]     = chr($byte);
          $this->gif        .= $Locals_ext.$Locals_img.$Locals_rgb.$Locals_tmp;
        }
      }
      else
      {
        $byte = ord($Locals_img[9]);
        $byte             |= 0x80;
        $byte             &= 0xF8;
        $byte             |= (ord($this->frameSources[$i][10]) & 0x07);
        $Locals_img[9]     = chr($byte);
        $this->gif        .= $Locals_ext.$Locals_img.$Locals_rgb.$Locals_tmp;
      }
    }
    else
    {
      $this->gif .= $Locals_ext.$Locals_img.$Locals_tmp;
    }

    $this->imgBuilt = true;
  }

  /**
   * Add the gif string footer char (old: GIFAddFooter)
   */
  public function gifAddFooter()
  {
    $this->gif .= ';';
  }

  /**
   * Compare two block and return the version (old: GIFBlockCompare)
   *
   * @param string  $globalBlock
   * @param string  $localBlock
   * @param integer $length
   *
   * @return integer
   */
  public function gifBlockCompare($globalBlock, $localBlock, $length)
  {
    for($i = 0; $i < $length; $i++)
    {
      if(    $globalBlock[3 * $i + 0] != $localBlock[3 * $i + 0]
          || $globalBlock[3 * $i + 1] != $localBlock[3 * $i + 1]
          || $globalBlock[3 * $i + 2] != $localBlock[3 * $i + 2]
        )
      {
        return 0;
      }
    }

    return 1;
  }

  /**
   * Encode an ASCII char into a string char (old: GIFWord)
   *
   * @param integer $char ASCII char
   *
   * @return string
   */
  public function encodeAsciiToChar($char)
  {
    return(chr($char & 0xFF).chr(($char >> 8) & 0xFF));
  }

  /**
   * Reset and clean the current object
   */
  public function reset()
  {
    $this->frameSources;
    $this->gif      = 'GIF89a'; // The GIF header
    $this->imgBuilt = false;
    $this->loop     = 0;
    $this->dis      = 2;
    $this->colour   = -1;
  }

  // Getter / Setter
  // ===================================================================================

  /**
   * Get the final GIF image string (old: GetAnimation)
   *
   * @return string
   */
  public function getGif()
  {
    return $this->gif;
  }
}