<?php

class BitStream {
          private $_data;
          private $_byte_offset;
          private $_bit_offset;
      function __construct($data) {
              $this->_data = $data;
          $this->_byte_offset = 0;
          $this->_bit_offset  = 0;
      }
      function getBits($bit_width) {
        $value = 0;
        for($i=0; $i< $bit_width; $i++) {
          $value <<= 1;
          $value |= $this->getBit();
        }
        return $value;
      }
      function getBit() {
              $shift_width = 7 - $this->_bit_offset;
          $bit = (ord($this->_data{$this->_byte_offset}) >> $shift_width) & 0x1;
          $this->_bit_offset ++;
          if ($this->_bit_offset == 8) {
            $this->_byte_offset ++;
            $this->_bit_offset = 0;
          }
          return $bit;
      }
      function getBytesLE($bytes) {
              $this->align();
          $value = 0;
          for ($i=0 ; $i<$bytes ; $i++) {
            $value >>= 8;
            $value |= $this->getByte() << (8 * ($bytes - 1));
          }
          return $value;
      }
      function getByte() {
              $this->align();
              $byte = ord($this->_data{$this->_byte_offset});
          $this->_byte_offset ++;
          return $byte;
      }
      function align() {
              if ($this->_bit_offset > 0) {
                  $this->_byte_offset ++;
              $this->_bit_offset = 0;
          }
      }
      function getByteOffset() {
              return $this->_byte_offset;
      }
      function setByteOffset($offset) {
              return $this->_byte_offset = $offset;
      }

}

class SWFEditor {
        private $_header = array();
    private $_block_list = array();
        function __construct($filename) {
                $fp = fopen($filename, 'rb');
        $magic = fread($fp, 3);
        $version = ord(fread($fp, 1));
        $len_le = fread($fp, 4); // little endian
        $len_a = unpack('V', $len_le);
        $filelength = $len_a[1];
                $this->_header['magic'] = $magic;
                $this->_header['version'] = $version;
        $this->_header['filelength'] = $filelength;
        if ($magic == 'FWS') {
                $movie_and_body = fread($fp, $filelength);
        } elseif ($magic == 'CWS') {
                $movie_and_body = gzuncompress(fread($fp, $filelength));
        } else {
                return ;
        }
        
        list($movie_header, $movie_header_length) =
                $this->get_movie_header($movie_and_body);
        $this->_header['movie_header'] = $movie_header;
        // 
        $offset = $movie_header_length;
        while(true) {
                list($block, $block_length) = $this->get_block($movie_and_body, $offset);
            $this->_block_list [] = $block;
            if ($block['tag'] == 0) {
                    break;
            }
            $offset += $block_length;
        }
        
    }
    function get_movie_header($movie_and_body) {
      $movie_header = array();
      $bs = new BitStream($movie_and_body);
      $movie_align = $bs->getBits(5);
      $movie_header['align'] = $movie_align;
      $movie_header['x_min'] = $bs->getBits($movie_align);
      $movie_header['x_max'] = $bs->getBits($movie_align);
      $movie_header['y_min'] = $bs->getBits($movie_align);
      $movie_header['y_max'] = $bs->getBits($movie_align);
      $bs->align();
      $movie_header['frame_rate_decimal'] = $bs->getByte();
      $movie_header['frame_rate_integer'] = $bs->getByte();
      $movie_header['frame_rate_count'] = $bs->getBytesLE(2);
      $movie_header_length = $bs->getByteOffset();
      return array($movie_header, $movie_header_length);
    }
    function get_block($data, $offset) {
      $first_offset = $offset;
      $bs = new BitStream($data);
      $bs->setByteOffset($offset);
      $tag_and_length =$bs->getBytesLE(2); // important
      $tag = $tag_and_length >> 6;
      $length = $tag_and_length & 0x3f;
      if ($length == 0x3f) {
              $length = $bs->getBytesLE(4);
      }
      $data_offset = $bs->getByteOffset();
      $block = array();
      $block['tag'] = $tag;
      $block['length'] = $length;
      $block['rawdata'] = substr($data, $data_offset, $length);
      return array($block, $data_offset + $length - $first_offset);
    }
    private $_tagNameTable = array(0 => 'End',
                       1 => 'ShowFrame',
                       2 => 'DefineShape',
                       6 => 'DefineBitsJPEG',
                       8 => 'JPEGTables',
                       9 => 'SetBackgroundColor',
                       12 =>'DoAction',
                       26 =>'PlaceObject2'
                       );

    function getTagName($tag) {
            if (isset($this->_tagNameTable[$tag])) {
                return $this->_tagNameTable[$tag];
        }
        return $tag;
    }
    function dump() {
                var_dump($this->_header);
        foreach ($this->_block_list as $block) {
                print 'tag=' . $this->getTagName($block['tag']) . ' length=' . $block['length'] . "\n";
        }
    }
}