<?php
/*
 * 
 * Trivially Enhanced CSS Converter, version 1.0
 * 
 * Copyright (c) 2007 Premek Brada <brada@kiv.zcu.cz>
 * Licenced under Creative Commons BY-NC-SA terms 
 * (http://creativecommons.org/licenses/by-nc-sa/3.0/).
 * 
 * Converts an enhanced CSS to the standard one. 
 * The enhancements handled are:
 * - // one-line comment
 * - @define CONSTANT value
 * - $CONSTANT expansion
 * 
 */


/* 
 * Example:
 */

$ESS_SOURCE = '

@define BG: white;  // the default background
@define CANVAS_WIDTH: 320px;

body { 
  background: $BG;
  // we do not use the canvas width here
  font-family: $FONT;
}
';

$CSS_OUTPUT = '

body {
  background: white;
  /* we do not use the canvas width here */
  font-family: /* ECSS: constant FONT not found */;
}
';

/*
 * Limitations:
 * - one-line comments within constant declarations (before ';') cause havoc
 * - constants are expanded even within comments
 */


/* ----- do not touch below ----------------------------------------- */

$CONST_IDENTIFIER = '[_A-Za-z][-_A-Za-z0-9]*';
// @define const value
$CONST_DEF = '/@define\s+('.$CONST_IDENTIFIER.')\s+(.*)\s*$/';
// { property: $const ; }
$CONST_USE = '/\$('.$CONST_IDENTIFIER.')/';
// one-line comment, C++ style
$ONE_LINE_COMMENT = '/(\/\/\s)(.*)$/';  // space required to prevent URL mistreatment


// no or special arg -> print usage and die
if (empty($_SERVER['QUERY_STRING']) || isset($_GET['help']) || isset($_GET['usage'])) {
  header("Content-type: text/plain");
  echo '

Trivially Enhanced CSS Converter, version 1.0

Copyright (c) 2007 Premek Brada <brada@kiv.zcu.cz>
Licenced under Creative Commons BY-NC-SA terms 
(http://creativecommons.org/licenses/by-nc-sa/3.0/).

Converts an enhanced CSS to the standard one. 
The enhancements handled are:
- // one-line comment
- @define CONSTANT value
- $CONSTANT expansion

Use the URI of the form 
  http://'.$_SERVER['SERVER_NAME'].$_SERVER['PHP_SELF'].'?f=http://your.domain/your-style.css
to run your CSS through the converter.

';
  die;
}

// which uri to parse
$CSS = isset($_GET['f']) ? $_GET['f'] : '';
if (!$CSS) {
  error_log("TECSS parser: No extended CSS to parse, exiting.");
  die;
}


$f = @fopen($CSS,"r");

if ($f) {
  header("Content-Type: text/css");
  $constants = array();
  while (!feof($f)) {
    $buffer = fgets($f, 4096);

    // create regular comment out of a one-liner
    if ( strstr($buffer,'//') ) {
      $res = preg_replace($ONE_LINE_COMMENT, '/* \2 */', trim($buffer));
      $buffer = $res."\n";
    }

    // (attempt to) expand a const 
    if ( strstr($buffer,'$') ) {
      preg_match($CONST_USE,$buffer, $matches);
      $constref = $matches[1];
      $is_const = array_key_exists( $constref, $constants );
      $constval = $is_const ? $constants[$constref] : '/* TECSS parser: constant '.$constref.' not found */';
      $res = preg_replace('/\$'.$constref.'/', $constval, $buffer);
      $buffer = $res;
    }

    // define a const
    if ( strstr($buffer,'@define') ) {
      $matches = array();
      $r = preg_match($CONST_DEF, trim($buffer), $matches);
      if ($r) {
        $constants[$matches[1]] = $matches[2];
      }
      $buffer = '';
    }

    echo $buffer;
   }
   fclose($f);
}
else {
  error_log("TECSS parser: Could not open CSS file $CSS to parse, exiting.");
}

?>