<?

function linkToMathImage ( $tex, $outputhash )
{
	global $wgMathPath;
	return "<img src=\"".$wgMathPath."/".$outputhash.".png\" alt=\"".wfEscapeHTML($tex)."\">";
}

function renderMath( $tex )
{
    global $wgUser, $wgMathDirectory, $wgTmpDirectory, $wgInputEncoding;
    $mf   = wfMsg( "math_failure" );
    $munk = wfMsg( "math_unknown_error" );

    $fname = "renderMath";

    $math = $wgUser->getOption("math");
    if ($math == 3)
	return ('$ '.wfEscapeHTML($tex).' $');

    $md5 = md5($tex);
    $md5_sql = mysql_escape_string(pack("H32", $md5));
    if ($math == 0)
	$sql = "SELECT math_outputhash FROM math WHERE math_inputhash = '".$md5_sql."'";
    else
	$sql = "SELECT math_outputhash,math_html_conservativeness,math_html FROM math WHERE math_inputhash = '".$md5_sql."'";

    $res = wfQuery( $sql, DB_READ, $fname );

	if( $rpage = wfFetchObject ( $res ) ) {
		$outputhash = unpack( "H32md5", $rpage->math_outputhash . "                " );
		$outputhash = $outputhash ['md5'];
		if( file_exists( "$wgMathDirectory/$outputhash.png" ) ) {
			if (($math == 0) || ($rpage->math_html == '') || (($math == 1) && ($rpage->math_html_conservativeness != 2)) || (($math == 4) && ($rpage->math_html_conservativeness == 0)))
			    return linkToMathImage ( $tex, $outputhash );
			else
		    	return $rpage->math_html;
		}
	}
	
	$cmd = "./math/texvc ".escapeshellarg($wgTmpDirectory)." ".
		      escapeshellarg($wgMathDirectory)." ".escapeshellarg($tex)." ".escapeshellarg($wgInputEncoding);
	$contents = `$cmd`;

	if (strlen($contents) == 0)
	    return "<b>".$mf." (".$munk."): ".wfEscapeHTML($tex)."</b>";
	$retval = substr ($contents, 0, 1);
	if (($retval == "C") || ($retval == "M") || ($retval == "L")) {
	    if ($retval == "C")
		$conservativeness = 2;
	    else if ($retval == "M")
		$conservativeness = 1;
	    else
		$conservativeness = 0;
	    $outdata = substr ($contents, 33);

	    $i = strpos($outdata, "\000");

	    $outhtml = substr($outdata, 0, $i);
	    $mathml = substr($outdata, $i+1);

	    $sql_html = "'".mysql_escape_string($outhtml)."'";
	    $sql_mathml = "'".mysql_escape_string($mathml)."'";
	} else if (($retval == "c") || ($retval == "m") || ($retval == "l"))  {
	    $outhtml = substr ($contents, 33);
	    if ($retval == "c")
		$conservativeness = 2;
	    else if ($retval == "m")
		$conservativeness = 1;
	    else
		$conservativeness = 0;
	    $sql_html = "'".mysql_escape_string($outhtml)."'";
	    $mathml = '';
	    $sql_mathml = 'NULL';
	} else if ($retval == "X") {
	    $outhtml = '';
	    $mathml = substr ($contents, 33);
	    $sql_html = 'NULL';
	    $sql_mathml = "'".mysql_escape_string($mathml)."'";
	    $conservativeness = 0;
	} else if ($retval == "+") {
	    $outhtml = '';
	    $mathml = '';
	    $sql_html = 'NULL';
	    $sql_mathml = 'NULL';
	    $conservativeness = 0;
	} else {
	    if ($retval == "E")
		$errmsg = wfMsg( "math_lexing_error" );
	    else if ($retval == "S")
		$errmsg = wfMsg( "math_syntax_error" );
	    else if ($retval == "F")
		$errmsg = wfMsg( "math_unknown_function" );
	    else
		$errmsg = $munk;
	    return "<h3>".$mf." (".$errmsg.substr($contents, 1)."): ".wfEscapeHTML($tex)."</h3>";
	}

	$outmd5 = substr ($contents, 1, 32);
	if (!preg_match("/^[a-f0-9]{32}$/", $outmd5))
	    return "<b>".$mf." (".$munk."): ".wfEscapeHTML($tex)."</b>";

	$outmd5_sql = mysql_escape_string(pack("H32", $outmd5));

	$sql = "REPLACE INTO math VALUES ('".$md5_sql."', '".$outmd5_sql."', ".$conservativeness.", ".$sql_html.", ".$sql_mathml.")";
	
	$res = wfQuery( $sql, DB_READ, $fname );
	# we don't really care if it fails

	if (($math == 0) || ($rpage->math_html == '') || (($math == 1) && ($conservativeness != 2)) || (($math == 4) && ($conservativeness == 0)))
	    return linkToMathImage($tex, $outmd5);
	else
	    return $outhtml;
}

?>