<?php
/**
 * Contain everything related to <math> </math> parsing
 * @package MediaWiki
 */

/**
 * Takes LaTeX fragments, sends them to a helper program (texvc) for rendering
 * to rasterized PNG and HTML and MathML approximations. An appropriate
 * rendering form is picked and returned.
 *
 * by Tomasz Wegrzanowski, with additions by Brion Vibber (2003, 2004)
 *
 * @package MediaWiki
 */

$wgTexvc = '/usr/bin/texvc';
#$wgMathPath='fileadmin/math';
#$wgMathDirectory=$PATH_site.$wgMathPath;
#$wgTmpDirectory=$wgMathDirectory.'/tmp';
#$wgInputEncoding='utf-8';

class     MathRenderer {
    var $mode = MW_MATH_MODERN;
    var $tex = '';
    var $inputhash = '';
    var $hash = '';
    var $html = '';
    var $mathml = '';
    var $conservativeness = 0;

    function MathRenderer( $tex ) {
        $this->tex = $tex;
     }

    function setOutputMode( $mode ) {
        $this->mode = $mode;
    }

    function render() {
        global $wgMathDirectory, $wgTmpDirectory, $wgInputEncoding;
        global $wgTexvc;
        $fname = 'MathRenderer::render';

        if( $this->mode == MW_MATH_SOURCE ) {
            # No need to render or parse anything more!
            return ('$ '.htmlspecialchars( $this->tex ).' $');
        }

        if( !$this->_recall() ) {
            # Ensure that the temp and output directories are available before continuing...
            if( !file_exists( $wgMathDirectory ) ) {
                if( !@mkdir( $wgMathDirectory ) ) {
                    return $this->_error( 'math_bad_output' );
                }
            } elseif( !is_dir( $wgMathDirectory ) || !is_writable( $wgMathDirectory ) ) {
                return $this->_error( 'math_bad_output' );
            }
            if( !file_exists( $wgTmpDirectory ) ) {
                if( !@mkdir( $wgTmpDirectory ) ) {
                    return $this->_error( 'math_bad_tmpdir' );
                }
            } elseif( !is_dir( $wgTmpDirectory ) || !is_writable( $wgTmpDirectory ) ) {
                return $this->_error( 'math_bad_tmpdir' );
            }

            if( function_exists( 'is_executable' ) && !is_executable( $wgTexvc ) ) {
                return $this->_error( 'math_notexvc' );
            }
            $cmd = $wgTexvc . ' ' .
                    escapeshellarg( $wgTmpDirectory ).' '.
                    escapeshellarg( $wgMathDirectory ).' '.
                    escapeshellarg( $this->tex ).' '.
                    escapeshellarg( $wgInputEncoding );

            #if ( wfIsWindows() ) {
            #    # Invoke it within cygwin sh, because texvc expects sh features in its default shell
            #    $cmd = 'sh -c ' . wfEscapeShellArg( $cmd );
            #}

            #wfDebug( "TeX: $cmd\n" );
            $contents = `$cmd`;
            #wfDebug( "TeX output:\n $contents\n---\n" );

            if (strlen($contents) == 0) {
                return $this->_error( 'math_unknown_error' );
            }

            $retval = substr ($contents, 0, 1);
            if (($retval == 'C') || ($retval == 'M') || ($retval == 'L')) {
                if ($retval == 'C')
                    $this->conservativeness = 2;
                else if ($retval == 'M')
                    $this->conservativeness = 1;
                else
                    $this->conservativeness = 0;
                $outdata = substr ($contents, 33);

                $i = strpos($outdata, "\000");

                $this->html = substr($outdata, 0, $i);
                $this->mathml = substr($outdata, $i+1);
            } else if (($retval == 'c') || ($retval == 'm') || ($retval == 'l'))  {
                $this->html = substr ($contents, 33);
                if ($retval == 'c')
                    $this->conservativeness = 2;
                else if ($retval == 'm')
                    $this->conservativeness = 1;
                else
                    $this->conservativeness = 0;
                $this->mathml = NULL;
            } else if ($retval == 'X') {
                $this->html = NULL;
                $this->mathml = substr ($contents, 33);
                $this->conservativeness = 0;
            } else if ($retval == '+') {
                $this->html = NULL;
                $this->mathml = NULL;
                $this->conservativeness = 0;
            } else {
                $errbit = htmlspecialchars( substr($contents, 1) );
                switch( $retval ) {
                    case 'E': return $this->_error( 'math_lexing_error', $errbit );
                    case 'S': return $this->_error( 'math_syntax_error', $errbit );
                    case 'F': return $this->_error( 'math_unknown_function', $errbit );
                    default:  return $this->_error( 'math_unknown_error', $errbit );
                }
            }

            $this->hash = substr ($contents, 1, 32);
            if (!preg_match("/^[a-f0-9]{32}$/", $this->hash)) {
                return $this->_error( 'math_unknown_error' );
            }

            if( !file_exists( "$wgMathDirectory/{$this->hash}.png" ) ) {
                return $this->_error( 'math_image_error' );
            }

            # Now save it back to the DB:
            #if ( !wfReadOnly() ) {
            #    $outmd5_sql = pack('H32', $this->hash);

            #    $md5_sql = pack('H32', $this->md5); # Binary packed, not hex

            #    $dbw =& wfGetDB( DB_MASTER );
            #    $dbw->replace( 'math', array( 'math_inputhash' ),
            #      array(
            #        'math_inputhash' => $md5_sql,
            #        'math_outputhash' => $outmd5_sql,
            #        'math_html_conservativeness' => $this->conservativeness,
            #        'math_html' => $this->html,
            #        'math_mathml' => $this->mathml,
            #      ), $fname, array( 'IGNORE' )
            #    );
            #}

        }

        return $this->_doRender();
    }

    function _error( $msg, $append = '' ) {
        $mf   = htmlspecialchars('math_failure'  );
        $munk = htmlspecialchars( 'math_unknown_error'  );
        $errmsg = htmlspecialchars(  $msg );
        $source = htmlspecialchars($this->tex);
        return "<strong class='error'>$mf ($errmsg$append): $source</strong>\n";
    }

    function _recall() {
        global $wgMathDirectory;
        $fname = 'MathRenderer::_recall';

        #$this->md5 = md5( $this->tex );
        #$dbr =& wfGetDB( DB_SLAVE );
        #$rpage = $dbr->selectRow( 'math',
        #    array( 'math_outputhash','math_html_conservativeness','math_html','math_mathml' ),
        #    array( 'math_inputhash' => pack("H32", $this->md5)), # Binary packed, not hex
        #    $fname
        #);

        #if( $rpage !== false ) {
        #    # Tailing 0x20s can get dropped by the database, add it back on if necessary:
        #    $xhash = unpack( 'H32md5', $rpage->math_outputhash . "                " );
        #    $this->hash = $xhash ['md5'];

        #    $this->conservativeness = $rpage->math_html_conservativeness;
        #    $this->html = $rpage->math_html;
        #    $this->mathml = $rpage->math_mathml;

        #    if( file_exists( "$wgMathDirectory/{$this->hash}.png" ) ) {
        #        return true;
        #    }
        #}

        # Missing from the database and/or the render cache
        return false;
    }

    /**
     * Select among PNG, HTML, or MathML output depending on
     */
    function _doRender() {
        if( $this->mode == MW_MATH_MATHML && $this->mathml != '' ) {
            return "<math xmlns='http://www.w3.org/1998/Math/MathML'>{$this->mathml}</math>";
        }
        if (($this->mode == MW_MATH_PNG) || ($this->html == '') ||
           (($this->mode == MW_MATH_SIMPLE) && ($this->conservativeness != 2)) ||
           (($this->mode == MW_MATH_MODERN || $this->mode == MW_MATH_MATHML) && ($this->conservativeness == 0))) {
            return $this->_linkToMathImage();
        } else {
            return '<span class="texhtml">'.$this->html.'</span>';
        }
    }

    function _linkToMathImage() {
        global $wgMathPath;
        $url = htmlspecialchars( "$wgMathPath/{$this->hash}.png" );
        $alt = trim(str_replace("\n", ' ', htmlspecialchars( $this->tex )));
        return "<img class='tex' src=\"$url\" alt=\"$alt\" />";
    }


        function _getHashPath() {
                global $wgMathDirectory;
                $path = $wgMathDirectory .'/'. substr($this->hash, 0, 1)
                                        .'/'. substr($this->hash, 1, 1)
                                        .'/'. substr($this->hash, 2, 1);
                wfDebug( "TeX: getHashPath, hash is: $this->hash, path is: $path\n" );
                return $path;
        }

        public static function renderMath( $tex ) {
                global $wgUser;
                $math = new MathRenderer( $tex );
                $math->setOutputMode( $wgUser->getOption('math'));
                return $math->render();
        }
}
?>