
<?
    # A PHP/XSLT based RDFS Schema browser/explorer.

    # (c) 2003 Morten Frederiksen
    # License: http://www.gnu.org/licenses/gpl

    $path=$_SERVER['DOCUMENT_ROOT'].$_SERVER['REQUEST_URI'];
    $path=preg_replace('|\?.+|','',$path);
    $rdfs2xhtml='rdfs-xhtml.xsl';
    $metadata=join('',@file('rdfs.rdf'));
    $xhtml='';
    $schema='';

    # Create XSLT parser.
    $xslt=xslt_create();
    xslt_set_error_handler($xslt,'xsltError');
    $xslterror='';

    if (preg_match('|^http:|',@$_GET['rdfs']))
    {
        # Try to retrieve schema.
        $rdfs=$_GET['rdfs'];
        $rdfs=preg_replace('|#.+$|','#',$rdfs);
        $schema=@file($rdfs);
        if ($schema)
        {
            # Extract RDF.
            $schema=@join('',$schema);
            # Try to convert to XHTML.
            if (!($xhtml=@xslt_process($xslt,'arg:/_xml','arg:/_xsl',NULL,
                    array('/_xsl'=>join('',file($rdfs2xhtml)),'/_xml'=>$schema),
                    array('uri'=>$rdfs,'language'=>'en','embed'=>'true'))))
            {
                # Try to extract inline RDF (assuming UTF-8, no external entities).
                $schema=preg_replace('|^.*(<\w+:RDF.+</\w+:RDF>).*$|s','$1',$schema);
                if (!($xhtml=@xslt_process($xslt,'arg:/_xml','arg:/_xsl',NULL,
                        array('/_xsl'=>join('',file($rdfs2xhtml)),'/_xml'=>$schema),
                        array('uri'=>$rdfs,'language'=>'en','embed'=>'true'))))
                    # Flag un-parsable RDF Schema.
                    $xhtml='<h1>Error</h1><p>Unable to parse RDF Schema ('.$rdfs.').</p><p>'.$xslterror.'</p>';
            };
        }
        else
            # Flag non-retrievable RDF Schema.
            $xhtml='<h1>Error</h1><p>Unable to find or read RDF Schema ('.$rdfs.').</p>';
    }
    elseif (@$_GET['rdfs']!='')
        $xhtml='<h1>Error</h1><p>Invalid request ('.$_GET['rdfs'].'), only absolute HTTP URLs allowed.</p>';

    if ($xhtml=='')
    {
        # Create service form.
        if (!($xhtml=@xslt_process($xslt,'arg:/_xml','arg:/_xsl',NULL,
                array('/_xsl'=>join('',@file('services-xhtml.xsl',1)),'/_xml'=>$metadata),
                array('path'=>$path))))
            $xhtml='<p>Unable to parse metadata.</p><p>'.$xslterror.'</p>';
    };

    # Transform metadata into header and footer.
    if (!($metahead=@xslt_process($xslt,'arg:/_xml','arg:/_xsl',NULL,
            array('/_xsl'=>join('',@file('metahead.xsl',1)),'/_xml'=>$metadata))))
        $metahead='<title>Parse error: '.$xslterror.'</title>';
    elseif (!($metatop=@xslt_process($xslt,'arg:/_xml','arg:/_xsl',NULL,
            array('/_xsl'=>join('',@file('metatop.xsl',1)),'/_xml'=>$metadata),
            array('path'=>$path,'uri'=>$rdfs))))
        $metatop='<p>Unable to parse metadata.</p><p>'.$xslterror.'</p>';
    elseif (!($metafoot=@xslt_process($xslt,'arg:/_xml','arg:/_xsl',NULL,
            array('/_xsl'=>join('',@file('metafoot.xsl',1)),'/_xml'=>$metadata))))
        $metafoot='<p>Unable to parse metadata.</p><p>'.$xslterror.'</p>';

    # Display page.
    print('<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
'.$metahead.'
    <style type="text/css">
table.schema { width: 100% }
.schema h4 { margin: 0 }
.schema h3 { padding-top: 1em }
.schema th { text-align: left; vertical-align: top }
.schema td { vertical-align: top }
.schema .details th { text-align: right; font-size: 80%; font-style: italic; vertical-align: top }
.schema .details td { font-size: 80% }
.schema dl { margin: 0; padding: 0 }
.schema dt { margin: 0; padding: 0; font-style: italic }
.schema dd { margin: 0 1em; padding: 0 }
    </style>
</head>
<body>
'.$metatop.'
  <div style="padding: 1em">
'.$xhtml.'
  </div>
'.$metafoot.'
</body>
<!--
'.str_replace('--','- -',$schema).'
-->
</html>');

    function xsltError($x,$e,$l,$f)
    {
        global $xslterror;
        $xslterror='Sablotron XSLT transformation error';
        reset($f);
        while(list($key,$val)=each($f))
        {
            if ($key=='line')
                $xslterror.=' on line '.$val;
            if ($key=='msg')
                $xslterror.=': <strong>'.$val.'</strong>';
        };
        $xslterror.='.';
    };

?>