Metadata.php

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<?php
/* Metadata.php -- provides DublinCore and CreativeCommons metadata
 * Copyright 2004, Evan Prodromou <evan@wikitravel.org>.
 * 
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

define("RDF_TYPE_PREFS", "application/rdf+xml,text/xml;q=0.7,application/xml;q=0.5,text/rdf;q=0.1");

function wfDublinCoreRdf($article) {
        
        $url = dcReallyFullUrl($article->mTitle);
        
        if (rdfSetup()) {
                dcPrologue($url);
                dcBasics($article);
                dcEpilogue();
        }
}

function wfCreativeCommonsRdf($article) {
        
        if (rdfSetup()) {
                global $wgRightsUrl;
                
                $url = dcReallyFullUrl($article->mTitle);
                
                ccPrologue();
                ccSubPrologue('Work', $url);
                dcBasics($article);
                if (isset($wgRightsUrl)) {
                        $url = htmlspecialchars( $wgRightsUrl );
                        print "    <cc:license rdf:resource=\"$url\" />\n";
                }
                
                ccSubEpilogue('Work');
                
                if (isset($wgRightsUrl)) {
                        $terms = ccGetTerms($wgRightsUrl);
                        if ($terms) {
                                ccSubPrologue('License', $wgRightsUrl);
                                ccLicense($terms);
                                ccSubEpilogue('License');
                        }
                }
        }
        
        ccEpilogue();
}

/* private */ function rdfSetup() {
        global $wgOut, $wgRdfMimeType, $_SERVER;
        
        $rdftype = wfNegotiateType(wfAcceptToPrefs($_SERVER['HTTP_ACCEPT']), wfAcceptToPrefs(RDF_TYPE_PREFS));
        
        if (!$rdftype) {
                wfHttpError(406, "Not Acceptable", wfMsg("notacceptable"));
                return false;
        } else {
                $wgOut->disable();
                header( "Content-type: {$rdftype}" );
                $wgOut->sendCacheControl();
                return true;
        }
}

/* private */ function dcPrologue($url) {
        global $wgOutputEncoding;
        
        $url = htmlspecialchars( $url );
        print "<" . "?xml version=\"1.0\" encoding=\"{$wgOutputEncoding}\" ?" . ">
                        
<!DOCTYPE rdf:RDF PUBLIC \"-//DUBLIN CORE//DCMES DTD 2002/07/31//EN\" \"http://dublincore.org/documents/2002/07/31/dcmes-xml/dcmes-xml-dtd.dtd\">
                        
<rdf:RDF xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"
         xmlns:dc=\"http://purl.org/dc/elements/1.1/\">
  <rdf:Description rdf:about=\"$url\">
";
}

/* private */ function dcEpilogue() {
        print "
  </rdf:Description>
</rdf:RDF>
";
}

/* private */ function dcBasics($article) {
        global $wgLanguageCode, $wgSitename;
        
        dcElement('title', $article->mTitle->getText());
        dcPageOrString('publisher', wfMsg('aboutpage'), $wgSitename);
        dcElement('language', $wgLanguageCode);
        dcElement('type', 'Text');
        dcElement('format', 'text/html');
        dcElement('identifier', dcReallyFullUrl($article->mTitle));
        dcElement('date', dcDate($article->getTimestamp()));

        $last_editor = $article->getUser();
        
        if ($last_editor == 0) {
            dcPerson('creator', 0);
        } else {
            dcPerson('creator', $last_editor, $article->getUserText(),
                     User::whoIsReal($last_editor));
        }

        $contributors = $article->getContributors();
        
        foreach ($contributors as $cid => $user_parts) {
                dcPerson('contributor', $cid, $user_parts[0], $user_parts[1]);
        }
        
        dcRights($article);
}

/* private */ function ccPrologue() {
        global $wgOutputEncoding;
        
        echo "<" . "?xml version='1.0'  encoding='{$wgOutputEncoding}' ?" . ">
           
<rdf:RDF xmlns:cc=\"http://web.resource.org/cc/\"
         xmlns:dc=\"http://purl.org/dc/elements/1.1/\"
         xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\">
";
}  

/* private */ function ccSubPrologue($type, $url) {
        $url = htmlspecialchars( $url );
        echo "  <cc:{$type} rdf:about=\"{$url}\">\n";
}  

/* private */ function ccSubEpilogue($type) {
        echo "  </cc:{$type}>\n";
}  

/* private */ function ccLicense($terms) {
        
        foreach ($terms as $term) {
                switch ($term) {
                case 're':
                        ccTerm('permits', "Reproduction"); break;
                case 'di':
                        ccTerm('permits', "Distribution"); break;
                case 'de':
                        ccTerm('permits', "DerivativeWorks"); break;
                case 'nc':
                        ccTerm('prohibits', "CommercialUse"); break;
                case 'no':
                        ccTerm('requires', "Notice"); break;
                case 'by':
                        ccTerm('requires', "Attribution"); break;
                case 'sa':
                        ccTerm('requires', "ShareAlike"); break;
                case 'sc':
                        ccTerm('requires', "SourceCode"); break;                
                }
        }
}

/* private */ function ccTerm($term, $name) {
        print "    <cc:{$term} rdf:resource=\"http://web.resource.org/cc/{$name}\" />\n";
}

/* private */ function ccEpilogue() {
        echo "</rdf:RDF>\n";
}

/* private */ function dcElement($name, $value) {
        $value = htmlspecialchars( $value );
        print "    <dc:{$name}>{$value}</dc:{$name}>\n";
}

/* private */ function dcDate($timestamp) {
        return substr($timestamp, 0, 4) . "-" 
                . substr($timestamp, 4, 2) . "-" 
                . substr($timestamp, 6, 2);
}

/* private */ function dcReallyFullUrl($title) {
        return $title->getFullURL();
}

/* private */ function dcPageOrString($name, $page, $str) {
        $nt = Title::newFromText($page);
        
        if (!$nt || $nt->getArticleID() == 0) {
                dcElement($name, $str);
        } else {
                dcPage($name, $nt);
        }
}

/* private */ function dcPage($name, $title) {
        dcUrl($name, dcReallyFullUrl($title));
}

/* private */ function dcUrl($name, $url) {
        $url = htmlspecialchars( $url );
        print "    <dc:{$name} rdf:resource=\"{$url}\" />\n";
}

/* private */ function dcPerson($name, $id, $user_name="", $user_real_name="") {
        global $wgLang;

        if ($id == 0) {
                dcElement($name, wfMsg("anonymous"));
        } else if ( !empty($user_real_name) ) {
                dcElement($name, $user_real_name);
        } else {
                # XXX: This shouldn't happen.
                if( empty( $user_name ) ) {
                        $user_name = User::whoIs($id);
                }
                dcPageOrString($name, $wgLang->getNsText(NS_USER) . ":" . $user_name, wfMsg("siteuser", $user_name));
        }
}

/* Takes an arg, for future enhancement with different rights for
 different pages. */

/* private */ function dcRights($article) {
        
        global $wgRightsPage, $wgRightsUrl, $wgRightsText;
        
        if (isset($wgRightsPage) &&
                ($nt = Title::newFromText($wgRightsPage))
                && ($nt->getArticleID() != 0)) {
                dcPage('rights', $nt);
        } else if (isset($wgRightsUrl)) {
                dcUrl('rights', $wgRightsUrl);
        } else if (isset($wgRightsText)) {
                dcElement('rights', $wgRightsText);
        }
}

/* private */ function ccGetTerms($url) {
        global $wgLicenseTerms;
        
        if (isset($wgLicenseTerms)) {
                return $wgLicenseTerms;
        } else {
                $known = getKnownLicenses();
                return $known[$url];
        }
}

/* private */ function getKnownLicenses() {
        
        $ccLicenses = array('by', 'by-nd', 'by-nd-nc', 'by-nc', 
                            'by-nc-sa', 'by-sa', 'nd', 'nd-nc',
                            'nc', 'nc-sa', 'sa');
        
        $knownLicenses = array();
        
        foreach ($ccLicenses as $license) {
                $lurl = "http://creativecommons.org/licenses/{$license}/1.0/";
                $knownLicenses[$lurl] = explode('-', $license);
                $knownLicenses[$lurl][] = 're';
                $knownLicenses[$lurl][] = 'di';
                $knownLicenses[$lurl][] = 'no';
                if (!in_array('nd', $knownLicenses[$lurl])) {
                        $knownLicenses[$lurl][] = 'de';
                }
        }
        
        /* Handle the GPL and LGPL, too. */
        
        $knownLicenses["http://creativecommons.org/licenses/GPL/2.0/"] =
                array('de', 're', 'di', 'no', 'sa', 'sc');
        $knownLicenses["http://creativecommons.org/licenses/LGPL/2.1/"] = 
                array('de', 're', 'di', 'no', 'sa', 'sc');
        $knownLicenses["http://www.gnu.org/copyleft/fdl.html"] = 
                array('de', 're', 'di', 'no', 'sa', 'sc');
        
        return $knownLicenses;
}

?>

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