<?php //$Id$

/**
 * Project:     phAnTOM: a simple Atom parsing class
 * File:        atom_parse.php includes code for parsing
 *              Atom feeds, and returning an Atom object
 * Author:      Jeremy Ashcraft <ashcraft@13monkeys.com>
 * Version:     0.1
 * License:     GPL
 *
 * The lastest version of phAnTOM can be obtained from:
 * http://www.simplog.org
 *
 * For questions, help, comments, discussion, etc., please join the
 * Simplog Atom mailing list:
 * simplog-atom@lists.sourceforge.net
 *
 * This code is based on the MagpieRSS parser v0.52 written
 * by Kellan Elliott-McCrea <kellan@protest.net> and released under the GPL
 */
 

/**
 * The lastest Atom feed spec is at http://diveintomark.org/public/2003/08/atom02spec.txt
 *
 *
 * RSS/Atom validators are readily available on the web at:
 * http://feeds.archive.org/validator/
 *
 */

class Atom {
    /*
     * Useage Example:
     *
     * $xml = "<?xml version="1.0"......
     *
     * $atom = new atom( $xml );
     *
     * // print feed title
     * print $atom->feed['title'];
     *
     * // print the title of each entry
     * foreach ($atom->entries as $entry ) {
     *	  print $entry[title];
     * }
     *
     */
     
    var $parser;
    
    var $current_item   = array();	// item currently being parsed
        var $entries        = array();	// collection of parsed items
    var $feed       = array();	// hash of channel fields
    
    var $parent_field   = array('RDF');
    var $author     = array();
    var $contributor    = array();
    var $current_field  = '';
    var $current_namespace  = false;
    
    var $ERROR = '';
    
/*======================================================================*\
    Function: MagpieRSS
    Purpose:  Constructor, sets up XML parser,parses source,
              and populates object.. 
    Input:	  String containing the RSS to be parsed
\*======================================================================*/
    function Atom ($source) {
        
        # if PHP xml isn't compiled in, die
        #
        if (!function_exists('xml_parser_create')) {
            $this->error( 'Failed to load PHP\'s XML Extension. ' . 
                          'http://www.php.net/manual/en/ref.xml.php',
                           E_USER_ERROR );
        }
        
        $parser = @xml_parser_create();
        
        if (!is_resource($parser))
        {
            $this->error( 'Failed to create an instance of PHP\'s XML parser. ' .
                          'http://www.php.net/manual/en/ref.xml.php',
                          E_USER_ERROR );
        }

        
        $this->parser = $parser;
        
        # pass in parser, and a reference to this object
        # setup handlers
        #
        xml_set_object( $this->parser, $this );
        xml_set_element_handler($this->parser, 'start_element', 'end_element');
        xml_set_character_data_handler( $this->parser, 'cdata' ); 
    
        
        $status = xml_parse( $this->parser, $source );
        
        if (! $status ) {
            $errorcode = xml_get_error_code( $this->parser );
            if ( $errorcode != XML_ERROR_NONE ) {
                $xml_error = xml_error_string( $errorcode );
                $error_line = xml_get_current_line_number($this->parser);
                $error_col = xml_get_current_column_number($this->parser);
                $errormsg = $xml_error .' at line '. $error_line .', column '. $error_col;

                $this->error( $errormsg );
            }
        }
        
        xml_parser_free( $this->parser );
    }
    
    function start_element ($p, $element, &$attrs) {
        $element    = strtolower( $element );
        # check for a namespace, and split if found
        #
        $namespace	= false;
        if ( strpos( $element, ':' ) ) {
            list($namespace, $element) = split( ':', $element, 2); 
        }
        $this->current_field = $element;
        if ( $namespace ) {
            $this->current_namespace = $namespace;
        }
        
        if ( $element == 'feed' ) {
            array_unshift( $this->parent_field, 'feed' );
        } else if ( $element == 'items' ) {
            array_unshift( $this->parent_field, 'items' );
        } else if ( $element == 'entry' ) {
            array_unshift( $this->parent_field, 'entry' );
        } else if ( $element == 'author' ) {
                        array_unshift( $this->parent_field, 'author' );
        } else if ( $element == 'contributor' ) {
                        array_unshift( $this->parent_field, 'contributor' );
                }
    }
    
    function end_element ($p, $element) {
        $element = strtolower($element);
                            
        if ( $element == 'entry' ) {	
            $this->entries[] = $this->current_item;
            $this->current_item = array();
            array_shift( $this->parent_field );
        } else if ( $element == 'feed' or $element == 'items' or 
                 $element == 'author' or $element == 'contributor') {
            array_shift( $this->parent_field );
        }
        
        $this->current_field = '';
        $this->current_namespace = false;
    }
    
    function cdata ($p, $text) {
        # skip item, channel, items first time we see them
        #
        if ( $this->parent_field[0] == $this->current_field or
             ! $this->current_field ) {
            return;
        } else if ( $this->parent_field[0] == 'feed') {
            if ( $this->current_namespace ) {
                $this->append(
                    $this->feed[ $this->current_namespace ][ $this->current_field ],
                    $text);
            } else {
                $this->append($this->feed[ $this->current_field ], $text);
            }
        
        } else if ( $this->parent_field[0] == 'entry' ) {
            if ( $this->current_namespace ) {
                $this->append(
                    $this->current_item[ $this->current_namespace ][$this->current_field ],
                    $text);
            } else {
                $this->append(
                    $this->current_item[ $this->current_field ],
                    $text );
            }
        } else if ( $this->parent_field[0] == 'author' ) {
                        if ( $this->current_namespace ) {
                                $this->append(
                                        $this->author[ $this->current_namespace ][ $this->current_field ],
                                        $text );
                        } else {
                                $this->append(
                                        $this->author[ $this->current_field ],
                                        $text );
                        }
                } else if ( $this->parent_field[0] == 'contributor' ) {
                        if ( $this->current_namespace ) {
                                $this->append(
                                        $this->contributor[ $this->current_namespace ][ $this->current_field ],
                                        $text );
                        } else {
                                $this->append(
                                        $this->contributor[ $this->current_field ],
                                        $text );
                        }
                }
    }
    
    function append (&$str1, $str2='') {
        if (!isset($str1) ) {
            $str1='';
        }
        $str1 .= $str2;
    }
    
    function error ($errormsg, $lvl=E_USER_WARNING) {
        // append PHP's error message if track_errors enabled
        if ( $php_errormsg ) { 
            $errormsg .= ' ('. $php_errormsg .')';
        }
        $this->ERROR = $errormsg;
        if ( ATOM_DEBUG ) {
            trigger_error( $errormsg, $lvl);		
        } else {
            error_log( $errormsg, 0);
        }
    }
        

/*======================================================================*\
    EVERYTHING BELOW HERE IS FOR DEBUGGING PURPOSES
\*======================================================================*/
    function show_list () {
        print '<ol>'."\n";
        foreach ($this->entries as $item) {
            print '<li>'. $this->show_entry( $item );
        }
        print '</ol>';
    }
    
    function show_feed () {
        print 'feed:<br />';
        print '<ul>';
        while ( list($key, $value) = each( $this->feed ) ) {
            print '<li> '. $key .': '. $value;
        }
        print '</ul>';
    }
    
    function show_entry ($item) {
        print 'entry: '. $item[title];
        print '<ul>';
        while ( list($key, $value) = each($item) ) {
            if ( is_array($value) ) {
                print '<br /><strong>'. $key .'</strong>';
                print '<ul>';
                while ( list( $ns_key, $ns_value) = each( $value ) ) {
                    print '<li>'. $ns_key .': '. $ns_value;
                }
                print '</ul>';
            } else {
                print '<li> '. $key .': '. $value;
            }
        }
        print '</ul>';
    }

/*======================================================================*\
    END DEBUGGING FUNCTIONS	
\*======================================================================*/
    
} # end class Atom
?>