<?php
/**
 * Atom Syndication Format PHP Library
 *
 * @package AtomLib
 * @link http://code.google.com/p/phpatomlib/
 *
 * @author Elias Torres <elias@torrez.us>
 * @version 0.4
 * @since 2.3.0
 */

/**
 * Structure that store common Atom Feed Properties
 *
 * @package AtomLib
 */
class AtomFeed {
	/**
	 * Stores Links
	 * @var array
	 * @access public
	 */
 var $links = array();
 /**
 * Stores Categories
 * @var array
 * @access public
 */
 var $categories = array();
	/**
	 * Stores Entries
	 *
	 * @var array
	 * @access public
	 */
 var $entries = array();
}

/**
 * Structure that store Atom Entry Properties
 *
 * @package AtomLib
 */
class AtomEntry {
	/**
	 * Stores Links
	 * @var array
	 * @access public
	 */
 var $links = array();
 /**
 * Stores Categories
 * @var array
	 * @access public
 */
 var $categories = array();
}

/**
 * AtomLib Atom Parser API
 *
 * @package AtomLib
 */
class AtomParser {

 var $NS = 'http://www.w3.org/2005/Atom';
 var $ATOM_CONTENT_ELEMENTS = array('content','summary','title','subtitle','rights');
 var $ATOM_SIMPLE_ELEMENTS = array('id','updated','published','draft');

 var $debug = false;

 var $depth = 0;
 var $indent = 2;
 var $in_content;
 var $ns_contexts = array();
 var $ns_decls = array();
 var $content_ns_decls = array();
 var $content_ns_contexts = array();
 var $is_xhtml = false;
 var $is_html = false;
 var $is_text = true;
 var $skipped_div = false;

 var $FILE = "php://input";

 var $feed;
 var $current;

	/**
	 * PHP5 constructor.
	 */
 function __construct() {

 $this->feed = new AtomFeed();
 $this->current = null;
 $this->map_attrs_func = array( __CLASS__, 'map_attrs' );
 $this->map_xmlns_func = array( __CLASS__, 'map_xmlns' );
 }

	/**
	 * PHP4 constructor.
	 */
	public function AtomParser() {
		self::__construct();
	}

	/**
	 * Map attributes to key="val"
	 *
	 * @param string $k Key
	 * @param string $v Value
	 * @return string
	 */
	public static function map_attrs($k, $v) {
		return "$k=\"$v\"";
	}

	/**
	 * Map XML namespace to string.
	 *
	 * @param indexish $p XML Namespace element index
	 * @param array $n Two-element array pair. [ 0 => {namespace}, 1 => {url} ]
	 * @return string 'xmlns="{url}"' or 'xmlns:{namespace}="{url}"'
	 */
	public static function map_xmlns($p, $n) {
		$xd = "xmlns";
		if( 0 < strlen($n[0]) ) {
			$xd .= ":{$n[0]}";
		}
		return "{$xd}=\"{$n[1]}\"";
	}

 function _p($msg) {
 if($this->debug) {
 print str_repeat(" ", $this->depth * $this->indent) . $msg ."\n";
 }
 }

 function error_handler($log_level, $log_text, $error_file, $error_line) {
 $this->error = $log_text;
 }

 function parse() {

 set_error_handler(array(&$this, 'error_handler'));

 array_unshift($this->ns_contexts, array());

 if ( ! function_exists( 'xml_parser_create_ns' ) ) {
 	trigger_error( __( "PHP's XML extension is not available. Please contact your hosting provider to enable PHP's XML extension." ) );
 	return false;
 }

 $parser = xml_parser_create_ns();
 xml_set_object($parser, $this);
 xml_set_element_handler($parser, "start_element", "end_element");
 xml_parser_set_option($parser,XML_OPTION_CASE_FOLDING,0);
 xml_parser_set_option($parser,XML_OPTION_SKIP_WHITE,0);
 xml_set_character_data_handler($parser, "cdata");
 xml_set_default_handler($parser, "_default");
 xml_set_start_namespace_decl_handler($parser, "start_ns");
 xml_set_end_namespace_decl_handler($parser, "end_ns");

 $this->content = '';

 $ret = true;

 $fp = fopen($this->FILE, "r");
 while ($data = fread($fp, 4096)) {
 if($this->debug) $this->content .= $data;

 if(!xml_parse($parser, $data, feof($fp))) {
 /* translators: 1: Error message, 2: Line number. */
 trigger_error(sprintf(__('XML Error: %1$s at line %2$s')."\n",
 xml_error_string(xml_get_error_code($parser)),
 xml_get_current_line_number($parser)));
 $ret = false;
 break;
 }
 }
 fclose($fp);

 xml_parser_free($parser);
 unset($parser);

 restore_error_handler();

 return $ret;
 }

 function start_element($parser, $name, $attrs) {

 $name_parts = explode(":", $name);
 $tag = array_pop($name_parts);

 switch($name) {
 case $this->NS . ':feed':
 $this->current = $this->feed;
 break;
 case $this->NS . ':entry':
 $this->current = new AtomEntry();
 break;
 };

 $this->_p("start_element('$name')");
 #$this->_p(print_r($this->ns_contexts,true));
 #$this->_p('current(' . $this->current . ')');

 array_unshift($this->ns_contexts, $this->ns_decls);

 $this->depth++;

 if(!empty($this->in_content)) {

 $this->content_ns_decls = array();

 if($this->is_html || $this->is_text)
 trigger_error("Invalid content in element found. Content must not be of type text or html if it contains markup.");

 $attrs_prefix = array();

 // resolve prefixes for attributes
 foreach($attrs as $key => $value) {
 $with_prefix = $this->ns_to_prefix($key, true);
 $attrs_prefix[$with_prefix[1]] = $this->xml_escape($value);
 }

 $attrs_str = join(' ', array_map($this->map_attrs_func, array_keys($attrs_prefix), array_values($attrs_prefix)));
 if(strlen($attrs_str) > 0) {
 $attrs_str = " " . $attrs_str;
 }

 $with_prefix = $this->ns_to_prefix($name);

 if(!$this->is_declared_content_ns($with_prefix[0])) {
 array_push($this->content_ns_decls, $with_prefix[0]);
 }

 $xmlns_str = '';
 if(count($this->content_ns_decls) > 0) {
 array_unshift($this->content_ns_contexts, $this->content_ns_decls);
 $xmlns_str .= join(' ', array_map($this->map_xmlns_func, array_keys($this->content_ns_contexts[0]), array_values($this->content_ns_contexts[0])));
 if(strlen($xmlns_str) > 0) {
 $xmlns_str = " " . $xmlns_str;
 }
 }

 array_push($this->in_content, array($tag, $this->depth, "<". $with_prefix[1] ."{$xmlns_str}{$attrs_str}" . ">"));

 } else if(in_array($tag, $this->ATOM_CONTENT_ELEMENTS) || in_array($tag, $this->ATOM_SIMPLE_ELEMENTS)) {
 $this->in_content = array();
 $this->is_xhtml = $attrs['type'] == 'xhtml';
 $this->is_html = $attrs['type'] == 'html' || $attrs['type'] == 'text/html';
 $this->is_text = !in_array('type',array_keys($attrs)) || $attrs['type'] == 'text';
 $type = $this->is_xhtml ? 'XHTML' : ($this->is_html ? 'HTML' : ($this->is_text ? 'TEXT' : $attrs['type']));

 if(in_array('src',array_keys($attrs))) {
 $this->current->$tag = $attrs;
 } else {
 array_push($this->in_content, array($tag,$this->depth, $type));
 }
 } else if($tag == 'link') {
 array_push($this->current->links, $attrs);
 } else if($tag == 'category') {
 array_push($this->current->categories, $attrs);
 }

 $this->ns_decls = array();
 }

 function end_element($parser, $name) {

 $name_parts = explode(":", $name);
 $tag = array_pop($name_parts);

 $ccount = count($this->in_content);

 # if we are *in* content, then let's proceed to serialize it
 if(!empty($this->in_content)) {
 # if we are ending the original content element
 # then let's finalize the content
 if($this->in_content[0][0] == $tag &&
 $this->in_content[0][1] == $this->depth) {
 $origtype = $this->in_content[0][2];
 array_shift($this->in_content);
 $newcontent = array();
 foreach($this->in_content as $c) {
 if(count($c) == 3) {
 array_push($newcontent, $c[2]);
 } else {
 if($this->is_xhtml || $this->is_text) {
 array_push($newcontent, $this->xml_escape($c));
 } else {
 array_push($newcontent, $c);
 }
 }
 }
 if(in_array($tag, $this->ATOM_CONTENT_ELEMENTS)) {
 $this->current->$tag = array($origtype, join('',$newcontent));
 } else {
 $this->current->$tag = join('',$newcontent);
 }
 $this->in_content = array();
 } else if($this->in_content[$ccount-1][0] == $tag &&
 $this->in_content[$ccount-1][1] == $this->depth) {
 $this->in_content[$ccount-1][2] = substr($this->in_content[$ccount-1][2],0,-1) . "/>";
 } else {
 # else, just finalize the current element's content
 $endtag = $this->ns_to_prefix($name);
 array_push($this->in_content, array($tag, $this->depth, "</$endtag[1]>"));
 }
 }

 array_shift($this->ns_contexts);

 $this->depth--;

 if($name == ($this->NS . ':entry')) {
 array_push($this->feed->entries, $this->current);
 $this->current = null;
 }

 $this->_p("end_element('$name')");
 }

 function start_ns($parser, $prefix, $uri) {
 $this->_p("starting: " . $prefix . ":" . $uri);
 array_push($this->ns_decls, array($prefix,$uri));
 }

 function end_ns($parser, $prefix) {
 $this->_p("ending: #" . $prefix . "#");
 }

 function cdata($parser, $data) {
 $this->_p("data: #" . str_replace(array("\n"), array("\\n"), trim($data)) . "#");
 if(!empty($this->in_content)) {
 array_push($this->in_content, $data);
 }
 }

 function _default($parser, $data) {
 # when does this gets called?
 }


 function ns_to_prefix($qname, $attr=false) {
 # split 'http://www.w3.org/1999/xhtml:div' into ('http','//www.w3.org/1999/xhtml','div')
 $components = explode(":", $qname);

 # grab the last one (e.g 'div')
 $name = array_pop($components);

 if(!empty($components)) {
 # re-join back the namespace component
 $ns = join(":",$components);
 foreach($this->ns_contexts as $context) {
 foreach($context as $mapping) {
 if($mapping[1] == $ns && strlen($mapping[0]) > 0) {
 return array($mapping, "$mapping[0]:$name");
 }
 }
 }
 }

 if($attr) {
 return array(null, $name);
 } else {
 foreach($this->ns_contexts as $context) {
 foreach($context as $mapping) {
 if(strlen($mapping[0]) == 0) {
 return array($mapping, $name);
 }
 }
 }
 }
 }

 function is_declared_content_ns($new_mapping) {
 foreach($this->content_ns_contexts as $context) {
 foreach($context as $mapping) {
 if($new_mapping == $mapping) {
 return true;
 }
 }
 }
 return false;
 }

 function xml_escape($string)
 {
 return str_replace(array('&','"',"'",'<','>'),
 array('&amp;','&quot;','&apos;','&lt;','&gt;'),
 $string );
 }
}