<?php
// includes
require_once 'util/InputExtractor.php';
/**
 * Enter description here ...
 * @author sysal
 *
 */
class XmlExtractor implements InputExtractor {

	private $docNode;
	private $currentNode;
	
	public function openInput($input){
		$this->docNode = new DOMDocument();
		$rc = $this->docNode->loadxml($input);
		if ($rc === false) throw new RuntimeException("Could not parse XML document.");
		$this->currentNode = $this->docNode;
	}
	
	public function toTop(){
		$this->currentNode = $this->docNode;
	}
	
	public function toParent(){
		$this->currentNode = $this->currentNode->parentNode;
	}
	
	public function extractElement($extr_ctl, &$elem, &$value, &$attrs) {
		$elem  = '';
		$value = null;
		$attrs = array();
		
		if ($extr_ctl == self::EC_BEG) {
			$srh_node = $this->currentNode->firstChild;
		} elseif ($extr_ctl == self::EC_CTN) {
			$srh_node = $this->currentNode->nextSibling;
		} else {
			return self::EC_END;
		}

		// search for next element node
		while ($srh_node !== null) {
			if ($srh_node->nodeType !== XML_ELEMENT_NODE) {
				$srh_node = $srh_node->nextSibling;
			} else {
				break;
			}
		}
		
		if ($srh_node !== null) {
			// element node found: extract tag name, value and attributes
		    $this->currentNode = $srh_node;
		    $this->getCurrentNodeData($elem, $value, $attrs);
			return self::EC_CTN;
		} else {
			// terminate / ascend subtree after child extraction
			if ($extr_ctl == self::EC_CTN) {
				$this->currentNode = $this->currentNode->parentNode;
			}
			return self::EC_END;
		}
		
	}
	function getCurrentNodeData(&$elem, &$value, &$attrs) {
	    $elem = $this->currentNode->tagName;
	    if (isset($this->currentNode->nodeValue)) {
	        $value = $this->currentNode->nodeValue;
	    }
	    for ($att_idx = 0; $att_idx < $this->currentNode->attributes->length; $att_idx++) {
	        $att_node = $this->currentNode->attributes->item($att_idx);
	        $attrs[$att_node->name] = $att_node->value;
	    }
	}
	function gotoChild($name) {
	   # return True/False, if child node could be found
	   $cntl = InputExtractor::EC_BEG;
	   while (($cntl = $this->extractElement($cntl, $elem, $value, $attrs)) != InputExtractor::EC_END) {
	       if ($elem == $name) return True;
	   }
	   return False;
	}
	function requireChild($name) {
	   # throws exception, if child not present
	   if (! $this->gotoChild($name)) throw Exception("Could not find node ".$name);
	}
}