<?php
session_register('Cart');
header('Content-Type: text/xml');
?>
<?php
        $newitem = $_POST["book"];
        $action = $_POST["action"];
        if ($_SESSION["Cart"] != "")
        {
            $MDA = $_SESSION["Cart"];
            if ($action == "Add")
            {
                if ($MDA[$newitem] != "")
                {  
                    $value = $MDA[$newitem] + 1;
                    $MDA[$newitem] = $value;
                    $_SESSION["Cart"] = $MDA; 
                    ECHO (toXml($MDA));    
                }
                else
                {
                    $MDA[$newitem] = "";
                    $_SESSION["Cart"] = $MDA;
                    ECHO (toXml($MDA));
                }
            }
            else
            {
                $value = $MDA[newitem];
                $MDA= "";
                $_SESSION["Cart"] = "";   
                ECHO (toXml($MDA));
            }
        }
        else
        {
            $MDA[$newitem] = "1";
            $_SESSION["Cart"] = $MDA;
            ECHO (toXml($MDA));
        }
        								
    
   function toXml($MDA)
    {
        $doc = new DomDocument('1.0');
        $cart = $doc->appendChild($doc->createElement('cart'));
        $total = 0;
        
        foreach ($MDA as $Item => $ItemName)
        {
            $book = $cart->appendChild($doc->createElement('book'));
    
            $title = $doc->appendChild($doc->createElement('Title'));
            $title->appendChild($doc->createTextNode($Item));
            
            $authors = $book->appendChild($doc->createElement('Authors'));
            $authors->appendChild($doc->createTextNode($_POST['authors']));
            
            $isbn = $book->appendChild($doc->createElement('ISBN'));
            $isbn->appendChild($doc->createTextNode($_POST['ISBN']));
            
            $price = str_replace("$","",$_POST['price']);
            $priceNode = $book->appendChild($doc->createElement('Price'));
            $priceNode->appendChild($doc->createTextNode($price));
    
            $quantity = $book->appendChild($doc->createElement('Quantity'));
            $quantity->appendChild($doc->createTextNode($ItemName));
            
            $book->appendChild($title);
            $book->appendChild($quantity);
            $book->appendChild($authors);
            $book->appendChild($isbn);
            $book->appendChild($priceNode);
            
            $total = $price * $ItemName;
      }
      
       $totalNode =  $cart->appendChild($doc->createElement('Total'));
       $totalNode->appendChild($doc->createTextNode($total));

       $strXml = $doc->saveXML(); 
       return $strXml;
    }

?>