Here is a simple function which zips folders with all sub folders or only a simple file... the $data var can be a string or an array...

<?php
public function un_zip($data,$arcpf,$mode='zip',$obj=''){
        $absoluterpfad = 'YOUR_BASE_PATH';
        $arcpf = $absoluterpfad.DS.$arcpf;
        if(is_object($obj)==false){
             $archiv = new ZipArchive();
             $archiv->open($arcpf,ZipArchive::CREATE);
        }else{$archiv =& $obj;}
        if($mode=='zip'){
           if(is_array($data)==true){
                 foreach($data as $dtmp){
                     $archiv =& un_zip($dtmp,$arcpf,'zip',&$archiv);
                 }
           }else{
            if(is_dir($data)==true){
                    $archiv->addEmptyDir(str_replace($absoluterpfad.DS,'',$data));
                  $files = scandir($data);
               $bad = array('.','..');
               $files = array_diff($files,$bad);
               foreach($files as $ftmp){
                   if(is_dir($data.DS.$ftmp)==true){
                        $archiv->addEmptyDir(str_replace($absoluterpfad.DS,'',$data.'/'.$ftmp));
                        $archiv =& un_zip($data.DS.$ftmp,$arcpf,'zip',&$archiv);
                   }elseif(is_file($data.DS.$ftmp)==true){
                    $archiv->addFile($data.DS.$ftmp,str_replace($absoluterpfad.DS,'',$data.'/'.$ftmp));
                   }
                 }
            }elseif(is_file($data)==true){$archiv->addFile($data,str_replace($absoluterpfad.DS,'',$data));}
           }
        }
        if(is_object($obj)==false){$archiv->close();}
        else{return $archiv;}
        if($mode=='unzip'){$archiv->extractTo($data);}
    }
?>