SIKOLAG Ci - Merubah Struktur Menu Dropdown ke Bootstrap

Assalamualaikum mas..
saya mau tanya untuk merubah menu dropdown di website SIKOLAG
 
Menu SIKOLAG
------------------------------------------------------------------------------------------------
<div class='main-menu sticky'>	
	<div class='wrapper'>";
		function main_menu() {
			$ci = & get_instance();
	        $query = $ci->db->query("SELECT id_menu, nama_menu, link, id_parent FROM menu where aktif='Ya' AND position='Bottom' order by urutan");
	        $menu = array('items' => array(),'parents' => array());
	        foreach ($query->result() as $menus) {
	            $menu['items'][$menus->id_menu] = $menus;
	            $menu['parents'][$menus->id_parent][] = $menus->id_menu;
	        }
	        if ($menu) {
	            $result = build_main_menu(0, $menu);
	            return $result;
	        }else{
	            return FALSE;
	        }
	    }
 
		function build_main_menu($parent, $menu) {
	        $html = "";
	        if (isset($menu['parents'][$parent])) {
	        	if ($parent=='0'){
		            $html .= "<ul class='the-menu'>";
		        }else{
		        	$html .= "<ul>";
		        }
	            foreach ($menu['parents'][$parent] as $itemId) {
	                if (!isset($menu['parents'][$itemId])) {
	                    if(preg_match("/^http/", $menu['items'][$itemId]->link)) {
	                        $html .= "<li><a target='_BLANK' href='".$menu['items'][$itemId]->link."'>".$menu['items'][$itemId]->nama_menu."</a></li>";
	                    }else{
	                        $html .= "<li><a href='".base_url().''.$menu['items'][$itemId]->link."'>".$menu['items'][$itemId]->nama_menu."</a></li>";
	                    }
	                }
	                if (isset($menu['parents'][$itemId])) {
	                    if(preg_match("/^http/", $menu['items'][$itemId]->link)) {
	                        $html .= "<li><a target='_BLANK' href='".$menu['items'][$itemId]->link."'><span>".$menu['items'][$itemId]->nama_menu."</span></a>";
	                    }else{
	                        $html .= "<li><a href='".base_url().''.$menu['items'][$itemId]->link."'><span>".$menu['items'][$itemId]->nama_menu."</span></a>";
	                    }
	                    $html .= build_main_menu($itemId, $menu);
	                    $html .= "</li>";
	                }
	            }
	            $html .= "</ul>";
	        }
	        return $html;
	    }
	    echo main_menu();
	echo "</div>
</div>";
 
 
Menu Yang diinginkan
------------------------------------------------------------------------------------------------
 
<nav>
  <div class="nav-wrapper">
    <a href="#!" class="brand-logo">Logo</a>
    <ul class="right hide-on-med-and-down">
      <li><a href="sass.html">Sass</a></li>
      <li><a href="badges.html">Components</a></li>
      <!-- Dropdown Trigger -->
      <li><a class="dropdown-button" href="#!" data-activates="dropdown1">Dropdown<i class="material-icons right">arrow_drop_down</i></a>
 
            <ul id="dropdown1" class="dropdown-content">
                  <li><a href="#!">one</a></li>
                  <li><a href="#!">two</a></li>
                  <li class="divider"></li>
                  <li><a href="#!">three</a></li>
           </ul>
      </li>
    </ul>
  </div>
</nav>
 
Mohon bantuannya mas. Terima Kasih