<?php
class BootstrapNavMenuWalker extends Walker_Nav_Menu {

	function start_lvl(&$output, $depth = 0, $args = Array()) {

		$indent = str_repeat("\t", $depth);
		$submenu = ($depth > 0) ? ' sub-menu' : '';
		$output .= "\n$indent<ul class=\"dropdown-menu$submenu depth_$depth\">\n";
	}

	function start_el(&$output, $item, $depth = 0, $args = array(), $id = 0) {

		$indent = ($depth) ? str_repeat("\t", $depth) : '';

		$li_attributes = '';
		$value = '';

		$classes = empty($item->classes) ? array() : (array) $item->classes;

		// managing divider: add divider class to an element to get a divider before it.
		$divider_class_position = array_search('divider', $classes);
		if ($divider_class_position !== false) {
			$output .= "<li class=\"divider\"></li>\n";
			unset($classes[$divider_class_position]);
		}

		$classes[] = ($args->has_children) ? 'dropdown' : '';
		$classes[] = ($item->current || $item->current_item_ancestor) ? 'active' : '';
		$classes[] = 'menu-item-' . $item->ID;
		if ($depth && $args->has_children) {
			$classes[] = 'dropdown-submenu';
		}

		$class_names = join(' ', apply_filters('nav_menu_css_class', array_filter($classes), $item, $args));
		$class_names = ' class="' . esc_attr($class_names) . '"';

		$id = apply_filters('nav_menu_item_id', 'menu-item-' . $item->ID, $item, $args);
		$id = strlen($id) ? ' id="' . esc_attr($id) . '"' : '';

		$output .= $indent . '<li' . $id . $value . $class_names . $li_attributes . '>';

		$attributes = !empty($item->attr_title) ? ' title="' . esc_attr($item->attr_title) . '"' : '';
		$attributes .=!empty($item->target) ? ' target="' . esc_attr($item->target) . '"' : '';
		$attributes .=!empty($item->xfn) ? ' rel="' . esc_attr($item->xfn) . '"' : '';
		$attributes .=!empty($item->url) ? ' href="' . esc_attr($item->url) . '"' : '';
		$attributes .= ($args->has_children) ? ' class="dropdown-toggle" data-toggle="dropdown"' : '';

		$item_output = $args->before;
		$item_output .= '<a' . $attributes . '>';
		$item_output .= $args->link_before . apply_filters('the_title', $item->title, $item->ID) . $args->link_after;
		$item_output .= ($depth == 0 && $args->has_children) ? ' <b class="caret"></b></a>' : '</a>';
		$item_output .= $args->after;

		$output .= apply_filters('walker_nav_menu_start_el', $item_output, $item, $depth, $args);
	}

	function display_element($element, &$children_elements, $max_depth, $depth = 0, $args, &$output) {
		//v($element);
		if (!$element)
			return;

		$id_field = $this->db_fields['id'];

		//display this element
		if (is_array($args[0]))
			$args[0]['has_children'] = !empty($children_elements[$element->$id_field]);
		else if (is_object($args[0]))
			$args[0]->has_children = !empty($children_elements[$element->$id_field]);
		$cb_args = array_merge(array(&$output, $element, $depth), $args);
		call_user_func_array(array(&$this, 'start_el'), $cb_args);

		$id = $element->$id_field;

		// descend only when the depth is right and there are childrens for this element
		if (($max_depth == 0 || $max_depth > $depth + 1) && isset($children_elements[$id])) {

			foreach ($children_elements[$id] as $child) {

				if (!isset($newlevel)) {
					$newlevel = true;
					//start the child delimiter
					$cb_args = array_merge(array(&$output, $depth), $args);
					call_user_func_array(array(&$this, 'start_lvl'), $cb_args);
				}
				$this->display_element($child, $children_elements, $max_depth, $depth + 1, $args, $output);
			}
			unset($children_elements[$id]);
		}

		if (isset($newlevel) && $newlevel) {
			//end the child delimiter
			$cb_args = array_merge(array(&$output, $depth), $args);
			call_user_func_array(array(&$this, 'end_lvl'), $cb_args);
		}

		//end this element
		$cb_args = array_merge(array(&$output, $element, $depth), $args);
		call_user_func_array(array(&$this, 'end_el'), $cb_args);
	}

}