<?php

/**
 * Bootstrap Walker Nav Menu
 *
 * @link https://github.com/wp-bootstrap/wp-bootstrap-navwalker
 * @package Bootstrap WP Starter
 */

// Check if Class Exists.
if (!class_exists('Bootstrap_Walker_Nav_Menu')) :

	class Bootstrap_Walker_Nav_Menu extends Walker_Nav_Menu
	{

		/**
		 * Whether the items_wrap contains schema microdata or not.
		 *
		 * @since 4.2.0
		 * @var boolean
		 */
		private $has_schema = false;

		/**
		 * Ensure the items_wrap argument contains microdata.
		 *
		 * @since 4.2.0
		 */
		public function __construct()
		{
			if (!has_filter('wp_nav_menu_args', array($this, 'add_schema_to_navbar_ul'))) {
				add_filter('wp_nav_menu_args', array($this, 'add_schema_to_navbar_ul'));
			}
		}

		/**
		 * Starts the list before the elements are added.
		 *
		 * @since WP 3.0.0
		 *
		 * @see Walker_Nav_Menu::start_lvl()
		 *
		 * @param string           $output Used to append additional content (passed by reference).
		 * @param int              $depth  Depth of menu item. Used for padding.
		 * @param WP_Nav_Menu_Args $args   An object of wp_nav_menu() arguments.
		 */
		public function start_lvl(&$output, $depth = 0, $args = null)
		{
			if (isset($args->item_spacing) && 'discard' === $args->item_spacing) {
				$t = '';
				$n = '';
			} else {
				$t = "\t";
				$n = "\n";
			}
			$indent = str_repeat($t, $depth);
			// Default class to add to the file.
			$classes = array('dropdown-menu');
			/**
			 * Filters the CSS class(es) applied to a menu list element.
			 *
			 * @since WP 4.8.0
			 *
			 * @param array    $classes The CSS classes that are applied to the menu `<ul>` element.
			 * @param stdClass $args    An object of `wp_nav_menu()` arguments.
			 * @param int      $depth   Depth of menu item. Used for padding.
			 */
			$class_names = join(' ', apply_filters('nav_menu_submenu_css_class', $classes, $args, $depth));
			$class_names = $class_names ? ' class="' . esc_attr($class_names) . '"' : '';

			/*
				 * The `.dropdown-menu` container needs to have a labelledby
				 * attribute which points to it's trigger link.
				 *
				 * Form a string for the labelledby attribute from the the latest
				 * link with an id that was added to the $output.
				 */
			$labelledby = '';
			// Find all links with an id in the output.
			preg_match_all('/(<a.*?id=\"|\')(.*?)\"|\'.*?>/im', $output, $matches);
			// With pointer at end of array check if we got an ID match.
			if (end($matches[2])) {
				// Build a string to use as aria-labelledby.
				$labelledby = 'aria-labelledby="' . esc_attr(end($matches[2])) . '"';
			}
			$output .= "{$n}{$indent}<ul$class_names $labelledby>{$n}";
		}

		/**
		 * Starts the element output.
		 *
		 * @since WP 3.0.0
		 * @since WP 4.4.0 The {@see 'nav_menu_item_args'} filter was added.
		 *
		 * @see Walker_Nav_Menu::start_el()
		 *
		 * @param string           $output Used to append additional content (passed by reference).
		 * @param WP_Nav_Menu_Item $item   Menu item data object.
		 * @param int              $depth  Depth of menu item. Used for padding.
		 * @param WP_Nav_Menu_Args $args   An object of wp_nav_menu() arguments.
		 * @param int              $id     Current item ID.
		 */
		public function start_el(&$output, $item, $depth = 0, $args = null, $id = 0)
		{
			if (isset($args->item_spacing) && 'discard' === $args->item_spacing) {
				$t = '';
				$n = '';
			} else {
				$t = "\t";
				$n = "\n";
			}
			$indent = ($depth) ? str_repeat($t, $depth) : '';

			if (false !== strpos($args->items_wrap, 'itemscope') && false === $this->has_schema) {
				$this->has_schema  = true;
				$args->link_before = '<span itemprop="name">' . $args->link_before;
				$args->link_after .= '</span>';
			}

			$classes = empty($item->classes) ? array() : (array) $item->classes;

			// Updating the CSS classes of a menu item in the WordPress Customizer preview results in all classes defined
			// in that particular input box to come in as one big class string.
			$split_on_spaces = function ($class) {
				return preg_split('/\s+/', $class);
			};
			$classes         = $this->flatten(array_map($split_on_spaces, $classes));

			/*
				 * Initialize some holder variables to store specially handled item
				 * wrappers and icons.
				 */
			$linkmod_classes = array();
			$icon_classes    = array();

			/*
				 * Get an updated $classes array without linkmod or icon classes.
				 *
				 * NOTE: linkmod and icon class arrays are passed by reference and
				 * are maybe modified before being used later in this function.
				 */
			$classes = self::separate_linkmods_and_icons_from_classes($classes, $linkmod_classes, $icon_classes, $depth);

			// Join any icon classes plucked from $classes into a string.
			$icon_class_string = join(' ', $icon_classes);

			/**
			 * Filters the arguments for a single nav menu item.
			 *
			 * @since WP 4.4.0
			 *
			 * @param WP_Nav_Menu_Args $args  An object of wp_nav_menu() arguments.
			 * @param WP_Nav_Menu_Item $item  Menu item data object.
			 * @param int              $depth Depth of menu item. Used for padding.
			 *
			 * @var WP_Nav_Menu_Args
			 */
			$args = apply_filters('nav_menu_item_args', $args, $item, $depth);

			// Add .dropdown or .active classes where they are needed.
			if ($this->has_children) {
				$classes[] = 'dropdown';
			}
			if (in_array('current-menu-item', $classes, true) || in_array('current-menu-parent', $classes, true)) {
				$classes[] = 'active';
			}

			// Add some additional default classes to the item.
			$classes[] = 'menu-item-' . $item->ID;
			$classes[] = 'nav-item';

			// Allow filtering the classes.
			$classes = apply_filters('nav_menu_css_class', array_filter($classes), $item, $args, $depth);

			// Form a string of classes in format: class="class_names".
			$class_names = join(' ', $classes);
			$class_names = $class_names ? ' class="' . esc_attr($class_names) . '"' : '';

			/**
			 * Filters the ID applied to a menu item's list item element.
			 *
			 * @since WP 3.0.1
			 * @since WP 4.1.0 The `$depth` parameter was added.
			 *
			 * @param string           $menu_id The ID that is applied to the menu item's `<li>` element.
			 * @param WP_Nav_Menu_Item $item    The current menu item.
			 * @param WP_Nav_Menu_Args $args    An object of wp_nav_menu() arguments.
			 * @param int              $depth   Depth of menu item. Used for padding.
			 */
			$id = apply_filters('nav_menu_item_id', 'menu-item-' . $item->ID, $item, $args, $depth);
			$id = $id ? ' id="' . esc_attr($id) . '"' : '';

			$output .= $indent . '<li ' . $id . $class_names . '>';

			// Initialize array for holding the $atts for the link item.
			$atts           = array();
			$atts['title']  = !empty($item->attr_title) ? $item->attr_title : '';
			$atts['target'] = !empty($item->target) ? $item->target : '';
			if ('_blank' === $item->target && empty($item->xfn)) {
				$atts['rel'] = 'noopener noreferrer';
			} else {
				$atts['rel'] = !empty($item->xfn) ? $item->xfn : '';
			}

			// If the item has_children add atts to <a>.
			if ($this->has_children && 0 === $depth) {
				$atts['href']          = '#';
				$atts['data-bs-toggle']   = 'dropdown';
				$atts['aria-haspopup'] = 'true';
				$atts['aria-expanded'] = 'false';
				$atts['class']         = 'dropdown-toggle nav-link';
				$atts['id']            = 'menu-item-dropdown-' . $item->ID;
			} else {
				if (true === $this->has_schema) {
					$atts['itemprop'] = 'url';
				}

				$atts['href'] = !empty($item->url) ? $item->url : '#';
				// For items in dropdowns use .dropdown-item instead of .nav-link.
				if ($depth > 0) {
					$atts['class'] = 'dropdown-item';
				} else {
					$atts['class'] = 'nav-link';
				}
			}

			$atts['aria-current'] = $item->current ? 'page' : '';

			// Update atts of this item based on any custom linkmod classes.
			$atts = self::update_atts_for_linkmod_type($atts, $linkmod_classes);

			// Allow filtering of the $atts array before using it.
			$atts = apply_filters('nav_menu_link_attributes', $atts, $item, $args, $depth);

			// Build a string of html containing all the atts for the item.
			$attributes = '';
			foreach ($atts as $attr => $value) {
				if (!empty($value)) {
					$value       = ('href' === $attr) ? esc_url($value) : esc_attr($value);
					$attributes .= ' ' . $attr . '="' . $value . '"';
				}
			}

			// Set a typeflag to easily test if this is a linkmod or not.
			$linkmod_type = self::get_linkmod_type($linkmod_classes);

			// START appending the internal item contents to the output.
			$item_output = isset($args->before) ? $args->before : '';

			/*
				 * This is the start of the internal nav item. Depending on what
				 * kind of linkmod we have we may need different wrapper elements.
				 */
			if ('' !== $linkmod_type) {
				// Is linkmod, output the required element opener.
				$item_output .= self::linkmod_element_open($linkmod_type, $attributes);
			} else {
				// With no link mod type set this must be a standard <a> tag.
				$item_output .= '<a' . $attributes . '>';
			}

			/*
				 * Initiate empty icon var, then if we have a string containing any
				 * icon classes form the icon markup with an <i> element. This is
				 * output inside of the item before the $title (the link text).
				 */
			$icon_html = '';
			if (!empty($icon_class_string)) {
				// Append an <i> with the icon classes to what is output before links.
				$icon_html = '<i class="' . esc_attr($icon_class_string) . '" aria-hidden="true"></i> ';
			}

			/** This filter is documented in wp-includes/post-template.php */
			$title = apply_filters('the_title', $item->title, $item->ID);

			/**
			 * Filters a menu item's title.
			 *
			 * @since WP 4.4.0
			 *
			 * @param string           $title The menu item's title.
			 * @param WP_Nav_Menu_Item $item  The current menu item.
			 * @param WP_Nav_Menu_Args $args  An object of wp_nav_menu() arguments.
			 * @param int              $depth Depth of menu item. Used for padding.
			 */
			$title = apply_filters('nav_menu_item_title', $title, $item, $args, $depth);

			// If the .sr-only class was set apply to the nav items text only.
			if (in_array('sr-only', $linkmod_classes, true)) {
				$title         = self::wrap_for_screen_reader($title);
				$keys_to_unset = array_keys($linkmod_classes, 'sr-only', true);
				foreach ($keys_to_unset as $k) {
					unset($linkmod_classes[$k]);
				}
			}

			// Put the item contents into $output.
			$item_output .= isset($args->link_before) ? $args->link_before . $icon_html . $title . $args->link_after : '';

			/*
				 * This is the end of the internal nav item. We need to close the
				 * correct element depending on the type of link or link mod.
				 */
			if ('' !== $linkmod_type) {
				// Is linkmod, output the required closing element.
				$item_output .= self::linkmod_element_close($linkmod_type);
			} else {
				// With no link mod type set this must be a standard <a> tag.
				$item_output .= '</a>';
			}

			$item_output .= isset($args->after) ? $args->after : '';

			// END appending the internal item contents to the output.
			$output .= apply_filters('walker_nav_menu_start_el', $item_output, $item, $depth, $args);
		}

		/**
		 * Menu fallback.
		 *
		 * If this function is assigned to the wp_nav_menu's fallback_cb variable
		 * and a menu has not been assigned to the theme location in the WordPress
		 * menu manager the function will display nothing to a non-logged in user,
		 * and will add a link to the WordPress menu manager if logged in as an admin.
		 *
		 * @param array $args passed from the wp_nav_menu function.
		 * @return string|void String when echo is false.
		 */
		public static function fallback($args)
		{
			if (!current_user_can('edit_theme_options')) {
				return;
			}

			// Initialize var to store fallback html.
			$fallback_output = '';

			// Menu container opening tag.
			$show_container = false;
			if ($args['container']) {
				/**
				 * Filters the list of HTML tags that are valid for use as menu containers.
				 *
				 * @since WP 3.0.0
				 *
				 * @param array $tags The acceptable HTML tags for use as menu containers.
				 *                    Default is array containing 'div' and 'nav'.
				 */
				$allowed_tags = apply_filters('wp_nav_menu_container_allowedtags', array('div', 'nav'));
				if (is_string($args['container']) && in_array($args['container'], $allowed_tags, true)) {
					$show_container   = true;
					$class            = $args['container_class'] ? ' class="menu-fallback-container ' . esc_attr($args['container_class']) . '"' : ' class="menu-fallback-container"';
					$id               = $args['container_id'] ? ' id="' . esc_attr($args['container_id']) . '"' : '';
					$fallback_output .= '<' . $args['container'] . $id . $class . '>';
				}
			}

			// The fallback menu.
			$class            = $args['menu_class'] ? ' class="menu-fallback-menu ' . esc_attr($args['menu_class']) . '"' : ' class="menu-fallback-menu"';
			$id               = $args['menu_id'] ? ' id="' . esc_attr($args['menu_id']) . '"' : '';
			$fallback_output .= '<ul' . $id . $class . '>';
			$fallback_output .= '<li class="nav-item"><a href="' . esc_url(admin_url('nav-menus.php')) . '" class="nav-link" title="' . esc_attr__('Add a menu', 'bootstrap-wp-starter') . '">' . esc_html__('Add a menu', 'bootstrap-wp-starter') . '</a></li>';
			$fallback_output .= '</ul>';

			// Menu container closing tag.
			if ($show_container) {
				$fallback_output .= '</' . $args['container'] . '>';
			}

			// if $args has 'echo' key and it's true echo, otherwise return.
			if (array_key_exists('echo', $args) && $args['echo']) {
				// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
				echo $fallback_output;
			} else {
				return $fallback_output;
			}
		}

		/**
		 * Filter to ensure the items_Wrap argument contains microdata.
		 *
		 * @since 4.2.0
		 *
		 * @param  array $args The nav instance arguments.
		 * @return array $args The altered nav instance arguments.
		 */
		public function add_schema_to_navbar_ul($args)
		{
			$wrap = $args['items_wrap'];
			if (strpos($wrap, 'SiteNavigationElement') === false) {
				$args['items_wrap'] = preg_replace('/(>).*>?\%3\$s/', ' itemscope itemtype="http://www.schema.org/SiteNavigationElement"$0', $wrap);
			}

			return $args;
		}

		/**
		 * Find any custom linkmod or icon classes and store in their holder
		 * arrays then remove them from the main classes array.
		 *
		 * Supported linkmods: .disabled, .dropdown-header, .dropdown-divider, .sr-only
		 * Supported iconsets: Font Awesome 4/5, Glypicons
		 *
		 * NOTE: This accepts the linkmod and icon arrays by reference.
		 *
		 * @since 4.0.0
		 *
		 * @param array   $classes         an array of classes currently assigned to the item.
		 * @param array   $linkmod_classes an array to hold linkmod classes.
		 * @param array   $icon_classes    an array to hold icon classes.
		 * @param integer $depth           an integer holding current depth level.
		 *
		 * @return array  $classes         a maybe modified array of classnames.
		 */
		private function separate_linkmods_and_icons_from_classes($classes, &$linkmod_classes, &$icon_classes, $depth)
		{
			// Loop through $classes array to find linkmod or icon classes.
			foreach ($classes as $key => $class) {
				/*
					 * If any special classes are found, store the class in it's
					 * holder array and and unset the item from $classes.
					 */
				if (preg_match('/^disabled|^sr-only/i', $class)) {
					// Test for .disabled or .sr-only classes.
					$linkmod_classes[] = $class;
					unset($classes[$key]);
				} elseif (preg_match('/^dropdown-header|^dropdown-divider|^dropdown-item-text/i', $class) && $depth > 0) {
					/*
						 * Test for .dropdown-header or .dropdown-divider and a
						 * depth greater than 0 - IE inside a dropdown.
						 */
					$linkmod_classes[] = $class;
					unset($classes[$key]);
				} elseif (preg_match('/^fa-(\S*)?|^fa(s|r|l|b)?(\s?)?$/i', $class)) {
					// Font Awesome.
					$icon_classes[] = $class;
					unset($classes[$key]);
				} elseif (preg_match('/^glyphicon-(\S*)?|^glyphicon(\s?)$/i', $class)) {
					// Glyphicons.
					$icon_classes[] = $class;
					unset($classes[$key]);
				}
			}

			return $classes;
		}

		/**
		 * Return a string containing a linkmod type and update $atts array
		 * accordingly depending on the decided.
		 *
		 * @since 4.0.0
		 *
		 * @param array $linkmod_classes array of any link modifier classes.
		 *
		 * @return string                empty for default, a linkmod type string otherwise.
		 */
		private function get_linkmod_type($linkmod_classes = array())
		{
			$linkmod_type = '';
			// Loop through array of linkmod classes to handle their $atts.
			if (!empty($linkmod_classes)) {
				foreach ($linkmod_classes as $link_class) {
					if (!empty($link_class)) {

						// Check for special class types and set a flag for them.
						if ('dropdown-header' === $link_class) {
							$linkmod_type = 'dropdown-header';
						} elseif ('dropdown-divider' === $link_class) {
							$linkmod_type = 'dropdown-divider';
						} elseif ('dropdown-item-text' === $link_class) {
							$linkmod_type = 'dropdown-item-text';
						}
					}
				}
			}
			return $linkmod_type;
		}

		/**
		 * Update the attributes of a nav item depending on the limkmod classes.
		 *
		 * @since 4.0.0
		 *
		 * @param array $atts            array of atts for the current link in nav item.
		 * @param array $linkmod_classes an array of classes that modify link or nav item behaviors or displays.
		 *
		 * @return array                 maybe updated array of attributes for item.
		 */
		private function update_atts_for_linkmod_type($atts = array(), $linkmod_classes = array())
		{
			if (!empty($linkmod_classes)) {
				foreach ($linkmod_classes as $link_class) {
					if (!empty($link_class)) {
						/*
							 * Update $atts with a space and the extra classname
							 * so long as it's not a sr-only class.
							 */
						if ('sr-only' !== $link_class) {
							$atts['class'] .= ' ' . esc_attr($link_class);
						}
						// Check for special class types we need additional handling for.
						if ('disabled' === $link_class) {
							// Convert link to '#' and unset open targets.
							$atts['href'] = '#';
							unset($atts['target']);
						} elseif ('dropdown-header' === $link_class || 'dropdown-divider' === $link_class || 'dropdown-item-text' === $link_class) {
							// Store a type flag and unset href and target.
							unset($atts['href']);
							unset($atts['target']);
						}
					}
				}
			}
			return $atts;
		}

		/**
		 * Wraps the passed text in a screen reader only class.
		 *
		 * @since 4.0.0
		 *
		 * @param string $text the string of text to be wrapped in a screen reader class.
		 * @return string      the string wrapped in a span with the class.
		 */
		private function wrap_for_screen_reader($text = '')
		{
			if ($text) {
				$text = '<span class="sr-only">' . $text . '</span>';
			}
			return $text;
		}

		/**
		 * Returns the correct opening element and attributes for a linkmod.
		 *
		 * @since 4.0.0
		 *
		 * @param string $linkmod_type a sting containing a linkmod type flag.
		 * @param string $attributes   a string of attributes to add to the element.
		 *
		 * @return string              a string with the openign tag for the element with attribibutes added.
		 */
		private function linkmod_element_open($linkmod_type, $attributes = '')
		{
			$output = '';
			if ('dropdown-item-text' === $linkmod_type) {
				$output .= '<span class="dropdown-item-text"' . $attributes . '>';
			} elseif ('dropdown-header' === $linkmod_type) {
				/*
					 * For a header use a span with the .h6 class instead of a real
					 * header tag so that it doesn't confuse screen readers.
					 */
				$output .= '<span class="dropdown-header h6"' . $attributes . '>';
			} elseif ('dropdown-divider' === $linkmod_type) {
				// This is a divider.
				$output .= '<div class="dropdown-divider"' . $attributes . '>';
			}
			return $output;
		}

		/**
		 * Return the correct closing tag for the linkmod element.
		 *
		 * @since 4.0.0
		 *
		 * @param string $linkmod_type a string containing a special linkmod type.
		 *
		 * @return string              a string with the closing tag for this linkmod type.
		 */
		private function linkmod_element_close($linkmod_type)
		{
			$output = '';
			if ('dropdown-header' === $linkmod_type || 'dropdown-item-text' === $linkmod_type) {
				/*
					 * For a header use a span with the .h6 class instead of a real
					 * header tag so that it doesn't confuse screen readers.
					 */
				$output .= '</span>';
			} elseif ('dropdown-divider' === $linkmod_type) {
				// This is a divider.
				$output .= '</div>';
			}
			return $output;
		}

		/**
		 * Flattens a multidimensional array to a simple array.
		 *
		 * @param array $array a multidimensional array.
		 *
		 * @return array a simple array
		 */
		public function flatten($array)
		{
			$result = array();
			foreach ($array as $element) {
				if (is_array($element)) {
					array_push($result, ...$this->flatten($element));
				} else {
					$result[] = $element;
				}
			}
			return $result;
		}
	}

endif;