MultilingualPress Add-on that get a Dropdown Language Menu

mlp-addon-site-link-admin-bar.php

<?php # -*- coding: utf-8 -*-
/**
 * Plugin Name: MultilingualPress Add-on that get a Dropdown Language Menu
 * Description: This is a simple add-on for the MultilingualPress plugin to get a dropdown language menu.
 * Author:      Inpsyde GmbH
 * Author URI:  http://inpsyde.com
 * Version:     2015-11-28
 * Text Domain: textdomain
 * License:     GPLv2+
 * Network:     true
 */

defined( 'ABSPATH' ) || die();

add_action( 'mlp_and_wp_loaded', array( MlpAddonDropdown::get_instance(), 'init' ) );

/**
 * Create a dropdown menu as example for custom usage.
 *
 * Class MlpAddonDropdown
 */
class MlpAddonDropdown {

	/**
	 * Plugin instance.
	 *
	 * @see get_instance()
	 * @type object
	 * @var $instance
	 */
	protected static $instance = NULL;

	/**
	 * Get instance.
	 *
	 * @return MlpAddonDropdown
	 */
	public static function get_instance() {

		if ( ! self::$instance instanceof self ) {
			self::$instance = new self;
		}

		return self::$instance;
	}

	/**
	 * Publish_Confirm constructor.
	 */
	public function __construct() {
	}

	/**
	 * Run the plugin working instance.
	 */
	public function init() {

		add_action( 'get_sidebar', array( $this, 'get_dropdown_menu' ) );
		add_action( 'the_content', array( $this, 'get_dropdown_menu' ) );
		// Include this only for testing.
		add_action( 'wp_print_styles', array( $this, 'add_bootstrap' ) );
	}

	/**
	 * Include Bootstrap for testing.
	 */
	public function add_bootstrap() {

		wp_register_script(
			'mlp_test_bootstrap',
			'http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js',
			array( 'jquery' )
		);
		wp_enqueue_script( 'mlp_test_bootstrap' );
		wp_register_style(
			'mlp_test_bootstrap',
			'http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css'
		);
		wp_enqueue_style( 'mlp_test_bootstrap' );
	}

	/**
	 * Get language items.
	 *
	 * @return array|void
	 */
	public function get_language_items() {

		$api = apply_filters( 'mlp_language_api', NULL );
		/** @var Mlp_Language_Api_Interface $api */
		if ( ! is_a( $api, 'Mlp_Language_Api_Interface' ) ) {
			return;
		}

		/**
		 * @type int    $site_id      Base site
		 * @type int    $content_id   post or term_taxonomy ID, *not* term ID
		 * @type string $type         @see Mlp_Language_Api::get_request_type()
		 * @type bool   $strict       When TRUE (default) only matching exact
		 *                                 translations will be included
		 * @type string $search_term  If you want to translate a search
		 * @type string $post_type    For post type archives
		 * @type bool   $include_base Include the base site in returned list
		 */
		$translations_args = array(
			'strict'       => FALSE,
			'include_base' => TRUE,
		);
		$translations      = $api->get_translations( $translations_args );
		if ( empty( $translations ) ) {
			return;
		}

		$items = array();
		/** @var Mlp_Translation_Interface $translation */
		foreach ( $translations as $site_id => $translation ) {

			$url = $translation->get_remote_url();
			if ( empty( $url ) ) {
				continue;
			}

			$language = $translation->get_language();
			$active   = FALSE;
			if ( get_current_blog_id() === $site_id ) {
				$active = TRUE;
			}

			$items[ $site_id ] = array(
				'url'    => $url,
				'http'   => $language->get_name( 'http' ),
				'name'   => $language->get_name( 'native' ),
				'active' => $active,
			);
		}

		return $items;
	}

	/**
	 * Format each item to usable link.
	 *
	 * @param $items
	 *
	 * @return array
	 */
	public function get_formated_links( $items ) {

		$links = array();
		foreach ( $items as $item ) {

			$hreflang = '';
			if ( ! empty ( $item[ 'http' ] ) ) {
				$hreflang = ' hreflang="' . esc_attr( $item[ 'http' ] ) . '"';
			}

			$active = '';
			if ( $item[ 'active' ] ) {
				$active = ' class="active"';
			}

			$links[] = sprintf(
				'<a href="%1$s" role="menuitem" rel="nofollow"%2$s%3$s>%4$s</a>',
				esc_url( $item[ 'url' ] ),
				$hreflang,
				$active,
				$item[ 'name' ]
			);
		}

		return $links;
	}

	/**
	 * Show dropdown markup.
	 */
	public function get_dropdown_menu() {

		$items = $this->get_language_items();
		$items = $this->get_formated_links( $items );
		?>
		<div class="dropdown">
			<button class="btn btn-primary dropdown-toggle" type="button"
				data-toggle="dropdown"><?php esc_attr_e( 'Dropdown Example', 'textdomain' ); ?>
				<span class="caret"></span>
			</button>
			<ul class="dropdown-menu" role="menu" aria-labelledby="menu1">
			<?php foreach ( $items as $item ) {
				echo '<li>' . $item . '</li>';
			} ?>
			</ul>
		</div>
		<?php
	}
}