<?php
/**
 * Admin Menu Registration
 *
 * @package automattic/jetpack-admin-ui
 */

namespace Automattic\Jetpack\Admin_UI;

/**
 * This class offers a wrapper to add_submenu_page and makes sure stand-alone plugin's menu items are always added under the Jetpack top level menu.
 * If the Jetpack top level was not previously registered by other plugin, it will be registered here.
 */
class Admin_Menu {

	const PACKAGE_VERSION = '0.1.1';

	/**
	 * Whether this class has been initialized
	 *
	 * @var boolean
	 */
	private static $initialized = false;

	/**
	 * List of menu items enqueued to be added
	 *
	 * @var array
	 */
	private static $menu_items = array();

	/**
	 * Initialize the class and set up the main hook
	 *
	 * @return void
	 */
	public static function init() {
		if ( ! self::$initialized ) {
			self::$initialized = true;
			add_action( 'admin_menu', array( __CLASS__, 'admin_menu_hook_callback' ), 1000 ); // Jetpack uses 998.
		}
	}

	/**
	 * Enqueue styles for the top level menu
	 *
	 * @return void
	 */
	public static function enqueue_style() {
		wp_enqueue_style(
			'jetpack-admin-ui',
			plugin_dir_url( __FILE__ ) . 'css/jetpack-icon.css',
			array(),
			self::PACKAGE_VERSION
		);
	}

	/**
	 * Callback to the admin_menu hook that will register the enqueued menu items
	 *
	 * @return void
	 */
	public static function admin_menu_hook_callback() {
		$can_see_toplevel_menu  = true;
		$jetpack_plugin_present = class_exists( 'Jetpack_React_Page' );

		if ( ! $jetpack_plugin_present ) {
			add_action( 'admin_print_scripts', array( __CLASS__, 'enqueue_style' ) );
			add_menu_page(
				'Jetpack',
				'Jetpack',
				'read',
				'jetpack',
				'__return_null',
				'div',
				3
			);

			// If Jetpack plugin is not present, user will only be able to see this menu if they have enough capability to at least one of the sub menus being added.
			$can_see_toplevel_menu = false;
		}

		foreach ( self::$menu_items as $menu_item ) {
			if ( ! current_user_can( $menu_item['capability'] ) ) {
				continue;
			}

			$can_see_toplevel_menu = true;

			add_submenu_page(
				'jetpack',
				$menu_item['page_title'],
				$menu_item['menu_title'],
				$menu_item['capability'],
				$menu_item['menu_slug'],
				$menu_item['function'],
				$menu_item['position']
			);
		}

		if ( ! $jetpack_plugin_present ) {
			remove_submenu_page( 'jetpack', 'jetpack' );
		}

		if ( ! $can_see_toplevel_menu ) {
			remove_menu_page( 'jetpack' );
		}
	}

	/**
	 * Adds a new submenu to the Jetpack Top level menu
	 *
	 * The parameters this method accepts are the same as @see add_submenu_page. This class will
	 * aggreagate all menu items registered by stand-alone plugins and make sure they all go under the same
	 * Jetpack top level menu. It will also handle the top level menu registration in case the Jetpack plugin is not present.
	 *
	 * @param string   $page_title  The text to be displayed in the title tags of the page when the menu
	 *                              is selected.
	 * @param string   $menu_title  The text to be used for the menu.
	 * @param string   $capability  The capability required for this menu to be displayed to the user.
	 * @param string   $menu_slug   The slug name to refer to this menu by. Should be unique for this menu
	 *                              and only include lowercase alphanumeric, dashes, and underscores characters
	 *                              to be compatible with sanitize_key().
	 * @param callable $function    The function to be called to output the content for this page.
	 * @param int      $position    The position in the menu order this item should appear.
	 *
	 * @return string The resulting page's hook_suffix
	 */
	public static function add_menu( $page_title, $menu_title, $capability, $menu_slug, $function, $position = null ) {
		self::init();
		self::$menu_items[] = compact( 'page_title', 'menu_title', 'capability', 'menu_slug', 'function', 'position' );

		/**
		 * Let's return the page hook so consumers can use.
		 * We know all pages will be under Jetpack top level menu page, so we can hardcode the first part of the string.
		 * Using get_plugin_page_hookname here won't work because the top level page is not registered yet.
		 */
		return 'jetpack_page_' . $menu_slug;
	}

}
