felixarntz/oop-admin-pages

<?php
/**
 * WordPress_Admin_Panels class
 *
 * @package Leaves_And_Love\OOP_Admin_Pages\Admin_Page\WordPress_Admin_Panels
 * @since 1.0.0
 */

namespace Leaves_And_Love\OOP_Admin_Pages\Admin_Page\WordPress_Admin_Panels;

use Leaves_And_Love\OOP_Admin_Pages\Exception\Invalid_Admin_Panel_Exception;

/**
 * Class holding the available WordPress admin panels.
 *
 * @since 1.0.0
 */
final class WordPress_Admin_Panels {

    const SITE    = 'site';
    const NETWORK = 'network';
    const USER    = 'user';

    /**
     * Available admin panels.
     *
     * @since 1.0.0
     * @static
     * @var array
     */
    private static $panels = array();

    /**
     * Whether the available admin panels have been initialized yet.
     *
     * @since 1.0.0
     * @static
     * @var bool
     */
    private static $initialized = false;

    /**
     * Gets an instance of an admin panel.
     *
     * @since 1.0.0
     * @static
     *
     * @param string $slug Admin panel identifier.
     * @return WordPress_Admin_Panel Admin panel instance.
     *
     * @throws Invalid_Admin_Panel_Exception Thrown when admin panel identifier is invalid.
     */
    public static function get_panel( string $slug ) : WordPress_Admin_Panel {
        self::maybe_initialize();

        if ( ! isset( self::$panels[ $slug ] ) ) {
            throw new Invalid_Admin_Panel_Exception( sprintf( 'An admin panel with the identifier %s is not available.', $slug ) );
        }

        return self::$panels[ $slug ];
    }

    /**
     * Gets the current admin panel.
     *
     * @since 1.0.0
     * @static
     *
     * @return WordPress_Admin_Panel Admin panel instance.
     */
    public static function get_current_panel() : WordPress_Admin_Panel {
        switch ( true ) {
            case is_user_admin():
                return self::get_panel( self::USER );
            case is_network_admin():
                return self::get_panel( self::NETWORK );
            default:
                return self::get_panel( self::SITE );
        }
    }

    /**
     * Instantiates the available admin panels as necessary.
     *
     * @since 1.0.0
     * @static
     */
    private static function maybe_initialize() {
        if ( self::$initialized ) {
            return;
        }

        self::initialize();

        self::$initialized = true;
    }

    /**
     * Instantiates the available admin panels.
     *
     * @since 1.0.0
     * @static
     */
    private static function initialize() {
        self::$panels = array(
            self::SITE    => new WordPress_Site_Admin_Panel(),
            self::NETWORK => new WordPress_Network_Admin_Panel(),
            self::USER    => new WordPress_User_Admin_Panel(),
        );
    }
}