strict-security-headers.php

<?php
/**
 * Plugin Name: Strict Security Headers
 * Plugin URI:  https://dualfocus.dev/products/strict-security-headers/
 * Description: Enables enforcement of strict security headers on a site.
 * Author: Dual Focus
 * Author URI: https://dualfocus.dev/
 * Version: 0.1.0
 * License: MPL-2.0
 * License URI: https://www.mozilla.org/en-US/MPL/2.0/
 * Text Domain: strict-security-headers
 *
 * @package StrictSecurityHeaders
 * @author Dual Focus <support@dualfocus.dev>
 */

namespace DualFocus\StrictSecurityHeaders;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

const AUTOLOADER = __DIR__ . '/vendor/autoload.php';

/**
 * Plugin Class
 *
 * Used to store common references, such as a file directory, for easy lookups.
 */
final class Plugin {
	/**
	 * Plugin version.
	 *
	 * @var array
	 */
	private static $version = '0.1.0';

	/**
	 * Plugin class instances.
	 *
	 * @var array
	 */
	private static $instances = [];

	/**
	 * Sets an instance in the registry with the specified key.
	 *
	 * @param string $key The key to associate with the instance.
	 * @param mixed  $instance The instance to be stored in the registry.
	 *
	 * @return void
	 */
	public static function set( $key, $instance ) {
		self::$instances[ $key ] = $instance;
	}

	/**
	 * Retrieves the instance from the registry associated with the specified key.
	 *
	 * @param string $key The key to retrieve the instance.
	 * @return mixed|null The instance associated with the key, or null if the key is not found.
	 */
	public static function get( $key ) {
		return self::$instances[ $key ] ?? null;
	}

	/**
	 * Retrieves all instances stored in the registry.
	 *
	 * @return array An array containing all instances stored in the registry.
	 */
	public static function instances() {
		return self::$instances;
	}

	/**
	 * Lookup a location relative to the main plugin directory.
	 *
	 * @param string  $loc The location, directory or file, to lookup.
	 * @param boolean $url True if requesting the URL, otherwise it is a path.
	 *
	 * @return string The location relative to the main plugin directory.
	 */
	public static function dir( $loc = '', $url = false ) {
		return ( true === $url ? \plugin_dir_url( __FILE__ ) : \plugin_dir_path( __FILE__ ) ) . $loc;
	}

	/**
	 * Alias for looking up a URL more easily.
	 *
	 * @param string $loc The location, directory or file, to reference.
	 *
	 * @return string The location relative to the main plugin directory, as a url.
	 */
	public static function url( $loc = '' ) {
		return self::dir( $loc, true );
	}

	/**
	 * Method for getting the plugin version, primarily for use in enqueues.
	 *
	 * @return string Plugin version.
	 */
	public static function version() {
		return ( defined( 'WP_DEBUG' ) && WP_DEBUG ) ? time() : self::$version;
	}
}

if ( is_readable( AUTOLOADER ) ) {
	require_once AUTOLOADER;

	Plugin::set( 'ContentSecurityPolicy', new ContentSecurityPolicy() );
	Plugin::set( 'StrictTransportSecurity', new StrictTransportSecurity() );
	Plugin::set( 'PermissionsPolicy', new PermissionsPolicy() );
	Plugin::set( 'ReferrerPolicy', new ReferrerPolicy() );
	Plugin::set( 'XContentTypeOptions', new XContentTypeOptions() );
	Plugin::set( 'XFrameOptions', new XFrameOptions() );

	foreach ( Plugin::instances() as $key => $instance ) {
		if ( method_exists( $instance, 'init' ) ) {
			$instance->init();
		}
	}
}