active-plugins-override.php

<?php
/**
 * Plugin Name: Active Plugins Override
 * Description: Install this as an mu-plugin to override the active plugins via query parameters.
 * Plugin URI: https://gist.github.com/westonruter/9c791f4f8cc1cc37e7b3f4bc2db9be97
 * Requires PHP: 7.2
 * Version: 0.1.0
 * Author: WordPress Performance Team
 * Author URI: https://make.wordpress.org/performance/
 * License: GPLv2 or later
 * License URI: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * Update URI: false
 * GitHub Plugin URI: https://gist.github.com/westonruter/9c791f4f8cc1cc37e7b3f4bc2db9be97
 * Primary Branch: main
 */

namespace ActivePluginsOverride;

if ( defined( 'WP_TESTS_PHPUNIT_POLYFILLS_PATH' ) ) {
	return;
}

/**
 * Gets the always-active plugins.
 *
 * @return array
 */
function get_always_active_plugins(): array {
	if ( defined( 'ALWAYS_ACTIVE_PLUGINS' ) ) {
		if ( is_string( ALWAYS_ACTIVE_PLUGINS ) ) {
			return explode( ',', ALWAYS_ACTIVE_PLUGINS );
		} elseif ( is_array( ALWAYS_ACTIVE_PLUGINS ) ) {
			return ALWAYS_ACTIVE_PLUGINS;
		}
	}
	return array();
}

/**
 * Gets a plugin slug.
 *
 * @param string $plugin_file Plugin file.
 * @return string Plugin slug.
 */
function get_plugin_slug( string $plugin_file ): string {
	$plugin_file = strtok( $plugin_file, '/' );
	return basename( $plugin_file, '.php' );
}

/**
 * Gets requested plugins.
 *
 * @param string[] $query_vars Query vars.
 * @return string[] Plugin slugs.
 */
function get_requested_plugins( array $query_vars ): array {
	$plugins = array();
	foreach ( $query_vars as $key ) {
		if ( isset( $_GET[ $key ] ) ) {
			if ( is_array( $_GET[ $key ] ) ) {
				$plugins = array_merge( $plugins, array_filter( $_GET[ $key ], 'is_string' ) );
			} else if ( is_string( $_GET[ $key ] ) ) {
				$plugins = array_merge( $plugins, explode( ',', $_GET[ $key ] ) );
			}
		}
	}

	if ( count( $plugins ) > 0 ) {
		$plugins = array_map(
			static function ( string $plugin ): string {
				return get_plugin_slug( sanitize_file_name( $plugin ) );
			},
			$plugins
		);
	}

	return $plugins;
}

/**
 * Gets active override plugins.
 *
 * @return string[] Plugins.
 */
function get_active_override_plugins(): array {
	return get_requested_plugins( array( 'active_plugins', 'enable_plugins', 'enabled_plugins' ) );
}

/**
 * Gets inactive override plugins.
 *
 * @return string[] Plugins.
 */
function get_inactive_override_plugins(): array {
	return get_requested_plugins( array( 'inactive_plugins', 'disable_plugins', 'disabled_plugins' ) );
}

add_filter(
	'option_active_plugins',
	static function ( $plugins ) {
		if ( ! is_array( $plugins ) ) {
			$plugins = array();
		}

		$active_override_plugins   = get_active_override_plugins();
		$inactive_override_plugins = get_inactive_override_plugins();
		if ( count( $active_override_plugins ) > 0 && count( $inactive_override_plugins ) > 0 ) {
			wp_die( 'You cannot supply both active and inactive plugins.', '', array( 'response' => 400 ) );
		}

		if ( count( $inactive_override_plugins ) > 0 ) {
			$plugins = array_filter(
				$plugins,
				static function ( $plugin ) use ( $inactive_override_plugins ): bool {
					return ! in_array( get_plugin_slug( $plugin ), $inactive_override_plugins, true );
				}
			);
		}

		if ( count( $active_override_plugins ) > 0 ) {

			// TODO: Parse out the "Requires Plugins" header from the force-enabled plugins.
			if ( count( array_intersect( $active_override_plugins, array( 'embed-optimizer', 'image-prioritizer' ) ) ) > 0 ) {
				$active_override_plugins[] = 'optimization-detective';
				$active_override_plugins[] = 'od-admin-ui';
			}

			$plugins = array();
			require_once ABSPATH . '/wp-admin/includes/plugin.php';
			foreach ( array_keys( get_plugins() ) as $installed_plugin_file ) {
				if ( in_array( get_plugin_slug( $installed_plugin_file ), $active_override_plugins, true ) ) {
					$plugins[] = $installed_plugin_file;
				}
			}
		}

		if (
			isset( $_GET['disable_all_plugins'] ) ||
			in_array( 'none', $active_override_plugins, true )
		) {
			$plugins = array();
		}

		return array_unique( array_merge( $plugins, get_always_active_plugins() ) );
	}
);