A WordPress plugin that manages the "Groups" plugin filters across a Multisite network.

groups-filters-manage.php

<?php
/**
 * Plugin Name: Manage Groups Filters
 * Plugin URI: https://gist.github.com/christianwach/334816adcb29565dbfe35fd8d5c6d5b5
 * Description: Manages the "Groups" plugin filters across a Multisite network.
 * Version: 1.0
 *
 * Put this plugin in /wp-content/mu-plugins/
 *
 * @package CMW_Groups_Filters_Manage
 */

// Exit if accessed directly.
defined( 'ABSPATH' ) || exit;

/**
 * Manage Groups Filters Class.
 *
 * A class that holds plugin functionality.
 *
 * @since 1.0
 */
class CMW_Groups_Filters_Manage {

	/**
	 * Constructor.
	 *
	 * @since 1.0
	 */
	public function __construct() {

		// Init when all plugins have loaded.
		add_action( 'plugins_loaded', [ $this, 'initialise' ] );

	}

	/**
	 * Initialises this object.
	 *
	 * @since 1.0
	 */
	public function initialise() {

		// Bail if the "Groups" plugin is not active on the loaded Site.
		if ( ! defined( 'GROUPS_CORE_VERSION' ) ) {
			return;
		}

		// Register hooks.
		$this->register_hooks();

	}

	/**
	 * Registers hooks.
	 *
	 * @since 1.0
	 */
	public function register_hooks() {

		// Ensure "Groups" only filters on Sites where it is active.
		add_action( 'switch_blog', [ $this, 'switch_to' ], 20, 3 );
		add_action( 'switch_blog', [ $this, 'switch_back' ], 21, 3 );

	}

	/**
	 * Toggles the "Groups" plugin callbacks when switching to a Site.
	 *
	 * @since 1.0
	 */
	public function switch_to( $new_blog_id, $prev_blog_id, $context ) {

		// Bail if not "switching to".
		if ( 'switch' !== $context ) {
			return;
		}

		// We need to make sure "is_plugin_active_for_network" is available.
		if ( ! function_exists( 'is_plugin_active_for_network' ) ) {
			require_once ABSPATH . '/wp-admin/includes/plugin.php';
		}

		// Toggle filter depending on whether the "Groups" plugin is active on the Site.
		if ( ! is_plugin_active( 'groups/groups.php' ) ) {
			$this->user_has_cap_hook_remove();
		} else {
			$this->user_has_cap_hook_add();
		}

	}

	/**
	 * Toggles the "Groups" plugin callbacks when restoring a Site.
	 *
	 * @since 1.0
	 */
	public function switch_back( $new_blog_id, $prev_blog_id, $context ) {

		// Bail if not "switching back".
		if ( 'restore' !== $context ) {
			return;
		}

		// We need to make sure "is_plugin_active_for_network" is available.
		if ( ! function_exists( 'is_plugin_active_for_network' ) ) {
			require_once ABSPATH . '/wp-admin/includes/plugin.php';
		}

		// Toggle filter depending on whether the "Groups" plugin is active on the Site.
		if ( ! is_plugin_active( 'groups/groups.php' ) ) {
			$this->user_has_cap_hook_remove();
		} else {
			$this->user_has_cap_hook_add();
		}

	}

	/**
	 * Removes the "Groups" plugin "user_has_cap" callback.
	 *
	 * @since 1.0
	 */
	public function user_has_cap_hook_remove() {

		// Don't remove when class not present.
		if ( ! class_exists( 'Groups_WordPress' ) ) {
			return;
		}

		// Don't remove when filter not present.
		if ( ! has_filter( 'user_has_cap', [ 'Groups_WordPress', 'user_has_cap' ] ) ) {
			return;
		}

		// Okay, remove the filter.
		remove_filter( 'user_has_cap', [ 'Groups_WordPress', 'user_has_cap' ], PHP_INT_MAX );

	}

	/**
	 * Adds the "Groups" plugin "user_has_cap" callback.
	 *
	 * @since 1.0
	 */
	public function user_has_cap_hook_add() {

		// Don't add when class not present.
		if ( ! class_exists( 'Groups_WordPress' ) ) {
			return;
		}

		// Don't add when filter is present.
		if ( has_filter( 'user_has_cap', [ 'Groups_WordPress', 'user_has_cap' ] ) ) {
			return;
		}

		// Okay, add the filter.
		add_filter( 'user_has_cap', [ 'Groups_WordPress', 'user_has_cap' ], PHP_INT_MAX, 4 );

	}

}

/**
 * Gets a reference to this plugin.
 *
 * @since 1.0
 *
 * @return CMW_Groups_Filters_Manage $plugin The plugin reference.
 */
function cmw_groups_filters_manage() {

	// Return instance.
	static $plugin;
	if ( ! isset( $plugin ) ) {
		$plugin = new CMW_Groups_Filters_Manage();
	}
	return $plugin;

}

// Bootstrap plugin.
cmw_groups_filters_manage();