PMPro - Restrict Categories on Sub-site in a Multisite Network

pmpro-restrict-categories-sub-site.php

<?php
/**
 * Restrict categories on the sub-site of a MS network.
 * Install as an mu-plugin (advanced users only)
 */
function my_pmpro_member_pmpro_has_membership_access_filter( $access, $post, $user, $levels ) {

	// If main site, leave alone.
	if ( is_main_site() || is_admin() ) {
		return $access;
	}

	// Get post object.
	global $post;
	if ( 'post' !== get_post_type() ) {
		return $access;
	}

	// Levels and categories to restrict.
	$categories_to_restrict = array(
		1 => array( // level ID.
			'general', // category slug.
			'uncategorized',
		),
		2 => array(
			'general',
			'restricted',
		),
	);

	$maybe_has_term = false;
	foreach ( $categories_to_restrict as $level_id => $categories ) {
		foreach ( $categories as $cat ) {
			if ( has_term( $cat, 'category', $post ) ) {
				$maybe_has_term = true;
			}
		}
	}

	if ( ! is_user_logged_in() && $maybe_has_term ) {
		return false;
	}

	// Get current level.
	global $current_user;
	$level = pmpro_getMembershipLevelForUser( $current_user->ID );

	// Return false on failure (no level).
	if ( ! $level ) {
		return false;
	}

	// If cat is set, see if in the restriction array.
	if ( $maybe_has_term && ! isset( $categories_to_restrict[ $level->id ] ) ) {
		return false;
	}

	// Nothing found, return as normal.
	return $access;
}
add_filter( 'pmpro_has_membership_access_filter', 'my_pmpro_member_pmpro_has_membership_access_filter', 10, 4 );