Disable Pressbooks features if Pressbooks isn't installed.

dist/mix-manifest.json

@@ -1,5 +1,5 @@
 {
     "/scripts/aldine.js": "/scripts/aldine.js?id=e0b974d636182fae8146",
-    "/styles/aldine.css": "/styles/aldine.css?id=bb6ed631d6965a12d276",
+    "/styles/aldine.css": "/styles/aldine.css?id=313d7502c19cb88b2c4e",
     "/scripts/customizer.js": "/scripts/customizer.js?id=f1f1f4225cba4c1b35f2"
 }

header.php

@@ -58,12 +58,12 @@
 						<?php switch_to_blog( 1 ); echo get_bloginfo( 'name', 'display' ); restore_current_blog(); ?>
 					</span> */ ?>
 				</a>
-				<h1><a href="{{ home_url('/' ); ?>"><?php echo get_bloginfo( 'name', 'display' ); ?></a></h1>
+				<h1><a href="<?php echo home_url('/' ); ?>"><?php echo get_bloginfo( 'name', 'display' ); ?></a></h1>
 				<p><?php echo get_bloginfo( 'description', 'display' ); ?></p>
 			</div>
 			<div class="header__end-container">
 				<nav class="header__nav js-header-nav" id="navigation">
-					<?php if ( function_exists( 'pb_meets_minimum_requirements' ) && pb_meets_minimum_requirements() ) : ?>
+					<?php if ( defined( 'PB_PLUGIN_VERSION' ) ) : ?>
 						<a href="<?php echo home_url( '/catalog' ); ?>">Catalog</a>
 					<?php endif; ?>
 					<?php if ( get_option( 'pb_network_contact_form' ) ) : ?>

inc/customizer/namespace.php

@@ -94,7 +94,7 @@ function customize_register( \WP_Customize_Manager $wp_customize ) {
 		'settings' => 'pb_network_twitter',
 	]);
 
-	if ( function_exists( 'pb_meets_minimum_requirements' ) && pb_meets_minimum_requirements() ) {
+	if ( defined( 'PB_PLUGIN_VERSION' ) ) {
 		$wp_customize->add_section('pb_front_page_catalog', [
 			'title' => __( 'Front Page Catalog', 'pressbooks-aldine' ),
 			'priority' => 25,

inc/helpers/namespace.php

@@ -30,7 +30,7 @@ function get_block_count() {
  * @param string $subject
  */
 function get_catalog_data( $page = 1, $per_page = 10, $orderby = 'title', $license = '', $subject = '' ) {
-	if ( function_exists( 'pb_meets_minimum_requirements' ) && pb_meets_minimum_requirements() ) {
+	if ( defined( 'PB_PLUGIN_VERSION' ) ) {
 			$request = new \WP_REST_Request( 'GET', '/pressbooks/v2/books' );
 			$request->set_query_params([
 				'page' => $page,
@@ -67,7 +67,7 @@ function get_catalog_data( $page = 1, $per_page = 10, $orderby = 'title', $licen
  * @return array
  */
 function get_catalog_licenses() {
-	if ( class_exists( '\\Pressbooks\\Licensing' ) ) {
+	if ( defined( 'PB_PLUGIN_VERSION' ) ) {
 		$licenses = ( new \Pressbooks\Licensing() )->getSupportedTypes();
 		foreach ( $licenses as $key => $value ) {
 			$licenses[ $key ] = preg_replace( '/\([^)]+\)/', '', $value['desc'] );

partials/content-page-catalog.php

@@ -22,7 +22,7 @@ $catalog_data = get_catalog_data( $current_page, 9, $orderby, $license, $subject
 $previous_page = ( $current_page > 1 ) ? $current_page - 1 : 0;
 $next_page = $current_page + 1;
 $licenses = get_catalog_licenses();
-$subject_groups = ( function_exists( '\\Pressbooks\\Metadata\\get_thema_subjects' ) ) ? \Pressbooks\Metadata\get_thema_subjects() : [];
+$subject_groups = ( defined( 'PB_PLUGIN_VERSION' ) ) ? \Pressbooks\Metadata\get_thema_subjects() : [];
 
 ?>