Workaround for WordPress/gutenberg#29484

init.php

@@ -22,7 +22,8 @@
 
 // Load funnel type classes.
 require WP_FUNNEL_DIR . 'src/legacy.php';
-require WP_FUNNEL_DIR . 'src/funnel.php';
+require WP_FUNNEL_DIR . 'src/dynamic.php';
+require WP_FUNNEL_DIR . 'src/natural.php';
 
 // Load other classes.
 require WP_FUNNEL_DIR . 'src/plugin.php';

src/funnel.php → src/dynamic.php

@@ -1,11 +1,11 @@
 <?php
 
 /**
- * Main funnel class.
+ * Dynamic funnel class.
  */
 namespace WP_Funnel_Manager;
 
-class Funnel_Type extends Legacy_Funnel_Type
+class Dynamic_Funnel_Type extends Legacy_Funnel_Type
 {
 	private $wp_id;
 	private $title;

src/natural.php

@@ -0,0 +1,45 @@
+<?php
+
+/**
+ * Natural funnel class.
+ */
+namespace WP_Funnel_Manager;
+
+class Natural_Funnel_Type extends Dynamic_Funnel_Type
+{
+	private $added_wp_link_pages = array();
+
+	public function __construct( $slug, $wp_id, $title, $blocks, $author )
+	{
+		parent::__construct( $slug, $wp_id, $title, $blocks, $author );
+	}
+
+	public function register()
+	{
+		parent::register();
+
+		// Workaround for https://github.com/WordPress/gutenberg/issues/29484
+		add_filter( 'the_content', array( $this, 'add_wp_link_pages' ), 0 );
+		add_filter( 'wp_link_pages_args', array( $this, 'added_wp_link_pages' ) );
+	}
+
+	public function added_wp_link_pages( $parsed_args )
+	{
+		$id = get_the_ID();
+		( get_post_type() !== $this->slug || isset( $this->added_wp_link_pages[ $id ] ) ) or $this->added_wp_link_pages[ $id ] = true;
+		return $parsed_args;
+	}
+
+	public function add_wp_link_pages( $content )
+	{
+		$id = get_the_ID();
+
+		if ( get_post_type() === $this->slug && $GLOBALS['multipage'] && !isset( $this->added_wp_link_pages[ $id ] ) )
+		{
+			$this->added_wp_link_pages[ $id ] = false;
+			return $content . wp_link_pages( array( 'echo' => 0 ) );
+		}
+
+		return $content;
+	}
+}

src/plugin.php

@@ -113,7 +113,7 @@ public function register_funnel_types()
 
 					if ( !$this->is_legacy || $slug !== 'funnel' )
 					{
-						$this->funnel_types[] = new Funnel_Type( $slug, $post->ID, $post->post_title, $post->post_content, $post->post_author );
+						$this->funnel_types[] = new Natural_Funnel_Type( $slug, $post->ID, $post->post_title, $post->post_content, $post->post_author );
 					}
 				}
 			}
@@ -163,7 +163,7 @@ public function menu()
 			$parent_capability = $this->is_legacy ? 'edit_posts' : $new_type_capability;
 
 			// Workaround for core ticket #52043. If the bug is encountered, the menu for one of the funnel types needs to be registered separately here.
-			$type = Funnel_Type::get_type_for_parent_menu();
+			$type = Dynamic_Funnel_Type::get_type_for_parent_menu();
 
 			if ( !is_null( $type ) || $this->is_legacy && $this->is_templated && !current_user_can( $parent_capability ) && current_user_can( $new_type_capability ) )
 			{