wp-graphql-posts-to-posts.php

<?php
/**
 * Plugin Name: WPGraphQL for Posts 2 Posts
 * Description: Creates WPGraphQL connections for all of your Posts 2 Posts connections.
 * Version:     0.5.0.2
 * Author:      Harness Software, Kellen Mace
 * Author URI:  https://harnessup.com/
 * License:     GPLv2 or later
 * License URI: http://www.gnu.org/licenses/gpl-2.0.html
 */

add_action(
	'plugins_loaded',
	function() {
		$autoload = plugin_dir_path( __FILE__ ) . 'vendor/autoload.php';

		$dependencies = [
			'Composer autoload files' => is_readable( $autoload ),
			'WPGraphQL'               => class_exists( 'WPGraphQL' ),
			'Posts 2 Posts'           => function_exists( '_p2p_load' ),
		];

		$missing_dependencies = array_keys( array_diff( $dependencies, array_filter( $dependencies ) ) );

		$display_admin_notice = function() use ( $missing_dependencies ) {
			?>
		<div class="notice notice-error">
			<p>The WPGraphQL for Posts 2 Posts plugin can't be loaded because these dependencies are missing:</p>
			<ul>
				<?php foreach ( $missing_dependencies as $missing_dependency ) : ?>
					<li><?php echo esc_html( $missing_dependency ); ?></li>
				<?php endforeach; ?>
			</ul>
		</div>
			<?php
		};

		// If dependencies are missing, display admin notice and return early.
		if ( $missing_dependencies ) {
			add_action( 'admin_notices', $display_admin_notice );
			add_action( 'network_admin_notices', $display_admin_notice ); // Needed for multisite only.

			return;
		}

		require_once $autoload;

		( new WPGraphQLPostsToPosts\WPGraphQLPostsToPosts() )->run();
	}
);