Add an mu-plugin for tweaking the Stream plugin to meet our needs (#172)

For now this just replaces Stream's posts connector with our own modified version so that it will log post changes correctly when made in the block editor. Other tweaks may follow.

mu-plugins/loader.php

@@ -6,3 +6,4 @@
 require_once __DIR__ . '/blocks/global-header-footer/blocks.php';
 require_once __DIR__ . '/global-fonts/index.php';
 require_once __DIR__ . '/skip-to/skip-to.php';
+require_once __DIR__ . '/stream-tweaks/index.php';

mu-plugins/stream-tweaks/class-connector-posts.php

@@ -0,0 +1,22 @@
+<?php
+/**
+ * Connector for Posts
+ *
+ * This is a hotfix for the Stream plugin to enable logging post changes that happen through an API context (i.e.
+ * in the block editor). This change has been merged in the GitHub repo for the Stream plugin, but as of version
+ * 3.8.2 it has not been released to the plugin directory.
+ */
+
+namespace WordPressdotorg\MU_Plugins\Stream_Tweaks;
+
+/**
+ * Class - Connector_Posts
+ */
+class Connector_Posts extends \WP_Stream\Connector_Posts {
+	/**
+	 * Register connector in the WP Frontend
+	 *
+	 * @var bool
+	 */
+	public $register_frontend = true;
+}

mu-plugins/stream-tweaks/index.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace WordPressdotorg\MU_Plugins\Stream_Tweaks;
+
+add_filter( 'wp_stream_connectors', __NAMESPACE__ . '\replace_posts_connector' );
+
+/**
+ * Substitute Stream's posts connector class for our modified version.
+ *
+ * @param array $connector_classes
+ *
+ * @return mixed
+ */
+function replace_posts_connector( $connector_classes ) {
+	if ( ! function_exists( 'wp_stream_get_instance' ) ) {
+		return $connector_classes;
+	}
+
+	require_once __DIR__ . '/class-connector-posts.php';
+
+	$stream_plugin_instance = wp_stream_get_instance();
+	$new_posts_connector = new Connector_Posts( $stream_plugin_instance->log ); // WordPressdotorg namespaced version.
+
+	// Remove the default posts connector class if it has been initialized.
+	if ( isset( $connector_classes[ $new_posts_connector->name ] ) ) {
+		unset( $connector_classes[ $new_posts_connector->name ] );
+	}
+
+	if ( $new_posts_connector->is_dependency_satisfied() ) {
+		$connector_classes[ $new_posts_connector->name ] = $new_posts_connector;
+	}
+
+	return $connector_classes;
+}