Header/Footer: Link homepage to root site URL on Rosetta sites.

See #49

Author: iandunn

mu-plugins/blocks/global-header-footer/blocks.php

@@ -354,6 +354,33 @@ function normalize_rosetta_items( $rosetta_items ) {
 	return $normalized_items;
 }
 
+/**
+ * Retrieve the URL of the home page.
+ *
+ * Most of the time it will just be `w.org/`, but Rosetta sites use the URL of the "root site" homepage.
+ */
+function get_home_url() {
+	/** @var Rosetta_Sites $rosetta */
+	global $rosetta;
+
+	$url = false;
+
+	if ( is_rosetta_site() ) {
+		$root_site = $rosetta->get_root_site_id();
+		switch_to_blog( $root_site );
+
+		$url = home_url();
+
+		restore_current_blog();
+	}
+
+	if ( ! $url ) {
+		$url = 'https://wordpress.org/';
+	}
+
+	return $url;
+}
+
 /**
  * Retrieve the URL to download WordPress.
  *

mu-plugins/blocks/global-header-footer/header.php

@@ -1,7 +1,7 @@
 <?php
 
 namespace WordPressdotorg\MU_Plugins\Global_Header_Footer\Header;
-use function WordPressdotorg\MU_Plugins\Global_Header_Footer\{ get_download_url };
+use function WordPressdotorg\MU_Plugins\Global_Header_Footer\{ get_home_url, get_download_url };
 
 defined( 'WPINC' ) || die();
 
@@ -18,15 +18,15 @@
 	<!-- The design calls for two logos, a small "mark" on mobile/tablet, and the full logo for desktops. -->
 	<!-- wp:image {"width":27,"height":27,"className":"global-header__wporg-logo-mark"} -->
 	<figure class="wp-block-image is-resized global-header__wporg-logo-mark">
-		<a href="https://wordpress.org/">
+		<a href="<?php echo esc_url( get_home_url() ); ?>">
 			<img src="https://wordpress.org/style/images/w-mark.svg" alt="WordPress.org" width="27" height="27" />
 		</a>
 	</figure>
 	<!-- /wp:image -->
 
 	<!-- wp:image {"width":160,"height":24,"className":"global-header__wporg-logo-full"} -->
 	<figure class="wp-block-image is-resized global-header__wporg-logo-full">
-		<a href="https://wordpress.org/">
+		<a href="<?php echo esc_url( get_home_url() ); ?>">
 			<img src="<?php echo plugin_dir_url( __FILE__ ) . 'images/wporg-logo.svg'; ?>" alt="WordPress.org" width="160" height="24" />
 		</a>
 	</figure>