Reset the post_author when user has been deleted

Sets the post_author to 2 if the actual post_author is not found

functions.php

@@ -41,3 +41,4 @@
 require(__DIR__.'/lib/tiny_mce.php');
 require(__DIR__.'/lib/image-default-link-type.php');
 require(__DIR__.'/lib/feeds.php');
+require(__DIR__.'/lib/set-archive-author.php');

lib/byline.php

@@ -4,17 +4,11 @@
 function gds_byline()
 {
 	?>
-	<span class="govuk-visually-hidden">Posted by: </span><?php
-	$tmp_author_id = get_post_field('post_author', $post->ID);
-	$tmp_user =  get_user_by('id', $author_id);
-	if (empty($tmp_user->user_login)) {
-		echo "Deleted user $tmp_author_id";
-		error_log("{$post->ID} has deleted user $tmp_author_id", 0);
+	<span class="govuk-visually-hidden">Posted by: </span>
+	<?php
+	if (function_exists('coauthors_posts_links')) {
+		coauthors_posts_links(', ');
 	} else {
-		if (function_exists('coauthors_posts_links')) {
-			coauthors_posts_links(', ');
-		} else {
-			?> <a href="<?php echo get_author_posts_url(get_the_author_meta('ID')) ?>" rel="author" class="govuk-link"><?php echo get_the_author() ?></a> <?php
-		}
+		?> <a href="<?php echo get_author_posts_url(get_the_author_meta('ID')) ?>" rel="author" class="govuk-link"><?php echo get_the_author() ?></a> <?php
 	}
 }

lib/set-archive-author.php

@@ -0,0 +1,16 @@
+<?php
+
+// Set the post_author to be "2"
+
+function set_archive_author($data, $postarr)
+{
+	$fix_types = ["page", "post", "attachment"];
+
+	if (!in_array($data['post_type'], $fix_types)) {
+		return $data;
+	}
+
+	$data['post_author'] = 2;
+
+	return $data;
+}

templates/entry-meta.php

@@ -1,5 +1,18 @@
-<div class="govuk-body-s">
-  <?php gds_byline(); ?>, <span class="govuk-visually-hidden">Posted on: </span><time class="updated" datetime="<?php echo get_the_time('c') ?>"><?php echo get_the_date('j F Y') ?></time>
+<div class="govuk-body-s"><?php
+
+// If the post is owned by a deleted user, set it to the archive user
+$tmp_author_id = get_post_field('post_author', $post->ID);
+if ($tmp_author_id > 2) {
+	$tmp_user = get_user_by('id', $tmp_author_id);
+	if (empty($tmp_user->user_login)) {
+		error_log("post {$post->ID} has deleted user $tmp_author_id", 0);
+		add_filter('wp_insert_post_data', 'set_archive_author', '99', 2);
+		wp_update_post($post);
+	}
+}
+
+gds_byline();
+?>, <span class="govuk-visually-hidden">Posted on: </span><time class="updated" datetime="<?php echo get_the_time('c') ?>"><?php echo get_the_date('j F Y') ?></time>
   -
   <span class="govuk-visually-hidden">Categories: </span>
   <?php echo get_the_category_list(', ') ?>