Adding Saburly Headless WP theme inspired by postlights serverless solution

wordpress/wp-content/themes/saburly-headless/inc/admin.php

@@ -0,0 +1,31 @@
+<?php
+/**
+ * By default, in Add/Edit Post, WordPress moves checked categories to the top of the list and unchecked to the bottom.
+ * When you have subcategories that you want to keep below their parents at all times, this makes no sense.
+ * This function removes automatic reordering so the categories widget retains its order regardless of checked state.
+ * Thanks to https://stackoverflow.com/a/12586404
+ *
+ * @param arr $args Array of arguments.
+ * @return arr
+ */
+function taxonomy_checklist_checked_ontop_filter( $args ) {
+    $args['checked_ontop'] = false;
+    return $args;
+}
+
+add_filter( 'wp_terms_checklist_args', 'taxonomy_checklist_checked_ontop_filter' );
+
+/**
+ * Customize the preview button in the WordPress admin to point to the headless client.
+ *
+ * @param  str $link The WordPress preview link.
+ * @return str The headless WordPress preview link.
+ */
+function set_headless_preview_link( $link ) {
+    return get_frontend_origin() . '/'
+        . '_preview/'
+        . get_the_ID() . '/'
+        . wp_create_nonce( 'wp_rest' );
+}
+
+add_filter( 'preview_post_link', 'set_headless_preview_link' );