1 files changed, 101 insertions, 0 deletions
diff --git a/wp-includes/blocks/categories.php b/wp-includes/blocks/categories.php
new file mode 100644
index 0000000..7e3979b
--- /dev/null
+++ b/wp-includes/blocks/categories.php
@@ -0,0 +1,101 @@
+<?php
+/**
+ * Server-side rendering of the `core/categories` block.
+ *
+ * @package WordPress
+ */
+
+/**
+ * Renders the `core/categories` block on server.
+ *
+ * @param array $attributes The block attributes.
+ *
+ * @return string Returns the categories list/dropdown markup.
+ */
+function render_block_core_categories( $attributes ) {
+	static $block_id = 0;
+	++$block_id;
+
+	$args = array(
+		'echo'         => false,
+		'hierarchical' => ! empty( $attributes['showHierarchy'] ),
+		'orderby'      => 'name',
+		'show_count'   => ! empty( $attributes['showPostCounts'] ),
+		'title_li'     => '',
+		'hide_empty'   => empty( $attributes['showEmpty'] ),
+	);
+	if ( ! empty( $attributes['showOnlyTopLevel'] ) && $attributes['showOnlyTopLevel'] ) {
+		$args['parent'] = 0;
+	}
+
+	if ( ! empty( $attributes['displayAsDropdown'] ) ) {
+		$id                       = 'wp-block-categories-' . $block_id;
+		$args['id']               = $id;
+		$args['show_option_none'] = __( 'Select Category' );
+		$wrapper_markup           = '<div %1$s><label class="screen-reader-text" for="' . esc_attr( $id ) . '">' . __( 'Categories' ) . '</label>%2$s</div>';
+		$items_markup             = wp_dropdown_categories( $args );
+		$type                     = 'dropdown';
+
+		if ( ! is_admin() ) {
+			// Inject the dropdown script immediately after the select dropdown.
+			$items_markup = preg_replace(
+				'#(?<=</select>)#',
+				build_dropdown_script_block_core_categories( $id ),
+				$items_markup,
+				1
+			);
+		}
+	} else {
+		$wrapper_markup = '<ul %1$s>%2$s</ul>';
+		$items_markup   = wp_list_categories( $args );
+		$type           = 'list';
+	}
+
+	$wrapper_attributes = get_block_wrapper_attributes( array( 'class' => "wp-block-categories-{$type}" ) );
+
+	return sprintf(
+		$wrapper_markup,
+		$wrapper_attributes,
+		$items_markup
+	);
+}
+
+/**
+ * Generates the inline script for a categories dropdown field.
+ *
+ * @param string $dropdown_id ID of the dropdown field.
+ *
+ * @return string Returns the dropdown onChange redirection script.
+ */
+function build_dropdown_script_block_core_categories( $dropdown_id ) {
+	ob_start();
+	?>
+	<script type='text/javascript'>
+	/* <![CDATA[ */
+	( function() {
+		var dropdown = document.getElementById( '<?php echo esc_js( $dropdown_id ); ?>' );
+		function onCatChange() {
+			if ( dropdown.options[ dropdown.selectedIndex ].value > 0 ) {
+				location.href = "<?php echo esc_url( home_url() ); ?>/?cat=" + dropdown.options[ dropdown.selectedIndex ].value;
+			}
+		}
+		dropdown.onchange = onCatChange;
+	})();
+	/* ]]> */
+	</script>
+	<?php
+	return ob_get_clean();
+}
+
+/**
+ * Registers the `core/categories` block on server.
+ */
+function register_block_core_categories() {
+	register_block_type_from_metadata(
+		__DIR__ . '/categories',
+		array(
+			'render_callback' => 'render_block_core_categories',
+		)
+	);
+}
+add_action( 'init', 'register_block_core_categories' );