// Calendar shouldn't be rendered

	// when there are no published posts on the site.

	if ( ! block_core_calendar_has_published_posts() ) {

		if ( is_user_logged_in() ) {

			return '<div>' . __( 'The calendar block is hidden because there are no published posts.' ) . '</div>';

		}

		return '';

	}

/**

 * Returns whether or not there are any published posts.

 *

 * Used to hide the calendar block when there are no published posts.

 * This compensates for a known Core bug: https://core.trac.wordpress.org/ticket/12016

 *

 * @return bool Has any published posts or not.

 */

function block_core_calendar_has_published_posts() {

	// Multisite already has an option that stores the count of the published posts.

	// Let's use that for multisites.

	if ( is_multisite() ) {

		return 0 < (int) get_option( 'post_count' );

	}

	// On single sites we try our own cached option first.

	$has_published_posts = get_option( 'wp_calendar_block_has_published_posts', null );

	if ( null !== $has_published_posts ) {

		return (bool) $has_published_posts;

	}

	// No cache hit, let's update the cache and return the cached value.

	return block_core_calendar_update_has_published_posts();

}

/**

 * Queries the database for any published post and saves

 * a flag whether any published post exists or not.

 *

 * @return bool Has any published posts or not.

 */

function block_core_calendar_update_has_published_posts() {

	global $wpdb;

	$has_published_posts = (bool) $wpdb->get_var( "SELECT 1 as test FROM {$wpdb->posts} WHERE post_type = 'post' AND post_status = 'publish' LIMIT 1" );

	update_option( 'wp_calendar_block_has_published_posts', $has_published_posts );

	return $has_published_posts;

}

// We only want to register these functions and actions when

// we are on single sites. On multi sites we use `post_count` option.

if ( ! is_multisite() ) {

	/**

	 * Handler for updating the has published posts flag when a post is deleted.

	 *

	 * @param int $post_id Deleted post ID.

	 */

	function block_core_calendar_update_has_published_post_on_delete( $post_id ) {

		$post = get_post( $post_id );

		if ( ! $post || 'publish' !== $post->post_status || 'post' !== $post->post_type ) {

			return;

		}

		block_core_calendar_update_has_published_posts();

	}

	/**

	 * Handler for updating the has published posts flag when a post status changes.

	 *

	 * @param string  $new_status The status the post is changing to.

	 * @param string  $old_status The status the post is changing from.

	 * @param WP_Post $post       Post object.

	 */

	function block_core_calendar_update_has_published_post_on_transition_post_status( $new_status, $old_status, $post ) {

		if ( $new_status === $old_status ) {

			return;

		}

		if ( 'post' !== get_post_type( $post ) ) {

			return;

		}

		if ( 'publish' !== $new_status && 'publish' !== $old_status ) {

			return;

		}

		block_core_calendar_update_has_published_posts();

	}

	add_action( 'delete_post', 'block_core_calendar_update_has_published_post_on_delete' );

	add_action( 'transition_post_status', 'block_core_calendar_update_has_published_post_on_transition_post_status', 10, 3 );

}