WordPress - Are We Really in Admin?

functions.php

/** 
 * is_in_admin
 * 
 * Check and see if we are indeed in the admin area of the site
 * 
 * @since 7.4
 * @access public
 * @static
 * @author Kevin Pirnie <[email protected]>
 * @package Kevin's Framework
 * 
 * @return bool Returns if we are or not
 * 
*/
public static function is_in_admin( ) : bool {

	// get the current URL
	$_current_url = home_url( add_query_arg( null, null ) );

	// get the admin URL
	$_admin_url = strtolower( admin_url( ) );

	// get the referrer
	$_referrer  = strtolower( wp_get_referer( ) );

	// let's see if it's a block update request
	$_block_update_request = self::is_rest_request( ) && strpos( $_admin_url, '/wp-admin/' ) > 0 && ! strpos( $_admin_url, '/wp-admin/admin-ajax.php' );

	// check it out
	if( $_block_update_request ) {

		// it is, return true
		return true;

	}

	// cloud this be an admin request?
	if ( 0 === strpos( $_current_url, $_admin_url ) ) {
		
		// did the user come from admin?
		if ( 0 === strpos( $_referrer, $_admin_url ) ) {

			// they did, return true
			return true;

		// otherwise
		} else {
			
			// is it an admin ajax request?
			if( function_exists( 'wp_doing_ajax' ) ) {
		
				// return if we are NOT
				return ! wp_doing_ajax( );
			
			// otherwise
			} else {
			
				// maybe we actually are?
				return ! ( defined( 'DOING_AJAX' ) && DOING_AJAX );
			
			}

		}
	
	}
	
	// otherwise just return false
	return false;

}