better error handling

includes/collection/class-followers.php

@@ -9,8 +9,7 @@ use Activitypub\Webfinger;
 use Activitypub\Model\Activity;
 use Activitypub\Model\Follower;
 
-use function Activitypub\safe_remote_get;
-use function Activitypub\safe_remote_post;
+use function Activitypub\is_tombstone;
 use function Activitypub\get_remote_metadata_by_actor;
 
 /**
@@ -152,6 +151,22 @@ class Followers {
 			)
 		);
 
+		register_term_meta(
+			self::TAXONOMY,
+			'errors',
+			array(
+				'type'              => 'string',
+				'single'            => false,
+				'sanitize_callback' => function( $value ) {
+					if ( ! is_string( $value ) ) {
+						throw new Exception( 'Error message is no valid string' );
+					}
+
+					return esc_sql( $value );
+				},
+			)
+		);
+
 		do_action( 'activitypub_after_register_taxonomy' );
 	}
 
@@ -197,12 +212,16 @@ class Followers {
 	public static function add_follower( $user_id, $actor ) {
 		$meta = get_remote_metadata_by_actor( $actor );
 
-		if ( ! $meta || is_wp_error( $meta ) || ! is_array( $meta ) ) {
-			return $meta;
+		$follower = new Follower( $actor );
+
+		if ( is_tombstone( $meta ) ) {
+			return;
+		} if ( empty( $meta ) || ! is_array( $meta ) || is_wp_error( $meta ) ) {
+			$follower->set_error( $meta );
+		} else {
+			$follower->from_meta( $meta );
 		}
 
-		$follower = new Follower( $actor );
-		$follower->from_meta( $meta );
 		$follower->upsert();
 
 		$result = wp_set_object_terms( $user_id, $follower->get_actor(), self::TAXONOMY, true );
@@ -299,9 +318,8 @@ class Followers {
 	 *
 	 * @return array The Term list of Followers, the format depends on $output
 	 */
-	public static function get_followers( $user_id, $output = ARRAY_N, $number = null, $offset = null ) {
-		$terms = new WP_Term_Query(
-			array(
+	public static function get_followers( $user_id, $output = ARRAY_N, $number = null, $offset = null, $hide_errors = false, $args = array() ) {
+		$defaults = array(
 			'taxonomy'   => self::TAXONOMY,
 			'hide_empty' => false,
 			'object_ids' => $user_id,
@@ -309,9 +327,20 @@ class Followers {
 			'offset'     => $offset,
 			'orderby'    => 'id',
 			'order'      => 'ASC',
-			)
 		);
 
+		if ( true === $hide_errors ) {
+			$defaults['meta_query'] = array(
+				array(
+					'key' => 'errors',
+					'compare' => 'NOT EXISTS',
+				),
+			);
+		}
+
+		$args  = wp_parse_args( $args, $defaults );
+		$terms = new WP_Term_Query( $args );
+
 		$items = array();
 
 		// change output format
@@ -358,6 +387,12 @@ class Followers {
 				'hide_empty' => false,
 				'object_ids' => $user_id,
 				'fields'     => 'ids',
+				'meta_query' => array(
+					array(
+						'key'     => 'inbox',
+						'compare' => 'EXISTS',
+					),
+				),
 			)
 		);
 

includes/functions.php

@@ -211,3 +211,24 @@ function get_author_description( $user_id ) {
 	}
 	return $description;
 }
+
+/**
+ * Check for Tombstone Objects
+ *
+ * @see https://www.w3.org/TR/activitypub/#delete-activity-outbox
+ *
+ * @param WP_Error $wp_error A WP_Error-Response of an HTTP-Request
+ *
+ * @return boolean true if HTTP-Code is 410 or 404
+ */
+function is_tombstone( $wp_error ) {
+	if ( ! is_wp_error( $wp_error ) ) {
+		return false;
+	}
+
+	if ( in_array( (int) $wp_error->get_error_code(), array( 404, 410 ), true ) ) {
+		return true;
+	}
+
+	return false;
+}

includes/model/class-follower.php

@@ -92,6 +92,22 @@ class Follower {
 	 */
 	private $meta;
 
+	/**
+	 * The latest received error.
+	 *
+	 * This will only temporary and will saved to $this->errors
+	 *
+	 * @var string
+	 */
+	private $error;
+
+	/**
+	 * A list of errors
+	 *
+	 * @var array
+	 */
+	private $errors;
+
 	/**
 	 * Maps the meta fields to the local db fields
 	 *
@@ -185,10 +201,39 @@ class Follower {
 		return null;
 	}
 
+	public function get_errors() {
+		if ( $this->errors ) {
+			return $this->errors;
+		}
+
+		$this->errors = get_term_meta( $this->id, 'errors' );
+		return $this->errors;
+	}
+
+	public function count_errors() {
+		$errors = $this->get_errors();
+
+		if ( is_array( $errors ) && ! empty( $errors ) ) {
+			return count( $errors );
+		}
+
+		return 0;
+	}
+
+	public function get_latest_error_message() {
+		$errors = $this->get_errors();
+
+		if ( is_array( $errors ) && ! empty( $errors ) ) {
+			return reset( $errors );
+		}
+
+		return '';
+	}
+
 	public function get_meta_by( $attribute ) {
 		$meta = $this->get_meta();
 
-		// try mapped data ($this->map_meta)
+		// try mapped data (see $this->map_meta)
 		foreach ( $this->map_meta as $remote => $local ) {
 			if ( $attribute === $local && isset( $meta[ $remote ] ) ) {
 				return $meta[ $remote ];
@@ -251,8 +296,21 @@ class Follower {
 
 		foreach ( $attributes as $attribute ) {
 			if ( $this->get( $attribute ) ) {
-				update_term_meta( $this->id, $attribute, $this->get( $attribute ), true );
+				update_term_meta( $this->id, $attribute, $this->get( $attribute ) );
 			}
 		}
+
+		if ( $this->error ) {
+			if ( is_string( $this->error ) ) {
+				$error = $this->error;
+			} elseif ( is_wp_error( $this->error ) ) {
+				$error = $this->error->get_error_message();
+			} else {
+				$error = __( 'Unknown Error or misconfigured Error-Message', 'activitypub' );
+			}
+
+			add_term_meta( $this->id, 'errors', $error );
+		}
+
 	}
 }

includes/table/class-followers.php

@@ -16,6 +16,8 @@ class Followers extends WP_List_Table {
 			'name'         => \__( 'Name', 'activitypub' ),
 			'username'     => \__( 'Username', 'activitypub' ),
 			'identifier'   => \__( 'Identifier', 'activitypub' ),
+			'errors'       => \__( 'Errors', 'activitypub' ),
+			'latest-error' => \__( 'Latest Error Message', 'activitypub' ),
 		);
 	}
 
@@ -51,6 +53,8 @@ class Followers extends WP_List_Table {
 				'name'         => esc_attr( $follower->get_name() ),
 				'username'     => esc_attr( $follower->get_username() ),
 				'identifier'   => esc_attr( $follower->get_actor() ),
+				'errors'       => $follower->count_errors(),
+				'latest-error' => $follower->get_latest_error_message(),
 			);
 
 			$this->items[] = $item;