tring( $timestamp ) ? $timestamp : number_format( $timestamp, 0, '', '' );

		return new \Jetpack_Tracks_Event(
			array_merge(
				$blog_details,
				(array) $properties,
				$identity,
				array(
					'_en' => $event_name,
					'_ts' => $timestamp_string,
				)
			)
		);
	}

	/**
	 * Get the identity to send to tracks.
	 *
	 * @param int $user_id The user id of the local user.
	 *
	 * @return array $identity
	 */
	public function tracks_get_identity( $user_id ) {

		// Meta is set, and user is still connected.  Use WPCOM ID.
		$wpcom_id = get_user_meta( $user_id, 'jetpack_tracks_wpcom_id', true );
		if ( $wpcom_id && $this->connection->is_user_connected( $user_id ) ) {
			return array(
				'_ut' => 'wpcom:user_id',
				'_ui' => $wpcom_id,
			);
		}

		// User is connected, but no meta is set yet.  Use WPCOM ID and set meta.
		if ( $this->connection->is_user_connected( $user_id ) ) {
			$wpcom_user_data = $this->connection->get_connected_user_data( $user_id );
			update_user_meta( $user_id, 'jetpack_tracks_wpcom_id', $wpcom_user_data['ID'] );

			return array(
				'_ut' => 'wpcom:user_id',
				'_ui' => $wpcom_user_data['ID'],
			);
		}

		// User isn't linked at all.  Fall back to anonymous ID.
		$anon_id = get_user_meta( $user_id, 'jetpack_tracks_anon_id', true );
		if ( ! $anon_id ) {
			$anon_id = \Jetpack_Tracks_Client::get_anon_id();
			add_user_meta( $user_id, 'jetpack_tracks_anon_id', $anon_id, false );
		}

		if ( ! isset( $_COOKIE['tk_ai'] ) && ! headers_sent() ) {
			setcookie( 'tk_ai', $anon_id, 0, COOKIEPATH, COOKIE_DOMAIN, is_ssl(), false ); // phpcs:ignore Jetpack.Functions.SetCookie -- This is a random string and should be fine.
		}

		return array(
			'_ut' => 'anon',
			'_ui' => $anon_id,
		);
	}
}