#lang racket/base
;; Assertions, Messages and Protocols for RacketMQ

(provide (struct-out notification)
         (struct-out update-subscription)
         (struct-out subscription)
         (struct-out subscription-settings)
         (struct-out local-topic-config)
         (struct-out topic-demand)
         (struct-out local-topic-demand)
         (struct-out local-host)
         (struct-out canonical-local-host))

;; A Topic is a URIString.

;; A Deadline is an (Option Number), where #f indicates "unbounded",
;; and numbers indicate a moment in time as a Unix epoch timestamp as
;; might be returned from `current-seconds`.

;; A Notification contains both `topic-name`, indicating the *local*
;; name for the topic that is being subscribed to, as well as
;; `canonical-topic`, which is the rel=self URL given by the upstream
;; topic itself. The former is our local key for finding resources;
;; the latter is a property of the topic content, not a property of
;; the subscription. The same is true of `canonical-hub`: it pertains
;; to the topic, not the subscription. The `topic-name` is the only
;; field pertaining to a subscription; all the others pertain to the
;; content.
(struct notification (topic-name ;; Topic
                      canonical-hub ;; Option URLString
                      canonical-topic ;; Option Topic
                      content ;; Bytes
                      content-type) ;; Option String
  #:prefab) ;; MESSAGE

;; (update-subscription Topic URLString (Option SubscriptionSettings))
(struct update-subscription (topic callback settings) #:prefab) ;; MESSAGE

;; (subscription Topic URLString SubscriptionSettings)
(struct subscription (topic callback settings-) #:prefab) ;; ASSERTION

(struct subscription-settings (expiry-deadline ;; Deadline
                               secret ;; Option Bytes
                               poll-interval-seconds) ;; Option Number
  #:prefab)

;; (local-topic-config Topic (Option Number) (Option Number))
(struct local-topic-config (name max-age max-count) #:prefab) ;; ASSERTION

;; (topic-demand Topic (Option Number))
(struct topic-demand (topic-name poll-interval-seconds) #:prefab) ;; ASSERTION

;; (local-topic-demand String)
(struct local-topic-demand (name) #:prefab) ;; ASSERTION

;; (local-host String)
(struct local-host (name port) #:prefab) ;; ASSERTION

;; (canonical-local-host String)
(struct canonical-local-host (name port) #:prefab) ;; ASSERTION