(.module:
  [lux #*
   [abstract
    [monad (#+ do)]]
   [control
    [io (#+ IO)]
    ["." try (#+ Try)]
    [concurrency
     ["." promise (#+ Promise)]
     ["." stm]]]
   [data
    [binary (#+ Binary)]]
   [world
    [net
     [uri (#+ URI)]]]])

(signature: #export (Repository !)
  (: (-> URI (! (Try Binary)))
     download)
  (: (-> URI Binary (! (Try Any)))
     upload))

(def: #export (async repository)
  (-> (Repository IO) (Repository Promise))
  (structure
   (def: (download uri)
     (promise.future (\ repository download uri)))

   (def: (upload uri content)
     (promise.future (\ repository upload uri content)))
   ))

(signature: #export (Simulation s)
  (: (-> URI s (Try [s Binary]))
     on_download)
  (: (-> URI Binary s (Try s))
     on_upload))

(def: #export (mock simulation init)
  (All [s] (-> (Simulation s) s (Repository Promise)))
  (let [state (stm.var init)]
    (structure
     (def: (download uri)
       (stm.commit
        (do {! stm.monad}
          [|state| (stm.read state)]
          (case (\ simulation on_download uri |state|)
            (#try.Success [|state| output])
            (do !
              [_ (stm.write |state| state)]
              (wrap (#try.Success output)))
            
            (#try.Failure error)
            (wrap (#try.Failure error))))))

     (def: (upload uri content)
       (stm.commit
        (do {! stm.monad}
          [|state| (stm.read state)]
          (case (\ simulation on_upload uri content |state|)
            (#try.Success |state|)
            (do !
              [_ (stm.write |state| state)]
              (wrap (#try.Success [])))
            
            (#try.Failure error)
            (wrap (#try.Failure error))))))
     )))