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

(type: .public (Repository !)
  (Interface
   (: Text
      description)
   (: (-> URI (! (Try Binary)))
      download)
   (: (-> URI Binary (! (Try Any)))
      upload)))

(def: .public (async repository)
  (-> (Repository IO) (Repository Async))
  (implementation
   (def: description
     (\ repository description))
   (def: (download uri)
     (async.future (\ repository download uri)))

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

(type: .public (Mock s)
  (Interface
   (: Text
      the_description)
   (: (-> URI s (Try [s Binary]))
      on_download)
   (: (-> URI Binary s (Try s))
      on_upload)))

(def: .public (mock mock init)
  (All [s] (-> (Mock s) s (Repository Async)))
  (let [state (stm.var init)]
    (implementation
     (def: description
       (\ mock the_description))
     
     (def: (download uri)
       (stm.commit!
        (do {! stm.monad}
          [|state| (stm.read state)]
          (case (\ mock on_download uri |state|)
            (#try.Success [|state| output])
            (do !
              [_ (stm.write |state| state)]
              (in (#try.Success output)))
            
            (#try.Failure error)
            (in (#try.Failure error))))))

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