module interfaceExtensionAndDelegation where 

open import Data.Product
open import Data.Nat.Base
open import Data.Nat.Show
open import Data.String.Base using (String; _++_)
open import Size
open import NativeIO
open import interactiveProgramsAgda using (ConsoleInterface; _>>=_; do; 
                                           IO; return; putStrLn;
                                           translateIOConsole )
open import objectsInAgda using (Interface; Method; Result; CellMethod; 
                                 get; put; CellResult; cellI; IOObject; 
                                 CellC; method; simpleCell )



data CounterMethod A : Set where
  super  :  (m : CellMethod A) → CounterMethod A
  stats  :  CounterMethod A

statsCellI : (A : Set) → Interface
Method  (statsCellI A)            =  CounterMethod A
Result  (statsCellI A) (super m)  =  Result (cellI A) m
Result  (statsCellI A) stats      =  Unit

CounterC : (i : Size) → Set
CounterC = IOObject ConsoleInterface (statsCellI String)

pattern getᶜ    = super get
pattern putᶜ x  = super (put x)

{- Methods of CounterC are now 
   getᶜ  (putᶜ x)   stats
-}


counterCell : ∀{i} (c : CellC i) (ngets nputs : ℕ) → CounterC i
method (counterCell c ngets nputs) getᶜ =
  method c get                                >>= λ { (s , c') →
  return (s , counterCell c' ( + ngets) nputs)  }

method (counterCell c ngets nputs) (putᶜ x) =
  method c (put x)                            >>= λ { (_ , c') →
  return (_ , counterCell c' ngets ( + nputs))  }

method (counterCell c ngets nputs) stats =
  do (putStrLn ("Counted "
    ++ show ngets ++ " calls to get and "
    ++ show nputs ++ " calls to put."))       λ _ →
  return (_ , counterCell c ngets nputs)

program : String → IO ConsoleInterface ∞ Unit
program arg =
  let c₀ = counterCell (simpleCell "Start")   in
  method c₀ getᶜ               >>= λ{ (s   , c₁) →
  do (putStrLn s)              λ _ →
  method c₁ (putᶜ arg)         >>= λ{ (_        , c₂) →
  method c₂ getᶜ               >>= λ{ (s'  , c₃) →
  do (putStrLn s')             λ _ →
  method c₃ (putᶜ "Over!")     >>= λ{ (_ , c₄) →
  method c₄ stats              >>= λ{ (_ , c₅) →
  return _                     }}}}}


main : NativeIO Unit
main = translateIOConsole (program "Hello")