{-# OPTIONS_GHC -Wno-unticked-promoted-constructors -Wno-missing-pattern-synonym-signatures #-}
{-# LANGUAGE RankNTypes, TypeInType, ScopedTypeVariables, TypeOperators, GADTs #-}
module Foreign.Erlang.Term2Experimental where

import           GHC.TypeLits
import           Data.Proxy
import qualified Foreign.Erlang.Term as SomeTerm
import qualified Data.Vector as V
import Data.String

data Terms =
  Atoms | AtomSymbols Symbol | Integers | Nils | Tupels [Terms] | Lists Terms Terms

data Term (t :: Terms) where
  Atom :: String -> Term 'Atoms
  AtomSymbol :: forall a . KnownSymbol a => Term ('AtomSymbols a)
  Integer :: Integer -> Term 'Integers
  Nil :: Term 'Nils
  Unit :: Term ('Tupels '[])
  ConsTuple :: Term t -> Term ('Tupels ts) -> Term ('Tupels (t ': ts))
  List :: [Term e] -> Term t -> Term ('Lists e t)

pattern Tup1 t1 = ConsTuple t1 Unit
pattern Tup2 t1 t2 = ConsTuple t1 (Tup1 t2)
pattern Tup3 t1 t2 t3 = ConsTuple t1 (Tup2 t2 t3)
pattern Tup4 t1 t2 t3 t4 = ConsTuple t1 (Tup3 t2 t3 t4)
pattern Tup5 t1 t2 t3 t4 t5 = ConsTuple t1 (Tup4 t2 t3 t4 t5)
pattern Tup6 t1 t2 t3 t4 t5 t6 = ConsTuple t1 (Tup5 t2 t3 t4 t5 t6)
pattern Tup7 t1 t2 t3 t4 t5 t6 t7 = ConsTuple t1 (Tup6 t2 t3 t4 t5 t6 t7)

-- instance SomeTerm.FromTerm (Term Atoms) where
--   fromTerm a@(SomeTerm.Atom _) = Just (Atom (show a))
--   fromTerm _ = Nothing

instance SomeTerm.ToTerm (Term t) where
  toTerm (Atom a) = SomeTerm.atom (fromString a)
  toTerm a@AtomSymbol =
    let px :: Term (AtomSymbols s) -> Proxy s
        px _ = Proxy
    in  SomeTerm.atom (fromString (symbolVal (px a)))
  toTerm (Integer i) = SomeTerm.integer i
  toTerm Nil = SomeTerm.Nil
  toTerm (List xs t) = SomeTerm.List (V.fromList (fmap SomeTerm.toTerm xs)) (SomeTerm.toTerm t)
  toTerm Unit = SomeTerm.tuple []
  toTerm xs@(ConsTuple _ _) = SomeTerm.tuple (go xs)
   where
     go :: Term (Tupels x_ys) -> [SomeTerm.Term]
     go (ConsTuple x ys) = SomeTerm.toTerm x : go ys
     go Unit = []

type EventTerm t = Term ('Tupels '[ 'AtomSymbols "Event" , t])

pattern Event :: Term t -> EventTerm t
pattern Event xx = Tup2 AtomSymbol xx

type BlubDown = 'Tupels [AtomSymbols "BlubDown" , Integers, Atoms ]

pattern BlubEvent :: Term 'Integers -> EventTerm BlubDown
pattern BlubEvent blubIndex  <- Event (Tup3 AtomSymbol blubIndex _)