{-# LANGUAGE DataKinds #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE TypeOperators #-}
module AST.UnMonoid (unMonoid, zero, plus) where

import AST
import Data


-- | Remove 'EZero', 'EPlus' and 'EOneHot' from the program by expanding them
-- into their concrete implementations.
unMonoid :: Ex env t -> Ex env t
unMonoid = \case
  EZero _ t e -> zero t e
  EPlus _ t a b -> plus t (unMonoid a) (unMonoid b)
  EOneHot _ t p a b -> onehot t p (unMonoid a) (unMonoid b)

  EVar _ t i -> EVar ext t i
  ELet _ rhs body -> ELet ext (unMonoid rhs) (unMonoid body)
  EPair _ a b -> EPair ext (unMonoid a) (unMonoid b)
  EFst _ e -> EFst ext (unMonoid e)
  ESnd _ e -> ESnd ext (unMonoid e)
  ENil _ -> ENil ext
  EInl _ t e -> EInl ext t (unMonoid e)
  EInr _ t e -> EInr ext t (unMonoid e)
  ECase _ e a b -> ECase ext (unMonoid e) (unMonoid a) (unMonoid b)
  ENothing _ t -> ENothing ext t
  EJust _ e -> EJust ext (unMonoid e)
  EMaybe _ a b e -> EMaybe ext (unMonoid a) (unMonoid b) (unMonoid e)
  ELNil _ t1 t2 -> ELNil ext t1 t2
  ELInl _ t e -> ELInl ext t (unMonoid e)
  ELInr _ t e -> ELInr ext t (unMonoid e)
  ELCase _ e a b c -> ELCase ext (unMonoid e) (unMonoid a) (unMonoid b) (unMonoid c)
  EConstArr _ n t x -> EConstArr ext n t x
  EBuild _ n a b -> EBuild ext n (unMonoid a) (unMonoid b)
  EFold1Inner _ cm a b c -> EFold1Inner ext cm (unMonoid a) (unMonoid b) (unMonoid c)
  ESum1Inner _ e -> ESum1Inner ext (unMonoid e)
  EUnit _ e -> EUnit ext (unMonoid e)
  EReplicate1Inner _ a b -> EReplicate1Inner ext (unMonoid a) (unMonoid b)
  EMaximum1Inner _ e -> EMaximum1Inner ext (unMonoid e)
  EMinimum1Inner _ e -> EMinimum1Inner ext (unMonoid e)
  EConst _ t x -> EConst ext t x
  EIdx0 _ e -> EIdx0 ext (unMonoid e)
  EIdx1 _ a b -> EIdx1 ext (unMonoid a) (unMonoid b)
  EIdx _ a b -> EIdx ext (unMonoid a) (unMonoid b)
  EShape _ e -> EShape ext (unMonoid e)
  EOp _ op e -> EOp ext op (unMonoid e)
  ECustom _ t1 t2 t3 a b c e1 e2 -> ECustom ext t1 t2 t3 (unMonoid a) (unMonoid b) (unMonoid c) (unMonoid e1) (unMonoid e2)
  EWith _ t a b -> EWith ext t (unMonoid a) (unMonoid b)
  EAccum _ t p a b e -> EAccum ext t p (unMonoid a) (unMonoid b) (unMonoid e)
  EError _ t s -> EError ext t s

zero :: SMTy t -> Ex env (ZeroInfo t) -> Ex env t
zero SMTNil _ = ENil ext
zero (SMTPair t1 t2) e =
  ELet ext e $ EPair ext (zero t1 (EFst ext (EVar ext (typeOf e) IZ)))
                         (zero t2 (ESnd ext (EVar ext (typeOf e) IZ)))
zero (SMTLEither t1 t2) _ = ELNil ext (fromSMTy t1) (fromSMTy t2)
zero (SMTMaybe t) _ = ENothing ext (fromSMTy t)
zero (SMTArr _ t) e = emap (zero t (EVar ext (tZeroInfo t) IZ)) e
zero (SMTScal t) _ = case t of
  STI32 -> EConst ext STI32 0
  STI64 -> EConst ext STI64 0
  STF32 -> EConst ext STF32 0.0
  STF64 -> EConst ext STF64 0.0

plus :: SMTy t -> Ex env t -> Ex env t -> Ex env t
plus SMTNil _ _ = ENil ext
plus (SMTPair t1 t2) a b =
  let t = STPair (fromSMTy t1) (fromSMTy t2)
  in ELet ext a $
     ELet ext (weakenExpr WSink b) $
       EPair ext (plus t1 (EFst ext (EVar ext t (IS IZ)))
                          (EFst ext (EVar ext t IZ)))
                 (plus t2 (ESnd ext (EVar ext t (IS IZ)))
                          (ESnd ext (EVar ext t IZ)))
plus (SMTLEither t1 t2) a b =
  let t = STLEither (fromSMTy t1) (fromSMTy t2)
  in ELet ext a $
     ELet ext (weakenExpr WSink b) $
       ELCase ext (EVar ext t (IS IZ))
         (EVar ext t IZ)
         (ELCase ext (EVar ext t (IS IZ))
           (EVar ext t (IS (IS IZ)))
           (ELInl ext (fromSMTy t2) (plus t1 (EVar ext (fromSMTy t1) (IS IZ)) (EVar ext (fromSMTy t1) IZ)))
           (EError ext t "plus l+r"))
         (ELCase ext (EVar ext t (IS IZ))
           (EVar ext t (IS (IS IZ)))
           (EError ext t "plus r+l")
           (ELInr ext (fromSMTy t1) (plus t2 (EVar ext (fromSMTy t2) (IS IZ)) (EVar ext (fromSMTy t2) IZ))))
plus (SMTMaybe t) a b =
  ELet ext b $
    EMaybe ext
      (EVar ext (STMaybe (fromSMTy t)) IZ)
      (EJust ext
        (EMaybe ext
          (EVar ext (fromSMTy t) IZ)
          (plus t (EVar ext (fromSMTy t) (IS IZ)) (EVar ext (fromSMTy t) IZ))
          (EVar ext (STMaybe (fromSMTy t)) (IS IZ))))
      (weakenExpr WSink a)
plus (SMTArr _ t) a b =
  ezipWith (plus t (EVar ext (fromSMTy t) (IS IZ)) (EVar ext (fromSMTy t) IZ))
           a b
plus (SMTScal t) a b = EOp ext (OAdd t) (EPair ext a b)

onehot :: SMTy t -> SAcPrj p t a -> Ex env (AcIdx p t) -> Ex env a -> Ex env t
onehot typ topprj idx arg = case (typ, topprj) of
  (_, SAPHere) ->
    ELet ext arg $
      EVar ext (fromSMTy typ) IZ

  (SMTPair t1 t2, SAPFst prj) ->
    ELet ext idx $
      let tidx = typeOf idx in
      ELet ext (onehot t1 prj (EFst ext (EVar ext (typeOf idx) IZ)) (weakenExpr WSink arg)) $
        let toh = fromSMTy t1 in
        EPair ext (EVar ext toh IZ)
                  (zero t2 (ESnd ext (EVar ext tidx (IS IZ))))
        
  (SMTPair t1 t2, SAPSnd prj) ->
    ELet ext idx $
      let tidx = typeOf idx in
      ELet ext (onehot t2 prj (ESnd ext (EVar ext (typeOf idx) IZ)) (weakenExpr WSink arg)) $
        let toh = fromSMTy t2 in
        EPair ext (zero t1 (EFst ext (EVar ext tidx (IS IZ))))
                  (EVar ext toh IZ)

  (SMTLEither t1 t2, SAPLeft prj) ->
    ELInl ext (fromSMTy t2) (onehot t1 prj idx arg)
  (SMTLEither t1 t2, SAPRight prj) ->
    ELInr ext (fromSMTy t1) (onehot t2 prj idx arg)

  (SMTMaybe t1, SAPJust prj) ->
    EJust ext (onehot t1 prj idx arg)

  (SMTArr n t1, SAPArrIdx prj) ->
    let tidx = tTup (sreplicate n tIx)
    in ELet ext idx $
         EBuild ext n (EShape ext (ESnd ext (EFst ext (EVar ext (typeOf idx) IZ)))) $
           eif (eidxEq n (EVar ext tidx IZ) (EFst ext (EFst ext (EVar ext (typeOf idx) (IS IZ)))))
             (onehot t1 prj (ESnd ext (EVar ext (typeOf idx) (IS IZ))) (weakenExpr (WSink .> WSink) arg))
             (ELet ext (EIdx ext (ESnd ext (EFst ext (EVar ext (typeOf idx) (IS IZ)))) (EVar ext tidx IZ)) $
                zero t1 (EVar ext (tZeroInfo t1) IZ))