{-# LANGUAGE FlexibleInstances      #-}
{-# LANGUAGE FlexibleContexts       #-}
{-# LANGUAGE UndecidableInstances   #-}
{-# LANGUAGE OverloadedStrings      #-}
{-# LANGUAGE TupleSections          #-}

{-# OPTIONS_GHC -Wno-orphans #-}
{-# OPTIONS_GHC -Wno-name-shadowing #-}

module Language.Haskell.Liquid.Transforms.CoreToLogic
  ( coreToDef
  , coreToFun
  , coreToLogic
  , mkLit, mkI, mkS
  , runToLogic
  , runToLogicWithBoolBinds
  , logicType
  , inlineSpecType
  , measureSpecType
  , weakenResult
  , normalize
  ) where

import           Data.ByteString                       (ByteString)
import           Prelude                               hiding (error)
import           Liquid.GHC.TypeRep   () -- needed for Eq 'Type'
import           Liquid.GHC.API       hiding (Expr, Located, panic)
import qualified Liquid.GHC.API       as Ghc
import qualified Liquid.GHC.API       as C
import qualified Data.List                             as L
import           Data.Maybe                            (listToMaybe)
import qualified Data.Text                             as T
import qualified Data.Char
import qualified Text.Printf as Printf
import           Data.Text.Encoding
import           Data.Text.Encoding.Error
import           Control.Monad.State
import           Control.Monad.Except
import           Control.Monad.Identity
import qualified Language.Fixpoint.Misc                as Misc
import qualified Language.Haskell.Liquid.Misc          as Misc
import           Language.Fixpoint.Types               hiding (panic, Error, R, simplify)
import qualified Language.Fixpoint.Types               as F
import qualified Liquid.GHC.Misc      as GM


import           Language.Haskell.Liquid.Bare.Types
import           Language.Haskell.Liquid.Bare.DataType
import           Language.Haskell.Liquid.Bare.Misc     (simpleSymbolVar)
import           Liquid.GHC.Play
import           Language.Haskell.Liquid.Types.Types   --     hiding (GhcInfo(..), GhcSpec (..), LM)
import           Language.Haskell.Liquid.Types.RefType

import qualified Data.HashMap.Strict                   as M

logicType :: (Reftable r) => Bool -> Type -> RRType r
logicType allowTC τ      = fromRTypeRep $ t { ty_binds = bs, ty_info = is, ty_args = as, ty_refts = rs}
  where
    t            = toRTypeRep $ ofType τ
    (bs, is, as, rs) = Misc.unzip4 $ dropWhile (isErasable . Misc.thd4) $ Misc.zip4 (ty_binds t) (ty_info t) (ty_args t) (ty_refts t)
    isErasable   = if allowTC then isEmbeddedClass else isClassType

{- | [NOTE:inlineSpecType type]: the refinement depends on whether the result type is a Bool or not:
      CASE1: measure f@logic :: X -> Bool <=> f@haskell :: x:X -> {v:Bool | v <=> (f@logic x)}
     CASE2: measure f@logic :: X -> Y    <=> f@haskell :: x:X -> {v:Y    | v = (f@logic x)}
 -}
-- formerly: strengthenResult
inlineSpecType :: Bool -> Var -> SpecType
inlineSpecType  allowTC v = fromRTypeRep $ rep {ty_res = res `strengthen` r , ty_binds = xs}
  where
    r              = MkUReft (mkR (mkEApp f (mkA <$> vxs))) mempty
    rep            = toRTypeRep t
    res            = ty_res rep
    xs             = intSymbol (symbol ("x" :: String)) <$> [1..length $ ty_binds rep]
    vxs            = dropWhile (isErasable . snd) $ zip xs (ty_args rep)
    isErasable     = if allowTC then isEmbeddedClass else isClassType
    f              = dummyLoc (symbol v)
    t              = ofType (GM.expandVarType v) :: SpecType
    mkA            = EVar . fst
    mkR            = if isBool res then propReft else exprReft

-- | Refine types of measures: keep going until you find the last data con!
--   this code is a hack! we refine the last data constructor,
--   it got complicated to support both
--   1. multi parameter measures     (see tests/pos/HasElem.hs)
--   2. measures returning functions (fromReader :: Reader r a -> (r -> a) )
--   TODO: SIMPLIFY by dropping support for multi parameter measures

-- formerly: strengthenResult'
measureSpecType :: Bool -> Var -> SpecType
measureSpecType allowTC v = go mkT [] [(1::Int)..] t
  where
    mkR | boolRes   = propReft
        | otherwise = exprReft
    mkT xs          = MkUReft (mkR $ mkEApp f (EVar <$> reverse xs)) mempty
    f               = dummyLoc (symbol v)
    t               = ofType (GM.expandVarType v) :: SpecType
    boolRes         =  isBool $ ty_res $ toRTypeRep t

    go f args i (RAllT a t r)    = RAllT a (go f args i t) r
    go f args i (RAllP p t)      = RAllP p $ go f args i t
    go f args i (RFun x ii t1 t2 r)
     | (if allowTC then isEmbeddedClass else isClassType) t1           = RFun x ii t1 (go f args i t2) r
    go f args i t@(RFun _ ii t1 t2 r)
     | hasRApps t               = RFun x' ii t1 (go f (x':args) (tail i) t2) r
                                       where x' = intSymbol (symbol ("x" :: String)) (head i)
    go f args _ t                = t `strengthen` f args

    hasRApps (RFun _ _ t1 t2 _) = hasRApps t1 || hasRApps t2
    hasRApps RApp {}          = True
    hasRApps _                = False


-- | 'weakenResult foo t' drops the singleton constraint `v = foo x y` 
--   that is added, e.g. for measures in /strengthenResult'. 
--   This should only be used _when_ checking the body of 'foo' 
--   where the output, is, by definition, equal to the singleton.
weakenResult :: Bool -> Var -> SpecType -> SpecType
weakenResult allowTC v t = F.notracepp msg t'
  where
    msg          = "weakenResult v =" ++ GM.showPpr v ++ " t = " ++ showpp t
    t'           = fromRTypeRep $ rep { ty_res = mapExprReft weaken (ty_res rep) }
    rep          = toRTypeRep t
    weaken x     = pAnd . filter ((Just vE /=) . isSingletonExpr x) . conjuncts
    vE           = mkEApp vF xs
    xs           = EVar . fst <$> dropWhile ((if allowTC then isEmbeddedClass else isClassType) . snd) xts
    xts          = zip (ty_binds rep) (ty_args rep)
    vF           = dummyLoc (symbol v)

type LogicM = ExceptT Error (StateT LState Identity)

data LState = LState
  { lsSymMap  :: LogicMap
  , lsError   :: String -> Error
  , lsEmb     :: TCEmb TyCon
  , lsBools   :: [Var]
  , lsDCMap   :: DataConMap
  }

throw :: String -> LogicM a
throw str = do
  fmkError  <- gets lsError
  throwError $ fmkError str

getState :: LogicM LState
getState = get

runToLogic
  :: TCEmb TyCon -> LogicMap -> DataConMap -> (String -> Error)
  -> LogicM t -> Either Error t
runToLogic = runToLogicWithBoolBinds []

runToLogicWithBoolBinds
  :: [Var] -> TCEmb TyCon -> LogicMap -> DataConMap -> (String -> Error)
  -> LogicM t -> Either Error t
runToLogicWithBoolBinds xs tce lmap dm ferror m
  = evalState (runExceptT m) $ LState
      { lsSymMap = lmap
      , lsError  = ferror
      , lsEmb    = tce
      , lsBools  = xs
      , lsDCMap  = dm
      }

coreAltToDef :: (Reftable r) => Bool -> LocSymbol -> Var -> [Var] -> Var -> Type -> [C.CoreAlt]
             -> LogicM [Def (Located (RRType r)) DataCon]
coreAltToDef allowTC x z zs y t alts
  | not (null litAlts) = measureFail x "Cannot lift definition with literal alternatives"
  | otherwise          = do
      d1s <- F.notracepp "coreAltDefs-1" <$> mapM (mkAlt x cc myArgs z) dataAlts
      d2s <- F.notracepp "coreAltDefs-2" <$>       mkDef x cc myArgs z  defAlts defExpr
      return (d1s ++ d2s)
  where
    myArgs   = reverse zs
    cc       = if eqType t boolTy then P else E
    defAlts  = GM.defaultDataCons (GM.expandVarType y) (Misc.fst3 <$> alts)
    defExpr  = listToMaybe [ e |   (C.DEFAULT  , _, e) <- alts ]
    dataAlts =             [ a | a@(C.DataAlt _, _, _) <- alts ]
    litAlts  =             [ a | a@(C.LitAlt _, _, _) <- alts ]

    -- mkAlt :: LocSymbol -> (Expr -> Body) -> [Var] -> Var -> (C.AltCon, [Var], C.CoreExpr)
    mkAlt x ctor _args dx (C.DataAlt d, xs, e)
      = Def x {- (toArgs id args) -} d (Just $ varRType dx) (toArgs Just xs')
      . ctor
      . (`subst1` (F.symbol dx, F.mkEApp (GM.namedLocSymbol d) (F.eVar <$> xs')))
     <$> coreToLg allowTC e
      where xs' = filter (not . if allowTC then GM.isEmbeddedDictVar else GM.isEvVar) xs
    mkAlt _ _ _ _ alt
      = throw $ "Bad alternative" ++ GM.showPpr alt

    mkDef x ctor _args dx (Just dtss) (Just e) = do
      eDef   <- ctor <$> coreToLg allowTC e
      -- let ys  = toArgs id args
      let dxt = Just (varRType dx)
      return  [ Def x {- ys -} d dxt (defArgs x ts) eDef | (d, _, ts) <- dtss ]

    mkDef _ _ _ _ _ _ =
      return []

toArgs :: Reftable r => (Located (RRType r) -> b) -> [Var] -> [(Symbol, b)]
toArgs f args = [(symbol x, f $ varRType x) | x <- args]

defArgs :: Monoid r => LocSymbol -> [Type] -> [(Symbol, Maybe (Located (RRType r)))]
defArgs x     = zipWith (\i t -> (defArg i, defRTyp t)) [0..]
  where
    defArg    = tempSymbol (val x)
    defRTyp   = Just . F.atLoc x . ofType

coreToDef :: Reftable r => Bool -> LocSymbol -> Var -> C.CoreExpr
          -> LogicM [Def (Located (RRType r)) DataCon]
coreToDef allowTC x _ e                   = go [] $ inlinePreds $ simplify allowTC  e
  where
    go args   (C.Lam  x e)        = go (x:args) e
    go args   (C.Tick _ e)        = go args e
    go (z:zs) (C.Case _ y t alts) = coreAltToDef allowTC x z zs y t alts
    go (z:zs) e
      | Just t <- isMeasureArg z  = coreAltToDef allowTC x z zs z t [(C.DEFAULT, [], e)]
    go _ _                        = measureFail x "Does not have a case-of at the top-level"

    inlinePreds   = inline (eqType boolTy . GM.expandVarType)

measureFail       :: LocSymbol -> String -> a
measureFail x msg = panic sp e
  where
    sp            = Just (GM.fSrcSpan x)
    e             = Printf.printf "Cannot create measure '%s': %s" (F.showpp x) msg


-- | 'isMeasureArg x' returns 'Just t' if 'x' is a valid argument for a measure.
isMeasureArg :: Var -> Maybe Type
isMeasureArg x
  | Just tc <- tcMb
  , Ghc.isAlgTyCon tc = F.notracepp "isMeasureArg" $ Just t
  | otherwise           = Nothing
  where
    t                   = GM.expandVarType x
    tcMb                = tyConAppTyCon_maybe t


varRType :: (Reftable r) => Var -> Located (RRType r)
varRType = GM.varLocInfo ofType

coreToFun :: Bool -> LocSymbol -> Var -> C.CoreExpr ->  LogicM ([Var], Either Expr Expr)
coreToFun allowTC _ _v e = go [] $ normalize allowTC e
  where
    isE = if allowTC then GM.isEmbeddedDictVar else isErasable
    go acc (C.Lam x e)  | isTyVar    x = go acc e
    go acc (C.Lam x e)  | isE x = go acc e
    go acc (C.Lam x e)  = go (x:acc) e
    go acc (C.Tick _ e) = go acc e
    go acc e            = (reverse acc,) . Right <$> coreToLg allowTC e


instance Show C.CoreExpr where
  show = GM.showPpr

coreToLogic :: Bool -> C.CoreExpr -> LogicM Expr
coreToLogic allowTC cb = coreToLg allowTC (normalize allowTC cb)


coreToLg :: Bool -> C.CoreExpr -> LogicM Expr
coreToLg allowTC  (C.Let (C.NonRec x (C.Coercion c)) e)
  = coreToLg allowTC (C.substExpr (C.extendCvSubst C.emptySubst x c) e)
coreToLg allowTC  (C.Let b e)
  = subst1 <$> coreToLg allowTC e <*>  makesub allowTC b
coreToLg allowTC (C.Tick _ e)          = coreToLg allowTC e
coreToLg allowTC (C.App (C.Var v) e)
  | ignoreVar v                = coreToLg allowTC e
coreToLg _allowTC (C.Var x)
  | x == falseDataConId        = return PFalse
  | x == trueDataConId         = return PTrue
  | otherwise                  = getState >>= eVarWithMap x . lsSymMap
coreToLg allowTC e@(C.App _ _)         = toPredApp allowTC e
coreToLg allowTC (C.Case e b _ alts)
  | eqType (GM.expandVarType b) boolTy  = checkBoolAlts alts >>= coreToIte allowTC e
-- coreToLg (C.Lam x e)           = do p     <- coreToLg e
--                                     tce   <- lsEmb <$> getState
--                                     return $ ELam (symbol x, typeSort tce (GM.expandVarType x)) p
coreToLg allowTC (C.Case e b _ alts)   = do p <- coreToLg allowTC e
                                            casesToLg allowTC b p alts
coreToLg _ (C.Lit l)             = case mkLit l of
                                          Nothing -> throw $ "Bad Literal in measure definition" ++ GM.showPpr l
                                          Just i  -> return i
coreToLg allowTC (C.Cast e c)          = do (s, t) <- coerceToLg c
                                            e'     <- coreToLg allowTC e
                                            return (ECoerc s t e')
-- elaboration reuses coretologic
-- TODO: fix this
coreToLg True (C.Lam x e) = do p     <- coreToLg True e
                               tce   <- lsEmb <$> getState
                               return $ ELam (symbol x, typeSort tce (GM.expandVarType x)) p
coreToLg _ e@(C.Lam _ _)        = throw ("Cannot transform lambda abstraction to Logic:\t" ++ GM.showPpr e ++
                                            "\n\n Try using a helper function to remove the lambda.")
coreToLg _ e                     = throw ("Cannot transform to Logic:\t" ++ GM.showPpr e)




coerceToLg :: Coercion -> LogicM (Sort, Sort)
coerceToLg = typeEqToLg . coercionTypeEq

coercionTypeEq :: Coercion -> (Type, Type)
coercionTypeEq co
  | Ghc.Pair s t <- -- GM.tracePpr ("coercion-type-eq-1: " ++ GM.showPpr co) $
                       coercionKind co
  = (s, t)

typeEqToLg :: (Type, Type) -> LogicM (Sort, Sort)
typeEqToLg (s, t) = do
  tce   <- gets lsEmb
  let tx = typeSort tce . expandTypeSynonyms
  return $ F.notracepp "TYPE-EQ-TO-LOGIC" (tx s, tx t)

checkBoolAlts :: [C.CoreAlt] -> LogicM (C.CoreExpr, C.CoreExpr)
checkBoolAlts [(C.DataAlt false, [], efalse), (C.DataAlt true, [], etrue)]
  | false == falseDataCon, true == trueDataCon
  = return (efalse, etrue)

checkBoolAlts [(C.DataAlt true, [], etrue), (C.DataAlt false, [], efalse)]
  | false == falseDataCon, true == trueDataCon
  = return (efalse, etrue)
checkBoolAlts alts
  = throw ("checkBoolAlts failed on " ++ GM.showPpr alts)

casesToLg :: Bool -> Var -> Expr -> [C.CoreAlt] -> LogicM Expr
casesToLg allowTC v e alts = mapM (altToLg allowTC e) normAlts >>= go
  where
    normAlts       = normalizeAlts alts
    go :: [(C.AltCon, Expr)] -> LogicM Expr
    go [(_,p)]     = return (p `subst1` su)
    go ((d,p):dps) = do c <- checkDataAlt d e
                        e' <- go dps
                        return (EIte c p e' `subst1` su)
    go []          = panic (Just (getSrcSpan v)) "Unexpected empty cases in casesToLg"
    su             = (symbol v, e)

checkDataAlt :: C.AltCon -> Expr -> LogicM Expr
checkDataAlt (C.DataAlt d) e = return $ EApp (EVar (makeDataConChecker d)) e
checkDataAlt C.DEFAULT     _ = return PTrue
checkDataAlt (C.LitAlt l)  e
  | Just le <- mkLit l       = return (EEq le e)
  | otherwise                = throw $ "Oops, not yet handled: checkDataAlt on Lit: " ++ GM.showPpr l

-- | 'altsDefault' reorders the CoreAlt to ensure that 'DEFAULT' is at the end.
normalizeAlts :: [C.CoreAlt] -> [C.CoreAlt]
normalizeAlts alts      = ctorAlts ++ defAlts
  where
    (defAlts, ctorAlts) = L.partition isDefault alts
    isDefault (c,_,_)   = c == C.DEFAULT

altToLg :: Bool -> Expr -> C.CoreAlt -> LogicM (C.AltCon, Expr)
altToLg allowTC de (a@(C.DataAlt d), xs, e) = do
  p  <- coreToLg allowTC e
  dm <- gets lsDCMap
  let su = mkSubst $ concat [ dataConProj dm de d x i | (x, i) <- zip (filter (not . if allowTC then GM.isEmbeddedDictVar else GM.isEvVar) xs) [1..]]
  return (a, subst su p)

altToLg allowTC _ (a, _, e)
  = (a, ) <$> coreToLg allowTC e

dataConProj :: DataConMap -> Expr -> DataCon -> Var -> Int -> [(Symbol, Expr)]
dataConProj dm de d x i = [(symbol x, t), (GM.simplesymbol x, t)]
  where
    t | primDataCon  d  = de
      | otherwise       = EApp (EVar $ makeDataConSelector (Just dm) d i) de

primDataCon :: DataCon -> Bool
primDataCon d = d == intDataCon

coreToIte :: Bool -> C.CoreExpr -> (C.CoreExpr, C.CoreExpr) -> LogicM Expr
coreToIte allowTC e (efalse, etrue)
  = do p  <- coreToLg allowTC e
       e1 <- coreToLg allowTC efalse
       e2 <- coreToLg allowTC etrue
       return $ EIte p e2 e1

toPredApp :: Bool -> C.CoreExpr -> LogicM Expr
toPredApp allowTC p = go . Misc.mapFst opSym . splitArgs allowTC $ p
  where
    opSym = fmap GM.dropModuleNamesAndUnique . tomaybesymbol
    go (Just f, [e1, e2])
      | Just rel <- M.lookup f brels
      = PAtom rel <$> coreToLg allowTC e1 <*> coreToLg allowTC e2
    go (Just f, [e])
      | f == symbol ("not" :: String)
      = PNot <$>  coreToLg allowTC e
      | f == symbol ("len" :: String)
      = EApp (EVar "len") <$> coreToLg allowTC e
    go (Just f, [e1, e2])
      | f == symbol ("||" :: String)
      = POr <$> mapM (coreToLg allowTC) [e1, e2]
      | f == symbol ("&&" :: String)
      = PAnd <$> mapM (coreToLg allowTC) [e1, e2]
      | f == symbol ("==>" :: String)
      = PImp <$> coreToLg allowTC e1 <*> coreToLg allowTC e2
      | f == symbol ("<=>" :: String)
      = PIff <$> coreToLg allowTC e1 <*> coreToLg allowTC e2
    go (Just f, [es])
      | f == symbol ("or" :: String)
      = POr  . deList <$> coreToLg allowTC es
      | f == symbol ("and" :: String)
      = PAnd . deList <$> coreToLg allowTC es
    go (_, _)
      = toLogicApp allowTC p

    deList :: Expr -> [Expr]
    deList (EApp (EApp (EVar cons) e) es)
      | cons == symbol ("GHC.Types.:" :: String)
      = e:deList es
    deList (EVar nil)
      | nil == symbol ("GHC.Types.[]" :: String)
      = []
    deList e
      = [e]

toLogicApp :: Bool -> C.CoreExpr -> LogicM Expr
toLogicApp allowTC e = do
  let (f, es) = splitArgs allowTC e
  case f of
    C.Var _ -> do args <- mapM (coreToLg allowTC) es
                  lmap <- lsSymMap <$> getState
                  def  <- (`mkEApp` args) <$> tosymbol f
                  (\x -> makeApp def lmap x args) <$> tosymbol' f
    _       -> do fe   <- coreToLg allowTC f
                  args <- mapM (coreToLg allowTC) es
                  return $ foldl EApp fe args

makeApp :: Expr -> LogicMap -> Located Symbol-> [Expr] -> Expr
makeApp _ _ f [e]
  | val f == symbol ("GHC.Num.negate" :: String)
  = ENeg e
  | val f == symbol ("GHC.Num.fromInteger" :: String)
  , ECon c <- e
  = ECon c
  | (modName, sym) <- GM.splitModuleName (val f)
  , symbol ("Ghci" :: String) `isPrefixOfSym` modName
  , sym == "len"
  = EApp (EVar sym) e

makeApp _ _ f [e1, e2]
  | Just op <- M.lookup (val f) bops
  = EBin op e1 e2
  -- Hack for typeclass support. (overriden == without Eq constraint defined at Ghci)
  | (modName, sym) <- GM.splitModuleName (val f)
  , symbol ("Ghci" :: String) `isPrefixOfSym` modName
  , Just op <- M.lookup (mappendSym (symbol ("GHC.Num." :: String)) sym) bops
  = EBin op e1 e2

makeApp def lmap f es
  = eAppWithMap lmap f es def
  -- where msg = "makeApp f = " ++ show f ++ " es = " ++ show es ++ " def = " ++ show def

eVarWithMap :: Id -> LogicMap -> LogicM Expr
eVarWithMap x lmap = do
  f'     <- tosymbol' (C.Var x :: C.CoreExpr)
  -- let msg = "eVarWithMap x = " ++ show x ++ " f' = " ++ show f'
  return $ eAppWithMap lmap f' [] (varExpr x)

varExpr :: Var -> Expr
varExpr x
  | isPolyCst t = mkEApp (dummyLoc s) []
  | otherwise   = EVar s
  where
    t           = GM.expandVarType x
    s           = symbol x

isPolyCst :: Type -> Bool
isPolyCst (ForAllTy _ t) = isCst t
isPolyCst _              = False

isCst :: Type -> Bool
isCst (ForAllTy _ t) = isCst t
isCst FunTy{}        = False
isCst _              = True


brels :: M.HashMap Symbol Brel
brels = M.fromList [ (symbol ("==" :: String), Eq)
                   , (symbol ("/=" :: String), Ne)
                   , (symbol (">=" :: String), Ge)
                   , (symbol (">" :: String) , Gt)
                   , (symbol ("<=" :: String), Le)
                   , (symbol ("<" :: String) , Lt)
                   ]

bops :: M.HashMap Symbol Bop
bops = M.fromList [ (numSymbol "+", Plus)
                  , (numSymbol "-", Minus)
                  , (numSymbol "*", Times)
                  , (numSymbol "/", Div)
                  , (realSymbol "/", Div)
                  , (numSymbol "%", Mod)
                  ]
  where
    numSymbol :: String -> Symbol
    numSymbol =  symbol . (++) "GHC.Num."
    realSymbol :: String -> Symbol
    realSymbol =  symbol . (++) "GHC.Real."

splitArgs :: Bool -> C.Expr t -> (C.Expr t, [C.Arg t])
splitArgs allowTC e = (f, reverse es)
 where
    (f, es) = go e

    go (C.App (C.Var i) e) | ignoreVar i       = go e
    go (C.App f (C.Var v)) | if allowTC then GM.isEmbeddedDictVar v else isErasable v   = go f
    go (C.App f e) = (f', e:es) where (f', es) = go f
    go f           = (f, [])

tomaybesymbol :: C.CoreExpr -> Maybe Symbol
tomaybesymbol (C.Var x) = Just $ symbol x
tomaybesymbol _         = Nothing

tosymbol :: C.CoreExpr -> LogicM (Located Symbol)
tosymbol e
 = case tomaybesymbol e of
    Just x -> return $ dummyLoc x
    _      -> throw ("Bad Measure Definition:\n" ++ GM.showPpr e ++ "\t cannot be applied")

tosymbol' :: C.CoreExpr -> LogicM (Located Symbol)
tosymbol' (C.Var x) = return $ dummyLoc $ symbol x
tosymbol' e        = throw ("Bad Measure Definition:\n" ++ GM.showPpr e ++ "\t cannot be applied")

makesub :: Bool -> C.CoreBind -> LogicM (Symbol, Expr)
makesub allowTC (C.NonRec x e) =  (symbol x,) <$> coreToLg allowTC e
makesub _       _              = throw "Cannot make Logical Substitution of Recursive Definitions"

mkLit :: Literal -> Maybe Expr
mkLit (LitNumber _ n _) = mkI n
-- mkLit (MachInt64  n)    = mkI n
-- mkLit (MachWord   n)    = mkI n
-- mkLit (MachWord64 n)    = mkI n
-- mkLit (LitInteger n _)  = mkI n
mkLit (LitFloat  n)    = mkR n
mkLit (LitDouble n)    = mkR n
mkLit (LitString    s)    = mkS s
mkLit (LitChar   c)    = mkC c
mkLit _                 = Nothing -- ELit sym sort

mkI :: Integer -> Maybe Expr
mkI = Just . ECon . I

mkR :: Rational -> Maybe Expr
mkR                    = Just . ECon . F.R . fromRational

mkS :: ByteString -> Maybe Expr
mkS                    = Just . ESym . SL  . decodeUtf8With lenientDecode

mkC :: Char -> Maybe Expr
mkC                    = Just . ECon . (`F.L` F.charSort)  . repr
  where
    repr               = T.pack . show . Data.Char.ord

ignoreVar :: Id -> Bool
ignoreVar i = simpleSymbolVar i `elem` ["I#", "D#"]

-- | Tries to determine if a 'CoreAlt' maps to one of the 'Integer' type constructors.
-- We need the disjuction for GHC >= 9, where the Integer now comes from the \"ghc-bignum\" package,
-- and it has different names for the constructors.
isBangInteger :: [C.CoreAlt] -> Bool
isBangInteger [(C.DataAlt s, _, _), (C.DataAlt jp,_,_), (C.DataAlt jn,_,_)]
  =  (symbol s  == "GHC.Integer.Type.S#"  || symbol s  == "GHC.Num.Integer.IS")
  && (symbol jp == "GHC.Integer.Type.Jp#" || symbol jp == "GHC.Num.Integer.IP")
  && (symbol jn == "GHC.Integer.Type.Jn#" || symbol jn == "GHC.Num.Integer.IN")
isBangInteger _ = False

isErasable :: Id -> Bool
isErasable v = F.notracepp msg $ isGhcSplId v && not (isDCId v)
  where
    msg      = "isErasable: " ++ GM.showPpr (v, Ghc.idDetails v)

isGhcSplId :: Id -> Bool
isGhcSplId v = isPrefixOfSym (symbol ("$" :: String)) (simpleSymbolVar v)

isDCId :: Id -> Bool
isDCId v = case Ghc.idDetails v of
  DataConWorkId _ -> True
  DataConWrapId _ -> True
  _               -> False

isANF :: Id -> Bool
isANF      v = isPrefixOfSym (symbol ("lq_anf" :: String)) (simpleSymbolVar v)

isDead :: Id -> Bool
isDead     = isDeadOcc . occInfo . Ghc.idInfo

class Simplify a where
  simplify :: Bool -> a -> a
  inline   :: (Id -> Bool) -> a -> a

  normalize :: Bool -> a -> a
  normalize allowTC = inline_preds . inline_anf . simplify allowTC
   where
    inline_preds = inline (eqType boolTy . GM.expandVarType)
    inline_anf   = inline isANF

instance Simplify C.CoreExpr where
  simplify _ e@(C.Var _)
    = e
  simplify _ e@(C.Lit _)
    = e
  simplify allowTC (C.App e (C.Type _))
    = simplify allowTC e
  simplify allowTC (C.App e (C.Var dict))  | (if allowTC then GM.isEmbeddedDictVar else isErasable) dict
    = simplify allowTC e
  simplify allowTC (C.App (C.Lam x e) _)   | isDead x
    = simplify allowTC e
  simplify allowTC (C.App e1 e2)
    = C.App (simplify allowTC e1) (simplify allowTC e2)
  simplify allowTC (C.Lam x e) | isTyVar x
    = simplify allowTC e
  simplify allowTC (C.Lam x e) | (if allowTC then GM.isEmbeddedDictVar else isErasable) x
    = simplify allowTC e
  simplify allowTC (C.Lam x e)
    = C.Lam x (simplify allowTC e)
  simplify allowTC (C.Let (C.NonRec x _) e) | (if allowTC then GM.isEmbeddedDictVar else isErasable) x
    = simplify allowTC e
  simplify allowTC (C.Let (C.Rec xes) e)    | all ((if allowTC then GM.isEmbeddedDictVar else isErasable) . fst) xes
    = simplify allowTC e
  simplify allowTC (C.Let xes e)
    = C.Let (simplify allowTC xes) (simplify allowTC e)
  simplify allowTC (C.Case e x _t alts@[(_,_,ee),_,_]) | isBangInteger alts
  -- XXX(matt): seems to be for debugging?
    = -- Misc.traceShow ("To simplify allowTC case") $ 
       sub (M.singleton x (simplify allowTC e)) (simplify allowTC ee)
  simplify allowTC (C.Case e x t alts)
    = C.Case (simplify allowTC e) x t (filter (not . isUndefined) (simplify allowTC <$> alts))
  simplify allowTC (C.Cast e c)
    = C.Cast (simplify allowTC e) c
  simplify allowTC (C.Tick _ e)
    = simplify allowTC e
  simplify _ (C.Coercion c)
    = C.Coercion c
  simplify _ (C.Type t)
    = C.Type t

  inline p (C.Let (C.NonRec x ex) e) | p x
                               = sub (M.singleton x (inline p ex)) (inline p e)
  inline p (C.Let xes e)       = C.Let (inline p xes) (inline p e)
  inline p (C.App e1 e2)       = C.App (inline p e1) (inline p e2)
  inline p (C.Lam x e)         = C.Lam x (inline p e)
  inline p (C.Case e x t alts) = C.Case (inline p e) x t (inline p <$> alts)
  inline p (C.Cast e c)        = C.Cast (inline p e) c
  inline p (C.Tick t e)        = C.Tick t (inline p e)
  inline _ (C.Var x)           = C.Var x
  inline _ (C.Lit l)           = C.Lit l
  inline _ (C.Coercion c)      = C.Coercion c
  inline _ (C.Type t)          = C.Type t

isUndefined :: (t, t1, C.Expr t2) -> Bool
isUndefined (_, _, e) = isUndefinedExpr e
  where
   -- auto generated undefined case: (\_ -> (patError @type "error message")) void
   isUndefinedExpr (C.App (C.Var x) _) | show x `elem` perrors = True
   isUndefinedExpr (C.Let _ e) = isUndefinedExpr e
   -- otherwise
   isUndefinedExpr _ = False

   perrors = ["Control.Exception.Base.patError"]


instance Simplify C.CoreBind where
  simplify allowTC (C.NonRec x e) = C.NonRec x (simplify allowTC e)
  simplify allowTC (C.Rec xes)    = C.Rec (Misc.mapSnd (simplify allowTC) <$> xes )

  inline p (C.NonRec x e) = C.NonRec x (inline p e)
  inline p (C.Rec xes)    = C.Rec (Misc.mapSnd (inline p) <$> xes)

instance Simplify C.CoreAlt where
  simplify allowTC (c, xs, e) = (c, xs, simplify allowTC e)
    -- where xs   = F.tracepp _msg xs0
    --      _msg = "isCoVars? " ++ F.showpp [(x, isCoVar x, varType x) | x <- xs0]
  inline p (c, xs, e) = (c, xs, inline p e)