{-# LANGUAGE CPP, MultiParamTypeClasses, FlexibleInstances,
             UndecidableInstances
  #-}

module Agda.Interaction.BasicOps where
{- TODO: The operations in this module should return Expr and not String,
         for this we need to write a translator from Internal to Abstract syntax.
-}


import Control.Monad.Error
import Control.Monad.Reader
import qualified Data.Map as Map
import Data.Map (Map)
import Data.List
import Data.Maybe

import Agda.Interaction.Monad

import qualified Agda.Syntax.Concrete as C -- ToDo: Remove with instance of ToConcrete
import Agda.Syntax.Position
import Agda.Syntax.Abstract
import Agda.Syntax.Common
import Agda.Syntax.Info(ExprInfo(..),MetaInfo(..))
import Agda.Syntax.Internal (MetaId(..),Type(..),Term(..),Sort(..))
import Agda.Syntax.Translation.InternalToAbstract
import Agda.Syntax.Translation.AbstractToConcrete
import Agda.Syntax.Translation.ConcreteToAbstract
import Agda.Syntax.Scope.Base
import Agda.Syntax.Fixity(Precedence(..))
import Agda.Syntax.Parser

import Agda.TypeChecker
import Agda.TypeChecking.Conversion
import Agda.TypeChecking.Monad as M
import Agda.TypeChecking.MetaVars
import Agda.TypeChecking.Reduce
import Agda.TypeChecking.Substitute

import Agda.Utils.Monad
import Agda.Utils.Monad.Undo
import Agda.Utils.Pretty

#include "../undefined.h"
import Agda.Utils.Impossible

parseExprIn :: InteractionId -> Range -> String -> TCM Expr
parseExprIn ii rng s = do
    mId <- lookupInteractionId ii
    updateMetaVarRange mId rng
    mi  <- getMetaInfo <$> lookupMeta mId
    let pos = case rStart (getRange mi) of
                Just pos -> pos
                Nothing  -> __IMPOSSIBLE__
    e <- liftIO $ parsePosString exprParser pos s
    concreteToAbstract (clScope mi) e

giveExpr :: MetaId -> Expr -> TCM Expr
-- When translater from internal to abstract is given, this function might return
-- the expression returned by the type checker.
giveExpr mi e =
    do  mv <- lookupMeta mi
        withMetaInfo (getMetaInfo mv) $ metaTypeCheck' mi e mv

  where  metaTypeCheck' mi e mv =
            case mvJudgement mv of
		 HasType _ t  -> do
		    ctx <- getContextArgs
		    let t' = t `piApply` ctx
		    v	<- checkExpr e t'
		    case mvInstantiation mv of
			InstV v' ->
			  addConstraints =<< equalTerm t' v (v' `apply` ctx)
			_	 -> updateMeta mi v
		    reify v
		 IsSort _ -> __IMPOSSIBLE__

give :: InteractionId -> Maybe Range -> Expr -> TCM (Expr,[InteractionId])
give ii mr e = liftTCM $
     do  setUndo
         mi <- lookupInteractionId ii
         mis <- getInteractionPoints
         r <- getInteractionRange ii
         updateMetaVarRange mi $ maybe r id mr
         giveExpr mi e
         removeInteractionPoint ii
         mis' <- getInteractionPoints
         return (e, mis' \\ mis)


addDecl :: Declaration -> TCM ([InteractionId])
addDecl d =
    do   setUndo
         mis <- getInteractionPoints
         checkDecl d
         mis' <- getInteractionPoints
         return (mis' \\ mis)


refine :: InteractionId -> Maybe Range -> Expr -> TCM (Expr,[InteractionId])
-- If constants has a fixed arity, then it might be better to do
-- exact refinement.
refine ii mr e =
    do  mi <- lookupInteractionId ii
        mv <- lookupMeta mi
        let range = maybe (getRange mv) id mr
        let scope = M.getMetaScope mv
        tryRefine 10 range scope e
  where tryRefine :: Int -> Range -> ScopeInfo -> Expr -> TCM (Expr,[InteractionId])
        tryRefine nrOfMetas r scope e = try nrOfMetas e
           where try 0 e = throwError (strMsg "Can not refine")
                 try n e = give ii (Just r) e `catchError` (\_ -> try (n-1) (appMeta e))
                 appMeta :: Expr -> Expr
                 appMeta e =
                      let metaVar = QuestionMark
				  $ Agda.Syntax.Info.MetaInfo
				    { Agda.Syntax.Info.metaRange = r
                                    , Agda.Syntax.Info.metaScope = scope { scopePrecedence = ArgumentCtx }
				    , metaNumber = Nothing
				    }
                      in App (ExprRange $ r) e (Arg NotHidden $ unnamed metaVar)
                 --ToDo: The position of metaVar is not correct
                 --ToDo: The fixity of metavars is not correct -- fixed? MT

{-
refineExact :: InteractionId -> Maybe Range -> Expr -> TCM (Expr,[InteractionId])
refineExact ii mr e =
    do  mi <- lookupInteractionId ii
        mv <- lookupMeta mi
        let range = maybe (getRange mv) id mr
        let scope = M.getMetaScope mv
        (_,t) <- withMetaInfo (getMetaInfo mv) $ inferExpr e
        let arityt = arity t

        tryRefine 10 range scope e
  where tryRefine :: Int -> Range -> ScopeInfo -> Expr -> TCM (Expr,[InteractionId])
        tryRefine nrOfMetas r scope e = try nrOfMetas e
           where try 0 e = throwError (strMsg "Can not refine")
                 try n e = give ii (Just r) e `catchError` (\_ -> try (n-1) (appMeta e))
                 appMeta :: Expr -> Expr
                 appMeta e =
                      let metaVar = QuestionMark $ Agda.Syntax.Info.MetaInfo {Agda.Syntax.Info.metaRange = r,
                                                 Agda.Syntax.Info.metaScope = scope}
                      in App (ExprRange $ r) NotHidden e metaVar
                 --ToDo: The position of metaVar is not correct





abstract :: InteractionId -> Maybe Range -> TCM (Expr,[InteractionId])
abstract ii mr


refineExact :: InteractionId -> Expr -> TCM (Expr,[InteractionId])
refineExact ii e =
    do
-}


{-| Evaluate the given expression in the current environment -}
evalInCurrent :: Expr -> TCM Expr
evalInCurrent e =
    do  t <- newTypeMeta_
	v <- checkExpr e t
	v' <- normalise v
	reify v'


evalInMeta :: InteractionId -> Expr -> TCM Expr
evalInMeta ii e =
   do 	m <- lookupInteractionId ii
	mi <- getMetaInfo <$> lookupMeta m
	withMetaInfo mi $
	    evalInCurrent e


data Rewrite =  AsIs | Instantiated | HeadNormal | Normalised

--rewrite :: Rewrite -> Term -> TCM Term
rewrite AsIs	     t = return t
rewrite Instantiated t = return t   -- reify does instantiation
rewrite HeadNormal   t = reduce t
rewrite Normalised   t = normalise t


data OutputForm a b
      = OfType b a | CmpInType Comparison a b b
      | JustType b | CmpTypes Comparison b b
      | JustSort b | CmpSorts Comparison b b
      | Guard (OutputForm a b) [OutputForm a b]
      | Assign b a
      | IsEmptyType a

-- | A subset of 'OutputForm'.

data OutputForm' a b = OfType' { ofName :: b
                               , ofExpr :: a
                               }

outputFormId :: OutputForm a b -> b
outputFormId o = case o of
  OfType i _        -> i
  CmpInType _ _ i _ -> i
  JustType i        -> i
  CmpTypes _ i _    -> i
  JustSort i        -> i
  CmpSorts _ i _    -> i
  Guard o _         -> outputFormId o
  Assign i _        -> i
  IsEmptyType _     -> __IMPOSSIBLE__   -- Should never be used on IsEmpty constraints

instance Functor (OutputForm a) where
    fmap f (OfType e t)           = OfType (f e) t
    fmap f (JustType e)           = JustType (f e)
    fmap f (JustSort e)           = JustSort (f e)
    fmap f (CmpInType cmp t e e') = CmpInType cmp t (f e) (f e')
    fmap f (CmpTypes cmp e e')    = CmpTypes cmp (f e) (f e')
    fmap f (CmpSorts cmp e e')    = CmpSorts cmp (f e) (f e')
    fmap f (Guard o os)           = Guard (fmap f o) (fmap (fmap f) os)
    fmap f (Assign m e)           = Assign (f m) e
    fmap f (IsEmptyType a)        = IsEmptyType a

instance Reify Constraint (OutputForm Expr Expr) where
    reify (ValueCmp cmp t u v) = CmpInType cmp <$> reify t <*> reify u <*> reify v
    reify (TypeCmp cmp t t')   = CmpTypes cmp <$> reify t <*> reify t'
    reify (SortCmp cmp s s')   = CmpSorts cmp <$> reify s <*> reify s'
    reify (Guarded c cs) = do
	o  <- reify c
	os <- mapM (withConstraint reify) cs
	return $ Guard o os
    reify (UnBlock m) = do
        mi <- mvInstantiation <$> lookupMeta m
        case mi of
          BlockedConst t -> do
            e  <- reify t
            m' <- reify (MetaV m [])
            return $ Assign m' e
          PostponedTypeCheckingProblem cl -> enterClosure cl $ \(e, a, _) -> do
            a <- reify a
            return $ OfType e a
          Open{}  -> __IMPOSSIBLE__
          InstS{} -> __IMPOSSIBLE__
          InstV{} -> __IMPOSSIBLE__
    reify (IsEmpty a) = IsEmptyType <$> reify a

showComparison :: Comparison -> String
showComparison CmpEq  = " = "
showComparison CmpLeq = " =< "

instance (Show a,Show b) => Show (OutputForm a b) where
    show (OfType e t)           = show e ++ " : " ++ show t
    show (JustType e)           = "Type " ++ show e
    show (JustSort e)           = "Sort " ++ show e
    show (CmpInType cmp t e e') = show e ++ showComparison cmp ++ show e' ++ " : " ++ show t
    show (CmpTypes  cmp t t')   = show t ++ showComparison cmp ++ show t'
    show (CmpSorts cmp s s')    = show s ++ showComparison cmp ++ show s'
    show (Guard o os)           = show o ++ "  |  " ++ show os
    show (Assign m e)           = show m ++ " := " ++ show e
    show (IsEmptyType a)        = "Is empty: " ++ show a

instance (ToConcrete a c, ToConcrete b d) =>
         ToConcrete (OutputForm a b) (OutputForm c d) where
    toConcrete (OfType e t) = OfType <$> toConcrete e <*> toConcrete t
    toConcrete (JustType e) = JustType <$> toConcrete e
    toConcrete (JustSort e) = JustSort <$> toConcrete e
    toConcrete (CmpInType cmp t e e') =
             CmpInType cmp <$> toConcrete t <*> toConcrete e <*> toConcrete e'
    toConcrete (CmpTypes cmp e e') = CmpTypes cmp <$> toConcrete e <*> toConcrete e'
    toConcrete (CmpSorts cmp e e') = CmpSorts cmp <$> toConcrete e <*> toConcrete e'
    toConcrete (Guard o os) = Guard <$> toConcrete o <*> toConcrete os
    toConcrete (Assign m e) = Assign <$> toConcrete m <*> toConcrete e
    toConcrete (IsEmptyType a) = IsEmptyType <$> toConcrete a

instance (Pretty a, Pretty b) => Pretty (OutputForm' a b) where
  pretty (OfType' e t) = pretty e <+> text ":" <+> pretty t

instance (ToConcrete a c, ToConcrete b d) =>
            ToConcrete (OutputForm' a b) (OutputForm' c d) where
  toConcrete (OfType' e t) = OfType' <$> toConcrete e <*> toConcrete t

--ToDo: Move somewhere else
instance ToConcrete InteractionId C.Expr where
    toConcrete (InteractionId i) = return $ C.QuestionMark noRange (Just i)
instance ToConcrete MetaId C.Expr where
    toConcrete (MetaId i) = return $ C.Underscore noRange (Just i)

judgToOutputForm :: Judgement a c -> OutputForm a c
judgToOutputForm (HasType e t) = OfType e t
judgToOutputForm (IsSort s)    = JustSort s


mkUndo :: TCM ()
mkUndo = undo

--- Printing Operations
getConstraint :: Int -> TCM (OutputForm Expr Expr)
getConstraint ci =
    do  cc <- lookupConstraint ci
        cc <- reduce cc
        withConstraint reify cc


getConstraints :: TCM [OutputForm C.Expr C.Expr]
getConstraints = liftTCM $ do
    cs <- mapM (withConstraint (abstractToConcrete_ <.> reify)) =<< reduce =<< M.getConstraints
    ss <- mapM toOutputForm =<< getSolvedInteractionPoints
    return $ ss ++ cs
  where
    toOutputForm (ii, mi, e) = do
      mv <- getMetaInfo <$> lookupMeta mi
      withMetaInfo mv $ do
        let m = QuestionMark $ MetaInfo noRange emptyScopeInfo (Just $ fromIntegral ii)
        abstractToConcrete_ $ Assign m e

getSolvedInteractionPoints :: TCM [(InteractionId, MetaId, Expr)]
getSolvedInteractionPoints = do
  is <- getInteractionPoints
  concat <$> mapM solution is
  where
    solution i = do
      m  <- lookupInteractionId i
      mv <- lookupMeta m
      withMetaInfo (getMetaInfo mv) $ do
        args  <- getContextArgs
        scope <- getScope
        let sol v = do e <- reify v; return [(i, m, ScopedExpr scope e)]
            unsol = return []
        case mvInstantiation mv of
          InstV{}                        -> sol (MetaV m args)
          InstS{}                        -> sol (Sort $ MetaS m)
          Open{}                         -> unsol
          BlockedConst{}                 -> unsol
          PostponedTypeCheckingProblem{} -> unsol

typeOfMetaMI :: Rewrite -> MetaId -> TCM (OutputForm Expr MetaId)
typeOfMetaMI norm mi =
     do mv <- lookupMeta mi
	withMetaInfo (getMetaInfo mv) $
	  rewriteJudg mv (mvJudgement mv)
   where
    rewriteJudg mv (HasType i t) = do
      t <- rewrite norm t
      vs <- getContextArgs
      OfType i <$> reify (t `piApply` vs)
    rewriteJudg mv (IsSort i)    = return $ JustSort i


typeOfMeta :: Rewrite -> InteractionId -> TCM (OutputForm Expr InteractionId)
typeOfMeta norm ii =
     do mi <- lookupInteractionId ii
        out <- typeOfMetaMI norm mi
        return $ fmap (\_ -> ii) out


typeOfMetas :: Rewrite -> TCM ([OutputForm Expr InteractionId],[OutputForm Expr MetaId])
-- First visible metas, then hidden
typeOfMetas norm = liftTCM $
    do	ips <- getInteractionPoints
        js <- mapM (typeOfMeta norm) ips
        hidden <- hiddenMetas
        return $ (js,hidden)
   where hiddenMetas =    --TODO: Change so that it uses getMetaMI above
            do is <- getInteractionMetas
	       store <- Map.filterWithKey (openAndImplicit is) <$> getMetaStore
               let mvs = Map.keys store
               mapM (typeOfMetaMI norm) mvs
          where
               openAndImplicit is x (MetaVar _ _ _ M.Open _)		 = x `notElem` is
	       openAndImplicit is x (MetaVar _ _ _ (M.BlockedConst _) _) = True
	       openAndImplicit _ _ _					 = False

-- Gives a list of names and corresponding types.

contextOfMeta :: InteractionId -> Rewrite -> TCM [OutputForm' Expr Name]
contextOfMeta ii norm = do
  info <- getMetaInfo <$> (lookupMeta =<< lookupInteractionId ii)
  let localVars = map ctxEntry . envContext . clEnv $ info
  withMetaInfo info $ gfilter visible <$> reifyContext localVars
  where gfilter p = catMaybes . map p
        visible (OfType x y) | show x /= "_" = Just (OfType' x y)
                             | otherwise     = Nothing
	visible _	     = __IMPOSSIBLE__
        reifyContext xs = escapeContext (length xs) $ foldr out (return []) $ reverse xs
	out (Arg h (x,t)) rest = do
	  t' <- reify =<< rewrite norm t
	  ts <- addCtx x (Arg h t) rest
	  return $ OfType x t' : ts


{-| Returns the type of the expression in the current environment -}
typeInCurrent :: Rewrite -> Expr -> TCM Expr
typeInCurrent norm e =
    do 	(_,t) <- inferExpr e
        v <- rewrite norm t
        reify v



typeInMeta :: InteractionId -> Rewrite -> Expr -> TCM Expr
typeInMeta ii norm e =
   do 	m <- lookupInteractionId ii
	mi <- getMetaInfo <$> lookupMeta m
	withMetaInfo mi $
	    typeInCurrent norm e

withInteractionId :: InteractionId -> TCM a -> TCM a
withInteractionId i ret = do
  m <- lookupInteractionId i
  withMetaId m ret

withMetaId :: MetaId -> TCM a -> TCM a
withMetaId m ret = do
  info <- lookupMeta m
  withMetaInfo (mvInfo info) ret

-------------------------------
----- Help Functions ----------
-------------------------------





