-- GSoC 2015 - Haskell bindings for OpenCog.
{-# LANGUAGE GADTs         #-}
{-# LANGUAGE DataKinds     #-}
{-# LANGUAGE TypeOperators #-}

-- | This Module defines some useful data types for proper interaction
-- with the AtomSpace C wrapper library.
-- Intended for internal use only.
module OpenCog.AtomSpace.Internal (
      Handle(..)
    , HandleSeq(..)
    , TVRaw(..)
    , fromTVRaw
    , toTVRaw
    , TVTypeEnum(..)
    , tvMAX_PARAMS
    ) where

import Foreign                       (Ptr)
import Data.Functor                  ((<$>))
import Data.Typeable                 (cast,Typeable)
import OpenCog.AtomSpace.Sugar       (noTv)
import OpenCog.AtomSpace.Types       (AtomName(..),AtomType(..)
                                     ,Atom(..),TruthVal(..))

type Handle = Ptr ()
type HandleSeq = Ptr Handle
-- Constant with the maximum number of parameters in any type of TV.
tvMAX_PARAMS :: Int
tvMAX_PARAMS = 5

-- TV enum type to work with TruthValueTypes from
-- <opencog/truthvalue/TruthValue.h> definition.
-- Note: this data type must be always similar to the definition on ../TruthValue.h.
-- The order of enum types MUST be exactly the same on both sites.
data TVTypeEnum = NULL_TRUTH_VALUE
                | SIMPLE_TRUTH_VALUE
                | COUNT_TRUTH_VALUE
                | INDEFINITE_TRUTH_VALUE
                | FUZZY_TRUTH_VALUE
                | PROBABILISTIC_TRUTH_VALUE
    deriving (Enum,Eq,Show)

data TVRaw = TVRaw TVTypeEnum [Double] deriving (Eq,Show)

toTVRaw :: TruthVal -> TVRaw
toTVRaw (SimpleTV a b     ) = TVRaw SIMPLE_TRUTH_VALUE [a,b]
toTVRaw (CountTV a b c    ) = TVRaw COUNT_TRUTH_VALUE [a,b,c]
toTVRaw (IndefTV a b c d e) = TVRaw INDEFINITE_TRUTH_VALUE [a,b,c,d,e]
toTVRaw (FuzzyTV a b      ) = TVRaw FUZZY_TRUTH_VALUE [a,b]
toTVRaw (ProbTV a b c     ) = TVRaw PROBABILISTIC_TRUTH_VALUE [a,b,c]

fromTVRaw :: TVRaw -> TruthVal
fromTVRaw (TVRaw SIMPLE_TRUTH_VALUE (a:b:_))  = SimpleTV a b
fromTVRaw (TVRaw COUNT_TRUTH_VALUE (a:b:c:_)) = CountTV a b c
fromTVRaw (TVRaw INDEFINITE_TRUTH_VALUE (a:b:c:d:e:_)) = IndefTV a b c d e
fromTVRaw (TVRaw FUZZY_TRUTH_VALUE (a:b:_))   = FuzzyTV a b
fromTVRaw (TVRaw PROBABILISTIC_TRUTH_VALUE (a:b:c:_))  = ProbTV a b c