{-# LANGUAGE EmptyDataDecls #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE CApiFFI #-}
module OpenCascade.TopoDS.Types
( Shape
, CompSolid
, Compound
, Edge
, Face
, Shell
, Solid
, Vertex
, Wire
, Builder
)

where


import OpenCascade.Inheritance
import OpenCascade.TopAbs.ShapeEnum
import qualified OpenCascade.TopAbs.ShapeEnum as ShapeEnum
import Foreign.Ptr
import Foreign.C


data Shape
data CompSolid
data Compound
data Edge
data Face
data Shell
data Solid
data Vertex
data Wire

data Builder

-- duplicate definition of shape type from TopoDS.Shape
-- to simultaniously avoid Orphan Instances + circular dependencies
foreign import capi unsafe "hs_TopoDS_Shape.h hs_TopoDS_Shape_ShapeType" rawShapeType :: Ptr Shape -> IO CInt

shapeType :: Ptr Shape -> IO ShapeEnum
shapeType s = toEnum . fromIntegral <$> rawShapeType s

enumDowncast :: ShapeEnum -> Ptr Shape -> IO (Maybe (Ptr t))
enumDowncast enum p = do
    e <- shapeType p
    return $ if e == enum 
                then Just (castPtr p)
                else Nothing


instance SubTypeOf Shape Compound

instance DiscriminatedSubTypeOf Shape Compound where
    downcast = enumDowncast ShapeEnum.Compound


instance SubTypeOf Shape CompSolid

instance DiscriminatedSubTypeOf Shape CompSolid where
    downcast = enumDowncast ShapeEnum.CompSolid


instance SubTypeOf Shape Solid

instance DiscriminatedSubTypeOf Shape Solid where
    downcast = enumDowncast ShapeEnum.Solid


instance SubTypeOf Shape Shell

instance DiscriminatedSubTypeOf Shape Shell where
    downcast = enumDowncast ShapeEnum.Shell


instance SubTypeOf Shape Face

instance DiscriminatedSubTypeOf Shape Face where
    downcast = enumDowncast ShapeEnum.Face

instance SubTypeOf Shape Wire

instance DiscriminatedSubTypeOf Shape Wire where
    downcast = enumDowncast ShapeEnum.Wire


instance SubTypeOf Shape Edge

instance DiscriminatedSubTypeOf Shape Edge where
    downcast = enumDowncast ShapeEnum.Edge


instance SubTypeOf Shape Vertex

instance DiscriminatedSubTypeOf Shape Vertex where
    downcast = enumDowncast ShapeEnum.Vertex