{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE StrictData #-}
{- |
Concerns a custom layers datatype that has a fixed number of strict elements.
Contains helpers that use the structure with indices.
 -}
module Layers
    ( Layers (..)
    , Lay (..)
    , lay0
    , lay1
    , lay2
    , lay3
    , lay4
    , lay5
    , layIndices
    , getLay
    , foldLayersr
    , sequenceLayers
    , sequenceLayers_
    ) where
import Control.Lens

data Lay = L0 | L1 | L2 | L3 | L4 | L5

getLay :: Int -> Layers a -> a
{-# INLINE getLay #-}
getLay 0 = _lay0
getLay 1 = _lay1
getLay 2 = _lay2
getLay 3 = _lay3
getLay 4 = _lay4
getLay 5 = _lay5
getLay _ = undefined

layIndices :: Layers Int
layIndices = Layers 0 1 2 3 4 5

foldLayersr :: (Int -> a -> b -> b) -> b -> Layers a -> b
foldLayersr f x Layers
        { _lay0 = x0 
        , _lay1 = x1
        , _lay2 = x2 
        , _lay3 = x3 
        , _lay4 = x4 
        , _lay5 = x5 
        }
        = f 0 x0 . f 1 x1 . f 2 x2 . f 3 x3 . f 4 x4 $ f 5 x5 x
sequenceLayers_ :: (Int -> a -> IO b) -> Layers a -> IO ()
sequenceLayers_ f lays = sequence_ $ f <$> layIndices <*> lays
--    f Layers
--        { _lay0 = x0 
--        , _lay1 = x1
--        , _lay2 = x2 
--        , _lay3 = x3 
--        , _lay4 = x4 
--        , _lay5 = x5 
--        }
--        = f 0 x0 >> f 1 x1 >> f 2 x2 >> f 3 x3 >> f 4 x4 >> f 5 x5 >> return ()
--foldLayersl' :: (Int -> b -> a -> b) -> b -> Layers a -> b
--foldLayersl' f x Layers
--        { _lay0 = x0 
--        , _lay1 = x1
--        , _lay2 = x2 
--        , _lay3 = x3 
--        , _lay4 = x4 
--        , _lay5 = x5 
--        }
--        = f 0 x0 . f 1 x1 . f 2 x2 . f 3 x3 . f 4 x4 $ f 5 x5 x

sequenceLayers :: (Int -> a -> IO b) -> Layers a -> IO (Layers b)
sequenceLayers f lays = sequence $ f <$> layIndices <*> lays

data Layers a = Layers
    { _lay0 :: a
    , _lay1 :: a
    , _lay2 :: a
    , _lay3 :: a
    , _lay4 :: a
    , _lay5 :: a
    }
-- boilerplate folows
instance Functor Layers where
    {-# INLINE fmap #-}
    fmap f Layers
        { _lay0 = the0
        , _lay1 = the1
        , _lay2 = the2
        , _lay3 = the3
        , _lay4 = the4
        , _lay5 = the5
        }
        = Layers
        { _lay0 = f the0
        , _lay1 = f the1
        , _lay2 = f the2
        , _lay3 = f the3
        , _lay4 = f the4
        , _lay5 = f the5
        }
instance Applicative Layers where
    {-# INLINE pure #-}
    pure a = Layers a a a a a a
    {-# INLINE (<*>) #-}
    (<*>) Layers
        { _lay0 = f0
        , _lay1 = f1
        , _lay2 = f2
        , _lay3 = f3
        , _lay4 = f4
        , _lay5 = f5
        }
        Layers
        { _lay0 = x0
        , _lay1 = x1
        , _lay2 = x2
        , _lay3 = x3
        , _lay4 = x4
        , _lay5 = x5
        }
        = Layers
        { _lay0 = f0 x0
        , _lay1 = f1 x1
        , _lay2 = f2 x2
        , _lay3 = f3 x3
        , _lay4 = f4 x4
        , _lay5 = f5 x5
        }
instance Foldable Layers where
    {-# INLINE foldr #-}
    foldr f x Layers
        { _lay0 = x0 
        , _lay1 = x1
        , _lay2 = x2 
        , _lay3 = x3 
        , _lay4 = x4 
        , _lay5 = x5 
        }
        = f x0 . f x1 . f x2 . f x3 . f x4 $ f x5 x
instance Traversable Layers where
    {-# INLINE traverse #-}
    traverse f Layers
        { _lay0 = x0 
        , _lay1 = x1
        , _lay2 = x2 
        , _lay3 = x3 
        , _lay4 = x4 
        , _lay5 = x5 
        } = Layers <$> f x0 <*> f x1 <*> f x2 <*> f x3 <*> f x4 <*> f x5

makeLenses ''Layers