{-# LANGUAGE ExistentialQuantification #-}
module Development.IDE.Types.Shake (Value(..), Values, Key(..), currentValue) where

import Control.DeepSeq
import Data.Dynamic
import Data.Hashable
import Data.HashMap.Strict
import Data.Typeable
import GHC.Generics
import Language.Haskell.LSP.Types

data Value v
    = Succeeded TextDocumentVersion v
    | Stale TextDocumentVersion v
    | Failed
    deriving (Functor, Generic, Show)

instance NFData v => NFData (Value v)

-- | Convert a Value to a Maybe. This will only return `Just` for
-- up2date results not for stale values.
currentValue :: Value v -> Maybe v
currentValue (Succeeded _ v) = Just v
currentValue (Stale _ _) = Nothing
currentValue Failed = Nothing

-- | The state of the all values.
type Values = HashMap (NormalizedFilePath, Key) (Value Dynamic)

-- | Key type
data Key = forall k . (Typeable k, Hashable k, Eq k, Show k) => Key k

instance Show Key where
  show (Key k) = show k

instance Eq Key where
    Key k1 == Key k2 | Just k2' <- cast k2 = k1 == k2'
                     | otherwise = False

instance Hashable Key where
    hashWithSalt salt (Key key) = hashWithSalt salt (typeOf key, key)