{-# LANGUAGE DeriveGeneric       #-}
{-# LANGUAGE RankNTypes          #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies        #-}
{-# LANGUAGE TypeOperators       #-}

module Data.Morpheus.Types.Custom
  ( Pair(..)
  , MapKind(..)
  , MapArgs(..)
  , mapKindFromList
  ) where

import           GHC.Generics (Generic)

data Pair k v =
  Pair
    { key   :: k
    , value :: v
    }
  deriving (Generic)

newtype MapArgs k =
  MapArgs
    { oneOf :: Maybe [k]
    }
  deriving (Generic)

data MapKind k v m =
  MapKind
    { size  :: Int
    , pairs :: MapArgs k -> m [Pair k v]
    }
  deriving (Generic)

mapKindFromList :: (Eq k, Monad m) => [(k, v)] -> MapKind k v m
mapKindFromList inputPairs =
  MapKind {size = length inputPairs, pairs = resolvePairs}
  where
    filterBy MapArgs {oneOf = Just list} =
      filter ((`elem` list) . fst) inputPairs
    filterBy _ = inputPairs
    resolvePairs = return . (map toGQLTuple . filterBy)
    toGQLTuple (x, y) = Pair x y