{-# OPTIONS_GHC -fno-warn-orphans #-}
{-# LANGUAGE CPP #-}

module Data.GenValidity.HashMap where
#if !MIN_VERSION_base(4,8,0)
import Control.Applicative (pure)
import Data.Functor ((<$>))
#endif
import Data.GenValidity
import Data.Validity.HashMap ()
import Test.QuickCheck

import Data.HashMap.Strict (HashMap)
import qualified Data.HashMap.Strict as HM
import Data.Hashable (Hashable)

instance (Hashable k, Eq k, GenUnchecked k, GenUnchecked v) =>
         GenUnchecked (HashMap k v) where
    genUnchecked = HM.fromList <$> genUnchecked
    shrinkUnchecked = fmap HM.fromList . shrinkUnchecked . HM.toList

instance (Hashable k, Eq k, GenValid k, GenValid v) =>
         GenValid (HashMap k v) where
    genValid = HM.fromList <$> genValid
    shrinkValid = fmap HM.fromList . shrinkValid . HM.toList

instance (Hashable k, Eq k, GenUnchecked k, GenInvalid k, GenUnchecked v, GenInvalid v) =>
         GenInvalid (HashMap k v) where
    genInvalid =
        sized $ \n -> do
            (k, v, m) <- genSplit3 n
            let go g1 g2 = do
                    key <- resize k g1
                    val <- resize v g2
                    rest <- resize m genUnchecked
                    pure $ HM.insert key val rest
            oneof [go genInvalid genUnchecked, go genUnchecked genInvalid]
    -- Note: HM.fromList <$> genInvalid does not work because of this line in the Data.HashMap documentation:
    -- 'If the list contains duplicate mappings, the later mappings take precedence.'