{-|
Module      : Test.Aeson.Internal.Utils
Description : Utility types, functions and values
Copyright   : (c) Plow Technologies, 2016
License     : BSD3
Maintainer  : mchaver@gmail.com
Stability   : Beta
-}


{-# LANGUAGE ScopedTypeVariables #-}

module Test.Aeson.Internal.Utils where

import           Control.Exception

import           Data.Aeson
import           Data.ByteString.Lazy (ByteString)
import           Data.Proxy

import           Prelude

import           Test.Hspec
import           Test.QuickCheck


data Settings = Settings {
  goldenDirectoryOption       :: GoldenDirectoryOption -- ^ use a custom directory name or use the generic "golden" directory.

, useModuleNameAsSubDirectory :: Bool -- ^ If true, use the module name in the file path, otherwise ignore it.

, sampleSize                  :: Int -- ^ How many instances of each type you want. If you use ADT versions than it will use the sample size for each constructor.
}

-- | A custom directory name or a preselected directory name.
data GoldenDirectoryOption = CustomDirectoryName String | GoldenDirectory

-- | The default settings for general use cases.
defaultSettings :: Settings
defaultSettings = Settings GoldenDirectory False 5

-- | put brackets around a String.
addBrackets :: String -> String
addBrackets s =
  if ' ' `elem` s
    then "(" ++ s ++ ")"
    else s

-- | [hspec](http://hspec.github.io/) style combinator to easily write tests
-- that check the a given operation returns the same value it was given, e.g.
-- roundtrip tests.
shouldBeIdentity :: (Eq a, Show a, Arbitrary a) =>
  Proxy a -> (a -> IO a) -> Property
shouldBeIdentity Proxy function =
  property $ \ (a :: a) -> function a `shouldReturn` a

-- | run decode in IO, if it returns Left then throw an error.
aesonDecodeIO :: FromJSON a => ByteString -> IO a
aesonDecodeIO bs = case eitherDecode bs of
  Right a -> return a
  Left msg -> throwIO $ ErrorCall
    ("aeson couldn't parse value: " ++ msg)