{-# LANGUAGE CPP                 #-}
{-# LANGUAGE NoImplicitPrelude   #-}
{-# LANGUAGE OverloadedStrings   #-}
{-# LANGUAGE ScopedTypeVariables #-}
module System.Etc.Spec (
    module Types
  , parseConfigSpec
  , readConfigSpec
  ) where

import Protolude hiding (catch)

import System.Etc.Internal.Spec.Types as Types
    (ConfigSpec, ConfigValue, ConfigurationError (..))

import Control.Monad.Catch (MonadCatch (..), MonadThrow (..))

import qualified Data.Aeson   as JSON
import qualified Data.Text    as Text
import qualified Data.Text.IO as Text (readFile)

import qualified System.Etc.Internal.Spec.JSON as JSON
#ifdef WITH_YAML
import qualified System.Etc.Internal.Spec.YAML as YAML
#endif

{-|

Parses a text input into a @ConfigSpec@, input can be JSON or YAML (if cabal
flag is set).

-}
parseConfigSpec
  :: (MonadCatch m, MonadThrow m, JSON.FromJSON cmd)
    => Text               -- ^ Text to be parsed
    -> m (ConfigSpec cmd) -- ^ returns ConfigSpec
#ifdef WITH_YAML
parseConfigSpec input =
   catch (JSON.parseConfigSpec input)
         (\(_ :: SomeException) ->  YAML.parseConfigSpec input)
#else
parseConfigSpec =
  JSON.parseConfigSpec
#endif

{-|

Reads contents of a file and parses into a @ConfigSpec@, file contents can be
either JSON or YAML (if cabal flag is set).

-}
readConfigSpec
  :: JSON.FromJSON cmd
  => Text -- ^ Filepath where contents are going to be read from and parsed
  -> IO (ConfigSpec cmd) -- ^ returns ConfigSpec
readConfigSpec filepath = do
  contents <- Text.readFile $ Text.unpack filepath
  parseConfigSpec contents