{-|
Module      : Network.Nakadi.Internal.Util
Description : Nakadi Client Utilities (Internal)
Copyright   : (c) Moritz Schulte 2017
License     : BSD3
Maintainer  : mtesseract@silverratio.net
Stability   : experimental
Portability : POSIX

Internal utility functions.
-}

{-# LANGUAGE TupleSections #-}

module Network.Nakadi.Internal.Util
  ( conduitDrainToLazyByteString
  , decodeThrow
  , sequenceSnd
  , extractQueryParametersFromPath
  ) where

import           Network.Nakadi.Internal.Prelude

import           Data.Aeson
import           Data.ByteString.Builder
import qualified Data.ByteString.Lazy            as ByteString.Lazy
import           Data.Conduit
import           Data.Conduit.Combinators        hiding (decodeUtf8, map)
import           Network.HTTP.Simple

import           Network.Nakadi.Types

conduitDrainToLazyByteString :: Monad m
                             => ConduitM () ByteString m ()
                             -> m ByteString.Lazy.ByteString
conduitDrainToLazyByteString conduit =
  toLazyByteString <$> (conduit $$ sinkBuilder)

decodeThrow :: (FromJSON a, MonadThrow m) => ByteString.Lazy.ByteString -> m a
decodeThrow s = case decode s of
  Just a  -> return a
  Nothing -> throwIO (DeserializationFailure s)

sequenceSnd :: Functor f => (a, f b) -> f (a, b)
sequenceSnd (a, fb) = (a,) <$> fb

extractQueryParametersFromPath :: String -> Maybe [(ByteString, ByteString)]
extractQueryParametersFromPath path =
  case parseRequest ("http://localhost" <> path) of
    Just req -> Just . catMaybes . map sequenceSnd . getRequestQueryString $ req
    Nothing -> Nothing