{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
module Servant.API.ContentTypes.Flat where

import Data.Proxy (Proxy(..))
import Network.HTTP.Media ((//))
import qualified Data.List.NonEmpty as NonEmpty

import Servant.API.ContentTypes
import Flat

-- | Content-type for instances of the 'Flat' class in the package
-- "flat".
data FlatFmt

-- | Mime-type using the word "hackage" and the name of the package "flat".
instance Accept FlatFmt where
    contentTypes :: Proxy FlatFmt -> NonEmpty MediaType
contentTypes Proxy FlatFmt
Proxy = forall a. [a] -> NonEmpty a
NonEmpty.fromList
        [ ByteString
"application" ByteString -> ByteString -> MediaType
// ByteString
"x-hackage-flat"
        , ByteString
"application" ByteString -> ByteString -> MediaType
// ByteString
"vnd.hackage.flat"
        ]

-- |
--
-- >>> mimeRender (Proxy :: Proxy FlatFmt) (3.14 :: Float)
-- "@H\245\195"
instance Flat a => MimeRender FlatFmt a where
    mimeRender :: Proxy FlatFmt -> a -> ByteString
mimeRender Proxy FlatFmt
Proxy = forall a b. (Flat a, AsByteString b) => a -> b
flatRaw

-- |
--
-- >>> let bsl = mimeRender (Proxy :: Proxy FlatFmt) (3.14 :: Float)
-- >>> mimeUnrender (Proxy :: Proxy FlatFmt) bsl :: Either String Float
-- Right 3.14
--
-- >>> mimeUnrender (Proxy :: Proxy FlatFmt) (bsl <> "trailing garbage") :: Either String Float
-- Left "Flat.unflatRaw: TooMuchSpace (0x...,S {currPtr = 0x..., usedBits = 0})"
--
-- >>> mimeUnrender (Proxy :: Proxy FlatFmt) ("preceding garbage" <> bsl) :: Either String Float
-- Left "Flat.unflatRaw: TooMuchSpace (0x...,S {currPtr = 0x..., usedBits = 0})"
instance Flat a => MimeUnrender FlatFmt a where
    mimeUnrender :: Proxy FlatFmt -> ByteString -> Either String a
mimeUnrender Proxy FlatFmt
Proxy = forall {a} {b} {b}. (a -> b) -> Either a b -> Either b b
mapLeft forall {a}. Show a => a -> String
prettyErr forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (Flat a, AsByteString b) => b -> Decoded a
unflatRaw
      where
        mapLeft :: (a -> b) -> Either a b -> Either b b
mapLeft a -> b
f = forall a c b. (a -> c) -> (b -> c) -> Either a b -> c
either (forall a b. a -> Either a b
Left forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> b
f) forall a b. b -> Either a b
Right
        prettyErr :: a -> String
prettyErr a
err = String
"Flat.unflatRaw: " forall a. [a] -> [a] -> [a]
++ forall {a}. Show a => a -> String
show a
err