servant/src/Servant/Common/Req.hs
2015-01-01 23:43:29 +01:00

153 lines
5 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Servant.Common.Req where
import Control.Applicative
import Control.Concurrent
import Control.Exception
import Control.Monad
import Control.Monad.Catch (MonadThrow)
import Control.Monad.IO.Class
import Control.Monad.Trans.Either
import Data.Aeson
import Data.Aeson.Parser
import Data.Aeson.Types
import Data.Attoparsec.ByteString
import Data.ByteString.Lazy hiding (pack)
import Data.String
import Data.String.Conversions
import Data.Text
import Data.Text.Encoding
import Network.HTTP.Client
import Network.HTTP.Types
import Network.URI
import Servant.Common.BaseUrl
import Servant.Common.Text
import System.IO.Unsafe
import qualified Network.HTTP.Client as Client
data Req = Req
{ reqPath :: String
, qs :: QueryText
, reqBody :: ByteString
, headers :: [(String, Text)]
}
defReq :: Req
defReq = Req "" [] "" []
appendToPath :: String -> Req -> Req
appendToPath p req =
req { reqPath = reqPath req ++ "/" ++ p }
appendToMatrixParams :: String
-> Maybe String
-> Req
-> Req
appendToMatrixParams pname pvalue req =
req { reqPath = reqPath req ++ ";" ++ pname ++ maybe "" ("=" ++) pvalue }
appendToQueryString :: Text -- ^ param name
-> Maybe Text -- ^ param value
-> Req
-> Req
appendToQueryString pname pvalue req =
req { qs = qs req ++ [(pname, pvalue)]
}
addHeader :: ToText a => String -> a -> Req -> Req
addHeader name val req = req { headers = headers req
++ [(name, toText val)]
}
setRQBody :: ByteString -> Req -> Req
setRQBody b req = req { reqBody = b }
reqToRequest :: (Functor m, MonadThrow m) => Req -> BaseUrl -> m Request
reqToRequest req (BaseUrl reqScheme reqHost reqPort) =
fmap (setheaders . setrqb . setQS ) $ parseUrl url
where url = show $ nullURI { uriScheme = case reqScheme of
Http -> "http:"
Https -> "https:"
, uriAuthority = Just $
URIAuth { uriUserInfo = ""
, uriRegName = reqHost
, uriPort = ":" ++ show reqPort
}
, uriPath = reqPath req
}
setrqb r = r { requestBody = RequestBodyLBS (reqBody req) }
setQS = setQueryString $ queryTextToQuery (qs req)
setheaders r = r { requestHeaders = Prelude.map toProperHeader (headers req) }
toProperHeader (name, val) =
(fromString name, encodeUtf8 val)
-- * performing requests
{-# NOINLINE __manager #-}
__manager :: MVar Manager
__manager = unsafePerformIO (newManager defaultManagerSettings >>= newMVar)
__withGlobalManager :: (Manager -> IO a) -> IO a
__withGlobalManager action = modifyMVar __manager $ \ manager -> do
result <- action manager
return (manager, result)
displayHttpRequest :: Method -> String
displayHttpRequest httpmethod = "HTTP " ++ cs httpmethod ++ " request"
performRequest :: Method -> Req -> (Int -> Bool) -> BaseUrl -> EitherT String IO (Int, ByteString)
performRequest reqMethod req isWantedStatus reqHost = do
partialRequest <- liftIO $ reqToRequest req reqHost
let request = partialRequest { Client.method = reqMethod
, checkStatus = \ _status _headers _cookies -> Nothing
}
eResponse <- liftIO $ __withGlobalManager $ \ manager ->
catchStatusCodeException $
Client.httpLbs request manager
case eResponse of
Left status ->
left (displayHttpRequest reqMethod ++ " failed with status: " ++ showStatus status)
Right response -> do
let status = Client.responseStatus response
unless (isWantedStatus (statusCode status)) $
left (displayHttpRequest reqMethod ++ " failed with status: " ++ showStatus status)
return $ (statusCode status, Client.responseBody response)
where
showStatus (Status code message) =
show code ++ " - " ++ cs message
performRequestJSON :: FromJSON result =>
Method -> Req -> Int -> BaseUrl -> EitherT String IO result
performRequestJSON reqMethod req wantedStatus reqHost = do
(_status, respBody) <- performRequest reqMethod req (== wantedStatus) reqHost
either
(\ message -> left (displayHttpRequest reqMethod ++ " returned invalid json: " ++ message))
return
(decodeLenient respBody)
catchStatusCodeException :: IO a -> IO (Either Status a)
catchStatusCodeException action =
catch (Right <$> action) $ \e ->
case e of
Client.StatusCodeException status _ _ -> return $ Left status
exc -> throwIO exc
-- | Like 'Data.Aeson.decode' but allows all JSON values instead of just
-- objects and arrays.
decodeLenient :: FromJSON a => ByteString -> Either String a
decodeLenient input = do
v :: Value <- parseOnly (Data.Aeson.Parser.value <* endOfInput) (cs input)
parseEither parseJSON v