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|
-- |
-- Module: Main.Util
-- Copyright: (c) 2014 Tomislav Viljetić
-- License: BSD3
-- Maintainer: Tomislav Viljetić <tomislav@viljetic.de>
--
-- Grab bag of utilities used by "Main". This module is used to keep
-- "Main" as application-focused as possible.
--
{-# LANGUAGE OverloadedStrings #-}
module Main.Util
(
-- * Data.List utilities
splitLast,
-- * Network.Wai utilities
pathInfoString,
handleMethod,
okJSON,
noContent,
badRequest,
badRequest',
forbidden,
notFound,
notAllowed,
conflict,
conflict',
internalServerError,
internalServerError',
) where
import Data.Aeson (encode, ToJSON)
import Data.Monoid
import qualified Data.ByteString.Char8 as BS8
import qualified Data.ByteString as BS
import qualified Data.ByteString.Lazy as LBS
import qualified Data.Text as T
import qualified Data.Text.Lazy.Encoding as LT
import qualified Data.Text.Lazy as LT
import Network.HTTP.Types
import Network.Wai
import Safe
splitLast :: [a] -> ([a], a)
splitLast xs =
(init xs, last xs)
-- | Like 'pathInfo', but returns 'String's instead.
pathInfoString :: Request -> [String]
pathInfoString = map T.unpack . pathInfo
-- | Route a request based on it's method.
-- If no application is associated with the request's method,
-- then 'notAllowed' is used.
handleMethod :: [(Method, Application)] -> Application
handleMethod apps req respond =
app req respond
where
app = lookupJustDef (notAllowed allow) (requestMethod req) apps
allow = map fst apps
okJSON :: ToJSON a => a -> Application
okJSON = respondJSON [] ok200
noContent :: Application
noContent = respondEmpty [] noContent204
badRequest :: Application
badRequest = respondEmpty [] badRequest400
badRequest' :: LT.Text -> Application
badRequest' = respondText [] badRequest400
forbidden :: Application
forbidden = respondEmpty [] forbidden403
notFound :: Application
notFound = respondEmpty [] notFound404
notAllowed :: [Method] -> Application
notAllowed allow =
respondEmpty [(hAllow, BS8.intercalate ", " allow)] methodNotAllowed405
conflict :: Application
conflict =
respondEmpty [] conflict409
conflict' :: BS.ByteString -> Application
conflict' msg =
respondEmpty [] status
where
status = mkStatus 409 $ "Conflict (" <> msg <> ")"
internalServerError :: Application
internalServerError =
respondEmpty [] internalServerError500
internalServerError' :: BS.ByteString -> Application
internalServerError' msg =
respondEmpty [] status
where
status = mkStatus 500 $ "Internal Server Error (" <> msg <> ")"
-- XXX currently it's not always possible to send a truly empty response.
-- because 'Network.Wai.Handler.Warp.Response.hasBody' only discriminates
-- by status code and request method. This means that empty responses may
-- contain superfluous headers like @Transfer-Encoding@. This behavior
-- should not cause any problems, though.
respondEmpty :: ResponseHeaders -> Status -> Application
respondEmpty extraHeaders status =
respondLBS status extraHeaders ""
respondJSON :: ToJSON a => ResponseHeaders -> Status -> a -> Application
respondJSON extraHeaders status =
respondLBS status headers . encode
where
headers = (hContentType, "application/json") : extraHeaders
respondText :: ResponseHeaders -> Status -> LT.Text -> Application
respondText extraHeaders status =
respondLBS status headers . LT.encodeUtf8
where
headers = (hContentType, "text/plain; charset=utf-8") : extraHeaders
respondLBS :: Status -> ResponseHeaders -> LBS.ByteString -> Application
respondLBS status headers bs _req respond =
respond $ responseLBS status headers bs
-- | HTTP Header names, missing from 'Network.HTTP.Types.Header'.
hAllow :: HeaderName
hAllow = "Allow"
|
