DebugHttpClient.hs

-- Copyright (c) 2009, Diego Souza
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-- | Minimum definition of a user agent required to implement oauth
-- service calls. This should suffice for most applications.
module Network.OAuth.Http.DebugHttpClient
       ( DebugClient(..)
       , stdDebugClient
       ) where

import Network.OAuth.Http.HttpClient
import Network.OAuth.Http.Request
import Network.OAuth.Http.Response
import Control.Monad.Trans

-- | A client that is able to debug interaction with HTTP servers.
data DebugClient c = DebugClient { backend  :: c
                                 , traceRq  :: Request -> IO ()
                                 , traceRp  :: Response -> IO ()
                                 , traceErr :: String -> IO ()
                                 }

-- | Creates the a instance which prints messages using putStrLn.
stdDebugClient :: (HttpClient c) => c -> DebugClient c
stdDebugClient c = DebugClient { backend  = c
                               , traceRq  = putStrLn . ("Request: " ++) . show
                               , traceRp  = putStrLn . ("Response: " ++) . show
                               , traceErr = putStrLn . ("Error: "++) . show
                               }

instance (HttpClient c) => HttpClient (DebugClient c) where
  runClient debug req = do { liftIO (traceRq debug $ req)
                           ; rsp <- runClient (backend debug) req
                           ; liftIO (either (traceErr debug) (traceRp debug) $ rsp)
                           ; return rsp
                           }