Simplify request creation logic

Previously, we were using `SimpleQuery` inside our Endpoint type, but
ultimately that meant pushing the work of creating those into the
endpoint creation. Ultimately, I think that's probably too noisy, and
that we can get by with a simple `(Text, Text)` representation of these
queries.

This leaves us in a bind though, because our upload endpoint is going to
deal with ByteString already. Moving that back and forth from Text to
ByteString seems like a waste of time, so I'd like to try to avoid that.

We can solve this issue by conflating the request method and the body
data into a sum type. We can then use this sum type to not only
differentiate between the different body formats, but also to determine
how to encode the particular body types for the request.

src/Helper/Twitter/Base.hs

@@ -12,7 +12,7 @@ import Helper.Twitter.Types
 
 makeRequest :: Endpoint -> Handler Request
 makeRequest e = parseRequest (url (endpointDomain e) (endpointPath e))
-    >>= addParams e
+    >>= addBody (endpointBody e)
     >>= forceSecure
     >>= signed
 
@@ -28,12 +28,15 @@ signed req = do
 forceSecure :: Request -> Handler Request
 forceSecure = return . setRequestSecure True
 
-addParams :: Endpoint -> Request -> Handler Request
-addParams (Endpoint _ _ POSTRequest b) = return . urlEncodedBody b
-addParams (Endpoint _ _ MultipartRequest b) = formDataBody (formBody b)
+addBody :: Body -> Request -> Handler Request
+addBody (PostBody b) = return . encodedBody b
+addBody (MultipartBody b) = formDataBody (formBody b)
 
-formBody :: SimpleQuery -> [Part]
-formBody b = map queryToPart b
+encodedBody :: [(Text, Text)] -> Request -> Request
+encodedBody = urlEncodedBody . map toQueryItem
   where
-    queryToPart :: SimpleQueryItem -> Part
-    queryToPart (k, v) = partBS (decodeUtf8 k) v
+    toQueryItem :: (Text, Text) -> SimpleQueryItem
+    toQueryItem (k, v) = (encodeUtf8 k, encodeUtf8 v)
+
+formBody :: [(Text, ByteString)] -> [Part]
+formBody = map (uncurry partBS)

src/Helper/Twitter/Endpoints.hs

@@ -6,23 +6,19 @@ module Helper.Twitter.Endpoints
 import Import
 import Helper.Twitter.Types
 
-import qualified Data.ByteString.Char8 as BS
-
 updateStatusEndpoint :: Text -> [Text] -> Endpoint
 updateStatusEndpoint status images = Endpoint
     { endpointDomain = "api"
     , endpointPath = "statuses/update.json"
-    , endpointType = POSTRequest
-    , endpointBody = [
-        (BS.pack "status", encodeUtf8 status),
-        (BS.pack "media_ids", encodeUtf8 $ intercalate "," images)
-      ]
+    , endpointBody = PostBody
+        [ ("status", status)
+        , ("media_ids",  intercalate "," images)
+        ]
     }
 
 uploadMediaEndpoint :: ByteString -> Endpoint
 uploadMediaEndpoint fileData = Endpoint
     { endpointDomain = "upload"
     , endpointPath = "media/upload.json"
-    , endpointType = MultipartRequest
-    , endpointBody = [(BS.pack "media", fileData)]
+    , endpointBody = MultipartBody [("media", fileData)]
     }

src/Helper/Twitter/Types.hs

@@ -3,7 +3,7 @@ module Helper.Twitter.Types
     , Credentials(..)
     , Tweet(..)
     , Media(..)
-    , RequestType(..)
+    , Body(..)
     ) where
 
 import ClassyPrelude.Yesod
@@ -32,14 +32,12 @@ instance FromJSON Media where
 
         return Media {..}
 
-data RequestType = POSTRequest | MultipartRequest
-    deriving (Eq, Show)
+data Body = PostBody [(Text, Text)] | MultipartBody [(Text, ByteString)]
 
 data Endpoint = Endpoint
     { endpointDomain :: String
     , endpointPath :: String
-    , endpointType :: RequestType
-    , endpointBody :: SimpleQuery
+    , endpointBody :: Body
     }
 
 data Credentials = Credentials
@@ -57,4 +55,3 @@ instance FromJSON Credentials where
         twitterAccessTokenSecret <- o .: "access-token-secret"
 
         return Credentials {..}
-