Recognize declined transactions from OK responses (#9)

Author: stevladimir

connexpay/src/Web/Connexpay/Payments.hs

@@ -5,6 +5,7 @@ module Web.Connexpay.Payments
   , ExpirationDate(..)
   , Customer(..)
   , RiskData(..)
+  , AuthorizeResult(..)
   , AuthResponse(..)
   , TransactionStatus(..)
   , authorisePayment
@@ -26,12 +27,13 @@ import Web.Connexpay.Types
 
 -- | Authorise a credit card payment.
 authorisePayment
-  :: Connexpay -> Env -> AuthRequest -> IO (Response AuthError AuthResponse)
-authorisePayment connexpay env raw = guessResponseErrorType guessAuthError <$>
-  doRequest connexpay env "authonlys" RequestBody
-    { raw
-    , logMasker = maskAuthRequest
-    }
+  :: Connexpay -> Env -> AuthRequest -> IO (Response AuthError AuthorizeResult)
+authorisePayment connexpay env raw =
+  bimapResponse (guessErrorType guessAuthError) postProcessAuthResponse <$>
+    doRequest connexpay env "authonlys" RequestBody
+      { raw
+      , logMasker = maskAuthRequest
+      }
 
 -- | Void payment
 voidPayment :: Connexpay -> Env -> VoidRequest -> IO (Response () ())

connexpay/src/Web/Connexpay/Payments/Types.hs

@@ -6,6 +6,7 @@ module Web.Connexpay.Payments.Types where
 import Data.Aeson
 import Data.Aeson.TH
 import Data.Fixed
+import Data.Function
 import Data.Int (Int32)
 import Data.Maybe
 import Data.Text (Text)
@@ -116,13 +117,38 @@ instance ToJSON RiskData where
 maskRiskData :: LogMasker RiskData
 maskRiskData = id
 
+data AuthorizeResult
+  = Authorized AuthResponse
+    -- ^ Transaction has been created and authorized successfully
+  | Declined AuthResponse
+    -- ^ Transaction has been created, but not authorized,
+    -- e.g. declined by internal Connexpay fraud checks
+  | Ambiguous AuthResponse
+    -- ^ We can't interpret the result, e.g. wasProcess=true,
+    -- but transaction status is not approved.
+    -- Something for further investigation.
+  deriving stock (Show)
+
+postProcessAuthResponse :: AuthResponse -> AuthorizeResult
+postProcessAuthResponse resp = resp & case (completed, statusOk) of
+  (True, True) -> Authorized
+  (False, False) -> Declined
+  _ -> Ambiguous
+  where
+    -- Connexpay documentation is not very clear about 'wasProcessed' semantics
+    -- when it is missing, so we are intentionally strict here with the idea
+    -- to warn about all 'Ambiguous' cases and adjust this code accordingly.
+    completed = resp.wasProcessed == Just True
+    statusOk = resp.status `elem` [TransactionApproved, TransactionApprovedWarning]
+
 data AuthResponse = AuthResponse
   { guid :: AuthOnlyGuid
   , status :: TransactionStatus
   , processorStatusCode :: Maybe Text
   , processorResponseMessage :: Maybe Text
   , addressVerificationCode :: Maybe Text
   , cvvVerificationCode :: Maybe Text
+  , wasProcessed :: Maybe Bool
   } deriving stock (Show)
 
 -- | Transaction status in Connexpay
@@ -139,7 +165,7 @@ data TransactionStatus
     -- ^ Processor errored out
   | TransactionOther Text
     -- ^ In case they return something unexpected
-  deriving stock (Show)
+  deriving stock (Eq, Show)
 
 instance FromJSON TransactionStatus where
   parseJSON = withText "TransactionStatus" $ pure . \case

connexpay/src/Web/Connexpay/Types.hs

@@ -67,8 +67,8 @@ bimapResponse f g = \case
   BadRequest body -> BadRequest body
   MissingOrExpiredToken -> MissingOrExpiredToken
 
-guessResponseErrorType :: (Error () -> e) -> Response () a -> Response e a
-guessResponseErrorType mkErr = bimapResponse (\e -> e { errorType = mkErr e }) id
+guessErrorType :: (Error () -> e) -> Error () -> Error e
+guessErrorType mkErr e = e { errorType = mkErr e }
 
 data Error e = Error
   { message :: Text