refactor: move walkJSPath to Config/JSPath.hs module

The logic to evaluate `JSPath` belongs to `JSPath.hs` module.
Hence, moving this logic from `Auth/Jwt.hs` to here.

Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>

src/PostgREST/Auth/Jwt.hs

@@ -16,14 +16,11 @@ module PostgREST.Auth.Jwt
   , parseClaims) where
 
 import qualified Data.Aeson                 as JSON
-import qualified Data.Aeson.Key             as K
 import qualified Data.Aeson.KeyMap          as KM
 import qualified Data.ByteString            as BS
 import qualified Data.ByteString.Internal   as BS
 import qualified Data.ByteString.Lazy.Char8 as LBS
 import qualified Data.Scientific            as Sci
-import qualified Data.Text                  as T
-import qualified Data.Vector                as V
 import qualified Jose.Jwk                   as JWT
 import qualified Jose.Jwt                   as JWT
 
@@ -34,8 +31,8 @@ import Data.Time.Clock         (UTCTime, nominalDiffTimeToSeconds)
 import Data.Time.Clock.POSIX   (utcTimeToPOSIXSeconds)
 
 import PostgREST.Auth.Types    (AuthResult (..))
-import PostgREST.Config     (AppConfig (..), FilterExp (..), JSPath,
+import PostgREST.Config        (AppConfig (..), audMatchesCfg)
-                             JSPathExp (..), audMatchesCfg)
+import PostgREST.Config.JSPath (walkJSPath)
 import PostgREST.Error         (Error (..),
                                 JwtClaimsError (AudClaimNotStringOrArray, ExpClaimNotNumber, IatClaimNotNumber, JWTExpired, JWTIssuedAtFuture, JWTNotInAudience, JWTNotYetValid, NbfClaimNotNumber, ParsingClaimsFailed),
                                 JwtDecodeError (..), JwtError (..))
@@ -128,24 +125,6 @@ parseClaims cfg@AppConfig{configJwtRoleClaimKey, configDbAnonRole} time mclaims
            , authRole = role
            }
   where
-    walkJSPath :: Maybe JSON.Value -> JSPath -> Maybe JSON.Value
-    walkJSPath x                      []                = x
-    walkJSPath (Just (JSON.Object o)) (JSPKey key:rest) = walkJSPath (KM.lookup (K.fromText key) o) rest
-    walkJSPath (Just (JSON.Array ar)) (JSPIdx idx:rest) = walkJSPath (ar V.!? idx) rest
-    walkJSPath (Just (JSON.Array ar)) [JSPFilter (EqualsCond txt)] = findFirstMatch (==) txt ar
-    walkJSPath (Just (JSON.Array ar)) [JSPFilter (NotEqualsCond txt)] = findFirstMatch (/=) txt ar
-    walkJSPath (Just (JSON.Array ar)) [JSPFilter (StartsWithCond txt)] = findFirstMatch T.isPrefixOf txt ar
-    walkJSPath (Just (JSON.Array ar)) [JSPFilter (EndsWithCond txt)] = findFirstMatch T.isSuffixOf txt ar
-    walkJSPath (Just (JSON.Array ar)) [JSPFilter (ContainsCond txt)] = findFirstMatch T.isInfixOf txt ar
-    walkJSPath _                      _                 = Nothing
-
-    findFirstMatch matchWith pattern = foldr checkMatch Nothing
-      where
-        checkMatch (JSON.String txt) acc
-            | pattern `matchWith` txt = Just $ JSON.String txt
-            | otherwise = acc
-        checkMatch _ acc = acc
-
     unquoted :: JSON.Value -> BS.ByteString
     unquoted (JSON.String t) = encodeUtf8 t
     unquoted v               = LBS.toStrict $ JSON.encode v

src/PostgREST/Config/JSPath.hs

@@ -1,12 +1,19 @@
 {-# OPTIONS_GHC -Wno-unused-do-bind #-}
+{-# LANGUAGE LambdaCase #-}
 module PostgREST.Config.JSPath
   ( JSPath
   , JSPathExp(..)
   , FilterExp(..)
   , dumpJSPath
   , pRoleClaimKey
+  , walkJSPath
   ) where
 
+import qualified Data.Aeson                    as JSON
+import qualified Data.Aeson.Key                as K
+import qualified Data.Aeson.KeyMap             as KM
+import qualified Data.Text                     as T
+import qualified Data.Vector                   as V
 import qualified Text.ParserCombinators.Parsec as P
 
 import Data.Either.Combinators       (mapLeft)
@@ -47,6 +54,22 @@ dumpJSPath (JSPFilter cond) = "[?(@" <> expr <> ")]"
         EndsWithCond text   -> " ==^ " <> show text
         ContainsCond text   -> " *== " <> show text
 
+-- | Evaluate JSPath on a JSON
+walkJSPath :: Maybe JSON.Value -> JSPath -> Maybe JSON.Value
+walkJSPath x                      []                = x
+walkJSPath (Just (JSON.Object o)) (JSPKey key:rest) = walkJSPath (KM.lookup (K.fromText key) o) rest
+walkJSPath (Just (JSON.Array ar)) (JSPIdx idx:rest) = walkJSPath (ar V.!? idx) rest
+walkJSPath (Just (JSON.Array ar)) [JSPFilter jspFilter] = case jspFilter of
+    EqualsCond txt     -> findFirstMatch (==) txt ar
+    NotEqualsCond txt  -> findFirstMatch (/=) txt ar
+    StartsWithCond txt -> findFirstMatch T.isPrefixOf txt ar
+    EndsWithCond txt   -> findFirstMatch T.isSuffixOf txt ar
+    ContainsCond txt   -> findFirstMatch T.isInfixOf txt ar
+  where
+    findFirstMatch matchWith pattern = find (\case
+      JSON.String txt -> pattern `matchWith` txt
+      _               -> False)
+walkJSPath _                      _                 = Nothing
 
 -- Used for the config value "role-claim-key"
 pRoleClaimKey :: Text -> Either Text JSPath