refactor: Move each Wai Middleware to a separate file

src/PostgREST/Logger.hs

@@ -0,0 +1,28 @@
+{-|
+Module      : PostgREST.Logger
+Description : Wai Middleware to log requests to stdout.
+-}
+module PostgREST.Logger (middleware) where
+
+import qualified Network.Wai                          as Wai
+import qualified Network.Wai.Middleware.RequestLogger as Wai
+
+import Network.HTTP.Types.Status (status400, status500)
+import System.IO.Unsafe          (unsafePerformIO)
+
+import PostgREST.Config (LogLevel (..))
+
+import Protolude
+
+middleware :: LogLevel -> Wai.Middleware
+middleware logLevel = case logLevel of
+  LogInfo  -> requestLogger (const True)
+  LogWarn  -> requestLogger (>= status400)
+  LogError -> requestLogger (>= status500)
+  LogCrit  -> requestLogger (const False)
+  where
+    requestLogger filterStatus = unsafePerformIO $ Wai.mkRequestLogger Wai.defaultRequestLoggerSettings
+      { Wai.outputFormat = Wai.ApacheWithSettings $
+          Wai.defaultApacheSettings
+            & Wai.setApacheRequestFilter (\_ res -> filterStatus $ Wai.responseStatus res)
+      }