alter endpoints to support dynamic versions

src/Util/Shared.hs

@@ -0,0 +1,22 @@
+module Util.Shared where
+
+import           Startlude
+
+import           Data.Char
+import qualified Data.Text                     as T
+import           Network.HTTP.Types
+import           Yesod.Core
+
+import           Foundation
+import           Lib.Registry
+import           Lib.Semver
+import           Lib.Types.Semver
+
+getVersionFromQuery :: KnownSymbol a => FilePath -> Extension a -> Handler (Maybe AppVersion)
+getVersionFromQuery rootDir ext = do
+    specString <- T.filter (not . isSpace) . fromMaybe "*" <$> lookupGetParam "spec"
+    spec       <- case readMaybe specString of
+        Nothing -> sendResponseStatus status400 ("Invalid App Version Specification" :: Text)
+        Just t  -> pure t
+    appVersions <- liftIO $ getAvailableAppVersions rootDir ext
+    pure $ version <$> getSpecifiedAppVersion spec appVersions