more command line interface improvements

1 files changed, 17 insertions, 3 deletions

diff --git a/CmdLine.hs b/CmdLine.hs
index ca574bb..6413cf7 100644
--- a/CmdLine.hs
+++ b/CmdLine.hs
@@ -3,14 +3,16 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
-module CmdLine (CmdLine(..), Mode(..), get, parse) where
+module CmdLine (CmdLine(..), Mode(..), get, parse, selectMode) where
 
 import Types
+import qualified Gpg
 import Options.Applicative
 import qualified Data.ByteString.UTF8 as BU8
+import System.Directory
 
 data CmdLine = CmdLine
-	{ mode :: Mode
+	{ mode :: Maybe Mode
 	, secretkeysource :: Maybe SecretKeySource
 	, testMode :: Bool
 	, gui :: Bool
@@ -22,7 +24,7 @@ data Mode = Backup | Restore | Benchmark
 
 parse :: Parser CmdLine
 parse = CmdLine
-	<$> (backup <|> restore <|> benchmark)
+	<$> optional (backup <|> restore <|> benchmark)
 	<*> optional (gpgswitch <|> fileswitch)
 	<*> testmodeswitch
 	<*> guiswitch
@@ -63,3 +65,15 @@ get = execParser opts
 		( fullDesc
 		<> header "keysafe - securely back up secret keys"
 		)
+
+-- | When a mode is not specified on the command line,
+-- default to backing up if a secret key exists, and otherwise restoring.
+selectMode :: CmdLine -> IO Mode
+selectMode cmdline = case mode cmdline of
+	Just m -> return m
+	Nothing -> case secretkeysource cmdline of
+		Just (KeyFile f) -> present <$> doesFileExist f
+		_ -> present . not . null <$> Gpg.listSecretKeys
+  where
+	present True = Backup
+	present False = Restore