tools: refactor: extract repo checks to utility method

code/hsec-tools/app/Command/NextID.hs

@@ -1,24 +1,10 @@
-{-# LANGUAGE LambdaCase #-}
-
 module Command.NextID where
 
-import Control.Monad (unless)
-import Data.Maybe (fromMaybe)
-import System.Exit (die)
-
-import Security.Advisories.Git (getRepoRoot)
 import Security.Advisories.Core.HsecId (printHsecId, getNextHsecId)
-import Security.Advisories.Filesystem (isSecurityAdvisoriesRepo, getGreatestId)
+import Security.Advisories.Filesystem (getGreatestId)
 
-runNextIDCommand :: Maybe FilePath -> IO ()
-runNextIDCommand mPath = do
-  let
-    path = fromMaybe "." mPath
-  repoPath <- getRepoRoot path >>= \case
-    Left _ -> die "Not a git repo"
-    Right a -> pure a
-  isRepo <- isSecurityAdvisoriesRepo repoPath
-  unless isRepo $
-    die "Not a security-advisories repo"
+import Util (ensureRepo)
 
-  getGreatestId repoPath >>= getNextHsecId >>= putStrLn . printHsecId
+runNextIDCommand :: Maybe FilePath -> IO ()
+runNextIDCommand mPath =
+  ensureRepo mPath >>= getGreatestId >>= getNextHsecId >>= putStrLn . printHsecId

code/hsec-tools/app/Command/Reserve.hs

@@ -2,16 +2,14 @@
 
 module Command.Reserve where
 
-import Control.Monad (unless, when)
-import Data.Maybe (fromMaybe)
+import Control.Monad (when)
 import System.Exit (die)
 import System.FilePath ((</>), (<.>))
 
 import Security.Advisories.Git
   ( add
   , commit
   , explainGitError
-  , getRepoRoot
   )
 import Security.Advisories.Core.HsecId
   ( placeholder
@@ -21,10 +19,11 @@ import Security.Advisories.Core.HsecId
 import Security.Advisories.Filesystem
   ( dirNameAdvisories
   , dirNameReserved
-  , isSecurityAdvisoriesRepo
   , getGreatestId
   )
 
+import Util (ensureRepo)
+
 -- | How to choose IDs when creating advisories or
 -- reservations.
 data IdMode
@@ -40,14 +39,7 @@ data CommitFlag = Commit | DoNotCommit
 
 runReserveCommand :: Maybe FilePath -> IdMode -> CommitFlag -> IO ()
 runReserveCommand mPath idMode commitFlag = do
-  let
-    path = fromMaybe "." mPath
-  repoPath <- getRepoRoot path >>= \case
-    Left _ -> die "Not a git repo"
-    Right a -> pure a
-  isRepo <- isSecurityAdvisoriesRepo repoPath
-  unless isRepo $
-    die "Not a security-advisories repo"
+  repoPath <- ensureRepo mPath
 
   hsid <- case idMode of
     IdModePlaceholder -> pure placeholder

code/hsec-tools/app/Util.hs

@@ -0,0 +1,21 @@
+{-# LANGUAGE LambdaCase #-}
+
+module Util where
+
+import Data.Maybe (fromMaybe)
+import System.Exit (die)
+
+import Security.Advisories.Filesystem (isSecurityAdvisoriesRepo)
+import Security.Advisories.Git (getRepoRoot)
+
+-- | Ensure the given path (or current directory "." if @Nothing@)
+-- is an advisory Git repo.  Return the (valid) repo root, or die
+-- with an error message.
+--
+ensureRepo :: Maybe FilePath -> IO FilePath
+ensureRepo mPath =
+  getRepoRoot (fromMaybe "." mPath) >>= \case
+    Left _          -> die "Not a git repo"
+    Right repoPath  -> isSecurityAdvisoriesRepo repoPath >>= \case
+      False -> die "Not a security-advisories repo"
+      True  -> pure repoPath

code/hsec-tools/hsec-tools.cabal

@@ -92,6 +92,7 @@ executable hsec-tools
   main-is:          Main.hs
   other-modules:    Command.Reserve
                     , Command.NextID
+                    , Util
 
   -- Modules included in this executable, other than Main.
   -- other-modules: