chore: resolve TODOs

1 files changed, 15 insertions, 3 deletions

diff --git a/app/Git.hs b/app/Git.hs
index eae3a85..2e8fa82 100644
--- a/app/Git.hs
+++ b/app/Git.hs
@@ -31,7 +31,7 @@ import Exception qualified as E
 import GHC.Generics (Generic)
 import Git.CommitHash
 import Patch qualified as A
-import Process (proc, sh)
+import Process (proc, sh, sh_)
 import Text.Printf (printf)
 
 getCommitHashes :: IO (NonEmpty T.Text)
@@ -96,6 +96,7 @@ readTextFileOfText = readTextFileOf LT.readFile LT.decodeUtf8
 
 readTextFileOfBS :: CommitHash -> FilePath -> IO LB.ByteString
 readTextFileOfBS = readTextFileOf LB.readFile id
+
 -- REVIEW Suggestion: we could use `id` instead of `\x -> x`
 --
 -- REVIEW OK!
@@ -118,9 +119,20 @@ resolveRef =
     . sh
     . proc "git rev-parse %"
 
--- TODO Throw if `prevHash` is not an ancestor of `hash`.
+-- | `getCommitsBetween prevCommit commit` returns the commits from `prevCommit` to `commit`. The result excludes `prevCommit`, but includes `commit`.
+--
+-- If `prevCommit` is  not an ancestor of `commit`, this functions throws `NoAncestor commit prevCommit`.
 getCommitsBetween :: CommitHash -> CommitHash -> IO [CommitHash]
-getCommitsBetween (Commit prevHash) (Commit hash) = do
+getCommitsBetween WorkingTree commit@(Commit _) =
+  throwIO (E.NoAncestor WorkingTree commit)
+getCommitsBetween WorkingTree WorkingTree = pure [WorkingTree]
+getCommitsBetween prevCommit WorkingTree =
+  fmap (++ [WorkingTree]) . getCommitsBetween prevCommit
+    =<< resolveRef "HEAD"
+getCommitsBetween prevCommit@(Commit prevHash) commit@(Commit hash) = do
+  catch
+    (sh_ (proc "git merge-base --is-ancestor % %" prevHash hash))
+    (\(_ :: E.ProcessException) -> throwIO (E.NoAncestor commit prevCommit))
   map (Commit . T.strip) . T.lines . T.decodeUtf8 . LB.toStrict
     <$> sh (proc "git log --format=%%H %..%" prevHash hash)