From eafbd88429a80f058efaa4efd28fbfb8271065c3 Mon Sep 17 00:00:00 2001
From: Alexander Foremny <aforemny@posteo.de>
Date: Fri, 20 Oct 2023 09:55:13 +0200
Subject: record both creation and update in provenance

---
 app/Issue/Provenance.hs | 47 +++++++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 16 deletions(-)

(limited to 'app/Issue/Provenance.hs')

diff --git a/app/Issue/Provenance.hs b/app/Issue/Provenance.hs
index f3d382c..4d69472 100644
--- a/app/Issue/Provenance.hs
+++ b/app/Issue/Provenance.hs
@@ -2,28 +2,45 @@
 
 module Issue.Provenance
   ( Provenance (..),
-    provenanceFromHEAD,
+    Commit (..),
+    Author (..),
+    commitFromHEAD,
   )
 where
 
+import Control.Exception (throwIO)
 import Data.Binary (Binary, Put, get, put)
 import Data.ByteString.Lazy.Char8 (toStrict)
 import Data.Fixed (Pico)
 import Data.Function ((&))
-import Data.Text (Text, lines, splitOn, unpack)
+import Data.Text (lines, splitOn, unpack)
+import Data.Text qualified as T
 import Data.Text.Encoding (decodeUtf8)
 import Data.Time.Calendar (Day (..), toModifiedJulianDay)
 import Data.Time.Clock (DiffTime, UTCTime (..), picosecondsToDiffTime)
+import Exception qualified as E
 import GHC.Generics (Generic)
 import Process (sh)
 import System.Process.Typed (setWorkingDir)
 import Prelude hiding (lines)
 
 data Provenance = Provenance
-  { firstCommit :: Text,
+  { first :: Commit,
+    last :: Commit
+  }
+  deriving (Show, Generic, Binary, Eq)
+
+data Commit = Commit
+  { -- TODO `T.Text` -> `CommitHash`
+    hash :: T.Text,
     date :: UTCTime,
-    authorEmail :: Text,
-    authorName :: Text
+    author :: Author
+  }
+  deriving (Show, Generic, Binary, Eq)
+
+data Author = Author
+  { name :: T.Text,
+    email :: T.Text
   }
   deriving (Show, Generic, Binary, Eq)
 
@@ -43,22 +60,20 @@ instance Binary DiffTime where
   get = fmap picosecondsToDiffTime get
   put = (put :: Pico -> Put) . realToFrac
 
-provenanceFromHEAD :: FilePath -> IO (Maybe Provenance)
-provenanceFromHEAD cwd = do
+commitFromHEAD :: FilePath -> IO Commit
+commitFromHEAD cwd = do
   rawProvenance <-
     fmap (splitOn "\NUL" . head . lines . decodeUtf8 . toStrict) $
       sh $
         "git show --quiet --format='%H%x00%ai%x00%ae%x00%an'"
           & setWorkingDir cwd
-  pure $ case rawProvenance of
-    firstCommit' : rawDate : authorEmail : authorName : _ ->
+  case rawProvenance of
+    hash : rawDate : authorEmail : authorName : _ ->
       let date = read (unpack rawDate)
-       in Just
-            Provenance
-              { firstCommit = firstCommit',
+       in pure
+            Commit
+              { hash = hash,
                 date = date,
-                authorEmail = authorEmail,
-                authorName = authorName
+                author = Author authorName authorEmail
               }
-    _ ->
-      Nothing
+    _ -> throwIO E.NoCommits
-- 
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