1 files changed, 47 insertions, 0 deletions
diff --git a/app/Issue/Group.hs b/app/Issue/Group.hs
new file mode 100644
index 0000000..69caf20
--- /dev/null
+++ b/app/Issue/Group.hs
@@ -0,0 +1,47 @@
+module Issue.Group
+  ( groupArg,
+    groupIssuesBy,
+  )
+where
+
+import Data.Map (Map)
+import Data.Map qualified as M
+import Data.Maybe (mapMaybe)
+import Data.Text qualified as T
+import Issue (Issue (..))
+import Issue.Tag (Tag (..))
+import Issue.Tag qualified as I
+import Options.Applicative qualified as O
+
+groupArg :: O.Parser (Maybe T.Text)
+groupArg =
+  O.optional
+    ( O.option
+        (O.maybeReader (parse . T.pack))
+        ( O.long "group"
+            <> O.metavar "TAG"
+            <> O.help "Group selected issues."
+        )
+    )
+  where
+    parse s
+      | "@" `T.isPrefixOf` s = Just (T.drop 1 s)
+      | otherwise = Nothing
+
+groupIssuesBy :: T.Text -> [Issue] -> Map T.Text [Issue]
+groupIssuesBy group issues =
+  foldl
+    ( \collected issue ->
+        foldl
+          (flip $ M.alter (Just . maybe [issue] (issue :)))
+          collected
+          (groupsOfIssue group issue)
+    )
+    M.empty
+    issues
+
+groupsOfIssue :: T.Text -> Issue -> [T.Text]
+groupsOfIssue group issue =
+  mapMaybe I.tagValue
+    . filter (\(Tag key _) -> key == group)
+    $ issue.tags ++ issue.internalTags