1 files changed, 68 insertions, 0 deletions
diff --git a/app/Issue/Sort.hs b/app/Issue/Sort.hs
new file mode 100644
index 0000000..1a0b3ff
--- /dev/null
+++ b/app/Issue/Sort.hs
@@ -0,0 +1,68 @@
+module Issue.Sort
+  ( Sort,
+    Order,
+    SortBy,
+    applySort,
+    sortArg,
+  )
+where
+
+import Data.List (sort, sortBy)
+import Data.Maybe (mapMaybe)
+import Data.Ord (comparing)
+import Data.Text (Text)
+import Data.Text qualified as T
+import Issue (Issue (..))
+import Issue.Tag (Tag (..))
+import Options.Applicative qualified as O
+
+data Sort = Sort Order SortBy
+  deriving (Show)
+
+data Order
+  = Asc
+  | Desc
+  deriving (Show, Eq)
+
+data SortBy
+  = SortByTag Text
+  deriving (Show)
+
+defaultSort :: Sort
+defaultSort = Sort Asc (SortByTag "@createdAt")
+
+sortArg :: O.Parser [Sort]
+sortArg =
+  O.many
+    ( O.option
+        (O.maybeReader (parse . T.pack))
+        ( O.long "sort"
+            <> O.short 's'
+            <> O.metavar "SORT"
+            <> O.help "Sort selected issues. (Defaults: `-@createdAt`)"
+        )
+    )
+  where
+    parse s
+      | "@" `T.isPrefixOf` s = Just (Sort Asc (SortByTag (T.drop 1 s)))
+      | "-@" `T.isPrefixOf` s = Just (Sort Desc (SortByTag (T.drop 2 s)))
+      | otherwise = Nothing
+
+applySort :: [Sort] -> [Issue] -> [Issue]
+applySort cs = compose (defaultSort : cs)
+  where
+    compose :: [Sort] -> ([Issue] -> [Issue])
+    compose = foldr (.) id . map toSort
+
+    toSort :: Sort -> ([Issue] -> [Issue])
+    toSort (Sort order sortBy') =
+      (if order == Desc then reverse else id)
+        . sortBy (comparing (applySortBy sortBy'))
+
+applySortBy :: SortBy -> Issue -> [Text]
+applySortBy (SortByTag k) i =
+  sort
+    ( mapMaybe
+        (\(Tag k' v) -> if k' == k then Just v else Nothing)
+        (i.tags ++ i.internalTags)
+    )