1 files changed, 25 insertions, 14 deletions
diff --git a/app/Issue/Filter.hs b/app/Issue/Filter.hs
index 90b75de..c330407 100644
--- a/app/Issue/Filter.hs
+++ b/app/Issue/Filter.hs
@@ -1,10 +1,11 @@
 module Issue.Filter
   ( Filter,
     filterArg,
-    applyFilter,
+    applyFilters,
   )
 where
 
+import Control.Applicative (liftA2)
 import Control.Arrow (second)
 import Data.Text (Text)
 import Data.Text qualified as T
@@ -12,9 +13,12 @@ import Issue (Issue (..))
 import Issue.Tag (Tag (..))
 import Options.Applicative qualified as O
 
-data Filter
-  = ExcludeByTag Text (Maybe Text)
-  | IncludeByTag Text (Maybe Text)
+data Filter = Filter Mode SimpleFilter deriving (Show)
+
+data Mode = Include | Exclude deriving (Show)
+
+data SimpleFilter
+  = ByTag Text (Maybe Text)
   deriving (Show)
 
 filterArg :: O.Parser [Filter]
@@ -31,9 +35,9 @@ filterArg =
   where
     parse s
       | "@" `T.isPrefixOf` s =
-          Just (uncurry IncludeByTag (splitValue (T.drop 1 s)))
+          Just (Filter Include (uncurry ByTag (splitValue (T.drop 1 s))))
       | "!@" `T.isPrefixOf` s =
-          Just (uncurry ExcludeByTag (splitValue (T.drop 2 s)))
+          Just (Filter Exclude (uncurry ByTag (splitValue (T.drop 2 s))))
       | otherwise = Nothing
 
     splitValue :: Text -> (Text, Maybe Text)
@@ -41,15 +45,22 @@ filterArg =
       (k, "") -> (k, Nothing)
       (k, v) -> (k, Just v)
 
-applyFilter :: [Filter] -> Issue -> Bool
-applyFilter [] _ = True
-applyFilter (IncludeByTag k v : fs) i =
-  applyByTag k v i && applyFilter fs i
-applyFilter (ExcludeByTag k v : fs) i =
-  not (applyByTag k v i) && applyFilter fs i
+applyFilters :: [Filter] -> ([Issue] -> [Issue])
+applyFilters fs = filter (filtersPredicate fs)
+
+filtersPredicate :: [Filter] -> (Issue -> Bool)
+filtersPredicate [] = \_ -> True
+filtersPredicate fs = foldr1 (liftA2 (&&)) (map filterPredicate fs)
+
+filterPredicate :: Filter -> (Issue -> Bool)
+filterPredicate (Filter m sf) = modePredicate m (simpleFilterPredicate sf)
+
+modePredicate :: Mode -> (Issue -> Bool) -> (Issue -> Bool)
+modePredicate Include p = p
+modePredicate Exclude p = not . p
 
-applyByTag :: Text -> Maybe Text -> Issue -> Bool
-applyByTag k v i = any ((&&) <$> matchKey <*> matchValue) i.tags
+simpleFilterPredicate :: SimpleFilter -> (Issue -> Bool)
+simpleFilterPredicate (ByTag k v) i = any ((&&) <$> matchKey <*> matchValue) i.tags
   where
     matchKey (Tag k' _) = k' == k
     matchValue (Tag _ v') = maybe True ((==) v') v