check for mismatched brackets

editor.hs

@@ -3,27 +3,53 @@ import Brick.Markup
 import Data.Maybe
 import Data.Monoid
 import Data.List
-import Data.Text (pack, singleton)
-import Data.Text.Markup ((@@))
+import Data.Tuple
+import Data.Text (pack, singleton, unpack)
+import Data.Text.Markup
+import Control.Monad
 import qualified Brick.Widgets.Edit as E
 import qualified Graphics.Vty as V
 
+import Control.Exception.Base
+import Debug.Trace
+
 data Name = Text deriving (Ord, Show, Eq)
 type St = E.Editor Name
 
+brackets = [('(',')'),('[',']'),('{','}')]
+
 initialState :: St
 initialState = E.editor Text drawContent Nothing ""
 
 drawContent :: [String] -> Widget n
-drawContent = markup . createMarkup . unlines
+drawContent = markup . (createMarkup []) . unlinesWA
 
-createMarkup :: String -> Markup V.Attr
-createMarkup [] = mempty
-createMarkup s@('"':ss) = case i of
-                            Just n -> (pack (take (2+n) s) @@ fg V.blue) <> (createMarkup (drop (1+n) ss))
+-- workaround because empty lines don't work with Markup
+unlinesWA :: [String] -> String
+unlinesWA [] = ""
+unlinesWA (l:ls) = l ++ (" \n" ++ unlinesWA ls)
+
+createMarkup :: String -> String -> Markup V.Attr
+createMarkup _ [] = mempty
+createMarkup p s@('"':ss) = case i of
+                            Just n -> (pack (take (2+n) s) @@ fg V.blue) <> (createMarkup (reverse (take (2+n) s) ++ s) (drop (1+n) ss))
                             Nothing -> pack s @@ fg V.red
     where i = elemIndex '"' ss
-createMarkup (c:ss) = (singleton c @@ fg V.white) <> (createMarkup ss)
+createMarkup p (c:ss) 
+    | isJust ob && mismatched (fromJust ob) ss 1 
+        || isJust cb && mismatched (swap $ fromJust cb) p 1 = (singleton c @@ bg V.red) <> r
+    | otherwise = (singleton c @@ fg V.white) <> r
+        where   ob = find ((== c).fst) brackets
+                cb = find ((== c).snd) brackets
+                r = createMarkup (c:p) ss
+        
+mismatched :: (Char, Char) -> String -> Int -> Bool
+mismatched _ _ 0 = False
+mismatched _ [] _ = True
+mismatched b@(ob, cb) (c:cs) d
+    | c == ob = mismatched b cs $ d+1
+    | c == cb = mismatched b cs $ d-1
+    | otherwise = mismatched b cs d
 
 drawUI :: St -> [Widget Name]
 drawUI st = [E.renderEditor True st]