import Brick
import Brick.Markup
import Data.Maybe
import Data.Monoid
import Data.List
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 []) . unlinesWA

-- 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 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]

appCursor :: St -> [CursorLocation Name] -> Maybe (CursorLocation Name)
appCursor st c = Just (head c)

appEvent :: St -> V.Event -> EventM Name (Next St)
appEvent st ev =
    case ev of
        V.EvKey V.KEsc [] -> halt st
        _ -> continue =<< E.handleEditorEvent ev st

theApp :: App St V.Event Name
theApp =
    App { appDraw = drawUI
          , appChooseCursor = appCursor
          , appHandleEvent = appEvent
          , appStartEvent = return
          , appAttrMap = const (attrMap V.defAttr [ ])
          , appLiftVtyEvent = id
          }

main = do
  st <- defaultMain theApp initialState
  putStrLn $ unlines $ E.getEditContents $ st