Implement basic UI

app/Main.hs

@@ -1,4 +1,46 @@
+{-# LANGUAGE OverloadedStrings #-}
+
 module Main where
 
+import           Brick
+import           Control.Monad
+import qualified Graphics.Vty     as Vty
+
+import           Profold.LineNode
+import           Profold.UiState
+
+data UiName = UiViewport
+  deriving (Show, Eq, Ord)
+
+myAppDraw :: UiState -> [Widget UiName]
+myAppDraw s = [viewport UiViewport Vertical $ renderUiState s]
+
+myHandleEvent :: UiState -> BrickEvent n e -> EventM n (Next UiState)
+myHandleEvent s (VtyEvent (Vty.EvKey Vty.KEsc _))         = halt s
+myHandleEvent s (VtyEvent (Vty.EvKey Vty.KUp _))          = continue $ moveFocusUp s
+myHandleEvent s (VtyEvent (Vty.EvKey Vty.KDown _))        = continue $ moveFocusDown s
+myHandleEvent s (VtyEvent (Vty.EvKey (Vty.KChar 'q') _))  = halt s
+myHandleEvent s (VtyEvent (Vty.EvKey (Vty.KChar 'k') _))  = continue $ moveFocusUp s
+myHandleEvent s (VtyEvent (Vty.EvKey (Vty.KChar 'j') _))  = continue $ moveFocusDown s
+myHandleEvent s (VtyEvent (Vty.EvKey (Vty.KChar '\t') _)) = continue $ toggleFold s
+myHandleEvent s  _                                        = continue s
+
+myAttrMap :: AttrMap
+myAttrMap = attrMap Vty.defAttr
+  [ ("focused", Vty.defAttr `Vty.withStyle` Vty.reverseVideo)
+  ]
+
+myApp :: App UiState () UiName
+myApp = App
+  { appDraw         = \s -> [renderUiState s]
+  , appChooseCursor = neverShowCursor
+  , appHandleEvent  = myHandleEvent
+  , appStartEvent   = pure
+  , appAttrMap      = const myAttrMap
+  }
+
 main :: IO ()
-main = putStrLn "Nothing to see here"
+main = void $ defaultMain myApp $ newUiState $ newLineNode "Hello world"
+  [ newLineNode " Child" []
+  , newLineNode " More children" []
+  ]