Execute action only if inputs are valid + better UX

lib-tui/GHCup/Brick/App.hs

@@ -66,6 +66,7 @@ import Optics.State (use)
 import Optics.State.Operators ((.=))
 import qualified GHCup.Brick.Widgets.Menus.CompileGHC as CompileGHC
 import qualified GHCup.Brick.Widgets.Menus.CompileHLS as CompileHLS
+import Control.Monad (when)
 
 app :: AttrMap -> AttrMap -> App BrickState () Name
 app attrs dimAttrs =
@@ -174,7 +175,8 @@ compileGHCHandler ev = do
       -> mode .= ContextPanel
     (VtyEvent (Vty.EvKey Vty.KEnter []), Just (MenuElement Common.OkButton)) -> do
         let iopts = ctx ^. Menu.menuStateL
-        Actions.withIOAction $ Actions.compileGHC iopts
+        when (Menu.isValidMenu ctx) 
+          (Actions.withIOAction $ Actions.compileGHC iopts)
     _ -> Common.zoom compileGHCMenu $ CompileGHC.handler ev
 
 
@@ -193,7 +195,8 @@ compileHLSHandler ev = do
       -> mode .= ContextPanel
     (VtyEvent (Vty.EvKey Vty.KEnter []), Just (MenuElement Common.OkButton)) -> do
         let iopts = ctx ^. Menu.menuStateL
-        Actions.withIOAction $ Actions.compileHLS iopts
+        when (Menu.isValidMenu ctx)
+          (Actions.withIOAction $ Actions.compileHLS iopts)
     _ -> Common.zoom compileHLSMenu $ CompileHLS.handler ev
 
 eventHandler :: BrickEvent Name e -> EventM Name BrickState ()

lib-tui/GHCup/Brick/Widgets/Menu.hs

@@ -93,7 +93,7 @@ idFormatter = const id
 
 -- | An error message
 type ErrorMessage = T.Text
-data ErrorStatus = Valid | Invalid ErrorMessage
+data ErrorStatus = Valid | Invalid ErrorMessage deriving (Eq)
 
 -- | A lens which does nothing. Usefull to defined no-op fields
 emptyLens :: Lens' s ()
@@ -137,6 +137,8 @@ data MenuField s n where
       , fieldName      :: n
       } -> MenuField s n
 
+isValidField :: MenuField s n -> Bool
+isValidField = (== Valid) . fieldStatus 
 
 makeLensesFor
   [ ("fieldLabel", "fieldLabelL")
@@ -226,7 +228,9 @@ type Button = MenuField
 
 createButtonInput :: FieldInput () () n
 createButtonInput = FieldInput () Right "" drawButton (const $ pure ())
-  where drawButton _ _ help _ amp = amp . centerV . renderAsHelpMsg $ help
+  where 
+    drawButton True (Invalid err) _    _ amp = amp . centerV . renderAsErrMsg $ err
+    drawButton _    _             help _ amp = amp . centerV . renderAsHelpMsg $ help
 
 createButtonField :: n -> Button s n
 createButtonField = MenuField emptyLens createButtonInput "" Valid
@@ -281,7 +285,6 @@ data Menu s n
     , menuName      :: n                 -- ^ The resource Name.
     }
 
-
 makeLensesFor
   [ ("menuFields", "menuFieldsL"), ("menuState", "menuStateL")
   , ("menuButtons", "menuButtonsL"), ("menuFocusRing", "menuFocusRingL")
@@ -289,6 +292,9 @@ makeLensesFor
   ]
   ''Menu
 
+isValidMenu :: Menu s n -> Bool
+isValidMenu = all isValidField . menuFields
+
 createMenu :: n -> s -> KeyCombination -> [Button s n] -> [MenuField s n] -> Menu s n
 createMenu n initial exitK buttons fields = Menu fields initial buttons ring exitK n
   where ring = F.focusRing $ [field & fieldName | field <- fields] ++ [button & fieldName | button <- buttons]
@@ -307,6 +313,9 @@ handlerMenu ev =
         Nothing -> pure ()
         Just n  -> do 
           updated_fields <- updateFields n (VtyEvent e) fields
+          if all isValidField updated_fields
+            then menuButtonsL %= fmap (fieldStatusL .~ Valid)
+            else menuButtonsL %= fmap (fieldStatusL .~ Invalid "Some fields are invalid")
           menuFieldsL .= updated_fields
     _ -> pure ()
  where

lib-tui/GHCup/Brick/Widgets/Menus/CompileGHC.hs

@@ -196,6 +196,7 @@ create k = Menu.createMenu CompileGHCBox initialState k buttons fields
        Menu.createButtonField (Common.MenuElement Common.OkButton)
            & Menu.fieldLabelL .~ "Compile"
            & Menu.fieldHelpMsgL .~ "Compile GHC from source with options below"
+           & Menu.fieldStatusL .~ Menu.Invalid "bootstrap GHC is mandatory"
       ]
 
 handler :: BrickEvent Name e -> EventM Name CompileGHCMenu ()