From 92a652496e323051fa782de9cf14da56336693b1 Mon Sep 17 00:00:00 2001
From: Nitin Prakash <prakash.nitin63@gmail.com>
Date: Mon, 24 Jun 2024 00:08:23 +0530
Subject: [PATCH] Reset scroll position when switching modals (#1971)

Closes #1901

When switching description modals or info panel in the bottom left corner, the viewport used to retail the scrolled state.
This PR attempts to reset the scroll position when we switch modals.
---
 src/swarm-tui/Swarm/TUI/Controller.hs      | 17 ++++++-----
 src/swarm-tui/Swarm/TUI/Controller/Util.hs |  7 +++++
 src/swarm-tui/Swarm/TUI/List.hs            | 35 ++++++++++++++--------
 3 files changed, 39 insertions(+), 20 deletions(-)

diff --git a/src/swarm-tui/Swarm/TUI/Controller.hs b/src/swarm-tui/Swarm/TUI/Controller.hs
index 1f2b91fa7..1d99ab134 100644
--- a/src/swarm-tui/Swarm/TUI/Controller.hs
+++ b/src/swarm-tui/Swarm/TUI/Controller.hs
@@ -444,12 +444,12 @@ handleMainEvent ev = do
     _ev -> do
       fring <- use $ uiState . uiGameplay . uiFocusRing
       case focusGetCurrent fring of
-        Just (FocusablePanel x) -> ($ ev) $ case x of
-          REPLPanel -> handleREPLEvent
-          WorldPanel -> handleWorldEvent
-          WorldEditorPanel -> EC.handleWorldEditorPanelEvent
-          RobotPanel -> handleRobotPanelEvent
-          InfoPanel -> handleInfoPanelEvent infoScroll
+        Just (FocusablePanel x) -> case x of
+          REPLPanel -> handleREPLEvent ev
+          WorldPanel -> handleWorldEvent ev
+          WorldEditorPanel -> EC.handleWorldEditorPanelEvent ev
+          RobotPanel -> handleRobotPanelEvent ev
+          InfoPanel -> handleInfoPanelEvent infoScroll ev
         _ -> continueWithoutRedraw
 
 -- | Set the game to Running if it was (auto) paused otherwise to paused.
@@ -1461,6 +1461,7 @@ handleInventoryListEvent ev = do
   case mList of
     Nothing -> continueWithoutRedraw
     Just l -> do
+      when (isValidListMovement ev) $ resetViewport infoScroll
       l' <- nestEventM' l (handleListEventWithSeparators ev (is _Separator))
       uiState . uiGameplay . uiInventory . uiInventoryList . _Just . _2 .= l'
 
@@ -1480,7 +1481,8 @@ handleInventorySearchEvent = \case
       uiInventorySearch .= Nothing
     gets focusedEntity >>= maybe continueWithoutRedraw descriptionModal
   -- Any old character: append to the current search string
-  CharKey c ->
+  CharKey c -> do
+    resetViewport infoScroll
     Brick.zoom (uiState . uiGameplay . uiInventory) $ do
       uiInventoryShouldUpdate .= True
       uiInventorySearch %= fmap (`snoc` c)
@@ -1510,6 +1512,7 @@ makeEntity e = do
 descriptionModal :: Entity -> EventM Name AppState ()
 descriptionModal e = do
   s <- get
+  resetViewport modalScroll
   uiState . uiGameplay . uiModal ?= generateModal s (DescriptionModal e)
 
 ------------------------------------------------------------
diff --git a/src/swarm-tui/Swarm/TUI/Controller/Util.hs b/src/swarm-tui/Swarm/TUI/Controller/Util.hs
index 9fcd31e0b..31961b661 100644
--- a/src/swarm-tui/Swarm/TUI/Controller/Util.hs
+++ b/src/swarm-tui/Swarm/TUI/Controller/Util.hs
@@ -52,6 +52,7 @@ pattern FKey c = VtyEvent (V.EvKey (V.KFun c) [])
 
 openModal :: ModalType -> EventM Name AppState ()
 openModal mt = do
+  resetViewport modalScroll
   newModal <- gets $ flip generateModal mt
   ensurePause
   uiState . uiGameplay . uiModal ?= newModal
@@ -110,3 +111,9 @@ hasDebugCapability :: Bool -> AppState -> Bool
 hasDebugCapability isCreative s =
   maybe isCreative (S.member CDebug . getCapabilitySet) $
     s ^? gameState . to focusedRobot . _Just . robotCapabilities
+
+-- | Resets the viewport scroll position
+resetViewport :: ViewportScroll Name -> EventM Name AppState ()
+resetViewport n = do
+  vScrollToBeginning n
+  hScrollToBeginning n
diff --git a/src/swarm-tui/Swarm/TUI/List.hs b/src/swarm-tui/Swarm/TUI/List.hs
index a0d1793db..621313a9e 100644
--- a/src/swarm-tui/Swarm/TUI/List.hs
+++ b/src/swarm-tui/Swarm/TUI/List.hs
@@ -3,7 +3,10 @@
 --
 -- A special modified version of 'Brick.Widgets.List.handleListEvent'
 -- to deal with skipping over separators.
-module Swarm.TUI.List (handleListEventWithSeparators) where
+module Swarm.TUI.List (
+  handleListEventWithSeparators,
+  isValidListMovement,
+) where
 
 import Brick (EventM)
 import Brick.Widgets.List qualified as BL
@@ -20,15 +23,21 @@ handleListEventWithSeparators ::
   (e -> Bool) ->
   EventM n (BL.GenericList n t e) ()
 handleListEventWithSeparators e isSep =
-  listSkip isSep movement
- where
-  movement = case e of
-    V.EvKey V.KUp [] -> Move One Bwd
-    V.EvKey (V.KChar 'k') [] -> Move One Bwd
-    V.EvKey V.KDown [] -> Move One Fwd
-    V.EvKey (V.KChar 'j') [] -> Move One Fwd
-    V.EvKey V.KHome [] -> Move Most Bwd
-    V.EvKey V.KEnd [] -> Move Most Fwd
-    V.EvKey V.KPageDown [] -> Move Page Fwd
-    V.EvKey V.KPageUp [] -> Move Page Bwd
-    _ -> NoMove
+  listSkip isSep (movement e)
+
+-- | A movement is considered legitimate when a key event
+-- results in @Move@ action.
+isValidListMovement :: V.Event -> Bool
+isValidListMovement e = movement e /= NoMove
+
+movement :: V.Event -> Move
+movement = \case
+  V.EvKey V.KUp [] -> Move One Bwd
+  V.EvKey (V.KChar 'k') [] -> Move One Bwd
+  V.EvKey V.KDown [] -> Move One Fwd
+  V.EvKey (V.KChar 'j') [] -> Move One Fwd
+  V.EvKey V.KHome [] -> Move Most Bwd
+  V.EvKey V.KEnd [] -> Move Most Fwd
+  V.EvKey V.KPageDown [] -> Move Page Fwd
+  V.EvKey V.KPageUp [] -> Move Page Bwd
+  _ -> NoMove