From 8114943cb16f56d85ea0f0467139e8537ac50e34 Mon Sep 17 00:00:00 2001
From: Raphaele Salvatore Licciardo <raphaele.salvatore@outlook.de>
Date: Fri, 7 Nov 2025 06:36:25 +0100
Subject: [PATCH] Fix page navigation scroll behavior to keep cursor at
 top/bottom

When pressing '.' (next page) or ',' (previous page), the selection
now stays at the bottom or top of the viewport respectively, instead
of being centered which caused items to scroll off. If the selection is not
already on the last/first line of the view, '.'/',' moves it there without
scrolling.

This implements a special case for page navigation as suggested by
the maintainer in issue #5017, keeping the cursor position consistent
with user expectations for page-based navigation.

Fixes #5017

Co-authored-by: Stefan Haller <stefan@haller-berlin.de>
---
 pkg/gui/controllers/list_controller.go | 52 +++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 2 deletions(-)

diff --git a/pkg/gui/controllers/list_controller.go b/pkg/gui/controllers/list_controller.go
index c935854b7..f772fb3d8 100644
--- a/pkg/gui/controllers/list_controller.go
+++ b/pkg/gui/controllers/list_controller.go
@@ -123,11 +123,59 @@ func (self *ListController) handleLineChangeAux(f func(int), change int) error {
 }
 
 func (self *ListController) HandlePrevPage() error {
-	return self.handleLineChange(-self.context.GetViewTrait().PageDelta())
+	return self.handlePageChange(-self.context.GetViewTrait().PageDelta())
 }
 
 func (self *ListController) HandleNextPage() error {
-	return self.handleLineChange(self.context.GetViewTrait().PageDelta())
+	return self.handlePageChange(self.context.GetViewTrait().PageDelta())
+}
+
+func (self *ListController) handlePageChange(delta int) error {
+	list := self.context.GetList()
+	view := self.context.GetViewTrait()
+
+	before := list.GetSelectedLineIdx()
+
+	viewPortStart, viewPortHeight := view.ViewPortYBounds()
+	beforeViewIdx := self.context.ModelIndexToViewIndex(before)
+	afterViewIdx := beforeViewIdx + delta
+	newModelIndex := self.context.ViewIndexToModelIndex(afterViewIdx)
+
+	if delta < 0 {
+		// Previous page: keep selection at top of viewport
+		indexAtTopOfPage := self.context.ViewIndexToModelIndex(viewPortStart)
+		if before != indexAtTopOfPage {
+			// If the selection isn't already at the top of the page, move it there without scrolling
+			list.MoveSelectedLine(indexAtTopOfPage - before)
+		} else {
+			// Otherwise, move the selection by one page and scroll
+			list.MoveSelectedLine(newModelIndex - before)
+
+			linesToScroll := afterViewIdx - viewPortStart
+			if linesToScroll < 0 {
+				view.ScrollUp(-linesToScroll)
+			}
+		}
+	} else {
+		// Next page: keep selection at bottom of viewport
+		indexAtBottomOfPage := self.context.ViewIndexToModelIndex(viewPortStart + viewPortHeight - 1)
+		if before != indexAtBottomOfPage {
+			// If the selection isn't already at the bottom of the page, move it there without scrolling
+			list.MoveSelectedLine(indexAtBottomOfPage - before)
+		} else {
+			// Otherwise, move the selection by one page and scroll
+			list.MoveSelectedLine(newModelIndex - before)
+
+			linesToScroll := afterViewIdx - (viewPortStart + viewPortHeight - 1)
+			if linesToScroll > 0 {
+				view.ScrollDown(linesToScroll)
+			}
+		}
+	}
+
+	self.context.HandleFocus(types.OnFocusOpts{})
+
+	return nil
 }
 
 func (self *ListController) HandleGotoTop() error {