From ce9fbe58b2688846e7c1e1041d2e92b876e2cf71 Mon Sep 17 00:00:00 2001
From: Stefan Haller <stefan@haller-berlin.de>
Date: Thu, 3 Jul 2025 18:24:04 +0200
Subject: [PATCH] Toggle only added/deleted lines in patch building view

This improves the experience when selecting a hunk generously with the mouse, by
dragging over it including some context lines above and below. Previously we
would consider the "moving end" of the selection range for whether things need
to be added or removed, but this doesn't make sense if it's a context line. Now
we consider the first actual change line that is included in the range.
---
 pkg/commands/patch/patch_builder.go            | 16 ++++------------
 .../controllers/patch_building_controller.go   | 18 ++++++++++++------
 pkg/gui/patch_exploring/state.go               | 14 ++++++++++++++
 3 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/pkg/commands/patch/patch_builder.go b/pkg/commands/patch/patch_builder.go
index 1edce0741..466b3da09 100644
--- a/pkg/commands/patch/patch_builder.go
+++ b/pkg/commands/patch/patch_builder.go
@@ -124,14 +124,6 @@ func (p *PatchBuilder) RemoveFile(filename string) error {
 	return nil
 }
 
-func getIndicesForRange(first, last int) []int {
-	indices := []int{}
-	for i := first; i <= last; i++ {
-		indices = append(indices, i)
-	}
-	return indices
-}
-
 func (p *PatchBuilder) getFileInfo(filename string) (*fileInfo, error) {
 	info, ok := p.fileInfoMap[filename]
 	if ok {
@@ -152,24 +144,24 @@ func (p *PatchBuilder) getFileInfo(filename string) (*fileInfo, error) {
 	return info, nil
 }
 
-func (p *PatchBuilder) AddFileLineRange(filename string, firstLineIdx, lastLineIdx int) error {
+func (p *PatchBuilder) AddFileLineRange(filename string, lineIndices []int) error {
 	info, err := p.getFileInfo(filename)
 	if err != nil {
 		return err
 	}
 	info.mode = PART
-	info.includedLineIndices = lo.Union(info.includedLineIndices, getIndicesForRange(firstLineIdx, lastLineIdx))
+	info.includedLineIndices = lo.Union(info.includedLineIndices, lineIndices)
 
 	return nil
 }
 
-func (p *PatchBuilder) RemoveFileLineRange(filename string, firstLineIdx, lastLineIdx int) error {
+func (p *PatchBuilder) RemoveFileLineRange(filename string, lineIndices []int) error {
 	info, err := p.getFileInfo(filename)
 	if err != nil {
 		return err
 	}
 	info.mode = PART
-	info.includedLineIndices, _ = lo.Difference(info.includedLineIndices, getIndicesForRange(firstLineIdx, lastLineIdx))
+	info.includedLineIndices, _ = lo.Difference(info.includedLineIndices, lineIndices)
 	if len(info.includedLineIndices) == 0 {
 		p.removeFile(info)
 	}
diff --git a/pkg/gui/controllers/patch_building_controller.go b/pkg/gui/controllers/patch_building_controller.go
index 94f987404..87328a15a 100644
--- a/pkg/gui/controllers/patch_building_controller.go
+++ b/pkg/gui/controllers/patch_building_controller.go
@@ -126,7 +126,6 @@ func (self *PatchBuildingController) toggleSelection() error {
 	self.context().GetMutex().Lock()
 	defer self.context().GetMutex().Unlock()
 
-	toggleFunc := self.c.Git().Patch.PatchBuilder.AddFileLineRange
 	filename := self.c.Contexts().CommitFiles.GetSelectedPath()
 	if filename == "" {
 		return nil
@@ -134,19 +133,26 @@ func (self *PatchBuildingController) toggleSelection() error {
 
 	state := self.context().GetState()
 
+	// Get added/deleted lines in the selected patch range
+	lineIndicesToToggle := state.ChangeLinesInSelectedPatchRange()
+	if len(lineIndicesToToggle) == 0 {
+		// Only context lines or header lines selected, so nothing to do
+		return nil
+	}
+
 	includedLineIndices, err := self.c.Git().Patch.PatchBuilder.GetFileIncLineIndices(filename)
 	if err != nil {
 		return err
 	}
-	currentLineIsStaged := lo.Contains(includedLineIndices, state.GetSelectedPatchLineIdx())
-	if currentLineIsStaged {
+
+	toggleFunc := self.c.Git().Patch.PatchBuilder.AddFileLineRange
+	firstSelectedChangeLineIsStaged := lo.Contains(includedLineIndices, lineIndicesToToggle[0])
+	if firstSelectedChangeLineIsStaged {
 		toggleFunc = self.c.Git().Patch.PatchBuilder.RemoveFileLineRange
 	}
 
 	// add range of lines to those set for the file
-	firstLineIdx, lastLineIdx := state.SelectedPatchRange()
-
-	if err := toggleFunc(filename, firstLineIdx, lastLineIdx); err != nil {
+	if err := toggleFunc(filename, lineIndicesToToggle); err != nil {
 		// might actually want to return an error here
 		self.c.Log.Error(err)
 	}
diff --git a/pkg/gui/patch_exploring/state.go b/pkg/gui/patch_exploring/state.go
index 53e120849..8c308b3d0 100644
--- a/pkg/gui/patch_exploring/state.go
+++ b/pkg/gui/patch_exploring/state.go
@@ -282,6 +282,20 @@ func (s *State) SelectedPatchRange() (int, int) {
 	return s.patchLineIndices[start], s.patchLineIndices[end]
 }
 
+// Returns the line indices of the selected patch range that are changes (i.e. additions or deletions)
+func (s *State) ChangeLinesInSelectedPatchRange() []int {
+	viewStart, viewEnd := s.SelectedViewRange()
+	patchStart, patchEnd := s.patchLineIndices[viewStart], s.patchLineIndices[viewEnd]
+	lines := s.patch.Lines()
+	indices := []int{}
+	for i := patchStart; i <= patchEnd; i++ {
+		if lines[i].IsChange() {
+			indices = append(indices, i)
+		}
+	}
+	return indices
+}
+
 func (s *State) CurrentLineNumber() int {
 	return s.patch.LineNumberOfLine(s.patchLineIndices[s.selectedLineIdx])
 }