Use non-sticky range diff when entering commit files panel

We make the name of the GetSelectedRefRangeForDiffFiles very specific on purpose
to make it clear that this is only for switching to diff files, so the
implementations can make assumptions about that (unlike GetSelectedRef, which is
used for different purposes and needs to stay more generic).

pkg/gui/context/commit_files_context.go

@@ -1,6 +1,8 @@
 package context
 
 import (
+	"fmt"
+
 	"github.com/jesseduffield/gocui"
 	"github.com/jesseduffield/lazygit/pkg/commands/models"
 	"github.com/jesseduffield/lazygit/pkg/gui/filetree"
@@ -75,12 +77,25 @@ func (self *CommitFilesContext) GetDiffTerminals() []string {
 	return []string{self.GetRef().RefName()}
 }
 
+func (self *CommitFilesContext) GetFromAndToForDiff() (string, string) {
+	if refs := self.GetRefRange(); refs != nil {
+		return refs.From.ParentRefName(), refs.To.RefName()
+	}
+	ref := self.GetRef()
+	return ref.ParentRefName(), ref.RefName()
+}
+
 func (self *CommitFilesContext) ModelSearchResults(searchStr string, caseSensitive bool) []gocui.SearchPosition {
 	return nil
 }
 
-func (self *CommitFilesContext) ReInit(ref types.Ref) {
+func (self *CommitFilesContext) ReInit(ref types.Ref, refRange *types.RefRange) {
 	self.SetRef(ref)
-	self.SetTitleRef(ref.Description())
+	self.SetRefRange(refRange)
+	if refRange != nil {
+		self.SetTitleRef(fmt.Sprintf("%s-%s", refRange.From.ShortRefName(), refRange.To.ShortRefName()))
+	} else {
+		self.SetTitleRef(ref.Description())
+	}
 	self.GetView().Title = self.Title()
 }

pkg/gui/context/reflog_commits_context.go

@@ -71,6 +71,11 @@ func (self *ReflogCommitsContext) GetSelectedRef() types.Ref {
 	return commit
 }
 
+func (self *ReflogCommitsContext) GetSelectedRefRangeForDiffFiles() *types.RefRange {
+	// It doesn't make much sense to show a range diff between two reflog entries.
+	return nil
+}
+
 func (self *ReflogCommitsContext) GetCommits() []*models.Commit {
 	return self.getModel()
 }

pkg/gui/context/stash_context.go

@@ -61,6 +61,11 @@ func (self *StashContext) GetSelectedRef() types.Ref {
 	return stash
 }
 
+func (self *StashContext) GetSelectedRefRangeForDiffFiles() *types.RefRange {
+	// It doesn't make much sense to show a range diff between two stash entries.
+	return nil
+}
+
 func (self *StashContext) GetDiffTerminals() []string {
 	itemId := self.GetSelectedItemId()
 

pkg/gui/controllers/commits_files_controller.go

@@ -136,9 +136,8 @@ func (self *CommitFilesController) GetOnRenderToMain() func() error {
 			return nil
 		}
 
-		ref := self.context().GetRef()
-		to := ref.RefName()
-		from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(ref.ParentRefName())
+		from, to := self.context().GetFromAndToForDiff()
+		from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(from)
 
 		cmdObj := self.c.Git().WorkingTree.ShowFileDiffCmdObj(from, to, reverse, node.GetPath(), false)
 		task := types.NewRunPtyTask(cmdObj.GetCmd())
@@ -250,9 +249,8 @@ func (self *CommitFilesController) canEditFiles(nodes []*filetree.CommitFileNode
 }
 
 func (self *CommitFilesController) openDiffTool(node *filetree.CommitFileNode) error {
-	ref := self.context().GetRef()
-	to := ref.RefName()
-	from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(ref.ParentRefName())
+	from, to := self.context().GetFromAndToForDiff()
+	from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(from)
 	_, err := self.c.RunSubprocess(self.c.Git().Diff.OpenDiffToolCmdObj(
 		git_commands.DiffToolCmdOptions{
 			Filepath:    node.GetPath(),
@@ -340,9 +338,8 @@ func (self *CommitFilesController) startPatchBuilder() error {
 func (self *CommitFilesController) currentFromToReverseForPatchBuilding() (string, string, bool) {
 	commitFilesContext := self.context()
 
-	ref := commitFilesContext.GetRef()
-	to := ref.RefName()
-	from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(ref.ParentRefName())
+	from, to := commitFilesContext.GetFromAndToForDiff()
+	from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(from)
 	return from, to, reverse
 }
 

pkg/gui/controllers/helpers/patch_building_helper.go

@@ -73,9 +73,8 @@ func (self *PatchBuildingHelper) RefreshPatchBuildingPanel(opts types.OnFocusOpt
 		return nil
 	}
 
-	ref := self.c.Contexts().CommitFiles.CommitFileTreeViewModel.GetRef()
-	to := ref.RefName()
-	from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(ref.ParentRefName())
+	from, to := self.c.Contexts().CommitFiles.GetFromAndToForDiff()
+	from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(from)
 	diff, err := self.c.Git().WorkingTree.ShowFileDiff(from, to, reverse, path, true)
 	if err != nil {
 		return err

pkg/gui/controllers/helpers/refresh_helper.go

@@ -285,7 +285,8 @@ func (self *RefreshHelper) refreshCommitsAndCommitFiles() {
 		// For now the awkwardness remains.
 		commit := self.c.Contexts().LocalCommits.GetSelected()
 		if commit != nil && commit.RefName() != "" {
-			self.c.Contexts().CommitFiles.ReInit(commit)
+			refRange := self.c.Contexts().LocalCommits.GetSelectedRefRangeForDiffFiles()
+			self.c.Contexts().CommitFiles.ReInit(commit, refRange)
 			_ = self.refreshCommitFilesContext()
 		}
 	}
@@ -386,9 +387,8 @@ func (self *RefreshHelper) RefreshAuthors(commits []*models.Commit) {
 }
 
 func (self *RefreshHelper) refreshCommitFilesContext() error {
-	ref := self.c.Contexts().CommitFiles.GetRef()
-	to := ref.RefName()
-	from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(ref.ParentRefName())
+	from, to := self.c.Contexts().CommitFiles.GetFromAndToForDiff()
+	from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(from)
 
 	files, err := self.c.Git().Loaders.CommitFileLoader.GetFilesInDiff(from, to, reverse)
 	if err != nil {

pkg/gui/controllers/switch_to_diff_files_controller.go

@@ -12,6 +12,7 @@ type CanSwitchToDiffFiles interface {
 	types.IListContext
 	CanRebase() bool
 	GetSelectedRef() types.Ref
+	GetSelectedRefRangeForDiffFiles() *types.RefRange
 }
 
 // Not using our ListControllerTrait because our 'selected' item is not a list item
@@ -46,8 +47,8 @@ func (self *SwitchToDiffFilesController) GetKeybindings(opts types.KeybindingsOp
 	bindings := []*types.Binding{
 		{
 			Key:               opts.GetKey(opts.Config.Universal.GoInto),
-			Handler:           self.withItem(self.enter),
-			GetDisabledReason: self.require(self.singleItemSelected(self.itemRepresentsCommit)),
+			Handler:           self.enter,
+			GetDisabledReason: self.canEnter,
 			Description:       self.c.Tr.ViewItemFiles,
 		},
 	}
@@ -56,10 +57,18 @@ func (self *SwitchToDiffFilesController) GetKeybindings(opts types.KeybindingsOp
 }
 
 func (self *SwitchToDiffFilesController) GetOnClick() func() error {
-	return self.withItemGraceful(self.enter)
+	return func() error {
+		if self.canEnter() == nil {
+			return self.enter()
+		}
+
+		return nil
+	}
 }
 
-func (self *SwitchToDiffFilesController) enter(ref types.Ref) error {
+func (self *SwitchToDiffFilesController) enter() error {
+	ref := self.context.GetSelectedRef()
+	refsRange := self.context.GetSelectedRefRangeForDiffFiles()
 	commitFilesContext := self.c.Contexts().CommitFiles
 
 	canRebase := self.context.CanRebase()
@@ -68,10 +77,12 @@ func (self *SwitchToDiffFilesController) enter(ref types.Ref) error {
 			if self.c.Modes().Diffing.Ref != ref.RefName() {
 				canRebase = false
 			}
+		} else if refsRange != nil {
+			canRebase = false
 		}
 	}
 
-	commitFilesContext.ReInit(ref)
+	commitFilesContext.ReInit(ref, refsRange)
 	commitFilesContext.SetSelection(0)
 	commitFilesContext.SetCanRebase(canRebase)
 	commitFilesContext.SetParentContext(self.context)
@@ -88,7 +99,15 @@ func (self *SwitchToDiffFilesController) enter(ref types.Ref) error {
 	return self.c.Context().Push(commitFilesContext)
 }
 
-func (self *SwitchToDiffFilesController) itemRepresentsCommit(ref types.Ref) *types.DisabledReason {
+func (self *SwitchToDiffFilesController) canEnter() *types.DisabledReason {
+	refRange := self.context.GetSelectedRefRangeForDiffFiles()
+	if refRange != nil {
+		return nil
+	}
+	ref := self.context.GetSelectedRef()
+	if ref == nil {
+		return &types.DisabledReason{Text: self.c.Tr.NoItemSelected}
+	}
 	if ref.RefName() == "" {
 		return &types.DisabledReason{Text: self.c.Tr.SelectedItemDoesNotHaveFiles}
 	}

pkg/gui/filetree/commit_file_tree_view_model.go

@@ -16,6 +16,8 @@ type ICommitFileTreeViewModel interface {
 
 	GetRef() types.Ref
 	SetRef(types.Ref)
+	GetRefRange() *types.RefRange // can be nil, in which case GetRef should be used
+	SetRefRange(*types.RefRange)  // should be set to nil when selection is not a range
 	GetCanRebase() bool
 	SetCanRebase(bool)
 }
@@ -25,9 +27,14 @@ type CommitFileTreeViewModel struct {
 	types.IListCursor
 	ICommitFileTree
 
-	// this is e.g. the commit for which we're viewing the files
+	// this is e.g. the commit for which we're viewing the files, if there is no
+	// range selection, or if the range selection can't be used for some reason
 	ref types.Ref
 
+	// this is a commit range for which we're viewing the files. Can be nil, in
+	// which case ref is used.
+	refRange *types.RefRange
+
 	// we set this to true when you're viewing the files within the checked-out branch's commits.
 	// If you're viewing the files of some random other branch we can't do any rebase stuff.
 	canRebase bool
@@ -42,6 +49,7 @@ func NewCommitFileTreeViewModel(getFiles func() []*models.CommitFile, log *logru
 		ICommitFileTree: fileTree,
 		IListCursor:     listCursor,
 		ref:             nil,
+		refRange:        nil,
 		canRebase:       false,
 	}
 }
@@ -54,6 +62,14 @@ func (self *CommitFileTreeViewModel) SetRef(ref types.Ref) {
 	self.ref = ref
 }
 
+func (self *CommitFileTreeViewModel) GetRefRange() *types.RefRange {
+	return self.refRange
+}
+
+func (self *CommitFileTreeViewModel) SetRefRange(refsForRange *types.RefRange) {
+	self.refRange = refsForRange
+}
+
 func (self *CommitFileTreeViewModel) GetCanRebase() bool {
 	return self.canRebase
 }