support drilling down into the files of a diff

pkg/commands/git.go

@@ -1052,14 +1052,29 @@ func (c *GitCommand) GetFilesInRef(parent string, isStash bool, patchManager *pa
 		command = "git stash show"
 	}
 
-	files, err := c.OSCommand.RunCommandWithOutput("%s --no-commit-id --name-only -r --no-renames %s", command, parent)
+	filenames, err := c.OSCommand.RunCommandWithOutput("%s --no-commit-id --name-only -r --no-renames %s", command, parent)
 	if err != nil {
 		return nil, err
 	}
 
+	return c.GetCommitFilesFromFilenames(filenames, parent, patchManager), nil
+}
+
+// GetFilesInDiff get the specified commit files
+func (c *GitCommand) GetFilesInDiff(from string, to string, parent string, patchManager *patch.PatchManager) ([]*CommitFile, error) {
+	filenames, err := c.OSCommand.RunCommandWithOutput("git diff --name-only %s %s", from, to)
+	if err != nil {
+		return nil, err
+	}
+
+	return c.GetCommitFilesFromFilenames(filenames, parent, patchManager), nil
+}
+
+// filenames string is something like "file1\nfile2\nfile3"
+func (c *GitCommand) GetCommitFilesFromFilenames(filenames string, parent string, patchManager *patch.PatchManager) []*CommitFile {
 	commitFiles := make([]*CommitFile, 0)
 
-	for _, file := range strings.Split(strings.TrimRight(files, "\n"), "\n") {
+	for _, file := range strings.Split(strings.TrimRight(filenames, "\n"), "\n") {
 		status := patch.UNSELECTED
 		if patchManager != nil && patchManager.Parent == parent {
 			status = patchManager.GetFileStatus(file)
@@ -1073,7 +1088,7 @@ func (c *GitCommand) GetFilesInRef(parent string, isStash bool, patchManager *pa
 		})
 	}
 
-	return commitFiles, nil
+	return commitFiles
 }
 
 // ShowCommitFile get the diff of specified commit file

pkg/gui/commit_files_panel.go

@@ -94,7 +94,24 @@ func (gui *Gui) refreshCommitFilesView() error {
 	}
 
 	isStash := gui.State.Panels.CommitFiles.refType == REF_TYPE_STASH
-	files, err := gui.GitCommand.GetFilesInRef(gui.State.Panels.CommitFiles.refName, isStash, gui.GitCommand.PatchManager)
+	refName := gui.State.Panels.CommitFiles.refName
+	diffing := gui.State.Modes.Diffing
+
+	var files []*commands.CommitFile
+	var err error
+	if diffing.Active() {
+		from := diffing.Ref
+		to := refName
+
+		if diffing.Reverse {
+			from, to = to, from
+		}
+
+		files, err = gui.GitCommand.GetFilesInDiff(from, to, refName, gui.GitCommand.PatchManager)
+	} else {
+		files, err = gui.GitCommand.GetFilesInRef(refName, isStash, gui.GitCommand.PatchManager)
+	}
+
 	if err != nil {
 		return gui.surfaceError(err)
 	}

pkg/gui/diffing.go

@@ -40,9 +40,10 @@ func (gui *Gui) currentDiffTerminals() []string {
 	switch gui.currentContextKey() {
 	case "":
 		return nil
-	case FILES_CONTEXT_KEY, COMMIT_FILES_CONTEXT_KEY:
-		// not supporting these for now because I'm not sure how it would actually work
-		return nil
+	case FILES_CONTEXT_KEY:
+		return []string{""}
+	case COMMIT_FILES_CONTEXT_KEY:
+		return []string{gui.State.Panels.CommitFiles.refName}
 	case LOCAL_BRANCHES_CONTEXT_KEY:
 		// for our local branches we want to include both the branch and its upstream
 		branch := gui.getSelectedBranch()
@@ -75,6 +76,19 @@ func (gui *Gui) currentDiffTerminal() string {
 	return names[0]
 }
 
+func (gui *Gui) currentlySelectedFilename() string {
+	switch gui.currentContextKey() {
+	case FILES_CONTEXT_KEY, COMMIT_FILES_CONTEXT_KEY:
+		item := gui.getSideContextSelectedItem()
+		if item == nil {
+			return ""
+		}
+		return item.ID()
+	default:
+		return ""
+	}
+}
+
 func (gui *Gui) diffStr() string {
 	output := gui.State.Modes.Diffing.Ref
 
@@ -82,9 +96,16 @@ func (gui *Gui) diffStr() string {
 	if right != "" {
 		output += " " + right
 	}
+
 	if gui.State.Modes.Diffing.Reverse {
 		output += " -R"
 	}
+
+	file := gui.currentlySelectedFilename()
+	if file != "" {
+		output += " -- " + file
+	}
+
 	return output
 }