feat: add unified diff view option (#63)

Author: markdorison

README.md

@@ -43,6 +43,20 @@ go install github.com/dlvhdr/diffnav@latest
 git config --global pager.diff diffnav
 ```
 
+## Flags
+
+| Flag | Description |
+|------|-------------|
+| `--side-by-side, -s` | Force side-by-side diff view |
+| `--unified, -u` | Force unified diff view |
+
+Example:
+
+```sh
+git diff | diffnav --unified
+git diff | diffnav -u
+```
+
 ## Configuration
 
 The config file is searched in this order:
@@ -76,6 +90,9 @@ ui:
 
   # Color filenames by git status (default: true)
   colorFileNames: false
+
+  # Use side-by-side diff view (default: true, set false for unified)
+  sideBySide: true
 ```
 
 | Option              | Type   | Default | Description                           |
@@ -87,6 +104,7 @@ ui:
 | `ui.searchTreeWidth`| int    | `50`    | Width of the search panel             |
 | `ui.icons`          | string | `nerd-fonts` | Icon style: `nerd-fonts`, `nerd-fonts-alt`, `unicode`, or `ascii` |
 | `ui.colorFileNames` | bool   | `true`  | Color filenames by git status |
+| `ui.sideBySide`     | bool   | `true`  | Use side-by-side diff view (false for unified) |
 
 ### Delta
 
@@ -107,6 +125,7 @@ If you want the exact delta configuration I'm using - [it can be found here](htt
 | <kbd>y</kbd>      | Copy file path       |
 | <kbd>i</kbd>      | Cycle icon style     |
 | <kbd>o</kbd>      | Open file in $EDITOR |
+| <kbd>s</kbd>      | Toggle side-by-side/unified view |
 | <kbd>Tab</kbd>    | Switch focus between the panes |
 | <kbd>q</kbd>      | Quit                 |
 

main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bufio"
+	"flag"
 	"fmt"
 	"io"
 	"os"
@@ -19,6 +20,13 @@ import (
 )
 
 func main() {
+	// Parse CLI flags
+	sideBySideFlag := flag.Bool("side-by-side", false, "Force side-by-side diff view")
+	flag.BoolVar(sideBySideFlag, "s", false, "Force side-by-side diff view (shorthand)")
+	unifiedFlag := flag.Bool("unified", false, "Force unified diff view")
+	flag.BoolVar(unifiedFlag, "u", false, "Force unified diff view (shorthand)")
+	flag.Parse()
+
 	zone.NewGlobal()
 
 	stat, err := os.Stdin.Stat()
@@ -78,6 +86,14 @@ func main() {
 		os.Exit(0)
 	}
 	cfg := config.Load()
+
+	// Override config with CLI flags if specified
+	if *unifiedFlag {
+		cfg.UI.SideBySide = false
+	} else if *sideBySideFlag {
+		cfg.UI.SideBySide = true
+	}
+
 	p := tea.NewProgram(ui.New(input, cfg), tea.WithMouseAllMotion())
 
 	if _, err := p.Run(); err != nil {

pkg/config/config.go

@@ -16,6 +16,7 @@ type UIConfig struct {
 	SearchTreeWidth int    `yaml:"searchTreeWidth"`
 	Icons           string `yaml:"icons"`          // "nerd-fonts" (default), "nerd-fonts-alt", "unicode", "ascii"
 	ColorFileNames  bool   `yaml:"colorFileNames"` // Color filenames by git status (default: true)
+	SideBySide      bool   `yaml:"sideBySide"`     // Side-by-side diff view (default: true)
 }
 
 type Config struct {
@@ -32,6 +33,7 @@ func DefaultConfig() Config {
 			SearchTreeWidth: 50,
 			Icons:           "nerd-fonts",
 			ColorFileNames:  true,
+			SideBySide:      true,
 		},
 	}
 }

pkg/ui/keys.go

@@ -13,6 +13,7 @@ type KeyMap struct {
 	Copy           key.Binding
 	TogglePanel    key.Binding
 	OpenInEditor   key.Binding
+	ToggleDiffView key.Binding
 }
 
 var keys = &KeyMap{
@@ -56,6 +57,10 @@ var keys = &KeyMap{
 		key.WithKeys("o"),
 		key.WithHelp("o", "open"),
 	),
+	ToggleDiffView: key.NewBinding(
+		key.WithKeys("s"),
+		key.WithHelp("s", "toggle side-by-side"),
+	),
 }
 
 func getKeys() []key.Binding {
@@ -69,6 +74,7 @@ func getKeys() []key.Binding {
 		keys.Search,
 		keys.Copy,
 		keys.OpenInEditor,
+		keys.ToggleDiffView,
 		keys.Quit,
 	}
 }

pkg/ui/mainModel.go

@@ -73,12 +73,13 @@ type mainModel struct {
 	draggingSidebar    bool
 	customSidebarWidth int
 	iconStyle          string
+	sideBySide         bool
 }
 
 func New(input string, cfg config.Config) mainModel {
-	m := mainModel{input: input, isShowingFileTree: cfg.UI.ShowFileTree, activePanel: FileTreePanel, config: cfg, iconStyle: cfg.UI.Icons}
+	m := mainModel{input: input, isShowingFileTree: cfg.UI.ShowFileTree, activePanel: FileTreePanel, config: cfg, iconStyle: cfg.UI.Icons, sideBySide: cfg.UI.SideBySide}
 	m.fileTree = filetree.New(cfg.UI.Icons, cfg.UI.ColorFileNames)
-	m.diffViewer = diffviewer.New()
+	m.diffViewer = diffviewer.New(cfg.UI.SideBySide)
 
 	m.help = help.New()
 	helpSt := lipgloss.NewStyle()
@@ -148,6 +149,10 @@ func (m mainModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 				cmds = append(cmds, dfCmd)
 			case "i":
 				m.cycleIconStyle()
+			case "s":
+				m.sideBySide = !m.sideBySide
+				cmd = m.diffViewer.SetSideBySide(m.sideBySide)
+				cmds = append(cmds, cmd)
 			case "tab":
 				if m.isShowingFileTree {
 					if m.activePanel == FileTreePanel {
@@ -371,7 +376,7 @@ func (m mainModel) View() string {
 		// Width(0) means only the border is rendered (1 char).
 		grabLine := lipgloss.NewStyle().
 			Width(0).
-			Height(m.height - m.footerHeight() - m.headerHeight() - 1).
+			Height(m.height-m.footerHeight()-m.headerHeight()-1).
 			Border(lipgloss.NormalBorder(), false, true, false, false).
 			BorderForeground(lipgloss.Color("8")).
 			Render("")

pkg/ui/panes/diffviewer/diffviewer.go

@@ -20,14 +20,16 @@ const dirHeaderHeight = 3
 
 type Model struct {
 	common.Common
-	vp     viewport.Model
-	buffer *bytes.Buffer
-	file   *gitdiff.File
+	vp         viewport.Model
+	buffer     *bytes.Buffer
+	file       *gitdiff.File
+	sideBySide bool
 }
 
-func New() Model {
+func New(sideBySide bool) Model {
 	return Model{
-		vp: viewport.Model{},
+		vp:         viewport.Model{},
+		sideBySide: sideBySide,
 	}
 }
 
@@ -76,7 +78,7 @@ func (m *Model) SetSize(width, height int) tea.Cmd {
 	m.Height = height
 	m.vp.Width = m.Width
 	m.vp.Height = m.Height - dirHeaderHeight
-	return diff(m.file, m.Width)
+	return diff(m.file, m.Width, m.sideBySide)
 }
 
 func (m Model) headerView() string {
@@ -117,13 +119,19 @@ func (m Model) headerView() string {
 func (m Model) SetFilePatch(file *gitdiff.File) (Model, tea.Cmd) {
 	m.buffer = new(bytes.Buffer)
 	m.file = file
-	return m, diff(m.file, m.Width)
+	return m, diff(m.file, m.Width, m.sideBySide)
 }
 
 func (m *Model) GoToTop() {
 	m.vp.GotoTop()
 }
 
+// SetSideBySide updates the diff view mode and re-renders.
+func (m *Model) SetSideBySide(sideBySide bool) tea.Cmd {
+	m.sideBySide = sideBySide
+	return diff(m.file, m.Width, m.sideBySide)
+}
+
 func (m *Model) LineUp(n int) {
 	m.vp.LineUp(n)
 }
@@ -142,19 +150,19 @@ func (m *Model) ScrollDown(lines int) {
 	m.vp.LineDown(lines)
 }
 
-
-func diff(file *gitdiff.File, width int) tea.Cmd {
+func diff(file *gitdiff.File, width int, sideBySidePreference bool) tea.Cmd {
 	if width == 0 || file == nil {
 		return nil
 	}
 	return func() tea.Msg {
-		sideBySide := !file.IsNew && !file.IsDelete
+		// Only use side-by-side if preference is true AND file is not new/deleted
+		useSideBySide := sideBySidePreference && !file.IsNew && !file.IsDelete
 		args := []string{
 			"--paging=never",
 			fmt.Sprintf("-w=%d", width),
 			fmt.Sprintf("--max-line-length=%d", width),
 		}
-		if sideBySide {
+		if useSideBySide {
 			args = append(args, "--side-by-side")
 		}
 		deltac := exec.Command("delta", args...)