feat: add n (next file) and p/N (previous file) shortcuts to jump between files (#98)

## Summary
- Add `n` to jump to the next file and `p`/`N` to jump to the previous
file, skipping directory nodes
- Works from any panel (file tree or diff viewer)

Closes #12

Author: pablospe

README.md

@@ -144,8 +144,10 @@ If you want the exact delta configuration I'm using - [it can be found here](htt
 
 | Key               | Description                      |
 | :---------------- | :------------------------------- |
-| <kbd>j</kbd>      | Next file                        |
-| <kbd>k</kbd>      | Previous file                    |
+| <kbd>j</kbd>      | Next node                        |
+| <kbd>k</kbd>      | Previous node                    |
+| <kbd>n</kbd>      | Next file                        |
+| <kbd>p</kbd> / <kbd>N</kbd> | Previous file          |
 | <kbd>Ctrl-d</kbd> | Scroll the diff down             |
 | <kbd>Ctrl-u</kbd> | Scroll the diff up               |
 | <kbd>e</kbd>      | Toggle the file tree             |

pkg/ui/keys.go

@@ -8,6 +8,8 @@ type KeyMap struct {
 	ToggleNode      key.Binding
 	Up              key.Binding
 	Down            key.Binding
+	NextFile        key.Binding
+	PrevFile        key.Binding
 	CtrlD           key.Binding
 	CtrlU           key.Binding
 	ToggleFileTree  key.Binding
@@ -42,6 +44,14 @@ var keys = &KeyMap{
 		key.WithKeys("down", "j"),
 		key.WithHelp("↓/j", "next file"),
 	),
+	NextFile: key.NewBinding(
+		key.WithKeys("n"),
+		key.WithHelp("n", "next file"),
+	),
+	PrevFile: key.NewBinding(
+		key.WithKeys("p", "N"),
+		key.WithHelp("p/N", "prev file"),
+	),
 	CtrlD: key.NewBinding(
 		key.WithKeys("ctrl+d"),
 		key.WithHelp("ctrl+d", "diff down"),
@@ -93,6 +103,8 @@ func KeyGroups() [][]key.Binding {
 		keys.SwitchPanel,
 		keys.Up,
 		keys.Down,
+		keys.NextFile,
+		keys.PrevFile,
 		keys.CtrlD,
 		keys.CtrlU,
 	}, {

pkg/ui/panes/diffviewer/diffviewer.go

@@ -69,9 +69,9 @@ func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
 	switch msg := msg.(type) {
 	case tea.KeyMsg:
 		switch msg.String() {
-		case "down", "j":
+		case "down", "j", "n":
 			break
-		case "up", "k":
+		case "up", "k", "N", "p":
 			break
 		default:
 			vp, vpCmd := m.vp.Update(msg)

pkg/ui/panes/filetree/filetree.go

@@ -131,6 +131,52 @@ func (m *Model) Up() {
 	m.t.Up()
 }
 
+// NextFile moves the cursor to the next file node, skipping directories.
+func (m *Model) NextFile() bool {
+	curr := m.t.NodeAtCurrentOffset()
+	if curr == nil {
+		return false
+	}
+	nodes := m.t.AllNodes()
+	found := false
+	for _, node := range nodes {
+		if !found {
+			if node.YOffset() == curr.YOffset() {
+				found = true
+			}
+			continue
+		}
+		if _, ok := node.GivenValue().(*filenode.FileNode); ok {
+			m.t.SetYOffset(node.YOffset())
+			return true
+		}
+	}
+	return false
+}
+
+// PrevFile moves the cursor to the previous file node, skipping directories.
+func (m *Model) PrevFile() bool {
+	curr := m.t.NodeAtCurrentOffset()
+	if curr == nil {
+		return false
+	}
+	nodes := m.t.AllNodes()
+	lastFileOffset := -1
+	for _, node := range nodes {
+		if node.YOffset() >= curr.YOffset() {
+			break
+		}
+		if _, ok := node.GivenValue().(*filenode.FileNode); ok {
+			lastFileOffset = node.YOffset()
+		}
+	}
+	if lastFileOffset >= 0 {
+		m.t.SetYOffset(lastFileOffset)
+		return true
+	}
+	return false
+}
+
 func (m *Model) SetCursorByPath(path string) {
 	if len(m.files) == 0 {
 		return

pkg/ui/tui.go

@@ -187,6 +187,12 @@ func (m mainModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 					m.activePanel = FileTreePanel
 				}
 			}
+		case key.Matches(msg, keys.PrevFile):
+			m, cmd = m.moveToFile(-1)
+			cmds = append(cmds, cmd)
+		case key.Matches(msg, keys.NextFile):
+			m, cmd = m.moveToFile(1)
+			cmds = append(cmds, cmd)
 		case key.Matches(msg, keys.Up):
 			if m.activePanel == FileTreePanel {
 				m, cmd = m.moveCursor(-1)
@@ -750,6 +756,27 @@ func abs(x int) int {
 	return x
 }
 
+func (m mainModel) moveToFile(movement int) (mainModel, tea.Cmd) {
+	var cmd tea.Cmd
+	var moved bool
+	switch movement {
+	case -1:
+		moved = m.fileTree.PrevFile()
+	case 1:
+		moved = m.fileTree.NextFile()
+	}
+
+	if !moved {
+		return m, nil
+	}
+
+	node := m.fileTree.GetCurrNode()
+	m, cmd = m.setNodeDiff(node)
+	m.diffViewer.GoToTop()
+
+	return m, cmd
+}
+
 func (m mainModel) moveCursor(movement int) (mainModel, tea.Cmd) {
 	var cmd tea.Cmd
 	switch movement {