feat(textarea): Add comprehensive text selection support

examples/textarea-selection/main.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/charmbracelet/bubbles/v2/textarea"
+	tea "github.com/charmbracelet/bubbletea/v2"
+	"github.com/charmbracelet/lipgloss/v2"
+)
+
+type model struct {
+	textarea textarea.Model
+}
+
+func initialModel() model {
+	ta := textarea.New()
+	ta.Placeholder = "Try text selection with mouse or Shift+arrows!"
+	ta.SetValue("Welcome to Bubbles!\n\nThis textarea now supports:\n- Mouse selection (click and drag)\n- Double-click to select words\n- Triple-click to select lines\n- Shift+arrows for keyboard selection\n- Ctrl+A to select all\n- Ctrl+C/X to copy/cut")
+	ta.Focus()
+	ta.SetWidth(60)
+	ta.SetHeight(10)
+
+	return model{textarea: ta}
+}
+
+func (m model) Init() tea.Cmd {
+	return textarea.Blink
+}
+
+func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	switch msg := msg.(type) {
+	case tea.WindowSizeMsg:
+		m.textarea.SetWidth(msg.Width)
+		m.textarea.SetHeight(msg.Height - 4)
+	case tea.KeyPressMsg:
+		if msg.String() == "ctrl+c" && !m.textarea.HasSelection() {
+			return m, tea.Quit
+		}
+	}
+
+	var cmd tea.Cmd
+	m.textarea, cmd = m.textarea.Update(msg)
+	return m, cmd
+}
+
+func (m model) View() string {
+	help := lipgloss.NewStyle().Foreground(lipgloss.Color("241"))
+
+	status := ""
+	if m.textarea.HasSelection() {
+		selected := m.textarea.GetSelectedText()
+		if len(selected) > 30 {
+			selected = selected[:27] + "..."
+		}
+		status = fmt.Sprintf("Selected: %q", selected)
+	}
+
+	return fmt.Sprintf(
+		"%s\n\n%s\n%s",
+		m.textarea.View(),
+		status,
+		help.Render("ctrl+c to quit • mouse/keyboard to select text"),
+	)
+}
+
+func main() {
+	p := tea.NewProgram(
+		initialModel(),
+		tea.WithAltScreen(),
+		tea.WithMouseAllMotion(), // Enable mouse support
+	)
+	if _, err := p.Run(); err != nil {
+		log.Fatal(err)
+	}
+}

textarea/selection_test.go

@@ -0,0 +1,93 @@
+package textarea
+
+import (
+	"testing"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTextSelection(t *testing.T) {
+	ta := New()
+	ta.SetValue("Hello world")
+
+	// Test SelectAll
+	ta.SelectAll()
+	assert.True(t, ta.HasSelection())
+	assert.Equal(t, "Hello world", ta.GetSelectedText())
+
+	// Test ClearSelection
+	ta.ClearSelection()
+	assert.False(t, ta.HasSelection())
+
+	// Test SetSelection
+	ta.SetSelection(
+		Position{Row: 0, Col: 0},
+		Position{Row: 0, Col: 5},
+	)
+	assert.Equal(t, "Hello", ta.GetSelectedText())
+
+	// Test DeleteSelection
+	ta.DeleteSelection()
+	assert.Equal(t, " world", ta.Value())
+}
+
+func TestMouseToPosition(t *testing.T) {
+	ta := New()
+	ta.SetValue("Line 1\nLine 2\nLine 3")
+	ta.SetWidth(20)
+
+	// Test position calculation
+	pos := ta.mouseToPosition(0, 0)
+	assert.Equal(t, Position{Row: 0, Col: 0}, pos)
+
+	pos = ta.mouseToPosition(5, 1)
+	assert.Equal(t, Position{Row: 1, Col: 5}, pos)
+}
+
+func TestWordSelection(t *testing.T) {
+	ta := New()
+	ta.SetValue("Hello beautiful world")
+
+	// Select "beautiful"
+	ta.SelectWord(Position{Row: 0, Col: 8})
+	assert.Equal(t, "beautiful", ta.GetSelectedText())
+}
+
+func TestLineSelection(t *testing.T) {
+	ta := New()
+	ta.SetValue("Line 1\nLine 2\nLine 3")
+
+	// Select second line
+	ta.SelectLine(1)
+	assert.Equal(t, "Line 2", ta.GetSelectedText())
+}
+
+func TestMultiLineSelection(t *testing.T) {
+	ta := New()
+	ta.SetValue("Line 1\nLine 2\nLine 3")
+
+	// Select from middle of first line to middle of second line
+	ta.SetSelection(
+		Position{Row: 0, Col: 3},
+		Position{Row: 1, Col: 3},
+	)
+	assert.Equal(t, "e 1\nLin", ta.GetSelectedText())
+}
+
+func TestSelectionBounds(t *testing.T) {
+	ta := New()
+	ta.SetValue("Test")
+
+	// Test out of bounds selection
+	ta.SetSelection(
+		Position{Row: 0, Col: -1},
+		Position{Row: 0, Col: 100},
+	)
+	assert.Equal(t, "Test", ta.GetSelectedText())
+
+	// Test inverted selection (end before start)
+	ta.SetSelection(
+		Position{Row: 0, Col: 3},
+		Position{Row: 0, Col: 1},
+	)
+	assert.Equal(t, "es", ta.GetSelectedText())
+}