doc: Add textarea examples (#357)

* chore: bump bubbles@master

* doc(textarea): Add example of `chat` application with textarea

* doc(textarea): Add example of `textarea` prompting the user to tell a story

* doc(textarea): Add example of `split-editors` on how to manage multiple textareas

examples/split-editors/main.go

@@ -0,0 +1,185 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/charmbracelet/bubbles/help"
+	"github.com/charmbracelet/bubbles/key"
+	"github.com/charmbracelet/bubbles/textarea"
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+)
+
+const (
+	initialInputs = 2
+	maxInputs     = 6
+	minInputs     = 1
+)
+
+var (
+	cursorLineStyle = lipgloss.NewStyle().
+			Background(lipgloss.Color("57")).
+			Foreground(lipgloss.Color("230"))
+
+	placeholderStyle = lipgloss.NewStyle().
+				Foreground(lipgloss.Color("238"))
+
+	focusedPlaceholderStyle = lipgloss.NewStyle().
+				Foreground(lipgloss.Color("99"))
+)
+
+type keymap = struct {
+	next, prev, add, remove, quit key.Binding
+}
+
+func newTextarea() textarea.Model {
+	t := textarea.New()
+	t.SetHeight(20)
+	t.Prompt = ""
+	t.Placeholder = "Type something"
+	t.ShowLineNumbers = true
+	t.Cursor.Style = lipgloss.NewStyle().Foreground(lipgloss.Color("212"))
+	t.FocusedStyle.Placeholder = focusedPlaceholderStyle
+	t.BlurredStyle.Placeholder = placeholderStyle
+	t.FocusedStyle.CursorLine = cursorLineStyle
+	t.KeyMap.DeleteWordBackward.SetEnabled(false)
+	t.KeyMap.LineNext = key.NewBinding(key.WithKeys("down"))
+	t.KeyMap.LinePrevious = key.NewBinding(key.WithKeys("up"))
+	t.Blur()
+	return t
+}
+
+type model struct {
+	width  int
+	keymap keymap
+	help   help.Model
+	inputs []textarea.Model
+	focus  int
+}
+
+func newModel() model {
+	m := model{
+		inputs: make([]textarea.Model, initialInputs),
+		help:   help.New(),
+		keymap: keymap{
+			next: key.NewBinding(
+				key.WithKeys("tab"),
+				key.WithHelp("tab", "next"),
+			),
+			prev: key.NewBinding(
+				key.WithKeys("shift+tab"),
+				key.WithHelp("shift+tab", "prev"),
+			),
+			add: key.NewBinding(
+				key.WithKeys("ctrl+n"),
+				key.WithHelp("ctrl+n", "add an editor"),
+			),
+			remove: key.NewBinding(
+				key.WithKeys("ctrl+w"),
+				key.WithHelp("ctrl+w", "remove an editor"),
+			),
+			quit: key.NewBinding(
+				key.WithKeys("esc", "ctrl+c"),
+				key.WithHelp("esc", "quit"),
+			),
+		},
+	}
+	for i := 0; i < initialInputs; i++ {
+		m.inputs[i] = newTextarea()
+	}
+	m.inputs[m.focus].Focus()
+	m.updateKeybindings()
+	return m
+}
+
+func (m model) Init() tea.Cmd {
+	return textarea.Blink
+}
+
+func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	var cmds []tea.Cmd
+
+	switch msg := msg.(type) {
+	case tea.KeyMsg:
+		switch {
+		case key.Matches(msg, m.keymap.quit):
+			for i := range m.inputs {
+				m.inputs[i].Blur()
+			}
+			return m, tea.Quit
+		case key.Matches(msg, m.keymap.next):
+			m.inputs[m.focus].Blur()
+			m.focus++
+			if m.focus > len(m.inputs)-1 {
+				m.focus = 0
+			}
+			cmd := m.inputs[m.focus].Focus()
+			cmds = append(cmds, cmd)
+		case key.Matches(msg, m.keymap.prev):
+			m.inputs[m.focus].Blur()
+			m.focus--
+			if m.focus < 0 {
+				m.focus = len(m.inputs) - 1
+			}
+			cmd := m.inputs[m.focus].Focus()
+			cmds = append(cmds, cmd)
+		case key.Matches(msg, m.keymap.add):
+			m.inputs = append(m.inputs, newTextarea())
+		case key.Matches(msg, m.keymap.remove):
+			m.inputs = m.inputs[:len(m.inputs)-1]
+			if m.focus > len(m.inputs)-1 {
+				m.focus = len(m.inputs) - 1
+			}
+		}
+	case tea.WindowSizeMsg:
+		m.width = msg.Width
+	}
+
+	m.updateKeybindings()
+	m.sizeInputs()
+
+	// Update all textareas
+	for i := range m.inputs {
+		newModel, cmd := m.inputs[i].Update(msg)
+		m.inputs[i] = newModel
+		cmds = append(cmds, cmd)
+	}
+
+	return m, tea.Batch(cmds...)
+}
+
+func (m *model) sizeInputs() {
+	for i := range m.inputs {
+		m.inputs[i].SetWidth(m.width / len(m.inputs))
+	}
+}
+
+func (m *model) updateKeybindings() {
+	m.keymap.add.SetEnabled(len(m.inputs) < maxInputs)
+	m.keymap.remove.SetEnabled(len(m.inputs) > minInputs)
+}
+
+func (m model) View() string {
+	help := m.help.ShortHelpView([]key.Binding{
+		m.keymap.next,
+		m.keymap.prev,
+		m.keymap.add,
+		m.keymap.remove,
+		m.keymap.quit,
+	})
+
+	var views []string
+	for i := range m.inputs {
+		views = append(views, m.inputs[i].View())
+	}
+
+	return lipgloss.JoinHorizontal(lipgloss.Top, views...) + "\n\n" + help
+}
+
+func main() {
+	if err := tea.NewProgram(newModel()).Start(); err != nil {
+		fmt.Println("Error while running program:", err)
+		os.Exit(1)
+	}
+}