Rename input to textinput + DefaultModel is now NewModel

textinput/textinput.go

@@ -0,0 +1,242 @@
+package textinput
+
+import (
+	"errors"
+	"time"
+
+	"github.com/charmbracelet/tea"
+	"github.com/muesli/termenv"
+)
+
+var (
+	// color is a helper for returning colors
+	color func(s string) termenv.Color = termenv.ColorProfile().Color
+)
+
+// ErrMsg indicates there's been an error. We don't handle errors in the this
+// package; we're expecting errors to be handle in the program that implements
+// this text input.
+type ErrMsg error
+
+// Model is the Tea model for this text input element
+type Model struct {
+	Err              error
+	Prompt           string
+	Value            string
+	Cursor           string
+	BlinkSpeed       time.Duration
+	Placeholder      string
+	TextColor        string
+	PlaceholderColor string
+	CursorColor      string
+
+	// CharLimit is the maximum amount of characters this input element will
+	// accept. If 0 or less, there's no limit.
+	CharLimit int
+
+	// Focus indicates whether user input focus should be on this input
+	// component. When false, don't blink and ignore keyboard input.
+	focus bool
+
+	blink bool
+	pos   int
+}
+
+// Focused returns the focus state on the model
+func (m Model) Focused() bool {
+	return m.focus
+}
+
+// Focus sets the focus state on the model
+func (m *Model) Focus() {
+	m.focus = true
+	m.blink = false
+}
+
+// Blur removes the focus state on the model
+func (m *Model) Blur() {
+	m.focus = false
+	m.blink = true
+}
+
+// colorText colorizes a given string according to the TextColor value of the
+// model
+func (m *Model) colorText(s string) string {
+	return termenv.
+		String(s).
+		Foreground(color(m.TextColor)).
+		String()
+}
+
+// colorPlaceholder colorizes a given string according to the TextColor value
+// of the model
+func (m *Model) colorPlaceholder(s string) string {
+	return termenv.
+		String(s).
+		Foreground(color(m.PlaceholderColor)).
+		String()
+}
+
+// CursorBlinkMsg is sent when the cursor should alternate it's blinking state
+type CursorBlinkMsg struct{}
+
+// NewModel creates a new model with default settings
+func NewModel() Model {
+	return Model{
+		Prompt:           "> ",
+		Value:            "",
+		BlinkSpeed:       time.Millisecond * 600,
+		Placeholder:      "",
+		TextColor:        "",
+		PlaceholderColor: "240",
+		CursorColor:      "",
+		CharLimit:        0,
+
+		focus: false,
+		blink: true,
+		pos:   0,
+	}
+}
+
+// Update is the Tea update loop
+func Update(msg tea.Msg, m Model) (Model, tea.Cmd) {
+	if !m.focus {
+		m.blink = true
+		return m, nil
+	}
+
+	switch msg := msg.(type) {
+
+	case tea.KeyMsg:
+		switch msg.Type {
+		case tea.KeyBackspace:
+			fallthrough
+		case tea.KeyDelete:
+			if len(m.Value) > 0 {
+				m.Value = m.Value[:m.pos-1] + m.Value[m.pos:]
+				m.pos--
+			}
+			return m, nil
+		case tea.KeyLeft:
+			if m.pos > 0 {
+				m.pos--
+			}
+			return m, nil
+		case tea.KeyRight:
+			if m.pos < len(m.Value) {
+				m.pos++
+			}
+			return m, nil
+		case tea.KeyCtrlF: // ^F, forward one character
+			fallthrough
+		case tea.KeyCtrlB: // ^B, back one charcter
+			fallthrough
+		case tea.KeyCtrlA: // ^A, go to beginning
+			m.pos = 0
+			return m, nil
+		case tea.KeyCtrlD: // ^D, delete char under cursor
+			if len(m.Value) > 0 && m.pos < len(m.Value) {
+				m.Value = m.Value[:m.pos] + m.Value[m.pos+1:]
+			}
+			return m, nil
+		case tea.KeyCtrlE: // ^E, go to end
+			m.pos = len(m.Value)
+			return m, nil
+		case tea.KeyCtrlK: // ^K, kill text after cursor
+			m.Value = m.Value[:m.pos]
+			m.pos = len(m.Value)
+			return m, nil
+		case tea.KeyCtrlU: // ^U, kill text before cursor
+			m.Value = m.Value[m.pos:]
+			m.pos = 0
+			return m, nil
+		case tea.KeyRune: // input a regular character
+			if m.CharLimit > 0 && len(m.Value) < m.CharLimit {
+				m.Value = m.Value[:m.pos] + string(msg.Rune) + m.Value[m.pos:]
+				m.pos++
+			}
+			return m, nil
+		default:
+			return m, nil
+		}
+
+	case ErrMsg:
+		m.Err = msg
+		return m, nil
+
+	case CursorBlinkMsg:
+		m.blink = !m.blink
+		return m, nil
+
+	default:
+		return m, nil
+	}
+}
+
+// View renders the textinput in its current state
+func View(model tea.Model) string {
+	m, ok := model.(Model)
+	if !ok {
+		return "could not perform assertion on model"
+	}
+
+	// Placeholder text
+	if m.Value == "" && m.Placeholder != "" {
+		return placeholderView(m)
+	}
+
+	v := m.colorText(m.Value[:m.pos])
+
+	if m.pos < len(m.Value) {
+		v += cursorView(string(m.Value[m.pos]), m)
+		v += m.colorText(m.Value[m.pos+1:])
+	} else {
+		v += cursorView(" ", m)
+	}
+	return m.Prompt + v
+}
+
+// placeholderView
+func placeholderView(m Model) string {
+	var (
+		v string
+		p = m.Placeholder
+	)
+
+	// Cursor
+	if m.blink && m.PlaceholderColor != "" {
+		v += cursorView(
+			m.colorPlaceholder(p[:1]),
+			m,
+		)
+	} else {
+		v += cursorView(p[:1], m)
+	}
+
+	// The rest of the placeholder text
+	v += m.colorPlaceholder(p[1:])
+
+	return m.Prompt + v
+}
+
+// cursorView style the cursor
+func cursorView(s string, m Model) string {
+	if m.blink {
+		return s
+	}
+	return termenv.String(s).
+		Foreground(color(m.CursorColor)).
+		Reverse().
+		String()
+}
+
+// Blink is the subscription that lets us know when to alternate the blinking
+// of the cursor.
+func Blink(model tea.Model) tea.Msg {
+	m, ok := model.(Model)
+	if !ok {
+		return ErrMsg(errors.New("could not assert given model to the model we expected; make sure you're passing as input model"))
+	}
+	time.Sleep(m.BlinkSpeed)
+	return CursorBlinkMsg{}
+}