tuio/internal/tui/form.go

package tui

import (
	"fmt"
	"strings"

	"charm.land/bubbles/v2/textinput"
	tea "charm.land/bubbletea/v2"
)

type FieldType int

const (
	FieldTypeText FieldType = iota
	FieldTypeSelect
	FieldTypePassword
	FieldTypeNumber
)

// defaultInputWidth is the visible width of text inputs before the first window-size
// message arrives. It must be > 0 (and ideally >= the longest placeholder) so the
// placeholder renders in full; it is overridden responsively via FormStep.SetWidth.
const defaultInputWidth = 50

type FormField struct {
	Id          string
	Label       string
	Placeholder string
	Default     string
	Type        FieldType
	Options     []string // for FieldTypeSelect
	OptionIdx   int      // for FieldTypeSelect
	CharLimit   int
	input       textinput.Model
}

type FormStep struct {
	Title  string
	Fields []FormField
	focus  int
}

func NewFormStep(title string, fields []FormField) FormStep {
	f := FormStep{Title: title, Fields: fields}
	for i := range f.Fields {
		if f.Fields[i].Type == FieldTypeSelect {
			for j, opt := range f.Fields[i].Options {
				// Apply default option
				if opt == f.Fields[i].Default {
					f.Fields[i].OptionIdx = j
					break
				}
			}
			continue
		}

		ti := textinput.New()
		ti.Placeholder = f.Fields[i].Placeholder
		// A non-zero width is required for the placeholder to render in full: with the
		// default width of 0 the textinput truncates the placeholder to its first rune.
		ti.SetWidth(defaultInputWidth)
		if f.Fields[i].Default != "" {
			ti.SetValue(f.Fields[i].Default)
		}

		if f.Fields[i].CharLimit > 0 {
			ti.CharLimit = f.Fields[i].CharLimit
		}

		if f.Fields[i].Type == FieldTypePassword {
			ti.EchoMode = textinput.EchoPassword
		}

		if i == 0 {
			ti.Focus()
		}

		f.Fields[i].input = ti
	}
	return f
}

// Update
func (f *FormStep) Update(msg tea.Msg) (done bool, cmd tea.Cmd) {
	focused := &f.Fields[f.focus]
	isSelect := focused.Type == FieldTypeSelect

	switch msg := msg.(type) {
	case tea.KeyPressMsg:
		switch msg.String() {
		// Select specific inputs
		case "left", "h":
			if isSelect && focused.OptionIdx > 0 {
				focused.OptionIdx--
			}

		case "right", "l":
			if isSelect && focused.OptionIdx < len(focused.Options)-1 {
				focused.OptionIdx++
			}

		// Generic inputs
		case "tab", "down":
			f.blurCurrent()
			f.focus = (f.focus + 1) % len(f.Fields)
			f.focusCurrent()

		case "shift+tab", "up":
			f.blurCurrent()
			f.focus = (f.focus - 1 + len(f.Fields)) % len(f.Fields)
			f.focusCurrent()

		case "enter":
			if f.focus == len(f.Fields)-1 {
				return true, nil
			}
			f.blurCurrent()
			f.focus++
			f.focusCurrent()
		}
	}

	var c tea.Cmd
	f.Fields[f.focus].input, c = f.Fields[f.focus].input.Update(msg)
	return false, c
}

func (f *FormStep) Values() map[string]string {
	out := make(map[string]string)
	for _, field := range f.Fields {
		if field.Type == FieldTypeSelect {
			out[field.Id] = field.Options[field.OptionIdx]
		} else {
			out[field.Id] = field.input.Value()
		}
	}
	return out
}

// SetWidth resizes every text input to w (selects are unaffected). Called on window
// resize so inputs fill the available terminal width and placeholders render in full.
func (f *FormStep) SetWidth(w int) {
	for i := range f.Fields {
		if f.Fields[i].Type == FieldTypeSelect {
			continue
		}
		f.Fields[i].input.SetWidth(w)
	}
}

// View
func (f FormStep) View() string {
	pad := strings.Repeat(" ", padding)
	var sb strings.Builder

	sb.WriteString(pad + TitleStyle.Render(f.Title) + "")

	for i, field := range f.Fields {
		sb.WriteString(renderField(field, i == f.focus))
	}

	return sb.String()
}

func renderField(field FormField, focused bool) string {
	pad := strings.Repeat(" ", padding)

	label := "  " + field.Label
	if focused {
		label = CursorStyle.Render("> " + field.Label)
	}

	var value string
	switch field.Type {
	case FieldTypeSelect:
		var opts []string
		for i, opt := range field.Options {
			if i == field.OptionIdx {
				opts = append(opts, SelectedStyle.Render("[ "+opt+" ]"))
			} else {
				opts = append(opts, DimStyle.Render("  "+opt+"  "))
			}
		}
		value = strings.Join(opts, " ")
		if focused {
			value += HelpStyle.Render("  ← →")
		}
	default:
		value = field.input.View()
	}

	return fmt.Sprintf("\n\n%s%s\n%s  %s", pad, label, pad, value)
}

// Helpers
func (f *FormStep) blurCurrent() {
	if f.Fields[f.focus].Type != FieldTypeSelect {
		f.Fields[f.focus].input.Blur()
	}
}

func (f *FormStep) focusCurrent() {
	if f.Fields[f.focus].Type != FieldTypeSelect {
		f.Fields[f.focus].input.Focus()
	}
}