From 0b8d905cecdcb3634a258e89644d048a366159d7 Mon Sep 17 00:00:00 2001
From: Pierre Roullon <pierre.roullon@gmail.com>
Date: Wed, 15 Jun 2022 09:12:20 +0200
Subject: [PATCH] feat: (widget) add Form widget

---
 _examples/form.go |  56 +++++++++++++++++++
 widgets/form.go   | 140 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 196 insertions(+)
 create mode 100644 _examples/form.go
 create mode 100644 widgets/form.go

diff --git a/_examples/form.go b/_examples/form.go
new file mode 100644
index 0000000..dcaff30
--- /dev/null
+++ b/_examples/form.go
@@ -0,0 +1,56 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+
+	ui "github.com/gizak/termui/v3"
+	"github.com/gizak/termui/v3/widgets"
+)
+
+func main() {
+	if err := ui.Init(); err != nil {
+		log.Fatalf("failed to initialize termui: %v", err)
+	}
+	defer ui.Close()
+
+	f0 := widgets.NewForm(
+		context.Background(),
+		"Add user",
+		func(ctx context.Context, validated bool, fields []*widgets.Field) {
+			ui.Close()
+			fmt.Printf("Form validated: %t. Values:\n", validated)
+			for _, f := range fields {
+				fmt.Printf("%s: %s\n", f.Name, f.Text)
+			}
+			os.Exit(0)
+		},
+		widgets.NewField("First name", ""),
+		widgets.NewField("Surname", ""),
+		widgets.NewField("Test", "Default value"),
+	)
+	f0.SetRect(0, 0, 50, 20)
+
+	p2 := widgets.NewParagraph()
+	p2.Title = "Multiline"
+	p2.Text = "Simple colored text\nwith label. It [can be](fg:red) multilined with \\n or [break automatically](fg:red,fg:bold)"
+	p2.SetRect(0, 50, 35, 55)
+	p2.BorderStyle.Fg = ui.ColorYellow
+
+	ui.Render(f0, p2)
+
+	uiEvents := ui.PollEvents()
+	for {
+		e := <-uiEvents
+		switch e.ID {
+		case "<C-c>":
+			return
+		default:
+			if !f0.IsDone() {
+				f0.Handle(e)
+			}
+		}
+	}
+}
diff --git a/widgets/form.go b/widgets/form.go
new file mode 100644
index 0000000..c65981e
--- /dev/null
+++ b/widgets/form.go
@@ -0,0 +1,140 @@
+package widgets
+
+import (
+	"context"
+	"fmt"
+
+	. "github.com/gizak/termui/v3"
+)
+
+type Field struct {
+	Name   string
+	Text   string
+	cursor int
+}
+
+type Form struct {
+	Paragraph
+
+	TextFgColor Style
+	TextBgColor Style
+	Fields      []*Field
+	Done        bool
+
+	ctx            context.Context
+	onExitCallback func(ctx context.Context, validated bool, fields []*Field)
+	fieldIdx       int
+}
+
+func NewField(name string, value string) *Field {
+	f := &Field{
+		Name: name,
+		Text: value,
+	}
+
+	return f
+}
+
+func NewForm(ctx context.Context, name string, callback func(ctx context.Context, validated bool, fields []*Field), fields ...*Field) *Form {
+
+	f := &Form{
+		Paragraph:      *NewParagraph(),
+		TextFgColor:    Theme.Paragraph.Text,
+		ctx:            ctx,
+		onExitCallback: callback,
+	}
+
+	for _, field := range fields {
+		f.Fields = append(f.Fields, field)
+	}
+
+	f.Border = true
+	f.Title = name
+	f._draw()
+	return f
+}
+
+// Handle input event
+// <Up> or <Down> to switch field
+// <Enter> will switch to next field or exit scan if last field
+func (f *Form) Handle(e Event) {
+	switch e.ID {
+	case "<Down>":
+		if f.fieldIdx < len(f.Fields)-1 {
+			f.fieldIdx++
+		}
+	case "<Up>":
+		if f.fieldIdx > 0 {
+			f.fieldIdx--
+		}
+	case "<Enter>":
+		if f.fieldIdx < len(f.Fields)-1 {
+			f.fieldIdx++
+		} else {
+			f.Done = true
+			f.onExitCallback(f.ctx, true, f.Fields)
+		}
+	case "<Esc>":
+		f.Done = true
+		f.onExitCallback(f.ctx, false, f.Fields)
+	default:
+		f.Fields[f.fieldIdx].Handle(e)
+	}
+	f._draw()
+	Render(f)
+}
+
+// Handle field input
+func (f *Field) Handle(e Event) {
+	switch e.ID {
+	case "<Backspace>":
+		if f.cursor > 0 {
+			f.Text = f.Text[:f.cursor-1] + f.Text[f.cursor:]
+		} else if len(f.Text) > 1 {
+			f.Text = f.Text[1:]
+		} else {
+			f.Text = ""
+		}
+		if f.cursor > 0 {
+			f.cursor--
+		}
+		if f.cursor > len(f.Text) {
+			f.cursor = len(f.Text)
+		}
+	case "<Right>":
+		if f.cursor < len(f.Text) {
+			f.cursor++
+		}
+	case "<Left>":
+		if f.cursor > 0 {
+			f.cursor--
+		}
+	case "<Space>":
+		f.Text = f.Text[:f.cursor] + " " + f.Text[f.cursor:]
+		f.cursor++
+	default:
+		f.Text = f.Text[:f.cursor] + e.ID + f.Text[f.cursor:]
+		f.cursor++
+	}
+}
+
+// IsDone return wether user has entered <Esc> or <Enter>
+func (f *Form) IsDone() bool {
+	return f.Done
+}
+
+func (f *Form) _draw() {
+	cursor := "[|](bg:white)"
+	f.Text = ""
+	for i, field := range f.Fields {
+		txt := field.Text
+		if i == f.fieldIdx && field.Text != "" {
+			begin := field.Text[:field.cursor]
+			end := field.Text[field.cursor:]
+			txt = begin + cursor + end
+		} else if i == f.fieldIdx {
+			txt = cursor
+		}
+		f.Text += fmt.Sprintf("%s: %s\n", field.Name, txt)
+	}
+}