package ui

import "9front/gui/draw"

// A Field is one line of editable text.
//
// Deliberately small: a cursor at the end, backspace, and ^U to clear.
// There is no selection, no mouse cursor placement and no history,
// because a form that asks for a summary and a time does not need them
// and every one of them is a place to get subtly wrong. A program that
// needs a real editor should hand the job to one.
type Field struct {
	Label string
	Value string
	R     draw.Rectangle // set by Draw, used for hit testing
}

// Draw paints the field and records where it landed in f.R, so the
// caller can make it clickable. It does not register a hit region
// itself: the first matching region wins a click, and a do-nothing one
// here would silently swallow the caller's.
func (u *UI) Draw(f *Field, r draw.Rectangle, focused bool) {
	f.R = r
	lw := u.F.Width("attendees ") + 8
	u.Text(draw.Point{X: r.Min.X, Y: r.Min.Y + 2}, "ink", f.Label)

	box := draw.Rect(r.Min.X+lw, r.Min.Y, r.Max.X, r.Max.Y)
	u.Fill(box, "bg")
	c := "rule"
	if focused {
		c = "border"
	}
	u.Border(box, c)

	s := f.Value
	if focused {
		s += "|"
	}
	// keep the end of the line in view: that is where you are typing
	for len(s) > 0 && u.F.Width(s) > box.Dx()-8 {
		s = s[1:]
	}
	u.Text(draw.Point{X: box.Min.X + 4, Y: box.Min.Y + 2}, "ink", s)
}

// oneLine keeps a paste to the first line: these are one-line fields,
// and a pasted paragraph would silently lose everything after the first
// newline anyway.
func oneLine(s string) string {
	for i, r := range s {
		if r == '\n' || r == '\r' {
			return s[:i]
		}
	}
	return s
}

// Key applies one typed rune and says whether it changed anything.
func (f *Field) Key(r rune) bool {
	switch r {
	case '\b', 0x7F: // backspace, del
		if f.Value == "" {
			return false
		}
		v := []rune(f.Value)
		f.Value = string(v[:len(v)-1])
		return true
	case 0x15: // ^U
		if f.Value == "" {
			return false
		}
		f.Value = ""
		return true
	case 0x16, 0x19: // ^V, ^Y: paste
		if v, err := draw.Snarfed("/dev"); err == nil {
			f.Value += oneLine(v)
			return true
		}
		return false
	case '\n', '\r', '\t', 0x1B:
		return false // the form deals with these
	}
	if r < ' ' {
		return false
	}
	f.Value += string(r)
	return true
}