Inverted, safe, foreground and background ANSI escape codes

ansi.go

/*
Create a string usage a web-safe version of the specified background color.

The foreground will be set to an inverse color for legibility.

Untested and definitely broken.
*/

func decorate(bgColor color.Color, s string) string {
	fgColor := inverse(bgColor)
	return setBackground(bgColor) + setForeground(fgColor) + code + "\u001b[0m"
}

func setForeground(c color.Color) string {
  return fmt.Sprintf("\x1b[38;5;%dm", websafeCode(c))
}

func setBackground(c color.Color) string {
  return fmt.Sprintf("\x1b[48;5;%dm", websafeCode(c))
}

func inverse(c color.Color) color.Color {
	r, g, b, a := c.RGBA()
	r = a - r
	g = a - g
	b = a - b
	return color.RGBA64{uint16(r), uint16(g), uint16(b), uint16(a)}
}

func websafeCode(c color.Color) int {
  // This doesn't really work.
 	var p color.Palette = palette.WebSafe
	return p.Index(c) 
}