doorgo/door/color.go

package door

import (
	"fmt"
	"log"
	"strings"
)

// Convert an array of int to \x1b[1;2;3m for ANSI Color
// output.
// https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters
// https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit
func Color(arg ...int) string {
	var result string = "\x1b["
	for i := range arg {
		result += fmt.Sprintf("%d;", arg[i])
	}
	result = result[:len(result)-1]
	result += "m"
	return result
}

// BUG(bugz) INVERSE does not work.

// Convert a string like "BRIGHT WHITE ON BLUE" into the expected
// ANSI Color codes.  You can use just the first 3 letters.
// Supports BRIGHT, BOLD, BLINK and ON (to set the background color).
// BLACK, RED, GREEN, BROWN / YELLOW, BLUE, MAGENTA, CYAN, WHITE
// https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters
// https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit
func ColorText(color string) string {
	// split on spaces, uppercase, match first 3 letter
	var result []int
	var bg bool

	result = append(result, 0)

	parts := strings.Fields(strings.ToUpper(color))
	for _, part := range parts {
		if len(part) > 3 {
			part = part[:3]
		}

		switch part {
		case "BLA":
			if bg {
				result = append(result, 40)
			} else {
				result = append(result, 30)
			}

		case "RED":
			if bg {
				result = append(result, 41)
			} else {
				result = append(result, 31)
			}

		case "GRE":
			if bg {
				result = append(result, 42)
			} else {
				result = append(result, 32)
			}

		case "BRO", "YEL":
			if bg {
				result = append(result, 43)
			} else {
				result = append(result, 33)
			}

		case "BLU":
			if bg {
				result = append(result, 44)
			} else {
				result = append(result, 34)
			}

		case "MAG":
			if bg {
				result = append(result, 45)
			} else {
				result = append(result, 35)
			}

		case "CYA":
			if bg {
				result = append(result, 46)
			} else {
				result = append(result, 36)
			}

		case "WHI":
			if bg {
				result = append(result, 47)
			} else {
				result = append(result, 37)
			}

		case "BOL", "BRI":
			result = append(result, 1)

		case "ON":
			bg = true

		case "BLI":
			result = append(result, 5)

		// Invert is't well supported in terminals
		// case "INV":
		//	result = append(result, 7)

		default:
			log.Panicf("ColorText Unknown: [%s] in %s\n", part, color)
		}

	}
	return Color(result...)
}