doorgo/door/color.go

package door

import (
	"log"
	"strconv"
	"strings"
)

// Profiling:
// go build -gcflags=-m=2 . 2>&1 | less
// What leaks to heap?

// Possibly make this so it is part of an ANSI package.
// DRY - Reuse.

// 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
	}
*/

func Color(arg []int) string {
	var result strings.Builder
	result.WriteString("\x1b[")
	for idx, i := range arg {
		if idx != 0 {
			result.WriteString(";")
		}
		result.WriteString(strconv.Itoa(i))
	}
	result.WriteString("m")
	return result.String()
}

// BUG(bugz) INVERSE does not work.

// Would I want to do something like:
// BRIGHT YELLOW or ON BLUE, and have it just change the
// color or the background?  Right now, I require the full
// color (FG & BG).

// 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 res [5]int
	var result []int = res[0:0]
	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)
}