Better hex color code generator

colorizer.go

package colorizer

import (
	"fmt"
	"math"
	"math/rand"
)

const (
	ratio      float64 = 1 / math.Phi
	saturation float64 = 0.5
	value      float64 = 0.95
)

func RandomHex() string {
	red, green, blue := randomRGB(rand.Float64())

	return "#" + getHex(red) + getHex(green) + getHex(blue)
}

func getHex(num int) string {
	hex := fmt.Sprintf("%x", num)
	if len(hex) == 1 {
		hex = "0" + hex
	}

	return hex
}

func randomRGB(hueSeed float64) (int, int, int) {
	hueSeed += ratio
	hueSeed = math.Mod(hueSeed, 1)

	return hsvToRGB(hueSeed, saturation, value)
}

func hsvToRGB(hue, saturation, value float64) (int, int, int) {
	segmentIndex := int(hue * 6)
	fractionalPart := hue*6 - float64(segmentIndex)
	minComponent := value * (1 - saturation)
	decreasingComponent := value * (1 - fractionalPart*saturation)
	increasingComponent := value * (1 - (1-fractionalPart)*saturation)

	var (
		red   float64
		green float64
		blue  float64
	)

	switch segmentIndex {
	case 0:
		red, green, blue = value, increasingComponent, minComponent
	case 1:
		red, green, blue = decreasingComponent, value, minComponent
	case 2:
		red, green, blue = minComponent, value, increasingComponent
	case 3:
		red, green, blue = minComponent, decreasingComponent, value
	case 4:
		red, green, blue = increasingComponent, minComponent, value
	case 5:
		red, green, blue = value, minComponent, decreasingComponent
	}

	return int(red * 255), int(green * 255), int(blue * 255)
}

We're using the HSV color space, as opposed to other OSS implementations that use the darker RGB color space.
You can read more about it here.

Also thanks to AvraamMavridis/randomcolor for the getHex function.