fic: Pick HSL function to generate random colors

admin/api/team.go

@@ -3,6 +3,7 @@ package api
 import (
 	"encoding/json"
 	"fmt"
+	"math/rand"
 	"strings"
 	"time"
 
@@ -155,6 +156,10 @@ func createTeam(_ httprouter.Params, body []byte) (interface{}, error) {
 		return nil, err
 	}
 
+	if ut.Color == 0 {
+		ut.Color = fic.HSL{rand.Float64(), 1, 0.5}.ToRGB()
+	}
+
 	return fic.CreateTeam(strings.TrimSpace(ut.Name), ut.Color, ut.ExternalId)
 }
 

backend/registration.go

@@ -82,7 +82,7 @@ func treatRegistration(pathname string, team_id string) {
 	} else if denyTeamCreation {
 		log.Printf("%s [ERR] Registration received, whereas team creation denied. Skipped.\n", id)
 	} else if validTeamName(nTeam.TeamName) {
-		if team, err := fic.CreateTeam(nTeam.TeamName, uint32(rand.Int31n(16581376))); err != nil {
+		if team, err := fic.CreateTeam(nTeam.TeamName, fic.HSL{H: rand.Float64(), L: 1, S: 0.5}.ToRGB(), ""); err != nil {
 			log.Printf("%s [ERR] Unable to register new team %s: %s\n", id, nTeam.TeamName, err)
 		} else {
 			registrationProcess(id, team, nTeam.Members, team_id)

libfic/utils.go

@@ -125,3 +125,57 @@ func Apr1Md5(password string, salt string) string {
 
 	return resultString
 }
+
+// Function copied from https://github.com/gerow/go-color/blob/master/color.go
+type HSL struct {
+	H, S, L float64
+}
+
+func hueToRGB(v1, v2, h float64) uint32 {
+	if h < 0 {
+		h += 1
+	}
+	if h > 1 {
+		h -= 1
+	}
+	var res float64
+	switch {
+	case 6*h < 1:
+		res = (v1 + (v2-v1)*6*h)
+	case 2*h < 1:
+		res = v2
+	case 3*h < 2:
+		res = v1 + (v2-v1)*((2.0/3.0)-h)*6
+	default:
+		res = v1
+	}
+	return uint32((res + 1/512.0) * 255)
+
+}
+
+func (c HSL) ToRGB() (rgb uint32) {
+	h := c.H
+	s := c.S
+	l := c.L
+
+	if s == 0 {
+		// it's gray
+		v := uint32((l + 1/512.0) * 255)
+		return v*65536 + v*256 + v
+	}
+
+	var v1, v2 float64
+	if l < 0.5 {
+		v2 = l * (1 + s)
+	} else {
+		v2 = (l + s) - (s * l)
+	}
+
+	v1 = 2*l - v2
+
+	r := hueToRGB(v1, v2, h+(1.0/3.0))
+	g := hueToRGB(v1, v2, h)
+	b := hueToRGB(v1, v2, h-(1.0/3.0))
+
+	return r*65536 + g*256 + b
+}