refactor: Removing math/rand in favor of crypto/rand

pkg/ketchup/ketchup.go

@@ -2,7 +2,6 @@ package ketchup
 
 import (
 	"html/template"
-	"math/rand"
 	"net/http"
 	"strings"
 	"time"
@@ -35,8 +34,6 @@ type App interface {
 }
 
 type app struct {
-	rand *rand.Rand
-
 	rendererApp       renderer.App
 	ketchupService    ketchup.App
 	userService       user.App
@@ -47,7 +44,6 @@ type app struct {
 // New creates new App from Config
 func New(rendererApp renderer.App, ketchupService ketchup.App, userService user.App, repositoryService repository.App) App {
 	return app{
-		rand:       rand.New(rand.NewSource(time.Now().UnixNano())),
 		tokenStore: NewTokenStore(),
 
 		rendererApp:       rendererApp,

pkg/ketchup/renderer.go

@@ -1,6 +1,9 @@
 package ketchup
 
 import (
+	"crypto/rand"
+	"fmt"
+	"math/big"
 	"net/http"
 	"time"
 
@@ -12,13 +15,20 @@ const (
 	suggestCount    = uint64(5)
 )
 
-func (a app) generateToken() (string, int64) {
-	questionID := a.rand.Int63n(int64(len(colors)))
-	return a.tokenStore.Store(questionID, time.Minute*5), questionID
+func (a app) generateToken() (string, int64, error) {
+	questionID, err := rand.Int(rand.Reader, big.NewInt(int64(len(colors))))
+	if err != nil {
+		return "", 0, fmt.Errorf("unable to generate random int: %w", err)
+	}
+
+	return a.tokenStore.Store(questionID, time.Minute*5), questionID.Int64(), nil
 }
 
 func (a app) PublicTemplateFunc(r *http.Request) (string, int, map[string]interface{}, error) {
-	token, questionID := a.generateToken()
+	token, questionID, err := a.generateToken()
+	if err != nil {
+		return "", http.StatusInternalServerError, nil, err
+	}
 
 	suggests, err := a.repositoryService.Suggest(r.Context(), []uint64{0}, 3)
 	if err != nil {