add regexp nickname validation to login page

.env.example

@@ -3,5 +3,5 @@
 #
 
 APP_NAME=litter-go
-APP_VERSION=0.35.15
+APP_VERSION=0.35.16
 GOLANG_VERSION=1.22

api/swagger.json

@@ -13,7 +13,7 @@
             "name": "MIT",
             "url": "https://github.com/krustowski/litter-go/blob/master/LICENSE"
         },
-        "version": "0.35.15"
+        "version": "0.35.16"
     },
     "host": "littr.eu",
     "basePath": "/api/v1",

pkg/backend/router.go

@@ -1,5 +1,5 @@
 // @title		litter-go
-// @version	 	0.35.15
+// @version	 	0.35.16
 // @description		nanoblogging platform as PWA built on go-app framework
 // @termsOfService	https://littr.eu/tos
 

pkg/frontend/login.go

@@ -4,6 +4,7 @@ import (
 	"crypto/sha512"
 	"encoding/json"
 	"fmt"
+	"regexp"
 	"strings"
 
 	"go.savla.dev/littr/configs"
@@ -94,6 +95,17 @@ func (c *loginContent) onClick(ctx app.Context, e app.Event) {
 			return
 		}
 
+		// don't allow special chars and spaces in the nickname
+		if !regexp.MustCompile(`^[a-zA-Z0-9]+$`).MatchString(nickname) {
+			toastText = "nickname can contain only chars a-z, A-Z and numbers"
+
+			ctx.Dispatch(func(ctx app.Context) {
+				c.toastText = toastText
+				c.toastShow = (toastText != "")
+			})
+			return
+		}
+
 		//passHash := sha512.Sum512([]byte(passphrase + app.Getenv("APP_PEPPER")))
 		passHash := sha512.Sum512([]byte(passphrase + appPepper))