all clients should be saved in cache

tokens.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+var secretKey = []byte("replace-with-env-variable")
+
+type UserClaims struct {
+	Name  string  `json:"name"`
+	Color [3]byte `json:"color"`
+	jwt.RegisteredClaims
+}
+
+func GetToken(client *Client) (string, error) {
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256,
+		UserClaims{
+			Name:  client.Name,
+			Color: client.Color,
+			RegisteredClaims: jwt.RegisteredClaims{
+				Subject:   strconv.Itoa(int(client.Id)),
+				ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour)),
+				IssuedAt:  jwt.NewNumericDate(time.Now()),
+			},
+		},
+	)
+	return token.SignedString(secretKey)
+}
+
+func SetClientFromToken(client *Client, tokenString string) error {
+	token, err := jwt.ParseWithClaims(tokenString, &UserClaims{}, func(t *jwt.Token) (interface{}, error) {
+		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
+		}
+		return secretKey, nil
+	})
+	if err != nil {
+		return err
+	}
+
+	claims, ok := token.Claims.(*UserClaims)
+	if !ok || !token.Valid {
+		return errors.New("invalid token")
+	}
+
+	id, err := strconv.ParseUint(claims.Subject, 10, 32)
+	if err != nil {
+		return fmt.Errorf("invalid subject: %w", err)
+	}
+
+	client.Id = uint32(id)
+	client.Name = claims.Name
+	client.Color = claims.Color
+
+	return nil
+}