Initial backend import

internal/auth/jwt.go

@@ -0,0 +1,45 @@
+package auth
+
+import (
+	"errors"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+type Claims struct {
+	AdminID int    `json:"admin_id"`
+	Email   string `json:"email"`
+	jwt.RegisteredClaims
+}
+
+func SignAdmin(secret string, adminID int, email string, ttl time.Duration) (string, error) {
+	claims := Claims{
+		AdminID: adminID,
+		Email:   email,
+		RegisteredClaims: jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(time.Now().Add(ttl)),
+			IssuedAt:  jwt.NewNumericDate(time.Now()),
+			Issuer:    IssuerAdmin,
+		},
+	}
+	t := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+	return t.SignedString([]byte(secret))
+}
+
+func ParseAdmin(secret, token string) (*Claims, error) {
+	claims := &Claims{}
+	parsed, err := jwt.ParseWithClaims(token, claims, func(t *jwt.Token) (any, error) {
+		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, errors.New("unexpected signing method")
+		}
+		return []byte(secret), nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	if !parsed.Valid || claims.Issuer != IssuerAdmin || claims.AdminID <= 0 {
+		return nil, errors.New("invalid token")
+	}
+	return claims, nil
+}