init push

internal/shared/pkg/timezone/timezone.go

@@ -0,0 +1,35 @@
+package timezone
+
+import (
+	"errors"
+	"strings"
+	"time"
+)
+
+const Default = "UTC"
+
+var (
+	ErrEmpty   = errors.New("timezone is required")
+	ErrInvalid = errors.New("timezone must be a valid IANA timezone")
+)
+
+func Normalize(name string) (string, error) {
+	tz := strings.TrimSpace(name)
+	if tz == "" {
+		return "", ErrEmpty
+	}
+
+	loc, err := time.LoadLocation(tz)
+	if err != nil {
+		return "", ErrInvalid
+	}
+	return loc.String(), nil
+}
+
+func WithDefault(name string) string {
+	tz := strings.TrimSpace(name)
+	if tz == "" {
+		return Default
+	}
+	return tz
+}