[#140] sdk: Refactor version type

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/version.go

@@ -6,23 +6,62 @@ import (
 	"github.com/nspcc-dev/neofs-api-go/v2/refs"
 )
 
-type (
-	Version struct {
-		Major uint32
-		Minor uint32
-	}
-)
+// Version represents v2-compatible version.
+type Version refs.Version
 
-var SDKVersion = Version{2, 0}
+const sdkMjr, sdkMnr = 2, 0
 
-func (v Version) String() string {
-	return fmt.Sprintf("v%d.%d", v.Major, v.Minor)
+// NewVersionFromV2 wraps v2 Version message to Version.
+func NewVersionFromV2(v *refs.Version) *Version {
+	return (*Version)(v)
 }
 
-func (v Version) ToV2Version() *refs.Version {
-	result := new(refs.Version)
-	result.SetMajor(v.Major)
-	result.SetMinor(v.Minor)
-
-	return result
+// NewVersion creates and initializes blank Version.
+//
+// Works similar as NewVersionFromV2(new(Version)).
+func NewVersion() *Version {
+	return NewVersionFromV2(new(refs.Version))
+}
+
+// SDKVersion returns Version instance that
+// initialized to current SDK revision number.
+func SDKVersion() *Version {
+	v := NewVersion()
+	v.SetMajor(sdkMjr)
+	v.SetMinor(sdkMnr)
+
+	return v
+}
+
+// GetMajor returns major number of the revision.
+func (v *Version) GetMajor() uint32 {
+	return (*refs.Version)(v).
+		GetMajor()
+}
+
+// SetMajor sets major number of the revision.
+func (v *Version) SetMajor(val uint32) {
+	(*refs.Version)(v).
+		SetMajor(val)
+}
+
+// GetMinor returns minor number of the revision.
+func (v *Version) GetMinor() uint32 {
+	return (*refs.Version)(v).
+		GetMinor()
+}
+
+// SetMinor sets minor number of the revision.
+func (v *Version) SetMinor(val uint32) {
+	(*refs.Version)(v).
+		SetMinor(val)
+}
+
+// ToV2 converts Version to v2 Version message.
+func (v *Version) ToV2() *refs.Version {
+	return (*refs.Version)(v)
+}
+
+func (v *Version) String() string {
+	return fmt.Sprintf("v%d.%d", v.GetMajor(), v.GetMinor())
 }