From 5902f96f3e7d81e2deffa354ddfafe0539141d05 Mon Sep 17 00:00:00 2001
From: Leonard Lyubich <leonard@nspcc.ru>
Date: Thu, 10 Sep 2020 14:30:29 +0300
Subject: [PATCH] [#140] sdk: Define checksum type

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
---
 pkg/checksum.go      | 74 ++++++++++++++++++++++++++++++++++++++++++++
 pkg/checksum_test.go | 40 ++++++++++++++++++++++++
 2 files changed, 114 insertions(+)
 create mode 100644 pkg/checksum.go
 create mode 100644 pkg/checksum_test.go

diff --git a/pkg/checksum.go b/pkg/checksum.go
new file mode 100644
index 0000000..4fa84cd
--- /dev/null
+++ b/pkg/checksum.go
@@ -0,0 +1,74 @@
+package pkg
+
+import (
+	"crypto/sha256"
+
+	"github.com/nspcc-dev/neofs-api-go/v2/refs"
+)
+
+// Checksum represents v2-compatible checksum.
+type Checksum refs.Checksum
+
+// ChecksumType represents the enumeration
+// of checksum types.
+type ChecksumType uint8
+
+const (
+	// ChecksumUnknown is an undefined checksum type.
+	ChecksumUnknown ChecksumType = iota
+
+	// ChecksumSHA256 is a SHA256 checksum type.
+	ChecksumSHA256
+
+	// ChecksumTZ is a Tillich-Zemor checksum type.
+	ChecksumTZ
+)
+
+// NewChecksumFromV2 wraps v2 Checksum message to Checksum.
+func NewChecksumFromV2(cV2 *refs.Checksum) *Checksum {
+	return (*Checksum)(cV2)
+}
+
+// NewVersion creates and initializes blank Version.
+//
+// Works similar as NewVersionFromV2(new(Version)).
+func NewChecksum() *Checksum {
+	return NewChecksumFromV2(new(refs.Checksum))
+}
+
+// GetType returns checksum type.
+func (c *Checksum) GetType() ChecksumType {
+	switch (*refs.Checksum)(c).GetType() {
+	case refs.SHA256:
+		return ChecksumSHA256
+	case refs.TillichZemor:
+		return ChecksumTZ
+	default:
+		return ChecksumUnknown
+	}
+}
+
+// GetSum returns checksum bytes.
+func (c *Checksum) GetSum() []byte {
+	return (*refs.Checksum)(c).GetSum()
+}
+
+// SetSHA256 sets checksum to SHA256 hash.
+func (c *Checksum) SetSHA256(v [sha256.Size]byte) {
+	checksum := (*refs.Checksum)(c)
+
+	checksum.SetType(refs.SHA256)
+	checksum.SetSum(v[:])
+}
+
+// SetTillichZemor sets checksum to Tillich-Zemor hash.
+func (c *Checksum) SetTillichZemor(v [64]byte) {
+	checksum := (*refs.Checksum)(c)
+
+	checksum.SetType(refs.TillichZemor)
+	checksum.SetSum(v[:])
+}
+
+func (c *Checksum) ToV2() *refs.Checksum {
+	return (*refs.Checksum)(c)
+}
diff --git a/pkg/checksum_test.go b/pkg/checksum_test.go
new file mode 100644
index 0000000..e0da6ef
--- /dev/null
+++ b/pkg/checksum_test.go
@@ -0,0 +1,40 @@
+package pkg
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"testing"
+
+	"github.com/nspcc-dev/neofs-api-go/v2/refs"
+	"github.com/stretchr/testify/require"
+)
+
+func TestChecksum(t *testing.T) {
+	c := NewChecksum()
+
+	cSHA256 := [sha256.Size]byte{}
+	_, _ = rand.Read(cSHA256[:])
+
+	c.SetSHA256(cSHA256)
+
+	require.Equal(t, ChecksumSHA256, c.GetType())
+	require.Equal(t, cSHA256[:], c.GetSum())
+
+	cV2 := c.ToV2()
+
+	require.Equal(t, refs.SHA256, cV2.GetType())
+	require.Equal(t, cSHA256[:], cV2.GetSum())
+
+	cTZ := [64]byte{}
+	_, _ = rand.Read(cSHA256[:])
+
+	c.SetTillichZemor(cTZ)
+
+	require.Equal(t, ChecksumTZ, c.GetType())
+	require.Equal(t, cTZ[:], c.GetSum())
+
+	cV2 = c.ToV2()
+
+	require.Equal(t, refs.TillichZemor, cV2.GetType())
+	require.Equal(t, cTZ[:], cV2.GetSum())
+}