//	   if err != nil {
//	   }
//	}
//	ETag = ETag.Format()
func (e ETag) Format() ETag {
	if !e.IsEncrypted() {
		return e
	}
	return e[len(e)-16:]
}

var _ Tagger = ETag{} // compiler check

// ETag returns the ETag itself.
//
// By providing this method ETag implements
// the Tagger interface.
func (e ETag) ETag() ETag { return e }

	// We must not use the http.Header().Set method here because some (broken)
	// clients expect the ETag header key to be literally "ETag" - not "Etag" (case-sensitive).
	// Therefore, we have to set the ETag directly as map entry.
	if objInfo.ETag != "" && !delete {
		w.Header()[xhttp.ETag] = []string{`"` + objInfo.ETag + `"`}
	}

	// Set the relevant version ID as part of the response header.

	sum := r.md5.Sum(nil)
	return ETag(sum)
}

// VerifyError is an error signaling that a
// computed ETag does not match an expected
// ETag.
type VerifyError struct {
	Expected ETag
	Computed ETag
}

func (v VerifyError) Error() string {
	return fmt.Sprintf("etag: expected ETag %q does not match computed ETag %q", v.Expected, v.Computed)
}

// UUIDHash - use uuid to make md5sum

		{[]CompletePart{{ETag: "wrong-md5-hash-string"}}, "0deb8cb07527b4b2669c861cb9653607-1", ""},

		// Single CompletePart with valid MD5 hash string.
		{[]CompletePart{{ETag: "cf1f738a5924e645913c984e0fe3d708"}}, "10dc1617fbcf0bd0858048cb96e6bd77-1", ""},

		// Multiple CompletePart with valid MD5 hash string.

		ETag:       "",
		ShouldFail: true, // ETag prefix is not a valid hex value
	},
	{
		ObjectKey:  [32]byte{},
		ObjectInfo: ObjectInfo{ETag: "16516b396f0f4d4f2a0e7177557bec4-1-2"},
		ETag:       "",
		ShouldFail: true, // ETag contains multiple: -
	},
}

func TestDecryptETag(t *testing.T) {
	for i, test := range decryptETagTests {

func (r *Reader) ActualSize() int64 { return r.actualSize }

// ETag returns the ETag computed by an underlying etag.Tagger.
// If the underlying io.Reader does not implement etag.Tagger
// it returns nil.
func (r *Reader) ETag() etag.ETag {
	if t, ok := r.src.(etag.Tagger); ok {
		return t.ETag()
	}
	return nil
}

// MD5Current returns the MD5 checksum of the content

var stringTests = []struct {
	ETag   ETag
	String string
}{
	{ETag: ETag{59, 131, 239, 150, 56, 127, 20, 101}, String: "3b83ef96387f1465"},                                                                  // 0
	{ETag: ETag{59, 131, 239, 150, 56, 127, 20, 101, 95, 200, 84, 221, 195, 198, 189, 87}, String: "3b83ef96387f14655fc854ddc3c6bd57"},             // 1

		12: {bucketName: bucket, objName: object, inputData: []byte("ijkl"), inputMeta: map[string]string{"etag": "09a0877d04abf8759f99adec02baf579"}, inputDataSize: int64(len("ijkl"))},

		etag = commonETag(etags, quorum)

		if etag != "" { // allow this fallback only if a non-empty etag is found.
			for index, e := range etags {
				if partsMetadata[index].IsValid() && e == etag {
					onlineDisks[index] = disks[index]
				} else {
					onlineDisks[index] = nil
				}
			}
			return onlineDisks, modTime, etag
		}
	}

// generates CopyObjectResponse from etag and lastModified time.
func generateCopyObjectResponse(etag string, lastModified time.Time) CopyObjectResponse {
	return CopyObjectResponse{
		ETag:         "\"" + etag + "\"",
		LastModified: amztime.ISO8601Format(lastModified.UTC()),
	}
}

// generates CopyObjectPartResponse from etag and lastModified time.