[#126] sdk: implement accounting rpc in client

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/client/accounting.go

@@ -0,0 +1,110 @@
+package client
+
+import (
+	"context"
+
+	"github.com/nspcc-dev/neofs-api-go/pkg/accounting"
+	"github.com/nspcc-dev/neofs-api-go/pkg/refs"
+	v2accounting "github.com/nspcc-dev/neofs-api-go/v2/accounting"
+	"github.com/nspcc-dev/neofs-api-go/v2/client"
+	v2refs "github.com/nspcc-dev/neofs-api-go/v2/refs"
+	v2signature "github.com/nspcc-dev/neofs-api-go/v2/signature"
+	"github.com/pkg/errors"
+)
+
+func (c Client) GetSelfBalance(ctx context.Context, opts ...CallOption) (*accounting.Decimal, error) {
+	owner, err := refs.NEO3WalletFromPublicKey(&c.key.PublicKey)
+	if err != nil {
+		return nil, err
+	}
+
+	return c.GetBalance(ctx, owner, opts...)
+}
+
+func (c Client) GetBalance(ctx context.Context, owner refs.NEO3Wallet, opts ...CallOption) (*accounting.Decimal, error) {
+	// check remote node version
+	switch c.remoteNode.Version.Major {
+	case 2:
+		return c.getBalanceV2(ctx, owner, opts...)
+	default:
+		return nil, unsupportedProtocolErr
+	}
+}
+
+func (c Client) getBalanceV2(ctx context.Context, owner refs.NEO3Wallet, opts ...CallOption) (*accounting.Decimal, error) {
+	// apply all available options
+	callOptions := defaultCallOptions()
+	for i := range opts {
+		opts[i].apply(&callOptions)
+	}
+
+	// create V2 unified structures
+	v2Owner := new(v2refs.OwnerID)
+	v2Owner.SetValue(owner[:])
+
+	reqBody := new(v2accounting.BalanceRequestBody)
+	reqBody.SetOwnerID(v2Owner)
+
+	req := new(v2accounting.BalanceRequest)
+	req.SetBody(reqBody)
+	req.SetMetaHeader(v2MetaHeaderFromOpts(callOptions))
+
+	err := v2signature.SignServiceMessage(c.key, req)
+	if err != nil {
+		return nil, err
+	}
+
+	switch c.remoteNode.Protocol {
+	case GRPC:
+		cli, err := v2AccountingClientFromOptions(c.opts)
+		if err != nil {
+			return nil, errors.Wrap(err, "can't create grpc client")
+		}
+
+		resp, err := cli.Balance(ctx, req)
+		if err != nil {
+			return nil, errors.Wrap(err, "transport error")
+		}
+
+		err = v2signature.VerifyServiceMessage(resp)
+		if err != nil {
+			return nil, errors.Wrap(err, "can't verify response message")
+		}
+
+		return &accounting.Decimal{
+			Decimal: *resp.GetBody().GetBalance(),
+		}, nil
+	default:
+		return nil, unsupportedProtocolErr
+	}
+}
+
+func v2AccountingClientFromOptions(opts *clientOptions) (cli *v2accounting.Client, err error) {
+	switch {
+	case opts.grpcOpts.v2AccountingClient != nil:
+		// return value from client cache
+		return opts.grpcOpts.v2AccountingClient, nil
+
+	case opts.grpcOpts.conn != nil:
+		cli, err = v2accounting.NewClient(v2accounting.WithGlobalOpts(
+			client.WithGRPCConn(opts.grpcOpts.conn)),
+		)
+
+	case opts.addr != "":
+		cli, err = v2accounting.NewClient(v2accounting.WithGlobalOpts(
+			client.WithNetworkAddress(opts.addr)),
+		)
+
+	default:
+		return nil, errors.New("lack of sdk client options to create accounting client")
+	}
+
+	// check if client correct and save in cache
+	if err != nil {
+		return nil, err
+	}
+
+	opts.grpcOpts.v2AccountingClient = cli
+
+	return cli, nil
+}