cli/wallet: add ability to save NEP5 transfer transaction

It allows to use multisig cli operations for multisig transaction creation and
send.

cli/wallet/nep5.go

@@ -1,12 +1,15 @@
 package wallet
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
+	"io/ioutil"
 
 	"github.com/nspcc-dev/neo-go/cli/flags"
 	"github.com/nspcc-dev/neo-go/pkg/encoding/address"
 	"github.com/nspcc-dev/neo-go/pkg/rpc/client"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract/context"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/wallet"
 	"github.com/urfave/cli"
@@ -82,6 +85,7 @@ func newNEP5Commands() []cli.Command {
 			Flags: []cli.Flag{
 				walletPathFlag,
 				rpcFlag,
+				outFlag,
 				timeoutFlag,
 				fromAddrFlag,
 				toAddrFlag,
@@ -341,11 +345,30 @@ func transferNEP5(ctx *cli.Context) error {
 		return cli.NewExitError(err, 1)
 	}
 
-	hash, err := c.TransferNEP5(acc, to, token.Hash, amount, gas)
+	tx, err := c.CreateNEP5TransferTx(acc, to, token.Hash, amount, gas)
 	if err != nil {
 		return cli.NewExitError(err, 1)
 	}
 
-	fmt.Println(hash.StringLE())
+	if outFile := ctx.String("out"); outFile != "" {
+		priv := acc.PrivateKey()
+		pub := priv.PublicKey()
+		sign := priv.Sign(tx.GetSignedPart())
+		scCtx := context.NewParameterContext("Neo.Core.ContractTransaction", tx)
+		if err := scCtx.AddSignature(acc.Contract, pub, sign); err != nil {
+			return cli.NewExitError(fmt.Errorf("can't add signature: %v", err), 1)
+		} else if data, err := json.Marshal(scCtx); err != nil {
+			return cli.NewExitError(fmt.Errorf("can't marshal tx to JSON: %v", err), 1)
+		} else if err := ioutil.WriteFile(outFile, data, 0644); err != nil {
+			return cli.NewExitError(fmt.Errorf("can't write tx to file: %v", err), 1)
+		}
+	} else {
+		_ = acc.SignTx(tx)
+		if err := c.SendRawTransaction(tx); err != nil {
+			return cli.NewExitError(err, 1)
+		}
+	}
+
+	fmt.Println(tx.Hash().StringLE())
 	return nil
 }

pkg/rpc/client/nep5.go

@@ -92,13 +92,14 @@ func (c *Client) NEP5TokenInfo(tokenHash util.Uint160) (*wallet.Token, error) {
 	return wallet.NewToken(tokenHash, name, symbol, decimals), nil
 }
 
-// TransferNEP5 creates an invocation transaction that invokes 'transfer' method
+// CreateNEP5TransferTx creates an invocation transaction for the 'transfer'
-// on a given token to move specified amount of NEP5 assets (in FixedN format
+// method of a given contract (token) to move specified amount of NEP5 assets
-// using contract's number of decimals) to given account.
+// (in FixedN format using contract's number of decimals) to given account and
-func (c *Client) TransferNEP5(acc *wallet.Account, to util.Uint160, token util.Uint160, amount int64, gas util.Fixed8) (util.Uint256, error) {
+// returns it. The returned transaction is not signed.
+func (c *Client) CreateNEP5TransferTx(acc *wallet.Account, to util.Uint160, token util.Uint160, amount int64, gas util.Fixed8) (*transaction.Transaction, error) {
 	from, err := address.StringToUint160(acc.Address)
 	if err != nil {
-		return util.Uint256{}, fmt.Errorf("bad account address: %v", err)
+		return nil, fmt.Errorf("bad account address: %v", err)
 	}
 	// Note: we don't use invoke function here because it requires
 	// 2 round trips instead of one.
@@ -120,11 +121,11 @@ func (c *Client) TransferNEP5(acc *wallet.Account, to util.Uint160, token util.U
 
 	result, err := c.InvokeScript(hex.EncodeToString(script))
 	if err != nil {
-		return util.Uint256{}, fmt.Errorf("can't add system fee to transaction: %v", err)
+		return nil, fmt.Errorf("can't add system fee to transaction: %v", err)
 	}
 	gasConsumed, err := util.Fixed8FromString(result.GasConsumed)
 	if err != nil {
-		return util.Uint256{}, fmt.Errorf("can't add system fee to transaction: %v", err)
+		return nil, fmt.Errorf("can't add system fee to transaction: %v", err)
 	}
 	if gasConsumed > 0 {
 		tx.SystemFee = gasConsumed
@@ -132,12 +133,25 @@ func (c *Client) TransferNEP5(acc *wallet.Account, to util.Uint160, token util.U
 
 	tx.ValidUntilBlock, err = c.CalculateValidUntilBlock()
 	if err != nil {
-		return util.Uint256{}, fmt.Errorf("can't calculate validUntilBlock: %v", err)
+		return nil, fmt.Errorf("can't calculate validUntilBlock: %v", err)
 	}
 
 	err = c.AddNetworkFee(tx, acc)
 	if err != nil {
-		return util.Uint256{}, fmt.Errorf("can't add network fee to transaction: %v", err)
+		return nil, fmt.Errorf("can't add network fee to transaction: %v", err)
+	}
+
+	return tx, nil
+}
+
+// TransferNEP5 creates an invocation transaction that invokes 'transfer' method
+// on a given token to move specified amount of NEP5 assets (in FixedN format
+// using contract's number of decimals) to given account and sends it to the
+// network returning just a hash of it.
+func (c *Client) TransferNEP5(acc *wallet.Account, to util.Uint160, token util.Uint160, amount int64, gas util.Fixed8) (util.Uint256, error) {
+	tx, err := c.CreateNEP5TransferTx(acc, to, token, amount, gas)
+	if err != nil {
+		return util.Uint256{}, err
 	}
 
 	if err := acc.SignTx(tx); err != nil {