implement ApproveDeposits and IsDepositApproved

EthProvider.go

@@ -7,11 +7,14 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/pkg/errors"
+	"github.com/zksync-sdk/zksync-go/contracts/ERC20"
 	"github.com/zksync-sdk/zksync-go/contracts/ZkSync"
 	"math/big"
 )
 
 type EthProvider interface {
+	ApproveDeposits(token *Token, limit *big.Int, options *GasOptions) (*types.Transaction, error)
+	IsDepositApproved(token *Token, userAddress common.Address, threshold *big.Int) (bool, error)
 	Deposit(token *Token, amount *big.Int, userAddress common.Address, options *GasOptions) (*types.Transaction, error)
 	SetAuthPubkeyHash(pubKeyHash string, zkNonce uint32, options *GasOptions) (*types.Transaction, error)
 	GetBalance() (*big.Int, error)
@@ -23,6 +26,7 @@ type EthProvider interface {
 type DefaultEthProvider struct {
 	client   *ethclient.Client
 	contract *ZkSync.ZkSync
+	address  common.Address
 	auth     *bind.TransactOpts
 }
 
@@ -31,6 +35,36 @@ type GasOptions struct {
 	GasLimit uint64   // Gas limit to set for the transaction execution (0 = estimate)
 }
 
+func (p *DefaultEthProvider) ApproveDeposits(token *Token, limit *big.Int, options *GasOptions) (*types.Transaction, error) {
+	tokenContract, err := ERC20.NewERC20(token.GetAddress(), p.client)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to load token contract")
+	}
+	if limit == nil {
+		// max approve amount 2^256 - 1
+		limit = big.NewInt(0).Sub(big.NewInt(0).Exp(big.NewInt(2), big.NewInt(256), nil), big.NewInt(1))
+	}
+	auth := p.getAuth(options)
+	return tokenContract.Approve(auth, p.address, limit)
+}
+
+func (p *DefaultEthProvider) IsDepositApproved(token *Token, userAddress common.Address, threshold *big.Int) (bool, error) {
+	tokenContract, err := ERC20.NewERC20(token.GetAddress(), p.client)
+	if err != nil {
+		return false, errors.Wrap(err, "failed to load token contract")
+	}
+	auth := &bind.CallOpts{}
+	allowed, err := tokenContract.Allowance(auth, userAddress, p.address)
+	if err != nil {
+		return false, errors.Wrap(err, "failed to call Allowance view of token contract")
+	}
+	if threshold == nil {
+		// default threshold 2^255
+		threshold = big.NewInt(0).Exp(big.NewInt(2), big.NewInt(255), nil)
+	}
+	return allowed.Cmp(threshold) >= 0, nil
+}
+
 func (p *DefaultEthProvider) Deposit(token *Token, amount *big.Int, userAddress common.Address, options *GasOptions) (*types.Transaction, error) {
 	auth := p.getAuth(options)
 	auth.Value = amount

Wallet.go

@@ -104,6 +104,7 @@ func (w *Wallet) CreateEthereumProvider(client *ethclient.Client) (*DefaultEthPr
 	return &DefaultEthProvider{
 		client:   client,
 		contract: contract,
+		address:  contractAddress.GetMainAddress(),
 		auth:     auth,
 	}, nil
 }