package native import ( "errors" "math/big" "github.com/nspcc-dev/neo-go/pkg/core/interop" "github.com/nspcc-dev/neo-go/pkg/core/state" "github.com/nspcc-dev/neo-go/pkg/crypto/hash" "github.com/nspcc-dev/neo-go/pkg/smartcontract" "github.com/nspcc-dev/neo-go/pkg/util" ) // GAS represents GAS native contract. type GAS struct { nep17TokenNative NEO *NEO } const gasName = "GAS" const gasContractID = -2 // GASFactor is a divisor for finding GAS integral value. const GASFactor = NEOTotalSupply const initialGAS = 30000000 // newGAS returns GAS native contract. func newGAS() *GAS { g := &GAS{} nep17 := newNEP17Native(gasName) nep17.symbol = "gas" nep17.decimals = 8 nep17.factor = GASFactor nep17.onPersist = chainOnPersist(onPersistBase, g.OnPersist) nep17.incBalance = g.increaseBalance nep17.ContractID = gasContractID g.nep17TokenNative = *nep17 onp := g.Methods["onPersist"] onp.Func = getOnPersistWrapper(g.onPersist) g.Methods["onPersist"] = onp return g } func (g *GAS) increaseBalance(_ *interop.Context, _ util.Uint160, si *state.StorageItem, amount *big.Int) error { acc, err := state.NEP17BalanceStateFromBytes(si.Value) if err != nil { return err } if sign := amount.Sign(); sign == 0 { return nil } else if sign == -1 && acc.Balance.Cmp(new(big.Int).Neg(amount)) == -1 { return errors.New("insufficient funds") } acc.Balance.Add(&acc.Balance, amount) if acc.Balance.Sign() != 0 { si.Value = acc.Bytes() } else { si.Value = nil } return nil } // Initialize initializes GAS contract. func (g *GAS) Initialize(ic *interop.Context) error { if err := g.nep17TokenNative.Initialize(ic); err != nil { return err } if g.nep17TokenNative.getTotalSupply(ic.DAO).Sign() != 0 { return errors.New("already initialized") } h, err := getStandbyValidatorsHash(ic) if err != nil { return err } g.mint(ic, h, big.NewInt(initialGAS*GASFactor)) return nil } // OnPersist implements Contract interface. func (g *GAS) OnPersist(ic *interop.Context) error { if len(ic.Block.Transactions) == 0 { return nil } for _, tx := range ic.Block.Transactions { absAmount := big.NewInt(tx.SystemFee + tx.NetworkFee) g.burn(ic, tx.Sender(), absAmount) } validators := g.NEO.GetNextBlockValidatorsInternal() primary := validators[ic.Block.ConsensusData.PrimaryIndex].GetScriptHash() var netFee int64 for _, tx := range ic.Block.Transactions { netFee += tx.NetworkFee } g.mint(ic, primary, big.NewInt(int64(netFee))) return nil } func getStandbyValidatorsHash(ic *interop.Context) (util.Uint160, error) { s, err := smartcontract.CreateDefaultMultiSigRedeemScript(ic.Chain.GetStandByValidators()) if err != nil { return util.Uint160{}, err } return hash.Hash160(s), nil } func chainOnPersist(fs ...func(*interop.Context) error) func(*interop.Context) error { return func(ic *interop.Context) error { for i := range fs { if fs[i] != nil { if err := fs[i](ic); err != nil { return err } } } return nil } }