import BigNumber from 'bignumber.js'; import * as _ from 'lodash'; import {TokenWrapper} from '../contract_wrappers/token_wrapper'; import {BalanceAndProxyAllowanceLazyStore} from '../stores/balance_proxy_allowance_lazy_store'; import {BlockParamLiteral, ExchangeContractErrs, TradeSide, TransferType} from '../types'; enum FailureReason { Balance = 'balance', ProxyAllowance = 'proxyAllowance', } const ERR_MSG_MAPPING = { [FailureReason.Balance]: { [TradeSide.Maker]: { [TransferType.Trade]: ExchangeContractErrs.InsufficientMakerBalance, [TransferType.Fee]: ExchangeContractErrs.InsufficientMakerFeeBalance, }, [TradeSide.Taker]: { [TransferType.Trade]: ExchangeContractErrs.InsufficientTakerBalance, [TransferType.Fee]: ExchangeContractErrs.InsufficientTakerFeeBalance, }, }, [FailureReason.ProxyAllowance]: { [TradeSide.Maker]: { [TransferType.Trade]: ExchangeContractErrs.InsufficientMakerAllowance, [TransferType.Fee]: ExchangeContractErrs.InsufficientMakerFeeAllowance, }, [TradeSide.Taker]: { [TransferType.Trade]: ExchangeContractErrs.InsufficientTakerAllowance, [TransferType.Fee]: ExchangeContractErrs.InsufficientTakerFeeAllowance, }, }, }; export class ExchangeTransferSimulator { private store: BalanceAndProxyAllowanceLazyStore; private UNLIMITED_ALLOWANCE_IN_BASE_UNITS: BigNumber; private static throwValidationError(failureReason: FailureReason, tradeSide: TradeSide, transferType: TransferType): never { const errMsg = ERR_MSG_MAPPING[failureReason][tradeSide][transferType]; throw new Error(errMsg); } constructor(token: TokenWrapper, defaultBlock: BlockParamLiteral) { this.store = new BalanceAndProxyAllowanceLazyStore(token, defaultBlock); this.UNLIMITED_ALLOWANCE_IN_BASE_UNITS = token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS; } /** * Simulates transferFrom call performed by a proxy * @param tokenAddress Address of the token to be transferred * @param from Owner of the transferred tokens * @param to Recipient of the transferred tokens * @param amountInBaseUnits The amount of tokens being transferred * @param tradeSide Is Maker/Taker transferring * @param transferType Is it a fee payment or a value transfer */ public async transferFromAsync(tokenAddress: string, from: string, to: string, amountInBaseUnits: BigNumber, tradeSide: TradeSide, transferType: TransferType): Promise { const balance = await this.store.getBalanceAsync(tokenAddress, from); const proxyAllowance = await this.store.getProxyAllowanceAsync(tokenAddress, from); if (proxyAllowance.lessThan(amountInBaseUnits)) { ExchangeTransferSimulator.throwValidationError(FailureReason.ProxyAllowance, tradeSide, transferType); } if (balance.lessThan(amountInBaseUnits)) { ExchangeTransferSimulator.throwValidationError(FailureReason.Balance, tradeSide, transferType); } await this.decreaseProxyAllowanceAsync(tokenAddress, from, amountInBaseUnits); await this.decreaseBalanceAsync(tokenAddress, from, amountInBaseUnits); await this.increaseBalanceAsync(tokenAddress, to, amountInBaseUnits); } private async decreaseProxyAllowanceAsync(tokenAddress: string, userAddress: string, amountInBaseUnits: BigNumber): Promise { const proxyAllowance = await this.store.getProxyAllowanceAsync(tokenAddress, userAddress); if (!proxyAllowance.eq(this.UNLIMITED_ALLOWANCE_IN_BASE_UNITS)) { this.store.setProxyAllowance(tokenAddress, userAddress, proxyAllowance.minus(amountInBaseUnits)); } } private async increaseBalanceAsync(tokenAddress: string, userAddress: string, amountInBaseUnits: BigNumber): Promise { const balance = await this.store.getBalanceAsync(tokenAddress, userAddress); this.store.setBalance(tokenAddress, userAddress, balance.plus(amountInBaseUnits)); } private async decreaseBalanceAsync(tokenAddress: string, userAddress: string, amountInBaseUnits: BigNumber): Promise { const balance = await this.store.getBalanceAsync(tokenAddress, userAddress); this.store.setBalance(tokenAddress, userAddress, balance.minus(amountInBaseUnits)); } }