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import * as _ from 'lodash';
import BigNumber from 'bignumber.js';
import {ExchangeContractErrs, TradeSide, TransferType, BlockParamLiteral} from '../types';
import {TokenWrapper} from '../contract_wrappers/token_wrapper';
import {BalanceAndProxyAllowanceLazyStore} from '../stores/balance_proxy_allowance_lazy_store';
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;
constructor(token: TokenWrapper) {
this.store = new BalanceAndProxyAllowanceLazyStore(token, BlockParamLiteral.Latest);
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<void> {
const balance = await this.store.getBalanceAsync(tokenAddress, from);
const proxyAllowance = await this.store.getProxyAllowanceAsync(tokenAddress, from);
if (proxyAllowance.lessThan(amountInBaseUnits)) {
this.throwValidationError(FailureReason.ProxyAllowance, tradeSide, transferType);
}
if (balance.lessThan(amountInBaseUnits)) {
this.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<void> {
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<void> {
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<void> {
const balance = await this.store.getBalanceAsync(tokenAddress, userAddress);
this.store.setBalance(tokenAddress, userAddress, balance.minus(amountInBaseUnits));
}
private throwValidationError(failureReason: FailureReason, tradeSide: TradeSide,
transferType: TransferType): Promise<never> {
const errMsg = ERR_MSG_MAPPING[failureReason][tradeSide][transferType];
throw new Error(errMsg);
}
}
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