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import { BlockParamLiteral, ExchangeContractErrs } from '@0xproject/types';
import { BigNumber } from '@0xproject/utils';
import { TokenWrapper } from '../contract_wrappers/token_wrapper';
import { BalanceAndProxyAllowanceLazyStore } from '../stores/balance_proxy_allowance_lazy_store';
import { TradeSide, TransferType } from '../types';
import { constants } from '../utils/constants';
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<void> {
// HACK: When simulating an open order (e.g taker is NULL_ADDRESS), we don't want to adjust balances/
// allowances for the taker. We do however, want to increase the balance of the maker since the maker
// might be relying on those funds to fill subsequent orders or pay the order's fees.
if (from === constants.NULL_ADDRESS && tradeSide === TradeSide.Taker) {
await this._increaseBalanceAsync(tokenAddress, to, amountInBaseUnits);
return;
}
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<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));
}
}
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