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-rw-r--r--packages/contract-wrappers/src/utils/exchange_transfer_simulator.ts111
1 files changed, 111 insertions, 0 deletions
diff --git a/packages/contract-wrappers/src/utils/exchange_transfer_simulator.ts b/packages/contract-wrappers/src/utils/exchange_transfer_simulator.ts
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+++ b/packages/contract-wrappers/src/utils/exchange_transfer_simulator.ts
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+import { ExchangeContractErrs } from '@0xproject/types';
+import { BigNumber } from '@0xproject/utils';
+
+import { AbstractBalanceAndProxyAllowanceLazyStore } from '../abstract/abstract_balance_and_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: AbstractBalanceAndProxyAllowanceLazyStore;
+ private static _throwValidationError(
+ failureReason: FailureReason,
+ tradeSide: TradeSide,
+ transferType: TransferType,
+ ): never {
+ const errMsg = ERR_MSG_MAPPING[failureReason][tradeSide][transferType];
+ throw new Error(errMsg);
+ }
+ constructor(store: AbstractBalanceAndProxyAllowanceLazyStore) {
+ this._store = store;
+ }
+ /**
+ * 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(constants.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));
+ }
+}