Add naive order state watcher implementation

Revalidate all orders upon event received and emit order states even if
not changed

1 files changed, 99 insertions, 0 deletions

diff --git a/src/utils/order_state_utils.ts b/src/utils/order_state_utils.ts
new file mode 100644
index 000000000..2a5becf9a
--- /dev/null
+++ b/src/utils/order_state_utils.ts
@@ -0,0 +1,99 @@
+import * as _ from 'lodash';
+import BigNumber from 'bignumber.js';
+import {
+    ExchangeContractErrs,
+    SignedOrder,
+    OrderRelevantState,
+    MethodOpts,
+    OrderState,
+    OrderStateValid,
+    OrderStateInvalid,
+} from '../types';
+import {ZeroEx} from '../0x';
+import {TokenWrapper} from '../contract_wrappers/token_wrapper';
+import {ExchangeWrapper} from '../contract_wrappers/exchange_wrapper';
+import {utils} from '../utils/utils';
+import {constants} from '../utils/constants';
+
+export class OrderStateUtils {
+    private tokenWrapper: TokenWrapper;
+    private exchangeWrapper: ExchangeWrapper;
+    constructor(tokenWrapper: TokenWrapper, exchangeWrapper: ExchangeWrapper) {
+        this.tokenWrapper = tokenWrapper;
+        this.exchangeWrapper = exchangeWrapper;
+    }
+    public async getOrderStateAsync(signedOrder: SignedOrder, methodOpts?: MethodOpts): Promise<OrderState> {
+        const orderRelevantState = await this.getOrderRelevantStateAsync(signedOrder, methodOpts);
+        const orderHash = ZeroEx.getOrderHashHex(signedOrder);
+        try {
+            this.validateIfOrderIsValid(signedOrder, orderRelevantState);
+            const orderState: OrderStateValid = {
+                isValid: true,
+                orderHash,
+                orderRelevantState,
+            };
+            return orderState;
+        } catch (err) {
+            const orderState: OrderStateInvalid = {
+                isValid: false,
+                orderHash,
+                error: err.message,
+            };
+            return orderState;
+        }
+    }
+    public async getOrderRelevantStateAsync(
+        signedOrder: SignedOrder, methodOpts?: MethodOpts): Promise<OrderRelevantState> {
+        const zrxTokenAddress = await this.exchangeWrapper.getZRXTokenAddressAsync();
+        const orderHash = ZeroEx.getOrderHashHex(signedOrder);
+        const makerBalance = await this.tokenWrapper.getBalanceAsync(
+            signedOrder.makerTokenAddress, signedOrder.maker, methodOpts,
+        );
+        const makerProxyAllowance = await this.tokenWrapper.getProxyAllowanceAsync(
+            signedOrder.makerTokenAddress, signedOrder.maker, methodOpts,
+        );
+        const makerFeeBalance = await this.tokenWrapper.getBalanceAsync(
+            zrxTokenAddress, signedOrder.maker, methodOpts,
+        );
+        const makerFeeProxyAllowance = await this.tokenWrapper.getProxyAllowanceAsync(
+            zrxTokenAddress, signedOrder.maker, methodOpts,
+        );
+        const filledTakerTokenAmount = await this.exchangeWrapper.getFilledTakerAmountAsync(orderHash, methodOpts);
+        const canceledTakerTokenAmount = await this.exchangeWrapper.getCanceledTakerAmountAsync(orderHash, methodOpts);
+        const orderRelevantState = {
+            makerBalance,
+            makerProxyAllowance,
+            makerFeeBalance,
+            makerFeeProxyAllowance,
+            filledTakerTokenAmount,
+            canceledTakerTokenAmount,
+        };
+        return orderRelevantState;
+    }
+    private validateIfOrderIsValid(signedOrder: SignedOrder, orderRelevantState: OrderRelevantState): void {
+        const unavailableTakerTokenAmount = orderRelevantState.canceledTakerTokenAmount.add(
+            orderRelevantState.filledTakerTokenAmount,
+        );
+        const availableTakerTokenAmount = signedOrder.takerTokenAmount.minus(unavailableTakerTokenAmount);
+        if (availableTakerTokenAmount.eq(0)) {
+            throw new Error(ExchangeContractErrs.OrderRemainingFillAmountZero);
+        }
+
+        if (orderRelevantState.makerBalance.eq(0)) {
+            throw new Error(ExchangeContractErrs.InsufficientMakerBalance);
+        }
+        if (orderRelevantState.makerProxyAllowance.eq(0)) {
+            throw new Error(ExchangeContractErrs.InsufficientMakerAllowance);
+        }
+        if (!signedOrder.makerFee.eq(0)) {
+            if (orderRelevantState.makerFeeBalance.eq(0)) {
+                throw new Error(ExchangeContractErrs.InsufficientMakerFeeBalance);
+            }
+            if (orderRelevantState.makerFeeProxyAllowance.eq(0)) {
+                throw new Error(ExchangeContractErrs.InsufficientMakerFeeAllowance);
+            }
+        }
+        // TODO Add linear function solver when maker token is ZRX #badass
+        // Return the max amount that's fillable
+    }
+}