1 files changed, 80 insertions, 0 deletions
diff --git a/packages/asset-buyer/src/order_fetchers/standard_relayer_api_order_fetcher.ts b/packages/asset-buyer/src/order_fetchers/standard_relayer_api_order_fetcher.ts
new file mode 100644
index 000000000..bf177b93b
--- /dev/null
+++ b/packages/asset-buyer/src/order_fetchers/standard_relayer_api_order_fetcher.ts
@@ -0,0 +1,80 @@
+import { APIOrder, HttpClient, OrderbookResponse } from '@0xproject/connect';
+import { SignedOrder } from '@0xproject/types';
+import { BigNumber } from '@0xproject/utils';
+import * as _ from 'lodash';
+
+import { constants } from '../constants';
+import {
+    AssetBuyerError,
+    OrderFetcher,
+    OrderFetcherRequest,
+    OrderFetcherResponse,
+    SignedOrderWithRemainingFillableMakerAssetAmount,
+} from '../types';
+import { assert } from '../utils/assert';
+import { orderUtils } from '../utils/order_utils';
+
+export class StandardRelayerAPIOrderFetcher implements OrderFetcher {
+    public readonly apiUrl: string;
+    private _sraClient: HttpClient;
+    /**
+     * Given an array of APIOrder objects from a standard relayer api, return an array
+     * of SignedOrderWithRemainingFillableMakerAssetAmounts
+     */
+    private static _getSignedOrderWithRemainingFillableMakerAssetAmountFromApi(
+        apiOrders: APIOrder[],
+    ): SignedOrderWithRemainingFillableMakerAssetAmount[] {
+        const result = _.map(apiOrders, apiOrder => {
+            const { order, metaData } = apiOrder;
+            // calculate remainingFillableMakerAssetAmount from api metadata, else assume order is completely fillable
+            const remainingFillableTakerAssetAmount = _.get(
+                metaData,
+                'remainingTakerAssetAmount',
+                order.takerAssetAmount,
+            );
+            const remainingFillableMakerAssetAmount = orderUtils.calculateRemainingMakerAssetAmount(
+                order,
+                remainingFillableTakerAssetAmount,
+            );
+            const newOrder = {
+                ...order,
+                remainingFillableMakerAssetAmount,
+            };
+            return newOrder;
+        });
+        return result;
+    }
+    /**
+     * Instantiates a new StandardRelayerAPIOrderFetcher instance
+     * @param   apiUrl  The relayer API base HTTP url you would like to interact with.
+     * @return  An instance of StandardRelayerAPIOrderFetcher
+     */
+    constructor(apiUrl: string) {
+        assert.isWebUri('apiUrl', apiUrl);
+        this.apiUrl = apiUrl;
+        this._sraClient = new HttpClient(apiUrl);
+    }
+    /**
+     * Given an object that conforms to OrderFetcherRequest, return the corresponding OrderFetcherResponse that satisfies the request.
+     * @param   orderFetchRequest   An instance of OrderFetcherRequest. See type for more information.
+     * @return  An instance of OrderFetcherResponse. See type for more information.
+     */
+    public async fetchOrdersAsync(orderFetchRequest: OrderFetcherRequest): Promise<OrderFetcherResponse> {
+        const { makerAssetData, takerAssetData, networkId } = orderFetchRequest;
+        const orderbookRequest = { baseAssetData: makerAssetData, quoteAssetData: takerAssetData };
+        const requestOpts = { networkId };
+        let orderbook: OrderbookResponse;
+        try {
+            orderbook = await this._sraClient.getOrderbookAsync(orderbookRequest, requestOpts);
+        } catch (err) {
+            throw new Error(AssetBuyerError.StandardRelayerApiError);
+        }
+        const apiOrders = orderbook.asks.records;
+        const orders = StandardRelayerAPIOrderFetcher._getSignedOrderWithRemainingFillableMakerAssetAmountFromApi(
+            apiOrders,
+        );
+        return {
+            orders,
+        };
+    }
+}