feat: expose new `getAvailableAssetDatasAsync` API

BREAKING CHANGE: the `OrderProvider` now requires a new method `getAvailableMakerAssetDatasAsync` and the `StandardRelayerAPIOrderProvider` requires the network id at init.

6 files changed, 54 insertions, 10 deletions

diff --git a/packages/asset-buyer/src/asset_buyer.ts b/packages/asset-buyer/src/asset_buyer.ts
index 34e2d9639..2bc80ac12 100644
--- a/packages/asset-buyer/src/asset_buyer.ts
+++ b/packages/asset-buyer/src/asset_buyer.ts
@@ -77,7 +77,8 @@ export class AssetBuyer {
     ): AssetBuyer {
         assert.isWeb3Provider('provider', provider);
         assert.isWebUri('sraApiUrl', sraApiUrl);
-        const orderProvider = new StandardRelayerAPIOrderProvider(sraApiUrl);
+        const networkId = options.networkId || constants.DEFAULT_ASSET_BUYER_OPTS.networkId;
+        const orderProvider = new StandardRelayerAPIOrderProvider(sraApiUrl, networkId);
         const assetBuyer = new AssetBuyer(provider, orderProvider, options);
         return assetBuyer;
     }
@@ -241,6 +242,15 @@ export class AssetBuyer {
         }
     }
     /**
+     * Get the asset data of all assets that are purchaseable with ether token (wETH) in the order provider passed in at init.
+     *
+     * @return  An array of asset data strings that can be purchased using wETH.
+     */
+    public async getAvailableAssetDatasAsync(): Promise<string[]> {
+        const etherTokenAssetData = this._getEtherTokenAssetDataOrThrow();
+        return this.orderProvider.getAvailableMakerAssetDatasAsync(etherTokenAssetData);
+    }
+    /**
      * Grab orders from the map, if there is a miss or it is time to refresh, fetch and process the orders
      */
     private async _getOrdersAndFillableAmountsAsync(
diff --git a/packages/asset-buyer/src/constants.ts b/packages/asset-buyer/src/constants.ts
index c912253bd..b2f025bdb 100644
--- a/packages/asset-buyer/src/constants.ts
+++ b/packages/asset-buyer/src/constants.ts
@@ -36,6 +36,6 @@ export const constants = {
     DEFAULT_ASSET_BUYER_OPTS,
     DEFAULT_BUY_QUOTE_EXECUTION_OPTS,
     DEFAULT_BUY_QUOTE_REQUEST_OPTS,
-    MAX_PER_PAGE: 10000,
+    MAX_PER_PAGE: 1000,
     EMPTY_ORDERS_AND_FILLABLE_AMOUNTS,
 };
diff --git a/packages/asset-buyer/src/order_providers/basic_order_provider.ts b/packages/asset-buyer/src/order_providers/basic_order_provider.ts
index 68406f19b..76685f27a 100644
--- a/packages/asset-buyer/src/order_providers/basic_order_provider.ts
+++ b/packages/asset-buyer/src/order_providers/basic_order_provider.ts
@@ -29,4 +29,13 @@ export class BasicOrderProvider implements OrderProvider {
         });
         return { orders };
     }
+    /**
+     * Given a taker asset data string, return all availabled paired maker asset data strings.
+     * @param   takerAssetData   A string representing the taker asset data.
+     * @return  An array of asset data strings that can be purchased using takerAssetData.
+     */
+    public async getAvailableMakerAssetDatasAsync(takerAssetData: string): Promise<string[]> {
+        const ordersWithTakerAssetData = _.filter(this.orders, { takerAssetData });
+        return _.map(ordersWithTakerAssetData, order => order.makerAssetData);
+    }
 }
diff --git a/packages/asset-buyer/src/order_providers/standard_relayer_api_order_provider.ts b/packages/asset-buyer/src/order_providers/standard_relayer_api_order_provider.ts
index 41fd1fb30..c6adcfc4a 100644
--- a/packages/asset-buyer/src/order_providers/standard_relayer_api_order_provider.ts
+++ b/packages/asset-buyer/src/order_providers/standard_relayer_api_order_provider.ts
@@ -1,7 +1,8 @@
 import { HttpClient } from '@0x/connect';
-import { APIOrder, OrderbookResponse } from '@0x/types';
+import { APIOrder, AssetPairsResponse, OrderbookResponse } from '@0x/types';
 import * as _ from 'lodash';
 
+import { constants } from '../constants';
 import {
     AssetBuyerError,
     OrderProvider,
@@ -14,6 +15,7 @@ import { orderUtils } from '../utils/order_utils';
 
 export class StandardRelayerAPIOrderProvider implements OrderProvider {
     public readonly apiUrl: string;
+    public readonly networkId: number;
     private readonly _sraClient: HttpClient;
     /**
      * Given an array of APIOrder objects from a standard relayer api, return an array
@@ -44,12 +46,15 @@ export class StandardRelayerAPIOrderProvider implements OrderProvider {
     }
     /**
      * Instantiates a new StandardRelayerAPIOrderProvider instance
-     * @param   apiUrl  The standard relayer API base HTTP url you would like to source orders from.
+     * @param   apiUrl      The standard relayer API base HTTP url you would like to source orders from.
+     * @param   networkId   The ethereum network id.
      * @return  An instance of StandardRelayerAPIOrderProvider
      */
-    constructor(apiUrl: string) {
+    constructor(apiUrl: string, networkId: number) {
         assert.isWebUri('apiUrl', apiUrl);
+        assert.isNumber('networkId', networkId);
         this.apiUrl = apiUrl;
+        this.networkId = networkId;
         this._sraClient = new HttpClient(apiUrl);
     }
     /**
@@ -59,9 +64,9 @@ export class StandardRelayerAPIOrderProvider implements OrderProvider {
      */
     public async getOrdersAsync(orderProviderRequest: OrderProviderRequest): Promise<OrderProviderResponse> {
         assert.isValidOrderProviderRequest('orderProviderRequest', orderProviderRequest);
-        const { makerAssetData, takerAssetData, networkId } = orderProviderRequest;
+        const { makerAssetData, takerAssetData } = orderProviderRequest;
         const orderbookRequest = { baseAssetData: makerAssetData, quoteAssetData: takerAssetData };
-        const requestOpts = { networkId };
+        const requestOpts = { networkId: this.networkId };
         let orderbook: OrderbookResponse;
         try {
             orderbook = await this._sraClient.getOrderbookAsync(orderbookRequest, requestOpts);
@@ -76,4 +81,24 @@ export class StandardRelayerAPIOrderProvider implements OrderProvider {
             orders,
         };
     }
+    /**
+     * Given a taker asset data string, return all availabled paired maker asset data strings.
+     * @param   takerAssetData   A string representing the taker asset data.
+     * @return  An array of asset data strings that can be purchased using takerAssetData.
+     */
+    public async getAvailableMakerAssetDatasAsync(takerAssetData: string): Promise<string[]> {
+        const requestOpts = { networkId: this.networkId, perPage: constants.MAX_PER_PAGE };
+        const assetPairsRequest = { assetDataA: takerAssetData };
+        const fullRequest = {
+            ...requestOpts,
+            ...assetPairsRequest,
+        };
+        let response: AssetPairsResponse;
+        try {
+            response = await this._sraClient.getAssetPairsAsync(fullRequest);
+        } catch (err) {
+            throw new Error(AssetBuyerError.StandardRelayerApiError);
+        }
+        return _.map(response.records, item => item.assetDataB.assetData);
+    }
 }
diff --git a/packages/asset-buyer/src/types.ts b/packages/asset-buyer/src/types.ts
index f15e7e934..3f1e6ff21 100644
--- a/packages/asset-buyer/src/types.ts
+++ b/packages/asset-buyer/src/types.ts
@@ -9,7 +9,6 @@ import { BigNumber } from '@0x/utils';
 export interface OrderProviderRequest {
     makerAssetData: string;
     takerAssetData: string;
-    networkId: number;
 }
 
 /**
@@ -27,10 +26,12 @@ export interface SignedOrderWithRemainingFillableMakerAssetAmount extends Signed
     remainingFillableMakerAssetAmount?: BigNumber;
 }
 /**
- * Given an OrderProviderRequest, get an OrderProviderResponse.
+ * gerOrdersAsync: Given an OrderProviderRequest, get an OrderProviderResponse.
+ * getAvailableMakerAssetDatasAsync: Given a taker asset data string, return all availabled paired maker asset data strings.
  */
 export interface OrderProvider {
     getOrdersAsync: (orderProviderRequest: OrderProviderRequest) => Promise<OrderProviderResponse>;
+    getAvailableMakerAssetDatasAsync: (takerAssetData: string) => Promise<string[]>;
 }
 
 /**
diff --git a/packages/asset-buyer/src/utils/assert.ts b/packages/asset-buyer/src/utils/assert.ts
index e8cb7f763..e5bfd2d81 100644
--- a/packages/asset-buyer/src/utils/assert.ts
+++ b/packages/asset-buyer/src/utils/assert.ts
@@ -29,7 +29,6 @@ export const assert = {
     isValidOrderProviderRequest(variableName: string, orderFetcherRequest: OrderProviderRequest): void {
         sharedAssert.isHexString(`${variableName}.makerAssetData`, orderFetcherRequest.makerAssetData);
         sharedAssert.isHexString(`${variableName}.takerAssetData`, orderFetcherRequest.takerAssetData);
-        sharedAssert.isNumber(`${variableName}.networkId`, orderFetcherRequest.networkId);
     },
     areValidProvidedOrders(variableName: string, orders: SignedOrder[]): void {
         if (orders.length === 0) {