From 4e59be9afce49fca8b396c305d5271c8299c85c1 Mon Sep 17 00:00:00 2001
From: Brandon Millman <brandon.millman@gmail.com>
Date: Sat, 15 Sep 2018 14:08:19 +0200
Subject: Implement ProvidedOrderFetcher

---
 .../src/order_fetchers/provided_order_fetcher.ts   | 41 ++++++++++++++++++++++
 .../standard_relayer_api_order_fetcher.ts          |  1 +
 packages/asset-buyer/src/utils/assert.ts           |  7 +++-
 3 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 packages/asset-buyer/src/order_fetchers/provided_order_fetcher.ts

diff --git a/packages/asset-buyer/src/order_fetchers/provided_order_fetcher.ts b/packages/asset-buyer/src/order_fetchers/provided_order_fetcher.ts
new file mode 100644
index 000000000..29b03f1c4
--- /dev/null
+++ b/packages/asset-buyer/src/order_fetchers/provided_order_fetcher.ts
@@ -0,0 +1,41 @@
+import { schemas } from '@0xproject/json-schemas';
+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 ProvidedOrderFetcher implements OrderFetcher {
+    public readonly providedOrders: SignedOrder[];
+    /**
+     * Instantiates a new ProvidedOrderFetcher instance
+     * @param   providedOrders  An array of objects that conform to SignedOrder to fetch from.
+     * @return  An instance of ProvidedOrderFetcher
+     */
+    constructor(providedOrders: SignedOrder[]) {
+        assert.doesConformToSchema('providedOrders', providedOrders, schemas.signedOrdersSchema);
+        this.providedOrders = providedOrders;
+    }
+    /**
+     * 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> {
+        assert.isValidOrderFetcherRequest('orderFetchRequest', orderFetchRequest);
+        const { makerAssetData, takerAssetData } = orderFetchRequest;
+        const orders = _.filter(this.providedOrders, order => {
+            return order.makerAssetData === makerAssetData && order.takerAssetData === takerAssetData;
+        });
+        return { orders };
+    }
+}
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
index bf177b93b..5688daf69 100644
--- 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
@@ -60,6 +60,7 @@ export class StandardRelayerAPIOrderFetcher implements OrderFetcher {
      * @return  An instance of OrderFetcherResponse. See type for more information.
      */
     public async fetchOrdersAsync(orderFetchRequest: OrderFetcherRequest): Promise<OrderFetcherResponse> {
+        assert.isValidOrderFetcherRequest('orderFetchRequest', orderFetchRequest);
         const { makerAssetData, takerAssetData, networkId } = orderFetchRequest;
         const orderbookRequest = { baseAssetData: makerAssetData, quoteAssetData: takerAssetData };
         const requestOpts = { networkId };
diff --git a/packages/asset-buyer/src/utils/assert.ts b/packages/asset-buyer/src/utils/assert.ts
index c4d611477..0085ca41e 100644
--- a/packages/asset-buyer/src/utils/assert.ts
+++ b/packages/asset-buyer/src/utils/assert.ts
@@ -2,7 +2,7 @@ import { assert as sharedAssert } from '@0xproject/assert';
 import { schemas } from '@0xproject/json-schemas';
 import * as _ from 'lodash';
 
-import { BuyQuote, OrderFetcher } from '../types';
+import { BuyQuote, OrderFetcher, OrderFetcherRequest } from '../types';
 
 export const assert = {
     ...sharedAssert,
@@ -20,4 +20,9 @@ export const assert = {
     isValidOrderFetcher(variableName: string, orderFetcher: OrderFetcher): void {
         sharedAssert.isFunction(`${variableName}.fetchOrdersAsync`, orderFetcher.fetchOrdersAsync);
     },
+    isValidOrderFetcherRequest(variableName: string, orderFetcherRequest: OrderFetcherRequest): void {
+        sharedAssert.isHexString(`${variableName}.makerAssetData`, orderFetcherRequest.makerAssetData);
+        sharedAssert.isHexString(`${variableName}.takerAssetData`, orderFetcherRequest.takerAssetData);
+        sharedAssert.isNumber(`${variableName}.networkId`, orderFetcherRequest.networkId);
+    },
 };
-- 
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