feat: Add balance and allowance checks for MultiAssetProxy

1 files changed, 87 insertions, 45 deletions

diff --git a/packages/contract-wrappers/src/fetchers/asset_balance_and_proxy_allowance_fetcher.ts b/packages/contract-wrappers/src/fetchers/asset_balance_and_proxy_allowance_fetcher.ts
index d10cffe57..376004f52 100644
--- a/packages/contract-wrappers/src/fetchers/asset_balance_and_proxy_allowance_fetcher.ts
+++ b/packages/contract-wrappers/src/fetchers/asset_balance_and_proxy_allowance_fetcher.ts
@@ -1,8 +1,9 @@
 // tslint:disable:no-unnecessary-type-assertion
 import { AbstractBalanceAndProxyAllowanceFetcher, assetDataUtils } from '@0x/order-utils';
-import { AssetProxyId, ERC20AssetData, ERC721AssetData } from '@0x/types';
+import { AssetProxyId, ERC20AssetData, ERC721AssetData, MultiAssetData } from '@0x/types';
 import { BigNumber } from '@0x/utils';
 import { BlockParamLiteral } from 'ethereum-types';
+import * as _ from 'lodash';
 
 import { ERC20TokenWrapper } from '../contract_wrappers/erc20_token_wrapper';
 import { ERC721TokenWrapper } from '../contract_wrappers/erc721_token_wrapper';
@@ -18,60 +19,101 @@ export class AssetBalanceAndProxyAllowanceFetcher implements AbstractBalanceAndP
     }
     public async getBalanceAsync(assetData: string, userAddress: string): Promise<BigNumber> {
         const decodedAssetData = assetDataUtils.decodeAssetDataOrThrow(assetData);
-        if (decodedAssetData.assetProxyId === AssetProxyId.ERC20) {
-            const decodedERC20AssetData = decodedAssetData as ERC20AssetData;
-            const balance = await this._erc20Token.getBalanceAsync(decodedERC20AssetData.tokenAddress, userAddress, {
-                defaultBlock: this._stateLayer,
-            });
-            return balance;
-        } else {
-            const decodedERC721AssetData = decodedAssetData as ERC721AssetData;
-            const tokenOwner = await this._erc721Token.getOwnerOfAsync(
-                decodedERC721AssetData.tokenAddress,
-                decodedERC721AssetData.tokenId,
-                {
+        let balance: BigNumber | undefined;
+        switch (decodedAssetData.assetProxyId) {
+            case AssetProxyId.ERC20:
+                const decodedERC20AssetData = decodedAssetData as ERC20AssetData;
+                balance = await this._erc20Token.getBalanceAsync(decodedERC20AssetData.tokenAddress, userAddress, {
                     defaultBlock: this._stateLayer,
-                },
-            );
-            const balance = tokenOwner === userAddress ? new BigNumber(1) : new BigNumber(0);
-            return balance;
+                });
+                break;
+            case AssetProxyId.ERC721:
+                const decodedERC721AssetData = decodedAssetData as ERC721AssetData;
+                const tokenOwner = await this._erc721Token.getOwnerOfAsync(
+                    decodedERC721AssetData.tokenAddress,
+                    decodedERC721AssetData.tokenId,
+                    {
+                        defaultBlock: this._stateLayer,
+                    },
+                );
+                balance = tokenOwner === userAddress ? new BigNumber(1) : new BigNumber(0);
+                break;
+            case AssetProxyId.MultiAsset:
+                // The `balance` for MultiAssetData is the total units of the entire `assetData` that are held by the `userAddress`.
+                for (const [
+                    index,
+                    nestedAssetDataElement,
+                ] of (decodedAssetData as MultiAssetData).nestedAssetData.entries()) {
+                    const nestedAmountElement = (decodedAssetData as MultiAssetData).amounts[index];
+                    const nestedAssetBalance = (await this.getBalanceAsync(
+                        nestedAssetDataElement,
+                        userAddress,
+                    )).dividedToIntegerBy(nestedAmountElement);
+                    if (_.isUndefined(balance) || nestedAssetBalance.lessThan(balance)) {
+                        balance = nestedAssetBalance;
+                    }
+                }
+                break;
+            default:
+                throw new Error(`Proxy with id ${decodedAssetData.assetProxyId} not supported`);
         }
+        return balance as BigNumber;
     }
     public async getProxyAllowanceAsync(assetData: string, userAddress: string): Promise<BigNumber> {
         const decodedAssetData = assetDataUtils.decodeAssetDataOrThrow(assetData);
-        if (decodedAssetData.assetProxyId === AssetProxyId.ERC20) {
-            const decodedERC20AssetData = decodedAssetData as ERC20AssetData;
-            const proxyAllowance = await this._erc20Token.getProxyAllowanceAsync(
-                decodedERC20AssetData.tokenAddress,
-                userAddress,
-                {
-                    defaultBlock: this._stateLayer,
-                },
-            );
-            return proxyAllowance;
-        } else {
-            const decodedERC721AssetData = decodedAssetData as ERC721AssetData;
-
-            const isApprovedForAll = await this._erc721Token.isProxyApprovedForAllAsync(
-                decodedERC721AssetData.tokenAddress,
-                userAddress,
-                {
-                    defaultBlock: this._stateLayer,
-                },
-            );
-            if (isApprovedForAll) {
-                return new BigNumber(this._erc20Token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
-            } else {
-                const isApproved = await this._erc721Token.isProxyApprovedAsync(
+        let proxyAllowance: BigNumber | undefined;
+        switch (decodedAssetData.assetProxyId) {
+            case AssetProxyId.ERC20:
+                const decodedERC20AssetData = decodedAssetData as ERC20AssetData;
+                proxyAllowance = await this._erc20Token.getProxyAllowanceAsync(
+                    decodedERC20AssetData.tokenAddress,
+                    userAddress,
+                    {
+                        defaultBlock: this._stateLayer,
+                    },
+                );
+                break;
+            case AssetProxyId.ERC721:
+                const decodedERC721AssetData = decodedAssetData as ERC721AssetData;
+                const isApprovedForAll = await this._erc721Token.isProxyApprovedForAllAsync(
                     decodedERC721AssetData.tokenAddress,
-                    decodedERC721AssetData.tokenId,
+                    userAddress,
                     {
                         defaultBlock: this._stateLayer,
                     },
                 );
-                const proxyAllowance = isApproved ? new BigNumber(1) : new BigNumber(0);
-                return proxyAllowance;
-            }
+                if (isApprovedForAll) {
+                    return new BigNumber(this._erc20Token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
+                } else {
+                    const isApproved = await this._erc721Token.isProxyApprovedAsync(
+                        decodedERC721AssetData.tokenAddress,
+                        decodedERC721AssetData.tokenId,
+                        {
+                            defaultBlock: this._stateLayer,
+                        },
+                    );
+                    proxyAllowance = isApproved ? new BigNumber(1) : new BigNumber(0);
+                }
+                break;
+            case AssetProxyId.MultiAsset:
+                // The `proxyAllowance` for MultiAssetData is the total units of the entire `assetData` that the proxies have been approved to spend by the `userAddress`.
+                for (const [
+                    index,
+                    nestedAssetDataElement,
+                ] of (decodedAssetData as MultiAssetData).nestedAssetData.entries()) {
+                    const nestedAmountElement = (decodedAssetData as MultiAssetData).amounts[index];
+                    const nestedAssetAllowance = (await this.getProxyAllowanceAsync(
+                        nestedAssetDataElement,
+                        userAddress,
+                    )).dividedToIntegerBy(nestedAmountElement);
+                    if (_.isUndefined(proxyAllowance) || nestedAssetAllowance.lessThan(proxyAllowance)) {
+                        proxyAllowance = nestedAssetAllowance;
+                    }
+                }
+                break;
+            default:
+                throw new Error(`Proxy with id ${decodedAssetData.assetProxyId} not supported`);
         }
+        return proxyAllowance as BigNumber;
     }
 }