Merge pull request #26 from 0xProject/erc20Wrapper

Implement TokenWrapper functions & tests

1 files changed, 93 insertions, 0 deletions

diff --git a/src/contract_wrappers/token_wrapper.ts b/src/contract_wrappers/token_wrapper.ts
new file mode 100644
index 000000000..35e008905
--- /dev/null
+++ b/src/contract_wrappers/token_wrapper.ts
@@ -0,0 +1,93 @@
+import * as _ from 'lodash';
+import * as BigNumber from 'bignumber.js';
+import {Web3Wrapper} from '../web3_wrapper';
+import {assert} from '../utils/assert';
+import {constants} from '../utils/constants';
+import {ContractWrapper} from './contract_wrapper';
+import * as TokenArtifacts from '../artifacts/Token.json';
+import * as ProxyArtifacts from '../artifacts/Proxy.json';
+import {TokenContract, ZeroExError} from '../types';
+
+const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 45730;
+
+export class TokenWrapper extends ContractWrapper {
+    private tokenContractsByAddress: {[address: string]: TokenContract};
+    constructor(web3Wrapper: Web3Wrapper) {
+        super(web3Wrapper);
+        this.tokenContractsByAddress = {};
+    }
+    public invalidateContractInstances() {
+        this.tokenContractsByAddress = {};
+    }
+    /**
+     * Returns an owner's ERC20 token balance.
+     */
+    public async getBalanceAsync(tokenAddress: string, ownerAddress: string): Promise<BigNumber.BigNumber> {
+        assert.isETHAddressHex('ownerAddress', ownerAddress);
+        assert.isETHAddressHex('tokenAddress', tokenAddress);
+
+        const tokenContract = await this.getTokenContractAsync(tokenAddress);
+        let balance = await tokenContract.balanceOf.call(ownerAddress);
+        // The BigNumber instance returned by Web3 is of a much older version then our own, we therefore
+        // should always re-instantiate the returned BigNumber after retrieval.
+        balance = new BigNumber(balance);
+        return balance;
+    }
+    /**
+     * Retrieves the allowance in baseUnits of the ERC20 token set to the 0x proxy contract
+     * by an owner address.
+     */
+    public async getProxyAllowanceAsync(tokenAddress: string, ownerAddress: string) {
+        assert.isETHAddressHex('ownerAddress', ownerAddress);
+        assert.isETHAddressHex('tokenAddress', tokenAddress);
+
+        const tokenContract = await this.getTokenContractAsync(tokenAddress);
+        const proxyAddress = await this.getProxyAddressAsync();
+        let allowanceInBaseUnits = await tokenContract.allowance.call(ownerAddress, proxyAddress);
+        allowanceInBaseUnits = new BigNumber(allowanceInBaseUnits);
+        return allowanceInBaseUnits;
+    }
+    /**
+     * Sets the 0x proxy contract's allowance to a specified number of a tokens' baseUnits on behalf
+     * of an owner address.
+     */
+    public async setProxyAllowanceAsync(tokenAddress: string, ownerAddress: string,
+                                        amountInBaseUnits: BigNumber.BigNumber) {
+        assert.isETHAddressHex('ownerAddress', ownerAddress);
+        assert.isETHAddressHex('tokenAddress', tokenAddress);
+        assert.isBigNumber('amountInBaseUnits', amountInBaseUnits);
+
+        const tokenContract = await this.getTokenContractAsync(tokenAddress);
+        const proxyAddress = await this.getProxyAddressAsync();
+        // Hack: for some reason default estimated gas amount causes `base fee exceeds gas limit` exception
+        // on testrpc. Probably related to https://github.com/ethereumjs/testrpc/issues/294
+        // TODO: Debug issue in testrpc and submit a PR, then remove this hack
+        const networkIdIfExists = await this.web3Wrapper.getNetworkIdIfExistsAsync();
+        const gas = networkIdIfExists === constants.TESTRPC_NETWORK_ID ? ALLOWANCE_TO_ZERO_GAS_AMOUNT : undefined;
+        await tokenContract.approve(proxyAddress, amountInBaseUnits, {
+            from: ownerAddress,
+            gas,
+        });
+    }
+    private async getTokenContractAsync(tokenAddress: string): Promise<TokenContract> {
+        let tokenContract = this.tokenContractsByAddress[tokenAddress];
+        if (!_.isUndefined(tokenContract)) {
+            return tokenContract;
+        }
+        const contractInstance = await this.instantiateContractIfExistsAsync((TokenArtifacts as any), tokenAddress);
+        tokenContract = contractInstance as TokenContract;
+        this.tokenContractsByAddress[tokenAddress] = tokenContract;
+        return tokenContract;
+    }
+    private async getProxyAddressAsync() {
+        const networkIdIfExists = await this.web3Wrapper.getNetworkIdIfExistsAsync();
+        const proxyNetworkConfigsIfExists = _.isUndefined(networkIdIfExists) ?
+                                       undefined :
+                                       (ProxyArtifacts as any).networks[networkIdIfExists];
+        if (_.isUndefined(proxyNetworkConfigsIfExists)) {
+            throw new Error(ZeroExError.CONTRACT_NOT_DEPLOYED_ON_NETWORK);
+        }
+        const proxyAddress = proxyNetworkConfigsIfExists.address;
+        return proxyAddress;
+    }
+}