1 files changed, 69 insertions, 0 deletions
diff --git a/packages/web3-wrapper/src/base_contract.ts b/packages/web3-wrapper/src/base_contract.ts
new file mode 100644
index 000000000..997ce97d3
--- /dev/null
+++ b/packages/web3-wrapper/src/base_contract.ts
@@ -0,0 +1,69 @@
+import { TxData, TxDataPayable } from '@0xproject/types';
+import * as ethersContracts from 'ethers-contracts';
+import * as _ from 'lodash';
+import * as Web3 from 'web3';
+
+import { Web3Wrapper } from './web3_wrapper';
+
+export class BaseContract {
+    protected _ethersInterface: ethersContracts.Interface;
+    protected _web3Wrapper: Web3Wrapper;
+    public abi: Web3.ContractAbi;
+    public address: string;
+    protected static _transformABIData(
+        abis: Web3.DataItem[],
+        values: any[],
+        transformation: (type: string, value: any) => any,
+    ): any {
+        return _.map(values, (value: any, i: number) =>
+            BaseContract._transformTypedData(abis[i].type, value, transformation),
+        );
+    }
+    protected static _lowercaseAddress(type: string, value: string): string {
+        return type === 'address' ? value.toLowerCase() : value;
+    }
+    protected static _bigNumberToString(type: string, value: string): string {
+        return _.isObject(value) && (value as any).isBigNumber ? value.toString() : value;
+    }
+    private static _transformTypedData(
+        type: string,
+        values: any,
+        transformation: (type: string, value: any) => any,
+    ): any {
+        const trailingArrayRegex = /\[\d*\]$/;
+        if (type.match(trailingArrayRegex)) {
+            const arrayItemType = type.replace(trailingArrayRegex, '');
+            return _.map(values, value => this._transformTypedData(arrayItemType, value, transformation));
+        } else {
+            return transformation(type, values);
+        }
+    }
+    protected async _applyDefaultsToTxDataAsync<T extends Partial<TxData | TxDataPayable>>(
+        txData: T,
+        estimateGasAsync?: (txData: T) => Promise<number>,
+    ): Promise<TxData> {
+        // Gas amount sourced with the following priorities:
+        // 1. Optional param passed in to public method call
+        // 2. Global config passed in at library instantiation
+        // 3. Gas estimate calculation + safety margin
+        const removeUndefinedProperties = _.pickBy;
+        const txDataWithDefaults = {
+            to: this.address,
+            ...removeUndefinedProperties(this._web3Wrapper.getContractDefaults()),
+            ...removeUndefinedProperties(txData as any),
+            // HACK: TS can't prove that T is spreadable.
+            // Awaiting https://github.com/Microsoft/TypeScript/pull/13288 to be merged
+        };
+        if (_.isUndefined(txDataWithDefaults.gas) && !_.isUndefined(estimateGasAsync)) {
+            const estimatedGas = await estimateGasAsync(txData);
+            txDataWithDefaults.gas = estimatedGas;
+        }
+        return txDataWithDefaults;
+    }
+    constructor(web3Wrapper: Web3Wrapper, abi: Web3.ContractAbi, address: string) {
+        this._web3Wrapper = web3Wrapper;
+        this.abi = abi;
+        this.address = address;
+        this._ethersInterface = new ethersContracts.Interface(abi);
+    }
+}