import {schemas, SchemaValidator} from '@0xproject/json-schemas'; import promisify = require('es6-promisify'); import * as _ from 'lodash'; import * as Web3 from 'web3'; import {AbiType} from './types'; // HACK: Gas estimates on testrpc don't take into account gas refunds. // Our calls can trigger max 8 gas refunds for SSTORE per transaction for 15k gas each which gives 120k. const GAS_MARGIN = 120000; export class Contract implements Web3.ContractInstance { public address: string; public abi: Web3.ContractAbi; private contract: Web3.ContractInstance; private defaults: Partial; private validator: SchemaValidator; // This class instance is going to be populated with functions and events depending on the ABI // and we don't know their types in advance [name: string]: any; constructor(web3ContractInstance: Web3.ContractInstance, defaults: Partial) { this.contract = web3ContractInstance; this.address = web3ContractInstance.address; this.abi = web3ContractInstance.abi; this.defaults = defaults; this.populateEvents(); this.populateFunctions(); this.validator = new SchemaValidator(); } private populateFunctions(): void { const functionsAbi = _.filter(this.abi, abiPart => abiPart.type === AbiType.Function); _.forEach(functionsAbi, (functionAbi: Web3.MethodAbi) => { if (functionAbi.constant) { const cbStyleCallFunction = this.contract[functionAbi.name].call; this[functionAbi.name] = { callAsync: promisify(cbStyleCallFunction, this.contract), }; } else { const cbStyleFunction = this.contract[functionAbi.name]; const cbStyleEstimateGasFunction = this.contract[functionAbi.name].estimateGas; const estimateGasAsync = promisify(cbStyleEstimateGasFunction, this.contract); this[functionAbi.name] = { estimateGasAsync, sendTransactionAsync: this.promisifyWithDefaultParams(cbStyleFunction, estimateGasAsync), }; } }); } private populateEvents(): void { const eventsAbi = _.filter(this.abi, abiPart => abiPart.type === AbiType.Event); _.forEach(eventsAbi, (eventAbi: Web3.EventAbi) => { this[eventAbi.name] = this.contract[eventAbi.name]; }); } private promisifyWithDefaultParams( web3CbStyleFunction: (...args: any[]) => void, estimateGasAsync: (...args: any[]) => Promise, ): (...args: any[]) => Promise { const promisifiedWithDefaultParams = async (...args: any[]) => { const promise = new Promise(async (resolve, reject) => { const lastArg = args[args.length - 1]; let txData: Partial = {}; if (!_.isUndefined(lastArg) && this.isTxData(lastArg)) { txData = args.pop(); } // 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; txData = { ...removeUndefinedProperties(this.defaults), ...removeUndefinedProperties(txData), }; if (_.isUndefined(txData.gas)) { try { const estimatedGas = await estimateGasAsync.apply(this.contract, [...args, txData]); const gas = estimatedGas + GAS_MARGIN; txData.gas = gas; } catch (err) { reject(err); return; } } const callback = (err: Error, data: any) => _.isNull(err) ? resolve(data) : reject(err); args.push(txData); args.push(callback); web3CbStyleFunction.apply(this.contract, args); }); return promise; }; return promisifiedWithDefaultParams; } private isTxData(lastArg: any): boolean { const isValid = this.validator.isValid(lastArg, schemas.txDataSchema); return isValid; } }