import * as Web3 from 'web3'; import * as _ from 'lodash'; import promisify = require('es6-promisify'); import {SchemaValidator, schemas} from '0x-json-schemas'; 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 === '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; this[functionAbi.name] = { estimateGasAsync: promisify(cbStyleEstimateGasFunction, this.contract), sendTransactionAsync: this.promisifyWithDefaultParams(cbStyleFunction), }; } }); } private populateEvents(): void { const eventsAbi = _.filter(this.abi, abiPart => abiPart.type === 'event'); _.forEach(eventsAbi, (eventAbi: Web3.EventAbi) => { this[eventAbi.name] = this.contract[eventAbi.name]; }); } private promisifyWithDefaultParams(fn: (...args: any[]) => void): (...args: any[]) => Promise { const promisifiedWithDefaultParams = (...args: any[]) => { const promise = new Promise((resolve, reject) => { const lastArg = args[args.length - 1]; let txData: Partial = {}; if (this.isTxData(lastArg)) { txData = args.pop(); } txData = { ...this.defaults, ...txData, }; const callback = (err: Error, data: any) => { if (_.isNull(err)) { resolve(data); } else { reject(err); } }; args.push(txData); args.push(callback); fn.apply(this.contract, args); }); return promise; }; return promisifiedWithDefaultParams; } private isTxData(lastArg: any): boolean { const isValid = this.validator.isValid(lastArg, schemas.txDataSchema); return isValid; } }