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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';
const GAS_MARGIN = 300000;
export class Contract implements Web3.ContractInstance {
public address: string;
public abi: Web3.ContractAbi;
private contract: Web3.ContractInstance;
private defaults: Partial<Web3.TxData>;
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<Web3.TxData>) {
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<number>,
): (...args: any[]) => Promise<any> {
const promisifiedWithDefaultParams = async (...args: any[]) => {
const promise = new Promise(async (resolve, reject) => {
const lastArg = args[args.length - 1];
let txData: Partial<Web3.TxData> = {};
if (this.isTxData(lastArg)) {
txData = args.pop();
}
// Gas amount sourced with the following priorities:
// 1. Optional param passed it 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;
}
}
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