eth_call

eth_call.js

'use strict';

const WEB3_URL = process.env.WEB3_URL;

const prom     = require('util').promisify;
const ethABI   = require('ethereumjs-abi');
const Web3     = require('web3');
const provider = new Web3.providers.HttpProvider(WEB3_URL);
const web3     = module.exports = new Web3(provider);
const sendAsync = prom(web3.currentProvider.sendAsync).bind(web3.currentProvider);

/**
 * Raw json rpc request to method eth_call.
 *
 * @param  {Object} txObject           Raw transaction object.
 * @param  {Number|String} blockNumber Block number or tag (e.g. 'latest', 'earliest' or 'pending').
 * @return {Object?}                   Response or null.
 */
async function call(params) {
    let response;

    let options = {
        jsonrpc: '2.0',
        method: 'eth_call',
        params: params,
        id: new Date().getTime()
    };

    try {
        console.log('before sendAsync');
        response = await sendAsync(options);
        console.log('after sendAsync');
    } catch (e) {
        console.error(e);
        return null;
    }

    return response;
}

/**
 * Get forecaster FR from User Storage.
 *
 * @param  {String} to                     Callee (User Storage contract).
 * @param  {String} forecasterAddress
 * @param  {String} [blockNumber='latest'] Block number or tag (e.g. 'latest', 'earliest' or 'pending').
 * @return {Number?}                       User FR at the time of particular block.
 */
web3.getFR = async function getFR(to, forecasterAddress, blockNumber='latest') {
    const data = '0x' + ethABI.simpleEncode('getFR(address)', forecasterAddress).toString('hex');

    const rawTx = {
        to: to,
        data: data
    };

    const response = await call([rawTx, blockNumber]);
    console.log(response);
    if (response) {
        return parseInt(response.result, 16);
    }

    return null;
};