path: root/packages/website/ts/blockchain_watcher.ts

import { BigNumber, intervalUtils, logUtils, promisify } from '@0xproject/utils';
import { Web3Wrapper } from '@0xproject/web3-wrapper';
import * as _ from 'lodash';
import { Dispatcher } from 'ts/redux/dispatcher';
import { utils } from 'ts/utils/utils';

export class BlockchainWatcher {
    private _dispatcher: Dispatcher;
    private _web3Wrapper: Web3Wrapper;
    private _prevNetworkId: number;
    private _shouldPollUserAddress: boolean;
    private _watchNetworkAndBalanceIntervalId: NodeJS.Timer;
    private _prevUserEtherBalanceInWei: BigNumber;
    private _prevUserAddressIfExists: string;
    constructor(
        dispatcher: Dispatcher,
        web3Wrapper: Web3Wrapper,
        networkIdIfExists: number,
        shouldPollUserAddress: boolean,
    ) {
        this._dispatcher = dispatcher;
        this._prevNetworkId = networkIdIfExists;
        this._shouldPollUserAddress = shouldPollUserAddress;
        this._web3Wrapper = web3Wrapper;
    }
    public destroy() {
        this._stopEmittingNetworkConnectionAndUserBalanceStateAsync();
        // HACK: stop() is only available on providerEngine instances
        const provider = this._web3Wrapper.getProvider();
        if (!_.isUndefined((provider as any).stop)) {
            (provider as any).stop();
        }
    }
    // This should only be called from the LedgerConfigDialog
    public updatePrevUserAddress(userAddress: string) {
        this._prevUserAddressIfExists = userAddress;
    }
    public startEmittingNetworkConnectionAndUserBalanceState() {
        if (!_.isUndefined(this._watchNetworkAndBalanceIntervalId)) {
            return; // we are already emitting the state
        }

        let prevNodeVersion: string;
        this._prevUserEtherBalanceInWei = new BigNumber(0);
        this._dispatcher.updateNetworkId(this._prevNetworkId);
        this._watchNetworkAndBalanceIntervalId = intervalUtils.setAsyncExcludingInterval(
            async () => {
                // Check for network state changes
                let currentNetworkId;
                try {
                    currentNetworkId = await this._web3Wrapper.getNetworkIdAsync();
                } catch (err) {
                    // Noop
                }
                if (currentNetworkId !== this._prevNetworkId) {
                    this._prevNetworkId = currentNetworkId;
                    this._dispatcher.updateNetworkId(currentNetworkId);
                }

                // Check for node version changes
                const currentNodeVersion = await this._web3Wrapper.getNodeVersionAsync();
                if (currentNodeVersion !== prevNodeVersion) {
                    prevNodeVersion = currentNodeVersion;
                    this._dispatcher.updateNodeVersion(currentNodeVersion);
                }

                if (this._shouldPollUserAddress) {
                    const addresses = await this._web3Wrapper.getAvailableAddressesAsync();
                    const userAddressIfExists = addresses[0];
                    // Update makerAddress on network change
                    if (this._prevUserAddressIfExists !== userAddressIfExists) {
                        this._prevUserAddressIfExists = userAddressIfExists;
                        this._dispatcher.updateUserAddress(userAddressIfExists);
                    }

                    // Check for user ether balance changes
                    if (!_.isUndefined(userAddressIfExists)) {
                        await this._updateUserWeiBalanceAsync(userAddressIfExists);
                    }
                } else {
                    // This logic is primarily for the Ledger, since we don't regularly poll for the address
                    // we simply update the balance for the last fetched address.
                    if (!_.isUndefined(this._prevUserAddressIfExists)) {
                        await this._updateUserWeiBalanceAsync(this._prevUserAddressIfExists);
                    }
                }
            },
            5000,
            (err: Error) => {
                logUtils.log(`Watching network and balances failed: ${err.stack}`);
                this._stopEmittingNetworkConnectionAndUserBalanceStateAsync();
            },
        );
    }
    private async _updateUserWeiBalanceAsync(userAddress: string) {
        const balanceInWei = await this._web3Wrapper.getBalanceInWeiAsync(userAddress);
        if (!balanceInWei.eq(this._prevUserEtherBalanceInWei)) {
            this._prevUserEtherBalanceInWei = balanceInWei;
            this._dispatcher.updateUserWeiBalance(balanceInWei);
        }
    }
    private _stopEmittingNetworkConnectionAndUserBalanceStateAsync() {
        if (!_.isUndefined(this._watchNetworkAndBalanceIntervalId)) {
            intervalUtils.clearAsyncExcludingInterval(this._watchNetworkAndBalanceIntervalId);
        }
    }
}