1 files changed, 107 insertions, 0 deletions
diff --git a/packages/website/ts/blockchain_watcher.ts b/packages/website/ts/blockchain_watcher.ts
new file mode 100644
index 000000000..d3801cef4
--- /dev/null
+++ b/packages/website/ts/blockchain_watcher.ts
@@ -0,0 +1,107 @@
+import { BigNumber, intervalUtils, 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) => {
+                utils.consoleLog(`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);
+        }
+    }
+}