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import * as _ from 'lodash';
import * as WebSocket from 'websocket';
import {
OrderbookChannel,
OrderbookChannelHandler,
OrderbookChannelMessageTypes,
OrderbookChannelSubscriptionOpts,
} from './types';
import { assert } from './utils/assert';
import { orderbookChannelMessageParser } from './utils/orderbook_channel_message_parser';
/**
* This class includes all the functionality related to interacting with a websocket endpoint
* that implements the standard relayer API v0
*/
export class WebSocketOrderbookChannel implements OrderbookChannel {
private readonly _client: WebSocket.w3cwebsocket;
private readonly _handler: OrderbookChannelHandler;
private readonly _subscriptionOptsList: OrderbookChannelSubscriptionOpts[] = [];
/**
* Instantiates a new WebSocketOrderbookChannel instance
* @param client A WebSocket client
* @param handler An OrderbookChannelHandler instance that responds to various
* channel updates
* @return An instance of WebSocketOrderbookChannel
*/
constructor(client: WebSocket.w3cwebsocket, handler: OrderbookChannelHandler) {
assert.isOrderbookChannelHandler('handler', handler);
// set private members
this._client = client;
this._handler = handler;
// attach client callbacks
this._client.onerror = err => {
this._handler.onError(this, err);
};
this._client.onclose = () => {
this._handler.onClose(this);
};
this._client.onmessage = message => {
this._handleWebSocketMessage(message);
};
}
/**
* Subscribe to orderbook snapshots and updates from the websocket
* @param subscriptionOpts An OrderbookChannelSubscriptionOpts instance describing which
* token pair to subscribe to
*/
public subscribe(subscriptionOpts: OrderbookChannelSubscriptionOpts): void {
assert.isOrderbookChannelSubscriptionOpts('subscriptionOpts', subscriptionOpts);
assert.assert(this._client.readyState === WebSocket.w3cwebsocket.OPEN, 'WebSocket connection is closed');
this._subscriptionOptsList.push(subscriptionOpts);
// TODO: update requestId management to use UUIDs for v2
const subscribeMessage = {
type: 'subscribe',
channel: 'orderbook',
requestId: this._subscriptionOptsList.length - 1,
payload: subscriptionOpts,
};
this._client.send(JSON.stringify(subscribeMessage));
}
/**
* Close the websocket and stop receiving updates
*/
public close(): void {
this._client.close();
}
private _handleWebSocketMessage(message: any): void {
if (_.isUndefined(message.data)) {
this._handler.onError(this, new Error(`Message does not contain data. Url: ${this._client.url}`));
return;
}
try {
const data = message.data;
const parserResult = orderbookChannelMessageParser.parse(data);
const subscriptionOpts = this._subscriptionOptsList[parserResult.requestId];
if (_.isUndefined(subscriptionOpts)) {
this._handler.onError(
this,
new Error(`Message has unknown requestId. Url: ${this._client.url} Message: ${data}`),
);
return;
}
switch (parserResult.type) {
case OrderbookChannelMessageTypes.Snapshot: {
this._handler.onSnapshot(this, subscriptionOpts, parserResult.payload);
break;
}
case OrderbookChannelMessageTypes.Update: {
this._handler.onUpdate(this, subscriptionOpts, parserResult.payload);
break;
}
default: {
this._handler.onError(
this,
new Error(`Message has unknown type parameter. Url: ${this._client.url} Message: ${data}`),
subscriptionOpts,
);
}
}
} catch (error) {
this._handler.onError(this, error);
}
}
}
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