feat: middleware support (#226)

Author: Meemaw

.github/workflows/ci.yml

@@ -20,6 +20,7 @@ jobs:
 
       - name: Install dependencies
         run: npm ci
+
       - name: Run linters
         run: npm run lint:check
 
@@ -37,6 +38,11 @@ jobs:
       - name: Run tests
         run: npm run test -- --coverage --ci --runInBand
 
+      - name: Upload code coverage
+        uses: coverallsapp/github-action@master
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+
   build:
     runs-on: ubuntu-latest
     steps:

README.md

@@ -1,6 +1,7 @@
 # OpenSea Stream API - JavaScript SDK
 
 [![https://badges.frapsoft.com/os/mit/mit.svg?v=102](https://badges.frapsoft.com/os/mit/mit.svg?v=102)](https://opensource.org/licenses/MIT)
+[![Coverage Status](https://coveralls.io/repos/github/ProjectOpenSea/stream-js/badge.svg?branch=main)](https://coveralls.io/github/ProjectOpenSea/stream-js?branch=main)
 [![styled with prettier](https://img.shields.io/badge/styled_with-prettier-ff69b4.svg)](https://github.com/prettier/prettier)
 
 A Javascript SDK for receiving updates from the OpenSea Stream API - pushed over websockets. We currently support the following event types on a per-collection basis:

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@opensea/stream-js",
-  "version": "0.0.23",
+  "version": "0.0.24",
   "description": "An SDK to receive pushed updates from OpenSea over websocket",
   "license": "MIT",
   "author": "OpenSea Developers",

src/client.ts

@@ -15,22 +15,25 @@ import {
   TraitOfferEvent,
   Callback,
   LogLevel,
-  Network
+  Network,
+  OnClientEvent
 } from './types';
 import { ENDPOINTS } from './constants';
 
 export class OpenSeaStreamClient {
   private socket: Socket;
   private channels: Map<string, Channel>;
   private logLevel: LogLevel;
+  private onEvent: OnClientEvent;
 
   constructor({
     network = Network.MAINNET,
     token,
     apiUrl,
     connectOptions,
     logLevel = LogLevel.INFO,
-    onError = (error) => this.error(error)
+    onError = (error) => this.error(error),
+    onEvent = () => true
   }: ClientConfig) {
     const endpoint = apiUrl || ENDPOINTS[network];
     const webTransportDefault =
@@ -44,6 +47,7 @@ export class OpenSeaStreamClient {
     this.socket.onError(onError);
     this.channels = new Map<string, Channel>();
     this.logLevel = logLevel;
+    this.onEvent = onEvent;
   }
 
   private debug(message: unknown) {
@@ -113,7 +117,14 @@ export class OpenSeaStreamClient {
     this.debug(`Fetching channel ${topic}`);
     const channel = this.getChannel(topic);
     this.debug(`Subscribing to ${eventType} events on ${topic}`);
-    channel.on(eventType, callback);
+
+    const onClientEvent = this.onEvent;
+    channel.on(eventType, (event) => {
+      if (onClientEvent(collectionSlug, eventType, event)) {
+        callback(event);
+      }
+    });
+
     return () => {
       this.debug(`Unsubscribing from ${eventType} events on ${topic}`);
       channel.leave().receive('ok', () => {

src/types.ts

@@ -1,5 +1,11 @@
 import type { SocketConnectOption } from 'phoenix';
 
+export type OnClientEvent = <Payload>(
+  collection: string,
+  eventType: EventType,
+  event: BaseStreamMessage<Payload>
+) => boolean;
+
 /**
  * OpenSea Stream API configuration object
  * @param token API key to use for API
@@ -8,6 +14,7 @@ import type { SocketConnectOption } from 'phoenix';
  * @param connectOptions `SocketConnectOption` type to use to connect to the Stream API socket.
  * @param onError a callback function to use whenever errors occur in the SDK.
  * @param logLevel `LogLevel` type to define the amount of logging the SDK should provide.
+ * @param onEvent a callback function to use whenever an event is emmited in the SDK. Can be used to globally apply some logic, e.g emitting metric/logging etc. If the onEvent handler returns false, event will be filtered and the subscription callback won't be invoked.
  */
 export type ClientConfig = {
   network?: Network;
@@ -16,6 +23,7 @@ export type ClientConfig = {
   connectOptions?: Partial<SocketConnectOption>;
   onError?: (error: unknown) => void;
   logLevel?: LogLevel;
+  onEvent?: OnClientEvent;
 };
 
 export enum Network {

tests/client.spec.ts

@@ -130,3 +130,141 @@ describe('event streams', () => {
     });
   });
 });
+
+describe('middleware', () => {
+  test('single', () => {
+    const collectionSlug = 'c1';
+
+    const onClientEvent = jest.fn().mockImplementation(() => true);
+
+    streamClient = new OpenSeaStreamClient({
+      token: 'test',
+      apiUrl: 'ws://localhost:1234',
+      connectOptions: { transport: WebSocket },
+      onEvent: onClientEvent
+    });
+
+    const socket = getSocket(streamClient);
+    jest
+      .spyOn(socket, 'endPointURL')
+      .mockImplementation(() => 'ws://localhost:1234');
+
+    const onEvent = jest.fn();
+
+    const listingEvent = mockEvent(EventType.ITEM_LISTED, {});
+    const saleEvent = mockEvent(EventType.ITEM_SOLD, {});
+
+    streamClient.onEvents(
+      collectionSlug,
+      [EventType.ITEM_LISTED, EventType.ITEM_SOLD],
+      (event) => onEvent(event)
+    );
+
+    server.send(
+      encode({
+        topic: collectionTopic(collectionSlug),
+        event: EventType.ITEM_LISTED,
+        payload: listingEvent
+      })
+    );
+
+    server.send(
+      encode({
+        topic: collectionTopic(collectionSlug),
+        event: EventType.ITEM_SOLD,
+        payload: saleEvent
+      })
+    );
+
+    expect(onClientEvent).nthCalledWith(
+      1,
+      collectionSlug,
+      EventType.ITEM_LISTED,
+      listingEvent
+    );
+
+    expect(onClientEvent).nthCalledWith(
+      2,
+      collectionSlug,
+      EventType.ITEM_SOLD,
+      saleEvent
+    );
+
+    expect(onEvent).nthCalledWith(1, listingEvent);
+    expect(onEvent).nthCalledWith(2, saleEvent);
+
+    streamClient.disconnect();
+  });
+
+  test('filter out events', () => {
+    const collectionSlug = 'c1';
+
+    const onClientEvent = jest
+      .fn()
+      .mockImplementation(
+        (_c, _e, event) => event.payload.chain === 'ethereum'
+      );
+
+    streamClient = new OpenSeaStreamClient({
+      token: 'test',
+      apiUrl: 'ws://localhost:1234',
+      connectOptions: { transport: WebSocket },
+      onEvent: onClientEvent
+    });
+
+    const socket = getSocket(streamClient);
+    jest
+      .spyOn(socket, 'endPointURL')
+      .mockImplementation(() => 'ws://localhost:1234');
+
+    const onEvent = jest.fn();
+
+    const ethereumListing = mockEvent(EventType.ITEM_LISTED, {
+      chain: 'ethereum'
+    });
+    const polygonListing = mockEvent(EventType.ITEM_LISTED, {
+      chain: 'polygon'
+    });
+
+    streamClient.onEvents(
+      collectionSlug,
+      [EventType.ITEM_LISTED, EventType.ITEM_SOLD],
+      (event) => onEvent(event)
+    );
+
+    server.send(
+      encode({
+        topic: collectionTopic(collectionSlug),
+        event: EventType.ITEM_LISTED,
+        payload: ethereumListing
+      })
+    );
+
+    server.send(
+      encode({
+        topic: collectionTopic(collectionSlug),
+        event: EventType.ITEM_SOLD,
+        payload: polygonListing
+      })
+    );
+
+    expect(onClientEvent).nthCalledWith(
+      1,
+      collectionSlug,
+      EventType.ITEM_LISTED,
+      ethereumListing
+    );
+
+    expect(onClientEvent).nthCalledWith(
+      2,
+      collectionSlug,
+      EventType.ITEM_SOLD,
+      polygonListing
+    );
+
+    expect(onEvent).toHaveBeenCalledTimes(1);
+    expect(onEvent).toHaveBeenCalledWith(ethereumListing);
+
+    streamClient.disconnect();
+  });
+});