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node
typescript
hono
htmx
atproto
refactor(appview): create event handler registry to eliminate duplication (#12)
Replace 18 nearly-identical event handler registrations in FirehoseService
with a declarative registry pattern. This eliminates boilerplate and makes
adding new collections easier.
Changes:
- Add EventHandlerRegistry class with fluent interface
- Refactor FirehoseService to use registry for handler setup
- Derive wantedCollections from registered handlers
- Add comprehensive unit tests for registry
Benefits:
- DRY compliance: Single place to configure collection handlers
- Easier to maintain: Clear declaration-based configuration
- Simpler to extend: Adding a collection now requires one .register() call
- Better testability: Registry can be tested independently
The setupEventHandlers() method went from 86 lines of repetitive code
to 12 lines that apply the registry and set up cursor/error handlers.
+255
-83
+132
apps/appview/src/lib/__tests__/event-handler-registry.test.ts
+132
apps/appview/src/lib/__tests__/event-handler-registry.test.ts
···
1
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import { describe, it, expect, vi } from "vitest";
2
+
import { EventHandlerRegistry } from "../event-handler-registry.js";
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describe("EventHandlerRegistry", () => {
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it("should register handlers for collections", () => {
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const registry = new EventHandlerRegistry();
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+
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registry.register({
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collection: "space.atbb.post",
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onCreate: vi.fn(),
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});
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+
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expect(registry.getCollections()).toEqual(["space.atbb.post"]);
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});
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+
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it("should support fluent interface", () => {
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const registry = new EventHandlerRegistry()
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.register({ collection: "space.atbb.post", onCreate: vi.fn() })
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.register({ collection: "space.atbb.forum.forum", onCreate: vi.fn() });
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+
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expect(registry.getCollections()).toEqual(["space.atbb.post", "space.atbb.forum.forum"]);
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});
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+
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it("should apply handlers to Jetstream instance", () => {
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const onCreate = vi.fn();
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const onUpdate = vi.fn();
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const onDelete = vi.fn();
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+
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const mockJetstream = {
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onCreate: vi.fn(),
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onUpdate: vi.fn(),
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onDelete: vi.fn(),
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};
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+
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const registry = new EventHandlerRegistry().register({
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collection: "space.atbb.post",
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onCreate,
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onUpdate,
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onDelete,
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});
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registry.applyTo(mockJetstream as any);
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+
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expect(mockJetstream.onCreate).toHaveBeenCalledWith("space.atbb.post", onCreate);
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expect(mockJetstream.onUpdate).toHaveBeenCalledWith("space.atbb.post", onUpdate);
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expect(mockJetstream.onDelete).toHaveBeenCalledWith("space.atbb.post", onDelete);
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});
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+
49
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it("should only register provided handlers", () => {
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const onCreate = vi.fn();
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const mockJetstream = {
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onCreate: vi.fn(),
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onUpdate: vi.fn(),
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onDelete: vi.fn(),
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};
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const registry = new EventHandlerRegistry().register({
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collection: "space.atbb.post",
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onCreate, // Only onCreate provided
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});
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registry.applyTo(mockJetstream as any);
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expect(mockJetstream.onCreate).toHaveBeenCalledWith("space.atbb.post", onCreate);
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expect(mockJetstream.onUpdate).not.toHaveBeenCalled();
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expect(mockJetstream.onDelete).not.toHaveBeenCalled();
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});
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+
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it("should clear all registrations", () => {
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const registry = new EventHandlerRegistry().register({
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collection: "space.atbb.post",
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onCreate: vi.fn(),
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});
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+
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expect(registry.getCollections()).toHaveLength(1);
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+
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registry.clear();
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expect(registry.getCollections()).toHaveLength(0);
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});
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+
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it("should handle multiple collections with partial handlers", () => {
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const mockJetstream = {
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onCreate: vi.fn(),
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onUpdate: vi.fn(),
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onDelete: vi.fn(),
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};
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+
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const postCreate = vi.fn();
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const forumUpdate = vi.fn();
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const categoryDelete = vi.fn();
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+
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const registry = new EventHandlerRegistry()
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.register({
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collection: "space.atbb.post",
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onCreate: postCreate,
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})
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.register({
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collection: "space.atbb.forum.forum",
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onUpdate: forumUpdate,
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})
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.register({
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collection: "space.atbb.forum.category",
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onDelete: categoryDelete,
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});
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+
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registry.applyTo(mockJetstream as any);
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+
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// Verify only the registered handlers were called
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expect(mockJetstream.onCreate).toHaveBeenCalledTimes(1);
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expect(mockJetstream.onCreate).toHaveBeenCalledWith("space.atbb.post", postCreate);
112
+
113
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expect(mockJetstream.onUpdate).toHaveBeenCalledTimes(1);
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expect(mockJetstream.onUpdate).toHaveBeenCalledWith("space.atbb.forum.forum", forumUpdate);
115
+
116
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expect(mockJetstream.onDelete).toHaveBeenCalledTimes(1);
117
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expect(mockJetstream.onDelete).toHaveBeenCalledWith("space.atbb.forum.category", categoryDelete);
118
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});
119
+
120
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it("should preserve registration order", () => {
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const registry = new EventHandlerRegistry()
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.register({ collection: "space.atbb.post", onCreate: vi.fn() })
123
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.register({ collection: "space.atbb.forum.forum", onCreate: vi.fn() })
124
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.register({ collection: "space.atbb.membership", onCreate: vi.fn() });
125
+
126
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expect(registry.getCollections()).toEqual([
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"space.atbb.post",
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"space.atbb.forum.forum",
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"space.atbb.membership",
130
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]);
131
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});
132
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});
+68
apps/appview/src/lib/event-handler-registry.ts
+68
apps/appview/src/lib/event-handler-registry.ts
···
1
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import type { Jetstream } from "@skyware/jetstream";
2
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3
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/**
4
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* Event operation types supported by Jetstream
5
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*/
6
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export type EventOperation = "create" | "update" | "delete";
7
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8
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/**
9
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* Handler function signature for any event operation
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*/
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export type EventHandler<T extends string = string> = (event: any) => Promise<void>;
12
+
13
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/**
14
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* Configuration for a single collection's event handlers
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*/
16
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export interface CollectionHandlers {
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collection: string;
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onCreate?: EventHandler;
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onUpdate?: EventHandler;
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onDelete?: EventHandler;
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}
22
+
23
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/**
24
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* Registry for managing Jetstream event handler registrations.
25
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* Eliminates boilerplate by automating handler setup for collections.
26
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*/
27
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export class EventHandlerRegistry {
28
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private registrations: CollectionHandlers[] = [];
29
+
30
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/**
31
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* Register handlers for a collection
32
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*/
33
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register(handlers: CollectionHandlers): this {
34
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this.registrations.push(handlers);
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return this; // Fluent interface
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}
37
+
38
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/**
39
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* Apply all registered handlers to a Jetstream instance
40
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*/
41
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applyTo(jetstream: Jetstream): void {
42
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for (const { collection, onCreate, onUpdate, onDelete } of this.registrations) {
43
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if (onCreate) {
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jetstream.onCreate(collection as any, onCreate);
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}
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if (onUpdate) {
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jetstream.onUpdate(collection as any, onUpdate);
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}
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if (onDelete) {
50
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jetstream.onDelete(collection as any, onDelete);
51
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}
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}
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}
54
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/**
56
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* Get all registered collection names
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*/
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getCollections(): string[] {
59
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return this.registrations.map((r) => r.collection);
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}
61
+
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/**
63
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* Clear all registrations (useful for testing)
64
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*/
65
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clear(): void {
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this.registrations = [];
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}
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}
+55
-83
apps/appview/src/lib/firehose.ts
+55
-83
apps/appview/src/lib/firehose.ts
···
4
4
import { CursorManager } from "./cursor-manager.js";
5
5
import { CircuitBreaker } from "./circuit-breaker.js";
6
6
import { ReconnectionManager } from "./reconnection-manager.js";
7
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import { EventHandlerRegistry } from "./event-handler-registry.js";
7
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8
9
/**
9
10
* Firehose service that subscribes to AT Proto Jetstream
···
27
28
private circuitBreaker: CircuitBreaker;
28
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private reconnectionManager: ReconnectionManager;
29
30
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// Event handler registry
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private handlerRegistry: EventHandlerRegistry;
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// Collections we're interested in (full lexicon IDs)
31
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private readonly wantedCollections = [
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"space.atbb.post",
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"space.atbb.forum.forum",
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"space.atbb.forum.category",
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"space.atbb.membership",
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"space.atbb.modAction",
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"space.atbb.reaction",
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];
35
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private readonly wantedCollections: string[];
39
36
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constructor(
41
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private db: Database,
···
48
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this.cursorManager = new CursorManager(db);
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this.circuitBreaker = new CircuitBreaker(100, () => this.stop());
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this.reconnectionManager = new ReconnectionManager(10, 5000);
48
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49
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// Build handler registry
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this.handlerRegistry = this.createHandlerRegistry();
51
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this.wantedCollections = this.handlerRegistry.getCollections();
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// Initialize with a placeholder - will be recreated with cursor in start()
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54
this.jetstream = this.createJetstream();
···
66
67
}
67
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/**
69
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* Set up event handlers for different record operations
70
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* Create and configure the event handler registry
70
71
*/
71
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private setupEventHandlers() {
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// Handle record creates
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this.jetstream.onCreate("space.atbb.post", (event) => {
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this.handlePostCreate(event);
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});
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this.jetstream.onCreate("space.atbb.forum.forum", (event) => {
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this.handleForumCreate(event);
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});
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this.jetstream.onCreate("space.atbb.forum.category", (event) => {
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this.handleCategoryCreate(event);
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});
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this.jetstream.onCreate("space.atbb.membership", (event) => {
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this.handleMembershipCreate(event);
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});
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this.jetstream.onCreate("space.atbb.modAction", (event) => {
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this.handleModActionCreate(event);
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});
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this.jetstream.onCreate("space.atbb.reaction", (event) => {
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this.handleReactionCreate(event);
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});
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// Handle record updates
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this.jetstream.onUpdate("space.atbb.post", (event) => {
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this.handlePostUpdate(event);
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});
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102
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this.jetstream.onUpdate("space.atbb.forum.forum", (event) => {
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this.handleForumUpdate(event);
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});
105
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this.jetstream.onUpdate("space.atbb.forum.category", (event) => {
107
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this.handleCategoryUpdate(event);
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});
109
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110
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this.jetstream.onUpdate("space.atbb.membership", (event) => {
111
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this.handleMembershipUpdate(event);
112
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});
113
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114
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this.jetstream.onUpdate("space.atbb.modAction", (event) => {
115
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this.handleModActionUpdate(event);
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});
117
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this.jetstream.onUpdate("space.atbb.reaction", (event) => {
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this.handleReactionUpdate(event);
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});
121
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122
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// Handle record deletes (tombstones)
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this.jetstream.onDelete("space.atbb.post", (event) => {
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this.handlePostDelete(event);
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});
126
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127
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this.jetstream.onDelete("space.atbb.forum.forum", (event) => {
128
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this.handleForumDelete(event);
129
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});
130
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131
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this.jetstream.onDelete("space.atbb.forum.category", (event) => {
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this.handleCategoryDelete(event);
133
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});
134
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135
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this.jetstream.onDelete("space.atbb.membership", (event) => {
136
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this.handleMembershipDelete(event);
137
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});
72
+
private createHandlerRegistry(): EventHandlerRegistry {
73
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return new EventHandlerRegistry()
74
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.register({
75
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collection: "space.atbb.post",
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onCreate: this.handlePostCreate,
77
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onUpdate: this.handlePostUpdate,
78
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onDelete: this.handlePostDelete,
79
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})
80
+
.register({
81
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collection: "space.atbb.forum.forum",
82
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onCreate: this.handleForumCreate,
83
+
onUpdate: this.handleForumUpdate,
84
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onDelete: this.handleForumDelete,
85
+
})
86
+
.register({
87
+
collection: "space.atbb.forum.category",
88
+
onCreate: this.handleCategoryCreate,
89
+
onUpdate: this.handleCategoryUpdate,
90
+
onDelete: this.handleCategoryDelete,
91
+
})
92
+
.register({
93
+
collection: "space.atbb.membership",
94
+
onCreate: this.handleMembershipCreate,
95
+
onUpdate: this.handleMembershipUpdate,
96
+
onDelete: this.handleMembershipDelete,
97
+
})
98
+
.register({
99
+
collection: "space.atbb.modAction",
100
+
onCreate: this.handleModActionCreate,
101
+
onUpdate: this.handleModActionUpdate,
102
+
onDelete: this.handleModActionDelete,
103
+
})
104
+
.register({
105
+
collection: "space.atbb.reaction",
106
+
onCreate: this.handleReactionCreate,
107
+
onUpdate: this.handleReactionUpdate,
108
+
onDelete: this.handleReactionDelete,
109
+
});
110
+
}
138
111
139
-
this.jetstream.onDelete("space.atbb.modAction", (event) => {
140
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this.handleModActionDelete(event);
141
-
});
142
-
143
-
this.jetstream.onDelete("space.atbb.reaction", (event) => {
144
-
this.handleReactionDelete(event);
145
-
});
112
+
/**
113
+
* Set up event handlers using the registry
114
+
*/
115
+
private setupEventHandlers() {
116
+
// Apply all handlers from the registry
117
+
this.handlerRegistry.applyTo(this.jetstream);
146
118
147
119
// Listen to all commits to track cursor
148
120
this.jetstream.on("commit", async (event) => {