Jakob Wennberg
72 lines
1.9 KiB
TypeScript
72 lines
1.9 KiB
TypeScript
import type { CoreEvent, CoreEventType, EventHandler } from './types'
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// Internal handler type — loose enough for the Map, but type-safe at the public API
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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type AnyHandler = (payload: any) => Promise<void> | void
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/**
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* In-process event bus.
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*
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* - Handlers run concurrently via Promise.allSettled (failing handler never crashes emitter)
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* - Module-level singleton (persists across requests in same process)
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* - One-way: core services emit, extensions subscribe
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*/
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class EventBus {
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private handlers = new Map<string, Set<AnyHandler>>()
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/**
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* Subscribe to an event type.
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* Returns an unsubscribe function.
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*/
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on<T extends CoreEventType>(
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eventType: T,
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handler: EventHandler<T>
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): () => void {
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if (!this.handlers.has(eventType)) {
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this.handlers.set(eventType, new Set())
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}
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const handlerSet = this.handlers.get(eventType)!
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handlerSet.add(handler as AnyHandler)
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return () => {
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handlerSet.delete(handler as AnyHandler)
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if (handlerSet.size === 0) {
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this.handlers.delete(eventType)
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}
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}
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}
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/**
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* Emit an event to all registered handlers.
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* Uses Promise.allSettled so a failing handler never crashes the emitter.
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*/
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async emit(event: CoreEvent): Promise<void> {
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const handlerSet = this.handlers.get(event.type)
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if (!handlerSet || handlerSet.size === 0) return
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const results = await Promise.allSettled(
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[...handlerSet].map((handler) => handler(event.payload))
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)
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for (const result of results) {
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if (result.status === 'rejected') {
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console.error(
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`[EventBus] Handler failed for "${event.type}":`,
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result.reason
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)
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}
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}
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}
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/**
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* Remove all handlers (useful for testing).
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*/
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clear(): void {
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this.handlers.clear()
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}
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}
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/** Module-level singleton */
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export const eventBus = new EventBus()
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