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import type { Logger } from "../contracts/extension.js";
import type {
EventHandler,
EventHookDescriptor,
FilterDescriptor,
FilterHandler,
ServiceHandle,
} from "../contracts/hooks.js";
import {
applyFilterChain,
dispatchEventAsync,
dispatchEventSync,
type FilterEntry,
sortFilters,
} from "./pure.js";
export interface Bus {
readonly on: <T>(hook: EventHookDescriptor<T>, handler: EventHandler<T>) => () => void;
readonly emit: <T>(hook: EventHookDescriptor<T>, payload: T) => void;
readonly emitAsync: <T>(
hook: EventHookDescriptor<T>,
payload: T,
timeoutMs?: number,
) => Promise<void>;
readonly addFilter: <T>(
hook: FilterDescriptor<T>,
fn: FilterHandler<T>,
opts?: { readonly priority?: number },
) => () => void;
readonly applyFilters: <T>(
hook: FilterDescriptor<T>,
value: T,
opts?: { readonly failClosed?: boolean },
) => Promise<T>;
readonly provideService: <T>(handle: ServiceHandle<T>, impl: T) => void;
readonly getService: <T>(handle: ServiceHandle<T>) => T;
}
interface StoredFilterEntry {
readonly fn: unknown;
readonly priority: number;
readonly order: number;
}
export function createBus(logger: Logger): Bus {
const eventHandlers = new Map<string, Set<unknown>>();
const filterEntries = new Map<string, StoredFilterEntry[]>();
const services = new Map<string, unknown>();
let filterOrderCounter = 0;
return {
on<T>(hook: EventHookDescriptor<T>, handler: EventHandler<T>): () => void {
let set = eventHandlers.get(hook.id);
if (set === undefined) {
set = new Set();
eventHandlers.set(hook.id, set);
}
const stored: unknown = handler;
set.add(stored);
return () => {
const current = eventHandlers.get(hook.id);
if (current !== undefined) current.delete(stored);
};
},
emit<T>(hook: EventHookDescriptor<T>, payload: T): void {
const set = eventHandlers.get(hook.id);
if (set === undefined || set.size === 0) return;
const handlers = [...set] as Array<EventHandler<T>>;
dispatchEventSync(handlers, payload, logger, hook.id);
},
async emitAsync<T>(
hook: EventHookDescriptor<T>,
payload: T,
timeoutMs?: number,
): Promise<void> {
const set = eventHandlers.get(hook.id);
if (set === undefined || set.size === 0) return;
const handlers = [...set] as Array<EventHandler<T>>;
await dispatchEventAsync(handlers, payload, logger, hook.id, timeoutMs);
},
addFilter<T>(
hook: FilterDescriptor<T>,
fn: FilterHandler<T>,
opts?: { readonly priority?: number },
): () => void {
let entries = filterEntries.get(hook.id);
if (entries === undefined) {
entries = [];
filterEntries.set(hook.id, entries);
}
const entry: StoredFilterEntry = {
fn,
priority: opts?.priority ?? 0,
order: filterOrderCounter++,
};
entries.push(entry);
return () => {
const current = filterEntries.get(hook.id);
if (current === undefined) return;
const idx = current.indexOf(entry);
if (idx !== -1) current.splice(idx, 1);
};
},
async applyFilters<T>(
hook: FilterDescriptor<T>,
value: T,
opts?: { readonly failClosed?: boolean },
): Promise<T> {
const entries = filterEntries.get(hook.id);
if (entries === undefined || entries.length === 0) return value;
const sorted = sortFilters(entries as ReadonlyArray<FilterEntry<T>>);
const fns = sorted.map((e) => e.fn) as Array<FilterHandler<T>>;
return applyFilterChain(fns, value, logger, hook.id, opts?.failClosed ?? false);
},
provideService<T>(handle: ServiceHandle<T>, impl: T): void {
if (services.has(handle.id)) {
throw new Error(
`Service "${handle.id}" is already provided. Only one provider per handle is allowed.`,
);
}
services.set(handle.id, impl);
},
getService<T>(handle: ServiceHandle<T>): T {
const impl = services.get(handle.id);
if (impl === undefined) {
throw new Error(
`Service "${handle.id}" has no provider. Call provideService before getService.`,
);
}
return impl as T;
},
};
}
|
