fix: Allow events without parameters

Currently `emit` requires two parameters even if the event type is set to `undefined`.
So `emit('foo')` will cause a Typescript error.

This fixes it by removing the second argument if the event type is set to undefined.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

lib/EventBus.ts

@@ -3,6 +3,7 @@
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
 import type { GenericEvents, NextcloudEvents } from './Event'
+import type { IsUndefined } from './types.d.ts'
 import { EventHandler } from './EventHandler'
 
 export interface EventBus<E extends GenericEvents = NextcloudEvents> {
@@ -37,5 +38,8 @@ export interface EventBus<E extends GenericEvents = NextcloudEvents> {
 	 * @param name Name of the event to emit
 	 * @param event Event payload to emit
 	 */
-	emit<EventName extends keyof E>(name: EventName, event: E[EventName]): void
+	emit<EventName extends keyof E>(
+		name: EventName,
+		...event: (IsUndefined<E[EventName]> extends true ? [] : [E[EventName]])
+	): void
 }

lib/EventHandler.ts

@@ -2,7 +2,7 @@
  * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
-import { Event } from './Event'
+import type { Event } from './Event'
 
 export interface EventHandler<T extends Event> {
 	(event: T): void

lib/ProxyBus.ts

@@ -7,8 +7,9 @@ import valid from 'semver/functions/valid.js'
 import major from 'semver/functions/major.js'
 
 import type { GenericEvents, NextcloudEvents } from './Event.js'
-import { EventBus } from './EventBus.js'
-import { EventHandler } from './EventHandler.js'
+import type { EventBus } from './EventBus.js'
+import type { EventHandler } from './EventHandler.js'
+import type { IsUndefined } from './types.d.ts'
 
 export class ProxyBus<E extends GenericEvents = NextcloudEvents>
 	implements EventBus<E>
@@ -48,7 +49,10 @@ export class ProxyBus<E extends GenericEvents = NextcloudEvents>
 		this.bus.unsubscribe(name, handler)
 	}
 
-	emit<EventName extends keyof E>(name: EventName, event: E[EventName]): void {
-		this.bus.emit(name, event)
+	emit<EventName extends keyof E>(
+		name: EventName,
+		...event: (IsUndefined<E[EventName]> extends true ? [] : [E[EventName]])
+	): void {
+		this.bus.emit(name, ...event)
 	}
 }

lib/SimpleBus.ts

@@ -2,9 +2,10 @@
  * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
-import { GenericEvents, NextcloudEvents } from './Event.js'
-import { EventBus } from './EventBus.js'
-import { EventHandler } from './EventHandler.js'
+import type { GenericEvents, NextcloudEvents } from './Event.js'
+import type { EventBus } from './EventBus.js'
+import type { EventHandler } from './EventHandler.js'
+import type { IsUndefined } from './types.d.ts'
 
 export class SimpleBus<E extends GenericEvents = NextcloudEvents>
 	implements EventBus<E>
@@ -37,10 +38,14 @@ export class SimpleBus<E extends GenericEvents = NextcloudEvents>
 		)
 	}
 
-	emit<EventName extends keyof E>(name: EventName, event: E[EventName]): void {
-		;(this.handlers.get(name) || []).forEach((h) => {
+	emit<EventName extends keyof E>(
+		name: EventName,
+		...event: (IsUndefined<E[EventName]> extends true ? [] : [E[EventName]])
+	): void {
+		const handlers = this.handlers.get(name) || []
+		handlers.forEach((h) => {
 			try {
-				h(event)
+				(h as EventHandler<typeof event[0]>)(event[0])
 			} catch (e) {
 				console.error('could not invoke event listener', e)
 			}

lib/index.ts

@@ -2,9 +2,11 @@
  * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
-import { EventBus } from './EventBus'
-import { EventHandler } from './EventHandler'
-import { NextcloudEvents } from './Event'
+import type { EventBus } from './EventBus'
+import type { EventHandler } from './EventHandler'
+import type { NextcloudEvents } from './Event'
+import type { IsUndefined } from './types.d.ts'
+
 import { ProxyBus } from './ProxyBus'
 import { SimpleBus } from './SimpleBus'
 
@@ -91,7 +93,7 @@ export function unsubscribe<K extends keyof NextcloudEvents>(
  */
 export function emit<K extends keyof NextcloudEvents>(
 	name: K,
-	event: NextcloudEvents[K],
+	...event: (IsUndefined<NextcloudEvents[K]> extends true ? [] : [NextcloudEvents[K]])
 ): void {
-	getBus().emit(name, event)
+	getBus().emit(name, ...event)
 }

lib/types.d.ts

@@ -0,0 +1,9 @@
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/**
+ * Helper to check if a type is undefined
+ */
+export type IsUndefined<T> = [T] extends [undefined] ? true : false