From 5eb2f5eeb4e846649957630127be2137845cdfe8 Mon Sep 17 00:00:00 2001
From: FlorianWoelki <FlorianWoelki@gmx.de>
Date: Sat, 6 Jul 2024 10:03:56 +0200
Subject: [PATCH] refactor: restructure events library

---
 src/lib/event/event.test.ts | 31 +++++++++++----------
 src/lib/event/event.ts      | 55 ++++++++++++++++++++-----------------
 src/lib/event/events.ts     | 11 ++++++--
 src/main.ts                 |  2 +-
 4 files changed, 55 insertions(+), 44 deletions(-)

diff --git a/src/lib/event/event.test.ts b/src/lib/event/event.test.ts
index b49620e2..45ef2442 100644
--- a/src/lib/event/event.test.ts
+++ b/src/lib/event/event.test.ts
@@ -1,6 +1,5 @@
 import { describe, it, vi, expect, beforeEach } from 'vitest';
 import { EventEmitter } from './event';
-import { AllIconsLoadedEvent } from './events';
 
 describe('EventEmitter', () => {
   let emitter: EventEmitter;
@@ -11,32 +10,34 @@ describe('EventEmitter', () => {
 
   it('should register and emit event listeners', () => {
     const listener = vi.fn();
-    emitter.on<AllIconsLoadedEvent>('allIconsLoaded', listener);
+    emitter.on('allIconsLoaded', listener);
 
-    emitter.emit({ type: 'allIconsLoaded' });
+    emitter.emit('allIconsLoaded');
 
-    expect(listener).toHaveBeenCalledWith({ type: 'allIconsLoaded' });
+    expect(listener).toHaveBeenCalledWith({ payload: undefined });
     expect(listener).toHaveBeenCalledTimes(1);
   });
 
   it('should unregister event listeners', () => {
     const listener = vi.fn();
-    emitter.on<AllIconsLoadedEvent>('allIconsLoaded', listener);
-    emitter.off<AllIconsLoadedEvent>('allIconsLoaded', listener);
+    emitter.on('allIconsLoaded', listener);
+    emitter.off('allIconsLoaded', listener);
 
-    emitter.emit({ type: 'allIconsLoaded' });
+    emitter.emit('allIconsLoaded');
 
     expect(listener).not.toHaveBeenCalled();
   });
 
   it('should support once-only event listeners', () => {
     const listener = vi.fn();
-    emitter.once<AllIconsLoadedEvent>('allIconsLoaded', listener);
+    emitter.once('allIconsLoaded', listener);
 
-    emitter.emit({ type: 'allIconsLoaded' });
-    emitter.emit({ type: 'allIconsLoaded' });
+    emitter.emit('allIconsLoaded');
+    emitter.emit('allIconsLoaded');
 
-    expect(listener).toHaveBeenCalledWith({ type: 'allIconsLoaded' });
+    expect(listener).toHaveBeenCalledWith({
+      payload: undefined,
+    });
     expect(listener).toHaveBeenCalledTimes(1);
   });
 
@@ -45,11 +46,11 @@ describe('EventEmitter', () => {
     const listener2 = vi.fn();
     const listener3 = vi.fn();
 
-    emitter.on<AllIconsLoadedEvent>('allIconsLoaded', listener1, 1);
-    emitter.on<AllIconsLoadedEvent>('allIconsLoaded', listener2, 2);
-    emitter.on<AllIconsLoadedEvent>('allIconsLoaded', listener3, 3);
+    emitter.on('allIconsLoaded', listener1, 1);
+    emitter.on('allIconsLoaded', listener2, 2);
+    emitter.on('allIconsLoaded', listener3, 3);
 
-    emitter.emit({ type: 'allIconsLoaded' });
+    emitter.emit('allIconsLoaded');
 
     expect(listener3).toHaveBeenCalled();
     expect(listener2).toHaveBeenCalled();
diff --git a/src/lib/event/event.ts b/src/lib/event/event.ts
index 9967d6fa..b7df2752 100644
--- a/src/lib/event/event.ts
+++ b/src/lib/event/event.ts
@@ -1,66 +1,71 @@
-type Events = 'allIconsLoaded';
+import type { EventType, EventMap, AnyEvent } from './events';
 
-export interface Event {
-  type: Events;
+export interface Event<P = unknown> {
+  payload?: P;
 }
 
-type EventListener<T extends Event> = (event: T) => void;
+type EventListener<E extends AnyEvent> = (event: E) => void;
 
-interface ListenerEntry<T extends Event> {
-  listener: EventListener<T>;
+interface ListenerEntry<E extends AnyEvent> {
+  listener: EventListener<E>;
   once: boolean;
   priority: number;
 }
 
 export class EventEmitter {
-  private listeners: { [key: string]: ListenerEntry<Event>[] } = {};
+  private listeners: { [K in EventType]?: ListenerEntry<AnyEvent>[] } = {};
 
-  on<T extends Event>(
-    type: T['type'],
-    listener: EventListener<T>,
-    priority: number = 0,
+  on<K extends EventType>(
+    type: K,
+    listener: EventListener<EventMap[K]>,
+    priority = 0,
   ): void {
     this.listeners[type] ??= [];
-    this.listeners[type].push({ listener, once: false, priority });
+    this.listeners[type]?.push({ listener, once: false, priority });
     this.sortListeners(type);
   }
 
-  once<T extends Event>(
-    type: T['type'],
-    listener: EventListener<T>,
-    priority: number = 0,
+  once<K extends EventType>(
+    type: K,
+    listener: EventListener<EventMap[K]>,
+    priority = 0,
   ): void {
     this.listeners[type] ??= [];
-    this.listeners[type].push({ listener, once: true, priority });
+    this.listeners[type]?.push({ listener, once: true, priority });
     this.sortListeners(type);
   }
 
-  off<T extends Event>(type: T['type'], listener: EventListener<T>): void {
+  off<K extends EventType>(
+    type: K,
+    listener: EventListener<EventMap[K]>,
+  ): void {
     if (!this.listeners[type]) {
       return;
     }
 
-    this.listeners[type] = this.listeners[type].filter(
+    this.listeners[type] = this.listeners[type]?.filter(
       (entry) => entry.listener !== listener,
     );
   }
 
-  emit<T extends Event>(event: T): void {
-    if (!this.listeners[event.type]) {
+  emit<K extends EventType>(type: K, payload?: EventMap[K]['payload']): void {
+    const listeners = this.listeners[type];
+    if (!listeners) {
       return;
     }
 
-    this.listeners[event.type].forEach((entry) => {
+    const event = { payload } as EventMap[K];
+    listeners.slice().forEach((entry) => {
       entry.listener(event);
       if (entry.once) {
-        this.off(event.type, entry.listener);
+        this.off(type, entry.listener);
       }
     });
   }
 
-  private sortListeners(type: string): void {
+  private sortListeners(type: EventType): void {
     if (this.listeners[type]) {
-      this.listeners[type].sort((a, b) => b.priority - a.priority);
+      this.listeners[type]?.sort((a, b) => b.priority - a.priority);
     }
   }
 }
diff --git a/src/lib/event/events.ts b/src/lib/event/events.ts
index 0c82a062..178b8741 100644
--- a/src/lib/event/events.ts
+++ b/src/lib/event/events.ts
@@ -1,5 +1,10 @@
 import { Event } from './event';
 
-export interface AllIconsLoadedEvent extends Event {
-  type: 'allIconsLoaded';
-}
+export type AllIconsLoadedEvent = Event<undefined>;
+
+export type EventMap = {
+  allIconsLoaded: AllIconsLoadedEvent;
+};
+
+export type EventType = keyof EventMap;
+export type AnyEvent = EventMap[EventType];
diff --git a/src/main.ts b/src/main.ts
index 9b64674f..7ca1b0d3 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -394,7 +394,7 @@ export default class IconFolderPlugin extends Plugin {
           resetPreloadedIcons();
         }
 
-        this.eventEmitter.emit({ type: 'allIconsLoaded' });
+        this.eventEmitter.emit('allIconsLoaded');
       });
 
       if (this.getSettings().iconInFrontmatterEnabled) {