From 3fc856c1abc8a41a7c3d7e0db743d94140466a13 Mon Sep 17 00:00:00 2001
From: krutoo <dima.krutoo@yandex.ru>
Date: Thu, 21 Mar 2024 10:22:11 +0500
Subject: [PATCH] #38
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- preset/node: добавлен адаптер EventEmitter в EventTarget (minor)
---
 .../utils/__test__/emitter-as-target.test.ts  | 99 +++++++++++++++++++
 src/preset/node/utils/emitter-as-target.ts    | 54 ++++++++++
 2 files changed, 153 insertions(+)
 create mode 100644 src/preset/node/utils/__test__/emitter-as-target.test.ts
 create mode 100644 src/preset/node/utils/emitter-as-target.ts

diff --git a/src/preset/node/utils/__test__/emitter-as-target.test.ts b/src/preset/node/utils/__test__/emitter-as-target.test.ts
new file mode 100644
index 0000000..9f7b717
--- /dev/null
+++ b/src/preset/node/utils/__test__/emitter-as-target.test.ts
@@ -0,0 +1,99 @@
+import { EventEmitter } from 'node:events';
+import { EmitterAsTarget } from '../emitter-as-target';
+
+describe('EmitterAsTarget', () => {
+  it('should works as regular event target', () => {
+    const emitter = new EventEmitter();
+    const target = new EmitterAsTarget(emitter);
+
+    const spy = jest.fn();
+
+    target.addEventListener('test', spy);
+    expect(spy).toHaveBeenCalledTimes(0);
+
+    target.dispatchEvent(new Event('test'));
+    expect(spy).toHaveBeenCalledTimes(1);
+
+    target.dispatchEvent(new Event('test'));
+    expect(spy).toHaveBeenCalledTimes(2);
+
+    target.removeEventListener('test', spy);
+    expect(spy).toHaveBeenCalledTimes(2);
+
+    target.dispatchEvent(new Event('test'));
+    expect(spy).toHaveBeenCalledTimes(2);
+  });
+
+  it('should callback as object', () => {
+    const emitter = new EventEmitter();
+    const target = new EmitterAsTarget(emitter);
+
+    const spy = jest.fn();
+
+    target.addEventListener('test', { handleEvent: spy });
+    expect(spy).toHaveBeenCalledTimes(0);
+
+    target.dispatchEvent(new Event('test'));
+    expect(spy).toHaveBeenCalledTimes(1);
+
+    target.dispatchEvent(new Event('test'));
+    expect(spy).toHaveBeenCalledTimes(2);
+
+    target.removeEventListener('test', { handleEvent: spy });
+    expect(spy).toHaveBeenCalledTimes(2);
+
+    target.dispatchEvent(new Event('test'));
+    expect(spy).toHaveBeenCalledTimes(2);
+  });
+
+  it('should handle callback as null', () => {
+    const emitter = new EventEmitter();
+    const target = new EmitterAsTarget(emitter);
+
+    expect(() => {
+      target.addEventListener('foo', null);
+    }).not.toThrow();
+
+    expect(() => {
+      target.removeEventListener('foo', null);
+    }).not.toThrow();
+  });
+
+  it('should work through emitter', () => {
+    const emitter = new EventEmitter();
+    const target = new EmitterAsTarget(emitter);
+
+    const spy = jest.fn();
+
+    emitter.on('test', spy);
+    expect(spy).toHaveBeenCalledTimes(0);
+
+    target.dispatchEvent(new Event('test'));
+    expect(spy).toHaveBeenCalledTimes(1);
+
+    target.dispatchEvent(new Event('test'));
+    expect(spy).toHaveBeenCalledTimes(2);
+
+    emitter.removeListener('test', spy);
+    expect(spy).toHaveBeenCalledTimes(2);
+
+    target.dispatchEvent(new Event('test'));
+    expect(spy).toHaveBeenCalledTimes(2);
+  });
+
+  it('should handle options.once', () => {
+    const emitter = new EventEmitter();
+    const target = new EmitterAsTarget(emitter);
+
+    const spy = jest.fn();
+
+    target.addEventListener('foo', spy, { once: true });
+    expect(spy).toHaveBeenCalledTimes(0);
+
+    target.dispatchEvent(new Event('foo'));
+    expect(spy).toHaveBeenCalledTimes(1);
+
+    target.dispatchEvent(new Event('foo'));
+    expect(spy).toHaveBeenCalledTimes(1);
+  });
+});
diff --git a/src/preset/node/utils/emitter-as-target.ts b/src/preset/node/utils/emitter-as-target.ts
new file mode 100644
index 0000000..bfce184
--- /dev/null
+++ b/src/preset/node/utils/emitter-as-target.ts
@@ -0,0 +1,54 @@
+import type { EventEmitter } from 'node:events';
+
+/**
+ * Наивная реализация обёртки, превращающей EventEmitter в EventTarget.
+ */
+export class EmitterAsTarget extends EventTarget {
+  private emitter: EventEmitter;
+
+  /** @inheritdoc */
+  constructor(emitter: EventEmitter) {
+    super();
+    this.emitter = emitter;
+  }
+
+  /** @inheritdoc */
+  addEventListener(
+    type: string,
+    callback: EventListenerOrEventListenerObject | null,
+    options?: AddEventListenerOptions | boolean,
+  ) {
+    if (!callback) {
+      return;
+    }
+
+    const listener = typeof callback === 'function' ? callback : callback.handleEvent;
+
+    switch (true) {
+      case typeof options === 'object' && options !== null && options.once: {
+        this.emitter.once(type, listener as (...args: any[]) => void);
+        break;
+      }
+      default: {
+        this.emitter.on(type, listener as (...args: any[]) => void);
+        break;
+      }
+    }
+  }
+
+  /** @inheritdoc */
+  removeEventListener(type: string, callback: EventListenerOrEventListenerObject | null) {
+    if (!callback) {
+      return;
+    }
+
+    const listener = typeof callback === 'function' ? callback : callback.handleEvent;
+
+    this.emitter.removeListener(type, listener as (...args: any[]) => void);
+  }
+
+  /** @inheritdoc */
+  dispatchEvent(event: Event) {
+    return this.emitter.emit(event.type, event);
+  }
+}