class MyEvent {
	constructor() {
		// 使用 Object 或 Map 存储，实现 O(1) 级别的查找
		this.events = new Map()
	}
	add(name, call) {
		if (!this.events.has(name)) {
			this.events.set(name, [])
		}
		this.events.get(name).push(call)
	}
	remove(name, call) {
		if (!this.events.has(name)) return

		if (!call) {
			this.events.delete(name)
		} else {
			const callbacks = this.events.get(name)
			const index = callbacks.indexOf(call)
			if (index !== -1) {
				callbacks.splice(index, 1)
			}
			// 如果该事件没有监听者了，彻底清理 key
			if (callbacks.length === 0) {
				this.events.delete(name)
			}
		}
	}
	emit(name, data) {
		const callbacks = this.events.get(name)
		if (callbacks) {
			// 使用 slice() 镜像一份副本，防止在执行回调过程中有 remove 操作导致索引错乱
			callbacks.slice().forEach((cb) => cb(data))
		}
	}
}
export default new MyEvent()