EventHandler.js

"use strict";

const Log = require('./Log');

class EventHandler {

    constructor(name) {
        this.name = name || 'unknown';
        this._listeners = [];
        this._once = new Set();
    }

    subscribe(callback, once) {
        if (this._listeners.indexOf(callback) !== -1) {
            Log.info("[Skip] Listener already subscribed");
        }
        this._listeners.push(callback);
        if (once) {
            this._once.add(callback);
        }
    }

    unsubscribe(callback) { return this.remove(callback); }
    remove(callback) {
        this._listeners = this._listeners.filter(c => c !== callback);
    }

    async emit(...args) {
        for (var i = 0; i < this._listeners.length; i++) {
            const callback = this._listeners[i];
            if (typeof callback === 'function') {
                try {
                    if (this._once.has(callback)) {
                        this.remove(callback);
                        this._once.delete(callback);
                    }
                    await callback(...args);
                } catch (e) {
                    Log.info('Error handling event: ' + this.name);
                    Log.debug(args);
                    Log.error(e);
                }
            }
        }
    }
}

module.exports = EventHandler;