import { LocalEvent } from "../types/local-event";
import { Logger } from "./logger";

/**
 * Listeners map.
 *
 * @export
 * @interface ListenerMap
 */
export interface ListenerMap {
    [event: string]: ListenerFunction[];
}

type ListenerData = any; // eslint-disable-line
export type ListenerFunction = (data?: ListenerData) => void;

/**
 * Basic implementation of an EventEmitter.
 *
 * @export
 * @abstract
 * @class EventEmitter
 */
export abstract class EventEmitter {
    /**
     * Add a new listener.
     *
     * @static
     * @param {LocalEvent} event Event name.
     * @param {ListenerFunction} listener Listener function.
     * @memberof EventEmitter
     */
    public static on(event: LocalEvent, listener: ListenerFunction) {
        let bucket = this.listeners[event];

        if (bucket == null) {
            this.listeners[event] = bucket = [];
        }

        bucket.push(listener);
    }

    /**
     * Remove all listeners from an event.
     *
     * @static
     * @param {LocalEvent} event Event name.
     * @memberof EventEmitter
     */
    public static off(event: LocalEvent) {
        this.listeners[event] = [];
    }

    /**
     * Trigger an event.
     *
     * @static
     * @param {LocalEvent} event Event name.
     * @param {ListenerData} [data] Event data.
     * @memberof EventEmitter
     */
    public static trigger(event: LocalEvent, data?: ListenerData) {
        try {
            const bucket = this.listeners[event];

            if (bucket != null) {
                for (const listener of bucket) {
                    listener(data);
                }
            }
        } catch (err) {
            Logger.log(err);
        }
    }

    private static listeners: ListenerMap = {};
}