export class ChatEvent {
    private static _callbacks: any = {};
    constructor() {

    }

    static on(eventName: string, callback) {
        if (!this._callbacks[eventName]) {
            this._callbacks[eventName] = [];
        }

        this._callbacks[eventName].push(callback);
    }


    static off(eventName: string, callback) {
        const callbacks = this._callbacks[eventName];
        if (!callbacks) {
            return;
        }

        let index = -1;
        for (let i = 0; i < callbacks.length; i++) {
            if (callbacks[i] === callback) {
                index = i;
                break;
            }
        }

        if (index < 0) {
            return;
        }

        this._callbacks[eventName].splice(index, 1);
    }

    static trigger(eventName: string, event: any) {
        const callbacks = this._callbacks[eventName];
        if (!callbacks || !callbacks.length) {
            return;
        }

        const args = Array.prototype.slice.call(arguments, 1);
        // tslint:disable-next-line: prefer-for-of
        for (let i = 0; i < callbacks.length; i++) {
            callbacks[i].apply(this, args);
        }
    }

}