/* Polyfill indexOf. */
var indexOf;

if (typeof Array.prototype.indexOf === 'function') {
    indexOf = function (haystack, needle) {
        return haystack.indexOf(needle);
    };
} else {
    indexOf = function (haystack, needle) {
        var i = 0, length = haystack.length, idx = -1, found = false;

        while (i < length && !found) {
            if (haystack[i] === needle) {
                idx = i;
                found = true;
            }

            i++;
        }

        return idx;
    };
};


/* Polyfill EventEmitter. */
var EventEmitter = function () {
    this.events = {};
};

EventEmitter.prototype.on = function (event, listener) {
    if (typeof this.events[event] !== 'object') {
        this.events[event] = [];
    }

    this.events[event].push(listener);
};

EventEmitter.prototype.removeListener = function (event, listener) {
    var idx;

    if (typeof this.events[event] === 'object') {
        idx = indexOf(this.events[event], listener);

        if (idx > -1) {
            this.events[event].splice(idx, 1);
        }
    }
};

EventEmitter.prototype.emit = async function (event) {
    console.debug('Event emitted: ' + event);

    var i, listeners, length, args = [].slice.call(arguments, 1);

    if (typeof this.events[event] === 'object') {
        listeners = this.events[event].slice();
        length = listeners.length;

        for (i = 0; i < length; i++) {
            try {
                await listeners[i].apply(this, args);
            }
            catch (err) {
                console.error(err);
                console.trace('Error in event listener');
            }
        }
    }
};

EventEmitter.prototype.once = function (event, listener) {
    this.on(event, function g () {
        this.removeListener(event, g);
        listener.apply(this, arguments);
    });
};

export { EventEmitter }
