"use strict";

const events = new Map();

function on(event, callback) {
    if (!events.has(event)) {
        events.set(event, []);
    }
    events.get(event).push(callback);
}

function emit(event, ...args) {
    if (events.has(event)) {
        for (const callback of events.get(event)) {
            try {
                callback(...args);
            } catch (error) {
                console.error(`Event error [${event}]:`, error);
            }
        }
    }
}

function once(event, callback) {
    const wrapper = (...args) => {
        off(event, wrapper);
        callback(...args);
    };
    on(event, wrapper);
}

function off(event, callback) {
    if (events.has(event)) {
        const callbacks = events.get(event);
        const index = callbacks.indexOf(callback);
        if (index > -1) {
            callbacks.splice(index, 1);
        }
    }
}

function removeAllListeners(event) {
    if (event) {
        events.delete(event);
    } else {
        events.clear();
    }
}

function listenerCount(event) {
    return events.has(event) ? events.get(event).length : 0;
}

module.exports = {
    on,
    emit,
    once,
    off,
    removeAllListeners,
    listenerCount,
    events
};