/**
 * Cookie Consent Core
 * events.js
 *
 * Tiny dependency-free event bus.
 */

export function createEventBus() {
    const listeners = new Map();

    function on(eventName, callback) {
        if (typeof eventName !== "string" || !eventName.trim()) {
            throw new TypeError("eventName must be a non-empty string.");
        }

        if (typeof callback !== "function") {
            throw new TypeError("callback must be a function.");
        }

        if (!listeners.has(eventName)) {
            listeners.set(eventName, new Set());
        }

        listeners.get(eventName).add(callback);
        return () => off(eventName, callback);
    }

    function once(eventName, callback) {
        const unsubscribe = on(eventName, (payload) => {
            unsubscribe();
            callback(payload);
        });

        return unsubscribe;
    }

    function off(eventName, callback) {
        const callbacks = listeners.get(eventName);

        if (!callbacks) {
            return false;
        }

        const removed = callbacks.delete(callback);

        if (callbacks.size === 0) {
            listeners.delete(eventName);
        }

        return removed;
    }

    function emit(eventName, payload) {
        const callbacks = listeners.get(eventName);

        if (!callbacks) {
            return;
        }

        [...callbacks].forEach((callback) => {
            try {
                callback(payload);
            } catch (error) {
                queueMicrotask(() => {
                    throw error;
                });
            }
        });
    }

    function clear(eventName) {
        if (typeof eventName === "string") {
            listeners.delete(eventName);
            return;
        }

        listeners.clear();
    }

    function listenerCount(eventName) {
        return listeners.get(eventName)?.size || 0;
    }

    return Object.freeze({
        on,
        once,
        off,
        emit,
        clear,
        listenerCount
    });
}

export const EVENT_NAMES = Object.freeze([
    "initialized",
    "consent:loaded",
    "consent:accepted",
    "consent:rejected",
    "consent:changed",
    "consent:revoked",
    "consent:expired",
    "consent:reset",
    "storage:error"
]);