import { IStorageEventData } from '../../types.ts';
/**
 * Callback function type for event listeners
 * @template T - The type of data passed to the callback
 */
export type Callback<T = unknown> = (event: IStorageEventData<T>) => void;
/**
 * Base observer class that provides event emitter functionality for state management classes.
 * Uses a registry pattern to maintain separate event systems for each inheriting class.
 */
export declare class Observer {
    private static eventRegistry;
    /**
     * Gets or creates the event registry for a specific class
     * @param target - The class constructor function
     * @returns The event registry for the target class
     */
    private static getRegistry;
    /**
     * Adds an event listener for the specified event
     * @template T - The type of data passed to the callback
     * @param event - The name of the event to listen for
     * @param callback - The callback function to execute when the event is emitted
     */
    static on<T = unknown>(event: string, callback: Callback<T>): void;
    /**
     * Adds a one-time event listener for the specified event
     * @template T - The type of data passed to the callback
     * @param event - The name of the event to listen for
     * @param callback - The callback function to execute once when the event is emitted
     */
    static once<T = unknown>(event: string, callback: Callback<T>): void;
    /**
     * Removes an event listener for the specified event
     * @template T - The type of data passed to the callback
     * @param event - The name of the event
     * @param callback - The callback function to remove
     */
    static off<T = unknown>(event: string, callback: Callback<T>): void;
    /**
     * Emits an event with the given data to all registered listeners
     * @template T - The type of data being emitted
     * @param event - The name of the event to emit
     * @param data - The data to pass to the event listeners
     */
    static emit<T = unknown>(event: string, data: IStorageEventData<T>): void;
    /**
     * Removes all event listeners for all events
     */
    static removeAllListeners(): void;
    /**
     * Removes all listeners for a specific event
     * @param event - The name of the event
     */
    static removeListener(event: string): void;
    /**
     * Gets the number of listeners for a specific event
     * @param event - The name of the event
     * @returns The total number of listeners (regular + once)
     */
    static listenerCount(event: string): number;
    /**
     * Gets an array of all event names that have listeners
     * @returns Array of event names
     */
    static eventNames(): (string | symbol)[];
}