import { type IComponent, type IContext, type LoadedModel } from "./engine_types.js";
/** The various events that can be dispatched by a Needle Engine {@link IContext} instance
 */
export declare enum ContextEvent {
    /** called when the context is registered to the registry, the context is not fully initialized at this point */
    ContextRegistered = "ContextRegistered",
    /** called before the first glb is loaded, can be used to initialize physics engine, is awaited */
    ContextCreationStart = "ContextCreationStart",
    /** Called when the context has been created, before the first frame */
    ContextCreated = "ContextCreated",
    /** Called after the first frame has been rendered after creation */
    ContextFirstFrameRendered = "ContextFirstFrameRendered",
    /** Called before the context gets destroyed */
    ContextDestroying = "ContextDestroying",
    /** Called when the context has been destroyed */
    ContextDestroyed = "ContextDestroyed",
    /** Called when the context could not find a camera during creation */
    MissingCamera = "MissingCamera",
    /** Called before the context is being cleared (all objects in the scene are being destroyed and state is reset) */
    ContextClearing = "ContextClearing",
    /** Called after the context has been cleared (all objects in the scene have been destroyed and state has been reset) */
    ContextCleared = "ContextCleared"
}
export type ContextEventArgs = {
    event: ContextEvent;
    context: IContext;
    files?: LoadedModel[];
};
export type ContextCallback = (evt: ContextEventArgs) => void | Promise<any> | IComponent;
/** Use to register to various Needle Engine context events and to get access to all current instances
 * e.g. when being created in the DOM
 * @example
 * ```typescript
 * import { NeedleEngine } from "./engine/engine_context_registry.js";
 * NeedleEngine.addContextCreatedCallback((evt) => {
 *    console.log("Context created", evt.context);
 * });
 * ```
 * */
export declare class ContextRegistry {
    /** The currently active (rendering) Needle Engine context */
    static get Current(): IContext;
    /** @internal */
    static set Current(ctx: IContext);
    /** Returns the array of all registered Needle Engine contexts. Do not modify */
    static get All(): import("./engine_context.js").Context[];
    /** All currently registered Needle Engine contexts. Do not modify */
    static Registered: IContext[];
    /** @internal Internal use only */
    static register(ctx: IContext): void;
    /** @internal Internal use only */
    static unregister(ctx: IContext): void;
    private static _callbacks;
    /**
     * Register a callback to be called when the given event occurs
     */
    static registerCallback(evt: ContextEvent, callback: ContextCallback): void;
    /** Unregister a callback */
    static unregisterCallback(evt: ContextEvent, callback: ContextCallback): void;
    /** @internal */
    static dispatchCallback(evt: ContextEvent, context: IContext, extras?: object): true | Promise<any[]>;
    /**
     * Register a callback to be called when a context is created
     */
    static addContextCreatedCallback(callback: ContextCallback): void;
    /**
     * Register a callback to be called when a context is registered
     */
    static addContextDestroyedCallback(callback: ContextCallback): void;
}
export { ContextRegistry as NeedleEngine };