import { watchFile } from "fs";

export interface IDestroyable {
    destroy();
}

export interface ICancellation {
    throwIfRequested(): void;
    isRequested(): boolean;
    isSupported(): boolean;
    register(cb: (e: any) => void): void;
}

/**
 * Интерфейс поддерживающий асинхронную активацию
 */
export interface IActivatable {
    /**
     * @returns Boolean indicates the current state
     */
    isActive(): boolean;

    /**
     * Starts the component activation
     * @param ct cancellation token for this operation
     */
    activate(ct?: ICancellation) : Promise<void>;

    /**
     * Starts the component deactivation
     * @param ct cancellation token for this operation
     */
    deactivate(ct?: ICancellation) : Promise<void>;

    /**
     * Sets the activation controller for this component
     * @param controller The activation controller
     * 
     * Activation controller checks whether this component
     * can be activated and manages the active state of the
     * component
     */
    setActivationController(controller: IActivationController);

    /**
     * Gets the current activation controller for this component
     */
    getActivationController(): IActivationController;
}

export interface IActivationController {
    activating(component: IActivatable, ct?: ICancellation): Promise<void>;

    activated(component: IActivatable, ct?: ICancellation): Promise<void>;

    deactivating(component: IActivatable, ct?: ICancellation): Promise<void>;

    deactivated(component: IActivatable, ct?: ICancellation): Promise<void>;

    deactivate(ct?: ICancellation): Promise<void>;

    activate(component: IActivatable, ct?: ICancellation): Promise<void>;

    getActive(): IActivatable;
}

export interface IAsyncComponent {
    getCompletion(): Promise<void>;
}

export interface ICancellable {
    cancel(reason?: any): void;
}

export interface IObserver<T> {
    (x:T): void;
}

export interface IObservable<T> {
    on(observer: IObserver<T>): IDestroyable;

    wait(ct?: ICancellation) : Promise<T>;
}