/**
 *
 */
export interface IDisposable {
    dispose(): void;
}

export interface ISubscription {
    unsubscribe(): void;
}

export function isDisposable(value: any): value is IDisposable {
    return !!value.dispose;
}

export function isSubscription(value: any): value is ISubscription {
    return !!value.unsubscribe;
}

export function canBeDisposed(value: any): value is IDisposableOrSubscription {
    return !!(value.dispose || value.unsubscribe) || typeof value === 'function';
}

export type IDisposableOrSubscription = IDisposable | ISubscription | (() => void);
// eslint-disable-next-line prefer-const
let empty: Disposable;

export class Disposable implements IDisposable, ISubscription {
    public static get empty() {
        return empty;
    }

    /* tslint:disable-next-line:no-reserved-keywords no-any */
    public static of(value: any) {
        if (!value) {
            return empty;
        }

        if (value.dispose) {
            return <IDisposable>value;
        }
        return new Disposable(value);
    }

    public static create(value: IDisposableOrSubscription): IDisposable & ISubscription;
    public static create(action: () => void): IDisposable & ISubscription;
    public static create(action: IDisposableOrSubscription | (() => void)) {
        return new Disposable(action);
    }

    private _action: () => void = () => {};
    private _isDisposed = false;

    constructor(value: IDisposableOrSubscription);
    /* tslint:disable-next-line:no-any */
    constructor(value: any) {
        if (!value) {
            return empty;
        }

        if (typeof value === 'function') {
            this._action = value;
        } else if (value.unsubscribe) {
            this._action = () => (<ISubscription>value).unsubscribe();
        } else if (value.dispose) {
            this._action = () => (<IDisposable>value).dispose();
        }
    }

    public get isDisposed() {
        return this._isDisposed;
    }

    public dispose() {
        if (this._isDisposed) return;
        this._isDisposed = true;
        this._action();
    }

    public unsubscribe(): void {
        this.dispose();
    }
}

empty = new Disposable(() => {
    /* */
});