/**
 * A promise with exposed resolve and reject methods. This allows you to create a promise without any parameters
 * and then call resolve or reject on it at any time. This enables you to hand out promises to callers without having
 * initiated or decided on how and when to resolve the promise with minimal overhead. Just call resolve on it and
 * all waiting parties will have their then function callbaks invoked.
 * 
 * The weird constructor is due to the special requirements and
 * expectations on the inner workings of a promise.
 * https://www.ecma-international.org/ecma-262/7.0/index.html#sec-newpromisecapability
 * https://stackoverflow.com/questions/48158730/extend-javascript-promise-and-resolve-or-reject-it-inside-constructor/48159603
 */
export class OpenPromise<T> extends Promise<T> {

    public resolve: ((value: T) => void);
    public reject: ((reason: any) => void);

    constructor(executor:
        (resolve: (value: T | PromiseLike<T>) => void, reject: (reason: any) => void) => void
        = (resolve: (value: T | PromiseLike<T>) => void, reject: (reason: any) => void) => { }) {
        let res, rej;
        super((resolve, reject) => {
            executor(resolve, reject);
            res = resolve;
            rej = reject;
        });
        this.resolve = res as unknown as (value?: T | PromiseLike<T> | undefined) => void;
        this.reject = rej as unknown as (reason?: any) => void;
    }
}