import { IQueue } from "./declarations";

export class Queue<T> implements IQueue<T> {

private promiseResolve: (value?: void | PromiseLike<void>) => void;

public constructor(private items?: T[]) {

this.items = this.items === undefined ? [] : this.items;

}

public enqueue(item: T): void {

this.items.unshift(item);

if (this.promiseResolve) {

this.promiseResolve();

}

}

public async dequeue(): Promise<T> {

if (!this.items.length) {

const promise = new Promise<void>((resolve, reject) => {

this.promiseResolve = resolve;

});

await promise;

this.promiseResolve = null;

}

return this.items.pop();

}

}