export default class Queue {
	private queue = 0
	private isPaused = false
	private throwError?: Error

	public constructor(
		private maxQueueLength = 5,
		private timeToWait = 500
	) {}

	public pause() {
		this.isPaused = true
	}

	public start() {
		this.isPaused = false
	}

	public updateCurrentQueueLength(len: number) {
		this.queue = len
	}

	public async add<T = any>(promise: Promise<T>) {
		while (this.queue >= this.maxQueueLength || this.isPaused) {
			await new Promise((res) => setTimeout(res, this.timeToWait))
		}
		this.updateCurrentQueueLength(this.queue+1)
		promise
			.then(() => {
				this.updateCurrentQueueLength(this.queue-1)
			}).catch((e) => {
				this.updateCurrentQueueLength(this.queue-1)
				this.throwError = e
			})
	}

	public async waitEnd() {
		while (this.queue !== 0) {
			if (this.throwError) {
				throw this.throwError
			}
			await new Promise((res) => setTimeout(res, this.timeToWait))
		}
	}
}