import { get } from 'svelte/store'
import { dbClockDrift } from './stores'
import { JobService } from './gen'
import pLimit from 'p-limit'

function subtractSeconds(date: Date, seconds: number): Date {
	date.setSeconds(date.getSeconds() - seconds)
	return date
}

function adjustDate(drift: number): Date {
	return new Date(Date.now() + drift)
}

export async function computeDrift() {
	if (get(dbClockDrift) == undefined) {
		const now = Date.now()
		const dbClock = await JobService.getDbClock()
		dbClockDrift.set(dbClock - now)
	}
}

export function forLater(scheduledString: string): boolean {
	return getDbClockNow() < subtractSeconds(new Date(scheduledString), 5)
}
const limit = pLimit(1)

export function getDbClockNow() {
	let drift = get(dbClockDrift)
	if (drift == undefined) {
		limit(() => computeDrift())
		drift = 0
	}
	return adjustDate(drift)
}