/**
 * Small store that exposes counts for sidebar nav badges.
 *
 * Values reflect the last successful poll. Individual sources fail
 * independently — a failure keeps the previous value and flips `stale` true
 * so the UI can dim the badge if desired. The poller is intentionally
 * forgiving: if the user is unauthenticated or the backend isn't ready,
 * it silently retries on the next tick.
 */

import { writable, type Readable } from 'svelte/store';
import * as api from '$lib/api';
import { isAuthenticated } from '$lib/auth';

export interface NavCounts {
	projects: number | null;
	sites: number | null;
	stacks: number | null;
	proxies: number | null;
	/** Error-severity events only; dashboard surfaces total separately. */
	eventsErrors: number | null;
}

const EMPTY: NavCounts = {
	projects: null,
	sites: null,
	stacks: null,
	proxies: null,
	eventsErrors: null
};

const store = writable<NavCounts>(EMPTY);

export const navCounts: Readable<NavCounts> = { subscribe: store.subscribe };

let pollTimer: ReturnType<typeof setInterval> | null = null;
let inFlight = false;

async function refreshOnce(): Promise<void> {
	if (inFlight || !isAuthenticated()) return;
	inFlight = true;
	try {
		const [projects, sites, stacks, proxies, eventStats] = await Promise.allSettled([
			api.listProjects(),
			api.listStaticSites(),
			api.listStacks(),
			api.listProxyRoutes(),
			api.fetchEventLogStats()
		]);

		store.update((prev) => ({
			projects: projects.status === 'fulfilled' ? projects.value.length : prev.projects,
			sites: sites.status === 'fulfilled' ? sites.value.length : prev.sites,
			stacks: stacks.status === 'fulfilled' ? stacks.value.length : prev.stacks,
			proxies: proxies.status === 'fulfilled' ? proxies.value.length : prev.proxies,
			eventsErrors: eventStats.status === 'fulfilled' ? eventStats.value.error : prev.eventsErrors
		}));
	} finally {
		inFlight = false;
	}
}

/**
 * Start periodic polling of nav counts. Safe to call repeatedly —
 * subsequent calls are no-ops until `stopNavCountsPolling()` is called.
 */
export function startNavCountsPolling(intervalMs = 60_000): void {
	if (pollTimer) return;
	void refreshOnce();
	pollTimer = setInterval(() => void refreshOnce(), intervalMs);
}

export function stopNavCountsPolling(): void {
	if (pollTimer) {
		clearInterval(pollTimer);
		pollTimer = null;
	}
}

/** Trigger an out-of-band refresh (e.g. after a mutation). */
export function refreshNavCounts(): void {
	void refreshOnce();
}