import type { H3Event } from "h3";
import webPush from "web-push";
import { readSubscriptions, writeSubscriptions } from "~/server/database";

let cachedVapidDetails: {
	subject: string,
	publicKey: string,
	privateKey: string,
} | undefined;

function useVapidDetails(event: H3Event) {
	if (cachedVapidDetails) {
		return cachedVapidDetails;
	}

	const runtimeConfig = useRuntimeConfig(event);
	if (!runtimeConfig.public.vapidPublicKey) throw new Error("NUXT_PUBLIC_VAPID_PUBLIC_KEY not set.")
	if (!runtimeConfig.vapidPrivateKey) throw new Error("NUXT_VAPID_PRIVATE_KEY not set.")

	return cachedVapidDetails = {
		subject: "mailto:webmaster@hornwitser.no",
		publicKey: runtimeConfig.public.vapidPublicKey,
		privateKey: runtimeConfig.vapidPrivateKey,
	}
}

export async function sendPush(event: H3Event, title: string, body: string) {
	const vapidDetails = useVapidDetails(event);
	const payload = JSON.stringify({ title, body });
	const subscriptions = await readSubscriptions();
	console.log(`Sending "${payload}" to ${subscriptions.length} subscribers`);
	const removeIndexes = [];
	for (let index = 0; index < subscriptions.length; index += 1) {
		const subscription = subscriptions[index];
		if (subscription.type !== "push")
			continue;
		try {
			await webPush.sendNotification(
				subscription.push as webPush.PushSubscription,
				payload,
				{
					TTL: 3600,
					urgency: "high",
					vapidDetails,
				}
			)
		} catch (err: any) {
			if (err?.statusCode === 410) {
				removeIndexes.push(index);
			} else {
				console.error("Received error sending push notice:", err.message, err?.statusCode)
				console.error(err);
			}
		}
	}
	if (removeIndexes.length) {
		console.log(`Removing indexes ${removeIndexes} from subscriptions`)
		removeIndexes.reverse();
		for (const index of removeIndexes) {
			subscriptions.splice(index, 1);
		}
		await writeSubscriptions(subscriptions);
	}
	console.log("Push notices sent");
}