/// <reference types="@sveltejs/kit" />
/// <reference no-default-lib="true"/>
/// <reference lib="esnext" />
/// <reference lib="webworker" />

import { build, files, version, prerendered } from '$service-worker';

// Create a unique cache name for this deployment
const CACHE = `sw-cache-${version}`;

const ASSETS = [
    ...build, // the app itself
    ...files, // everything in `static`,
    ...prerendered // dynamic routes
];

self.addEventListener('install', (event) => {
    // Create a new cache and add all files to it
    async function addFilesToCache() {
        const cache = await caches.open(CACHE);
        await cache.addAll(ASSETS);
    }

    event.waitUntil(addFilesToCache());
});

const channel = new BroadcastChannel('sw-messages');


self.addEventListener('activate', (event) => {
    // Remove previous cached data from disk
    async function deleteOldCaches() {
        for (const key of await caches.keys()) {
            if (key !== CACHE) await caches.delete(key);
        }
    }

    event.waitUntil(deleteOldCaches());
    channel.postMessage({title: 'Cache downloaded!'});
});

self.addEventListener('fetch', (event) => {
    // ignore POST requests etc
    if (event.request.method !== 'GET') return;

    async function respond() {
        const url = new URL(event.request.url);
        const cache = await caches.open(CACHE);

        // `build`/`files` can always be served from the cache
        if (ASSETS.includes(url.pathname)) {
            return cache.match(url.pathname);
        }

        // for everything else, try the network first, but
        // fall back to the cache if we're offline
        try {
            const response = await fetch(event.request);

            if (response.status === 200) {
                cache.put(event.request, response.clone());
            }

            return response;
        } catch {
            return cache.match(event.request);
        }
    }

    event.respondWith(respond());
});