"use strict";

// check logs at: chrome://serviceworker-internals/

const CACHE = "my-cache-1";

// self: ServiceWorkerGlobalScope
self.addEventListener("activate", ev => {
    // required for fetch hook??
    ev.waitUntil(clients.claim());
}, false);
self.addEventListener("fetch", ev => {
    console.log(`fetch ${ev.request.url}`);
    ev.respondWith(caches.open(CACHE).then(cache => {
        console.log("cache opened");
        return cache.match(ev.request).then(res => {
            console.log(`Cache ${res ? "" : "not"} found: ${ev.request.url}`);
            // response would be null, if throught to fetch() when null
            return res ? res : fetch(ev.request);
        });
    }));
}, false);
self.addEventListener("message", ev => {
    doAction(ev.data).catch(console.error);
}, false);

function doAction({action, url, as}) {
    console.log(action, url, "as", as);
    switch (action) {
    case "cache": return doCache(url, as);
    case "remove": return doRemove(url, as);
    default: return Promise.reject(Error(`invalid action: ${action}`));;
    }
}
function doCache(url, as) {
    const req = new Request(url, {mode: "no-cors"});
    return caches.open(CACHE).
        then(cache => Promise.all([
            fetch(req).then(res => cache.put(url, res)),
            fetch(req).then(res => cache.put(as, res)),
        ]));
}
function doRemove(url, as) {
    return caches.open(CACHE).
        then(cache => Promise.all([cache.delete(url), cache.delete(as)]));
}