const assets = ["<@ASSETS@>"];

const staticCacheName = "tytd-static-<@BUILD_TIME@>";

async function ThrowOnBadGateway(req)
{
    const resp = await fetch(req);
    if(resp.status === 502) throw new Error("Bad Gateway");
    return resp;
}

self.addEventListener('install',evt => {
    evt.waitUntil(
        caches.open(staticCacheName).then(cache =>{
            cache.addAll(assets);
        })
    );
});

self.addEventListener('activate',(evt)=>{
    evt.waitUntil(
        caches.keys().then(keys => {
            return Promise.all(keys.filter(key => key !== staticCacheName).map(key => caches.delete(key)));
        })
    );
});

self.addEventListener('fetch', evt => {
    
    evt.respondWith(

        caches.match(evt.request).then(cacheRes=>{
            console.warn('SW cacheRes:', cacheRes);
            return cacheRes || ThrowOnBadGateway(evt.request);
        }).catch((err)=>{
            console.warn('SW Fallback:', err.message);
            if(evt.request.headers.has('HX-Request'))
            {
                
                return new Response("",{
                    status: 200,
                    headers: {
                        'HX-Redirect': "/offline.html"
                    }
                });
            }
            else
            {
                return caches.match('/offline.html');

            }
        })
    );
});