/* Business Trip Day Tracker — offline shell.
   Cache-first on purpose: this app is a static document whose whole point is
   working in airplane mode, so a stale-by-a-day shell beats a failed load.
   Bump CACHE when index.html changes; activate() drops every older cache. */
var CACHE = "trip-tracker-v3";
var ASSETS = ["./", "./index.html", "./manifest.webmanifest", "./icon-512.png"];

self.addEventListener("install", function(e){
  e.waitUntil(
    caches.open(CACHE).then(function(c){
      /* addAll is all-or-nothing; one 404 would leave us with no offline copy
         at all, so fetch them individually and keep whatever succeeds. */
      return Promise.all(ASSETS.map(function(u){
        return fetch(u, {cache:"reload"})
          .then(function(r){ if(r && r.ok) return c.put(u, r); })
          .catch(function(){});
      }));
    }).then(function(){ return self.skipWaiting(); })
  );
});

self.addEventListener("activate", function(e){
  e.waitUntil(
    caches.keys().then(function(keys){
      return Promise.all(keys.map(function(k){
        return k === CACHE ? null : caches.delete(k);
      }));
    }).then(function(){ return self.clients.claim(); })
  );
});

self.addEventListener("fetch", function(e){
  var req = e.request;
  if(req.method !== "GET") return;
  if(new URL(req.url).origin !== self.location.origin) return;

  e.respondWith(
    caches.match(req, {ignoreSearch:true}).then(function(hit){
      if(hit) return hit;
      return fetch(req).then(function(res){
        if(res && res.ok){
          var copy = res.clone();
          caches.open(CACHE).then(function(c){ c.put(req, copy); });
        }
        return res;
      }).catch(function(){
        /* Offline and not cached — a navigation still gets the app shell. */
        if(req.mode === "navigate") return caches.match("./index.html");
        throw new Error("offline");
      });
    })
  );
});