// MyDay service worker (SPEC-009 §6, register A5).
//
// THE RULE: cache STATIC ASSETS ONLY. An authenticated response and a /{GUID}
// page are NEVER cached — and not merely "not cached": such a request is not
// intercepted by this worker at all, so it cannot reach a cache. Offline is
// explicitly out of scope.
//
// CACHEABLE_PREFIXES is kept in step with web.StaticCachePrefixes (Go) by
// TestAC5_ServiceWorkerPolicy — there is no second, drifting copy of the rule.
"use strict";

var CACHEABLE_PREFIXES = ["/static/"];
var CACHE_NAME = "myday-static-v1";

// isCacheable is the single gate: GET · same origin · a static asset.
function isCacheable(request) {
  if (request.method !== "GET") {
    return false;
  }
  var url = new URL(request.url);
  if (url.origin !== self.location.origin) {
    return false;
  }
  for (var i = 0; i < CACHEABLE_PREFIXES.length; i++) {
    if (url.pathname.indexOf(CACHEABLE_PREFIXES[i]) === 0) {
      return true;
    }
  }
  return false;
}

self.addEventListener("install", function (event) {
  // Nothing is precached (offline is out of scope) — just take over.
  event.waitUntil(self.skipWaiting());
});

self.addEventListener("activate", function (event) {
  event.waitUntil(
    caches
      .keys()
      .then(function (keys) {
        return Promise.all(
          keys
            .filter(function (key) {
              return key !== CACHE_NAME;
            })
            .map(function (key) {
              return caches.delete(key);
            })
        );
      })
      .then(function () {
        return self.clients.claim();
      })
  );
});

self.addEventListener("fetch", function (event) {
  // Anything that is not a static asset is NOT intercepted: an authenticated
  // response can never be read from — or written to — a cache (A5).
  if (!isCacheable(event.request)) {
    return;
  }
  event.respondWith(
    caches.open(CACHE_NAME).then(function (cache) {
      return cache.match(event.request).then(function (hit) {
        if (hit) {
          return hit;
        }
        return fetch(event.request).then(function (response) {
          if (response && response.ok && response.type === "basic") {
            cache.put(event.request, response.clone());
          }
          return response;
        });
      });
    })
  );
});