// ============================================================
// SERVICE WORKER — Cache shell, network-first for API
// Provides offline fallback for app shell while keeping
// API calls always fresh (critical for medical data accuracy)
// ============================================================

var CACHE_NAME = 'pedscribe-v12';
var SHELL_ASSETS = [
  '/',
  '/index.html',
  '/css/styles.css',
  '/js/app.js',
  '/js/auth.js',
  '/manifest.json'
];

// Install: precache app shell
self.addEventListener('install', function(event) {
  event.waitUntil(
    caches.open(CACHE_NAME).then(function(cache) {
      return cache.addAll(SHELL_ASSETS);
    }).then(function() {
      return self.skipWaiting();
    })
  );
});

// Activate: clear old caches
self.addEventListener('activate', function(event) {
  event.waitUntil(
    caches.keys().then(function(names) {
      return Promise.all(
        names.filter(function(name) { return name !== CACHE_NAME; })
             .map(function(name) { return caches.delete(name); })
      );
    }).then(function() {
      return self.clients.claim();
    })
  );
});

// Fetch: network-first for API, cache-first for static assets
self.addEventListener('fetch', function(event) {
  var url = new URL(event.request.url);

  // Only handle same-origin requests
  if (url.origin !== self.location.origin) return;

  // API calls — always network, never cache (medical data must be fresh)
  if (url.pathname.startsWith('/api/')) {
    event.respondWith(fetch(event.request));
    return;
  }

  // Component HTML — network-first with cache fallback
  if (url.pathname.startsWith('/components/')) {
    event.respondWith(
      fetch(event.request).then(function(response) {
        var clone = response.clone();
        caches.open(CACHE_NAME).then(function(cache) { cache.put(event.request, clone); });
        return response;
      }).catch(function() {
        return caches.match(event.request);
      })
    );
    return;
  }

  // Static assets (JS, CSS, icons) — network-first so code updates apply immediately
  if (url.pathname.match(/\.(js|css|png|ico|woff2?)$/)) {
    event.respondWith(
      fetch(event.request).then(function(response) {
        var clone = response.clone();
        caches.open(CACHE_NAME).then(function(cache) { cache.put(event.request, clone); });
        return response;
      }).catch(function() {
        return caches.match(event.request);
      })
    );
    return;
  }

  // HTML pages — network-first
  event.respondWith(
    fetch(event.request).then(function(response) {
      var clone = response.clone();
      caches.open(CACHE_NAME).then(function(cache) { cache.put(event.request, clone); });
      return response;
    }).catch(function() {
      return caches.match(event.request) || caches.match('/index.html');
    })
  );
});