const CACHE_NAME = 'ims-v1'

self.addEventListener('install', () => {
  self.skipWaiting()
})

self.addEventListener('activate', event => {
  event.waitUntil(
    caches.keys().then(keys =>
      Promise.all(keys.filter(k => k !== CACHE_NAME).map(k => caches.delete(k)))
    )
  )
  self.clients.claim()
})

self.addEventListener('fetch', event => {
  const url = new URL(event.request.url)

  // Only handle same-origin GET requests
  if (
    event.request.method !== 'GET' ||
    url.origin !== self.location.origin ||
    !url.pathname.startsWith('/')
  ) {
    return
  }

  // Skip API routes — always go to network
  if (url.pathname.startsWith('/api/')) return

  // Cache-first for immutable Next.js static assets
  if (url.pathname.startsWith('/_next/static/')) {
    event.respondWith(
      caches.match(event.request).then(cached => {
        if (cached) return cached
        return fetch(event.request).then(res => {
          if (res.ok) {
            const clone = res.clone()
            caches.open(CACHE_NAME).then(c => c.put(event.request, clone))
          }
          return res
        })
      })
    )
    return
  }

  // Network-first for pages — fall back to cache when offline
  event.respondWith(
    fetch(event.request)
      .then(res => {
        if (res.ok) {
          const clone = res.clone()
          caches.open(CACHE_NAME).then(c => c.put(event.request, clone))
        }
        return res
      })
      .catch(() => caches.match(event.request))
  )
})