import adapter from '@sveltejs/adapter-static';
import { sveltekit } from '@sveltejs/kit/vite';
import { defineConfig } from 'vite';
import { VitePWA } from 'vite-plugin-pwa';

// The adapter-static SPA fallback (build/index.html) is written by the adapter
// *after* every Vite plugin's build has finished, so at service-worker-build
// time there's no file for injectManifest to glob and hash. We instead give it
// a synthetic precache entry (below) with a revision that's fresh per build
// invocation, so the shell still gets correctly invalidated on every deploy.
const swIndexRevision = String(Date.now());

export default defineConfig({
	server: {
		proxy: {
			// Local dev only. In production Caddy does this same-origin proxy
			// (see deploy/Caddyfile) — the app only ever calls same-origin /api/v1.
			'/api': {
				target: 'http://localhost:8000',
				changeOrigin: true
			}
		}
	},
	plugins: [
		sveltekit({
			compilerOptions: {
				// Force runes mode for the project, except for libraries. Can be removed in svelte 6.
				runes: ({ filename }) =>
					filename.split(/[/\\]/).includes('node_modules') ? undefined : true
			},

			// SvelteKit has its own built-in convention for src/service-worker.{js,ts}:
			// it auto-detects the file by this exact path and runs its own separate,
			// very restricted build for it (only $service-worker, $env/static/public and
			// $app/env/public may be imported — nothing from npm). vite-plugin-pwa (below)
			// bundles and injects our actual service worker instead; if both run, the
			// SvelteKit's native pass executes *after* vite-plugin-pwa's and silently
			// overwrites its output with an un-bundled, un-injected file (the
			// self.__WB_MANIFEST placeholder is left as literal text — the app "works"
			// but nothing is ever precached). Point SvelteKit's lookup at a path that
			// doesn't exist so only vite-plugin-pwa's build runs.
			files: {
				serviceWorker: 'src/service-worker-disabled'
			},

			// Static SPA: no Node process in production. Caddy serves the build output
			// directly and falls back to index.html for client-side routes (see
			// docs/PLAN.md "Stack" and "The PWA decision"). Pair with `export const ssr =
			// false` in src/routes/+layout.ts — without that, SvelteKit still tries to
			// prerender/SSR routes and the static adapter fails the build.
			adapter: adapter({
				fallback: 'index.html'
			})
		}),
		VitePWA({
			// injectManifest, not generateSW: we hand-write the caching policy (cache-first
			// navigations, network-only for /api/*) in src/service-worker.ts. generateSW's
			// declarative config can't express "never cache this origin path" as precisely
			// as we want here — see docs/PLAN.md's caching table.
			//
			// We use the base vite-plugin-pwa plugin rather than @vite-pwa/sveltekit's
			// SvelteKit-specific wrapper: that wrapper's injectManifest build expects
			// SvelteKit's own built-in src/service-worker.{js,ts} convention to have
			// already transpiled our file, which only resolves SvelteKit's own three
			// virtual modules and rejects anything else. The base plugin bundles
			// src/service-worker.ts itself directly, which is what we want here.
			strategies: 'injectManifest',
			srcDir: 'src',
			filename: 'service-worker.ts',
			// We own the manifest as a plain static file (static/manifest.webmanifest),
			// linked explicitly from app.html, instead of letting the plugin generate one.
			manifest: false,
			// We register the service worker ourselves via virtual:pwa-register/svelte
			// (see src/lib/components/UpdateToast.svelte) so we can show an in-app update
			// prompt instead of the plugin's default injected register script.
			injectRegister: false,
			injectManifest: {
				injectionPoint: 'self.__WB_MANIFEST',
				// Default globPatterns is just JS/CSS/HTML — widen it to also precache
				// our icons and manifest so an offline install has everything it needs.
				globPatterns: ['**/*.{js,css,svg,png,webmanifest}'],
				// See the swIndexRevision comment above: the real build/index.html
				// doesn't exist yet when this runs, so we can't glob-hash it.
				additionalManifestEntries: [{ url: 'index.html', revision: swIndexRevision }]
			},
			devOptions: {
				// Keep the SW out of `pnpm dev` — dev already has instant HMR, and a dev-mode
				// SW is a common source of "why is my change not showing up" confusion.
				enabled: false,
				type: 'module'
			}
		})
	]
});