import { defineConfig, mergeConfig } from 'vite';
import { minwebide } from 'minwebide/vite';

// Cross-origin isolation makes SharedArrayBuffer available (numbl uses it
// for pause()/sleep timing). Dev/preview get it from plain response headers —
// no service worker involved. Production builds are for GitHub Pages, which
// can't set headers, so only there the coi-serviceworker is injected (the
// same approach numbl.org uses).
const coiHeaders = {
	'Cross-Origin-Embedder-Policy': 'require-corp',
	'Cross-Origin-Opener-Policy': 'same-origin',
};

const injectCoiServiceWorker = {
	name: 'inject-coi-serviceworker',
	apply: 'build' as const,
	transformIndexHtml() {
		// relative src so it resolves under the DEPLOY_BASE sub-path
		return [{ tag: 'script', attrs: { src: 'coi-serviceworker.js' }, injectTo: 'head' as const }];
	},
};

// DEPLOY_BASE is set by CI when building for GitHub Pages
// (the site is served from /numbl-web-ide/, not the domain root).
export default defineConfig(mergeConfig(minwebide(), {
	base: process.env.DEPLOY_BASE ?? '/',
	plugins: [injectCoiServiceWorker],
	server: { headers: coiHeaders },
	preview: { headers: coiHeaders },
}));