import { createHash } from 'node:crypto';
import { readFileSync } from 'node:fs';
import { defineConfig, type Plugin } from 'vite';
import react from '@vitejs/plugin-react';

/** Emits dist/sw.js with a build id, so a deploy that changes files installs a new worker (docs/07 §11). */
function serviceWorker(): Plugin {
  return {
    name: 'bg-service-worker',
    apply: 'build',
    generateBundle(_, bundle) {
      const src = readFileSync(new URL('./sw.js', import.meta.url), 'utf8');
      const offline = readFileSync(new URL('./public/offline.html', import.meta.url), 'utf8');
      const files = Object.keys(bundle).sort().join('\n');
      const build = createHash('sha256').update(src).update(offline).update(files).digest('hex').slice(0, 12);
      if (!src.includes("'__BUILD__'")) throw new Error('sw.js: VERSION placeholder missing');
      this.emitFile({ type: 'asset', fileName: 'sw.js', source: src.replace("'__BUILD__'", `'${build}'`) });
    },
  };
}

export default defineConfig({
  plugins: [react(), serviceWorker()],
  server: {
    port: 5173,
    proxy: {
      '/api': 'http://localhost:3000',
      '/healthz': 'http://localhost:3000',
      '/ws': { target: 'ws://localhost:3000', ws: true },
    },
  },
  build: {
    target: 'es2022',
    cssCodeSplit: true,
    sourcemap: false,
  },
});