import { defineConfig } from 'vite';
import { readFileSync, writeFileSync } from 'fs';

/** Vite plugin: generates dist/sw.js with precache URLs from the build manifest. */
function generateSW() {
  return {
    name: 'generate-sw',
    apply: 'build',
    closeBundle() {
      const staticAssets = [
        '/',
        '/manifest.json',
        '/icons/icon-192.svg',
        '/icons/icon-512.svg',
      ];

      try {
        const manifest = JSON.parse(readFileSync('dist/.vite/manifest.json', 'utf-8'));
        for (const entry of Object.values(manifest)) {
          staticAssets.push('/' + entry.file);
          if (entry.css) entry.css.forEach(f => staticAssets.push('/' + f));
        }
      } catch { /* manifest may not exist in dev */ }

      const template = readFileSync('sw.js', 'utf-8');
      const out = template.replace('__PRECACHE_URLS__', JSON.stringify(staticAssets, null, 4));
      writeFileSync('dist/sw.js', out);

      console.log('[generate-sw] wrote dist/sw.js with', staticAssets.length, 'precache URLs');
    },
  };
}

export default defineConfig({
  root: '.',
  build: {
    outDir: 'dist',
    assetsDir: 'assets',
    target: 'esnext',
    manifest: true,
    rollupOptions: {
      output: {
        manualChunks: {
          three: ['three'],
        },
      },
    },
  },
  plugins: [generateSW()],
  server: {
    host: true,
  },
});