import { defineConfig } from 'vite';
import react from '@vitejs/plugin-react';

// Minimal typing for process.env so we don't need @types/node just for this.
declare const process: { env: Record<string, string | undefined> };

// Where a `vite dev` session sends its API calls. Playpen prefers 8420 and walks
// upward if it's taken, so this is right unless you have two windows open — in
// which case read the real one out of PLAYPEN_REVIEW_URL in any of its terminals.
const apiPort = process.env.PLAYPEN_REVIEW_PORT || '8420';
const apiTarget = `http://127.0.0.1:${apiPort}`;

export default defineConfig({
  plugins: [react()],

  resolve: {
    // The syntax highlighter runs in a worker (see src/lib/highlight.ts), and one
    // package deep under refractor — decode-named-character-reference, pulled in
    // by the markup language to decode HTML entities — ships a browser build
    // that calls `document.createElement` at module scope. A worker has no
    // document, so importing refractor there threw before a line was highlighted.
    //
    // The package publishes a document-free build for exactly this case and
    // lists it first in its export map, under `worker`. Asking for that
    // condition is what picks it up. It resolves for the main bundle too, which
    // is what we want: it is the same function with a lookup table in place of
    // the DOM's entity parser, and one implementation beats two.
    conditions: ['worker'],
  },

  // Relative asset URLs, because the page is served from a tab's path
  // (`/t/tab3/`) and not from the server root. With an absolute base the
  // browser would ask for `/assets/app.js` and get the tab router instead.
  base: './',

  server: {
    port: 5173,
    proxy: {
      // A tab's own API and event stream. Matched as a regex so the HTML at
      // `/t/<id>/` still comes from Vite — only the calls underneath it are
      // forwarded, which is what lets hot reloading work against a live review.
      //
      // Open http://localhost:5173/t/<tabId>/ to develop against a real tab.
      '^/t/[^/]+/api': { target: apiTarget, changeOrigin: true },
      // The app-wide endpoints: /api/tabs and /api/health.
      '/api': { target: apiTarget, changeOrigin: true },
    },
  },

  build: {
    outDir: 'dist',
    emptyOutDir: true,

    // Fixed filenames rather than Vite's content hashes. The bundle is embedded
    // in the playpen binary (src/review/assets.zig), so the Zig side has to be
    // able to name the files at compile time — and cache busting buys nothing
    // for a bundle that only changes when the binary does.
    rollupOptions: {
      output: {
        entryFileNames: 'assets/app.js',
        chunkFileNames: 'assets/app.js',
        assetFileNames: 'assets/app[extname]',
        // One file, so there is one name to embed. The app is a few hundred
        // kilobytes loaded from localhost; splitting it saves nothing.
        manualChunks: undefined,
      },
    },
  },
});