// vite.test.config.ts — Plan 01-11 two-bundle separation.
//
// Extends the production `./vite.config.ts` with two delta knobs:
//   1. `mode: 'test'` — Vite statically replaces `import.meta.env.MODE`
//      everywhere in the input source with the string literal `'test'`.
//      The gated dynamic imports in src/background/index.ts +
//      src/offscreen/recorder.ts (Plan 01-11 Task 2) take the form
//      `if (import.meta.env.MODE === 'test') { await import('../test-hooks/...'); }`.
//      With mode='test' the comparison resolves to a live branch and
//      Rollup KEEPS the dynamic import; with the default mode='production'
//      the comparison is a static dead branch and Rollup tree-shakes the
//      `await import` away entirely (verified by the Tier-1 grep gate
//      `tests/background/no-test-hooks-in-prod-bundle.test.ts`).
//   2. `build.outDir: 'dist-test'` + `emptyOutDir: true` — emit to a
//      SEPARATE directory so a `npm run build` immediately after this
//      build does not clobber. Puppeteer harness consumes this path via
//      `puppeteer.launch({ enableExtensions: [<abs-path-to-dist-test>] })`.
//
// References:
//   - Vite mergeConfig: https://vite.dev/guide/api-javascript.html#mergeconfig
//   - Vite environment variables: https://vite.dev/guide/env-and-mode.html
//   - Rollup tree-shaking literal-comparison dead branches:
//     https://rollupjs.org/plugin-development/#how-rollup-handles-dynamic-imports

import { defineConfig, mergeConfig, type UserConfigExport } from 'vite';
import baseConfig from './vite.config';

const baseAsExport: UserConfigExport = baseConfig;

export default defineConfig(({ command, mode }) =>
  mergeConfig(
    typeof baseAsExport === 'function'
      ? baseAsExport({ command, mode, isPreview: false, isSsrBuild: false })
      : baseAsExport,
    {
      mode: 'test',
      build: {
        outDir: 'dist-test',
        emptyOutDir: true,
      },
    },
  ),
);