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

// Library mode: one prebuilt ESM chunk, published by CI and dropped onto the
// operator's volume. The operator never builds anything (MODULE_SYSTEM.md §2.5).
//
// The four externals are the whole contract with core. Declaring them external
// alone is not enough, though: rollup would emit bare `import 'react'`
// specifiers, which a browser cannot resolve without an import map — and CSP
// forbids the inline <script type="importmap"> that would provide one. So each
// is ALIASED to a two-line shim that re-exports from window.__rg, and the
// external list then only has to stop Vite from following them into node_modules
// this package does not have.
const shim = (f) => path.resolve(import.meta.dirname, 'src/shim', f)

export default defineConfig({
  plugins: [react()],
  resolve: {
    // EXACT matches, via the array form. Vite's object form does PREFIX
    // replacement, so a plain `react` key also rewrote `react/jsx-runtime` into
    // `src/shim/react.js/jsx-runtime` — a path that does not exist, and the
    // first thing this build hit.
    alias: [
      { find: /^react$/, replacement: shim('react.js') },
      { find: /^react\/jsx-runtime$/, replacement: shim('react-jsx-runtime.js') },
      { find: /^react-dom\/client$/, replacement: shim('react-dom-client.js') },
      { find: /^react-router-dom$/, replacement: shim('react-router-dom.js') },
    ],
  },
  build: {
    lib: {
      entry: path.resolve(import.meta.dirname, 'src/entry.jsx'),
      formats: ['es'],
      fileName: () => 'entry.js',
    },
    outDir: 'dist',
    emptyOutDir: true,
    // Same reason as core's client: no inline bootstrap script for
    // `script-src 'self'` to trip on.
    modulePreload: { polyfill: false },
  },
})