import { defineConfig } from 'vite';
import preact from '@preact/preset-vite';
import legacy from '@vitejs/plugin-legacy';
import { resolve } from 'node:path';
import { execSync } from 'node:child_process';

// The dev-server proxy target — same default (3000) as the server's own
// `process.env.PORT ?? 3000` in server/src/index.ts. Override with
// `WUTZ_SERVER_PORT` when running `dev:server` on a non-default port, e.g.:
//   PORT=4000 pnpm dev:server
//   WUTZ_SERVER_PORT=4000 pnpm dev:client
const serverTarget = `http://localhost:${process.env.WUTZ_SERVER_PORT ?? 3000}`;

// #68: baked into the bundle at build time so the client can show "which
// build is this" for bug triage without a server round-trip. Deploys run
// `pnpm build` from a git checkout (see deploy/wutzcalc.service), but this
// stays defensive against a tarball/CI-artifact deploy with no `.git` —
// falls back to 'dev' rather than failing the build.
function appVersion(): string {
  try {
    return execSync('git rev-parse --short HEAD', { cwd: __dirname }).toString().trim();
  } catch {
    return 'dev';
  }
}

export default defineConfig({
  define: {
    __APP_VERSION__: JSON.stringify(appVersion()),
  },
  plugins: [
    preact(),
    legacy({
      targets: ['ios >= 12', 'safari >= 12'],
      modernPolyfills: true,
      renderLegacyChunks: true,
    }),
  ],
  build: {
    target: 'es2017',
    rollupOptions: {
      input: {
        main: resolve(__dirname, 'index.html'),
        admin: resolve(__dirname, 'admin.html'),
        stats: resolve(__dirname, 'stats.html'),
      },
    },
  },
  server: {
    port: 5173,
    proxy: {
      '/api': serverTarget,
      '/healthz': serverTarget,
      // NOT a bare '/admin' prefix: that would also swallow the /admin and
      // /admin.html *page* requests themselves (and, since Vite's proxy
      // matches by string prefix, they do — '/admin' matches '/admin.html'
      // too), forwarding them to the backend instead of letting Vite serve
      // its own dev-mode admin.html. In dev the backend only has a stale
      // production build to fall back on (or nothing, if `client` was never
      // built), so the page ends up loaded with hashed prod asset paths that
      // don't exist in Vite's dev module graph — Vite's dev server then
      // answers those with its SPA-fallback HTML instead of JS, which is
      // exactly the "wrong MIME type" / NS_ERROR_CORRUPTED_CONTENT failure
      // reported for the admin page. Only the backend-owned endpoints need
      // to cross the proxy.
      '/admin/api': serverTarget,
      '/admin/login': serverTarget,
      '/admin/logout': serverTarget,
    },
  },
});