/**
 * Vite config: React SPA + Tailwind CSS 4.
 *
 * Dev server listens on 7365; `/api` is proxied to the **development** backend (127.0.0.1:7368 --
 * `pnpm dev:server`, deliberately not the installed server's 7364, which is routinely running at the
 * same time). Honors PORT so overriding the backend port moves the proxy with it, and
 * PENGUIN_API_PROXY overrides the whole target. SSE (text/event-stream) passes through http-proxy
 * transparently, no special config needed.
 * The vitest config is kept separate in vitest.config.ts (its embedded vite 5 types conflict with this
 * package's vite 7 plugin types, hence the separate file to avoid the clash).
 */
import react from "@vitejs/plugin-react";
import tailwindcss from "@tailwindcss/vite";
import { defineConfig } from "vite";

/**
 * Resolves the `/api` proxy target: PENGUIN_API_PROXY replaces it outright, otherwise the
 * development backend on PORT — the same variable `pnpm dev:server` binds — defaulting to 7368.
 *
 * Empty counts as unset, as everywhere else PORT is read in this repo (server/src/config.ts,
 * cli/src/commands/serve.ts, scripts/run-with-env.mjs). Here `??` would be actively harmful: an
 * exported-but-empty `PORT=` yields `http://127.0.0.1:` — port 80 — and every /api call would be
 * answered by whatever happens to listen there, silently and without an error, which is the exact
 * wrong-backend failure this default exists to prevent.
 *
 * Takes the environment as an argument so the resolution can be unit-tested (a vite config's
 * `server.proxy` cannot be exercised without starting a dev server).
 */
export function apiProxyTarget(env: Record<string, string | undefined> = process.env): string {
  return env.PENGUIN_API_PROXY || `http://127.0.0.1:${env.PORT || "7368"}`;
}

export default defineConfig({
  plugins: [react(), tailwindcss()],
  server: {
    // Fixed PenguinHarness dev port (stands alone — vite configs cannot import core TS,
    // so the numbers are literals here; the allocation table lives in core's internal/ports.ts).
    port: 7365,
    proxy: {
      "/api": {
        target: apiProxyTarget(),
        changeOrigin: false,
      },
    },
  },
});