import { ServerResponse } from "node:http";
import { defineConfig, type Plugin, type ProxyOptions } from "vite";
import { reactWithCompiler } from "./reactPlugin";
import { devOnlyGuard } from "./devOnlyGuard";

// During `vite dev` (host with Node), proxy API calls to the backend container.
// Use 127.0.0.1 (not "localhost") so Node doesn't resolve to IPv6 ::1, which the
// Docker port publish may not answer — that surfaces as proxy connection failures.
const target = "http://127.0.0.1:8080";
// changeOrigin:false keeps the original `Host: localhost:5173` header when proxying to the backend
// (the TCP target is still 127.0.0.1:8080 — changeOrigin only rewrites the header). The backend uses
// that header to send the OAuth redirect_uri back to :5173, so a Google login started on the Vite dev
// server returns to :5173 instead of the fixed :8080 callback. (Both are registered in the console.)
//
// A failed connect to the container (on Windows the Docker port publish now and then times one out)
// is a gateway failure, so it answers 502 like the prod reverse proxy: the app reads that as a
// passing connection loss (a quiet notice; a GET is retried once). Vite's own handler, which runs
// after this one and leaves an answered response alone, sends a bodiless 500 — read as a real
// server fault, the blocking error dialog.
const proxyOpts: ProxyOptions = {
  target,
  changeOrigin: false,
  configure: (proxy) =>
    proxy.on("error", (_err, _req, res) => {
      if (res instanceof ServerResponse && !res.headersSent) res.writeHead(502).end();
    }),
};
const proxy = {
  "/api": proxyOpts,
  "/auth": proxyOpts,
  "/healthz": proxyOpts,
};

// Two HTML entries: the app (index.html) and a public /watch/<token> link (watch.html), which loads
// only the player page. In a build the backend picks the file by path (`main.py`); this does the
// same for `vite dev`, whose history fallback would otherwise hand /watch/… the app.
const watchEntry = (): Plugin => ({
  name: "siftlode-watch-entry",
  configureServer(server) {
    server.middlewares.use((req, _res, next) => {
      if (req.url?.startsWith("/watch/")) req.url = "/watch.html";
      next();
    });
  },
  // The server answers every /watch/ link with the built watch.html, so a build without it would
  // ship a 500 for each one, and nothing downstream reads `dist` before prod does. Fail it here —
  // after Vite's own HTML plugin has emitted the pages (`enforce: "post"`), or none is there yet.
  enforce: "post",
  generateBundle(_options, bundle) {
    for (const page of ["index.html", "watch.html"]) {
      if (!(page in bundle)) this.error(`${page} was not built — add it to rollupOptions.input`);
    }
  },
});

export default defineConfig({
  plugins: [reactWithCompiler(), devOnlyGuard(), watchEntry()],
  server: { port: 5173, proxy },
  build: { outDir: "dist", rollupOptions: { input: ["index.html", "watch.html"] } },
});