// Copyright (c) 2026 Cloudflare, Inc.
// Licensed under the Apache 2.0 license found in the LICENSE-APACHE file or at:
//     https://opensource.org/licenses/Apache-2.0
// Distributed here as part of a work licensed under the AGPL-3.0-only (see LICENSE).

import type { AppLoadContext, EntryContext } from "react-router";
import { ServerRouter } from "react-router";
import { isbot } from "isbot";
import { renderToReadableStream } from "react-dom/server";
import { I18nextProvider } from "react-i18next";
import { getInstance } from "~/middleware/i18next";

export default async function handleRequest(
  request: Request,
  responseStatusCode: number,
  responseHeaders: Headers,
  routerContext: EntryContext,
  loadContext: AppLoadContext
) {
  let shellRendered = false;
  const userAgent = request.headers.get("user-agent");

  // [i18n-foundation] The per-request i18next instance created by
  // `i18nextMiddleware` (app/root.tsx) lives on the Router context, which is
  // the same object React Router passes here as the load context. Passing it
  // through `<I18nextProvider>` guarantees the SSR markup is rendered in the
  // detected language, so the client hydrates without a mismatch.
  // @ts-expect-error — with `future.v8_middleware` the context is a
  // `RouterContextProvider`, but the template types this arg as AppLoadContext.
  const i18n = getInstance(loadContext);

  const body = await renderToReadableStream(
    <I18nextProvider i18n={i18n}>
      <ServerRouter context={routerContext} url={request.url} />
    </I18nextProvider>,
    {
      onError(error: unknown) {
        responseStatusCode = 500;
        // Log streaming rendering errors from inside the shell.  Don't log
        // errors encountered during initial shell rendering since they'll
        // reject and get logged in handleDocumentRequest.
        if (shellRendered) {
          console.error(error);
        }
      },
    }
  );
  shellRendered = true;

  // Ensure requests from bots and SPA Mode renders wait for all content to load before responding
  // https://react.dev/reference/react-dom/server/renderToPipeableStream#waiting-for-all-content-to-load-for-crawlers-and-static-generation
  if ((userAgent && isbot(userAgent)) || routerContext.isSpaMode) {
    await body.allReady;
  }

  responseHeaders.set("Content-Type", "text/html");
  return new Response(body, {
    headers: responseHeaders,
    status: responseStatusCode,
  });
}