proxy.ts

import { NextResponse, type NextRequest } from "next/server";

export async function proxy(request: NextRequest) {
  const userAgent = request.headers.get("user-agent");

  const bots = [
    "googlebot", "yahoo! slurp", "bingbot", "yandex", "baiduspider",
    "facebookexternalhit", "twitterbot", "rogerbot", "linkedinbot", "embedly",
    "quora link preview", "showyoubot", "outbrain", "pinterest/0.",
    "developers.google.com/+/web/snippet", "slackbot", "vkshare", "w3c_validator",
    "redditbot", "applebot", "whatsapp", "flipboard", "tumblr", "bitlybot",
    "skypeuripreview", "nuzzel", "discordbot", "google page speed", "qwantify",
    "pinterestbot", "bitrix link preview", "xing-contenttabreceiver",
    "chrome-lighthouse", "telegrambot", "oai-searchbot", "chatgpt", "gptbot",
    "perplexity", "claudebot", "amazonbot", "integration-test", "iframely",
  ];

  const IGNORE_EXTENSIONS = [
    ".js", ".css", ".xml", ".less", ".png", ".jpg", ".jpeg", ".gif", ".pdf",
    ".doc", ".txt", ".ico", ".rss", ".zip", ".mp3", ".rar", ".exe", ".wmv",
    ".avi", ".ppt", ".mpg", ".mpeg", ".tif", ".wav", ".mov", ".psd", ".ai",
    ".xls", ".mp4", ".m4a", ".swf", ".dat", ".dmg", ".iso", ".flv", ".m4v",
    ".torrent", ".woff", ".woff2", ".ttf", ".otf", ".eot", ".svg", ".webp",
    ".avif", ".webmanifest",
  ];

  const isBot = !!userAgent && bots.some((bot) => userAgent.toLowerCase().includes(bot.toLowerCase()));
  const isPrerender = request.headers.get("X-Prerender");
  const pathname = new URL(request.url).pathname;
  // `extension` already includes the leading dot (e.g. ".woff2"), or "" for dotless paths.
  const extension = pathname.slice(((pathname.lastIndexOf(".") - 1) >>> 0) + 1).toLowerCase();
  const hasExtension = extension.length > 0;

  if (isPrerender || !isBot || (hasExtension && IGNORE_EXTENSIONS.includes(extension))) {
    return NextResponse.next();
  }

  const newURL = `http://service.prerender.io/${request.url}`;
  const newHeaders = new Headers(request.headers);
  newHeaders.set("X-Prerender-Token", process.env.PRERENDER_TOKEN ?? "");
  newHeaders.set("X-Prerender-Int-Type", "NextJS");

  try {
    const res = await fetch(new Request(newURL, { headers: newHeaders, redirect: "manual" }));

    const responseHeaders = new Headers(res.headers);
    responseHeaders.set("X-Redirected-From", request.url);
    responseHeaders.delete("content-encoding");
    responseHeaders.delete("content-length");
    responseHeaders.delete("transfer-encoding");

    const { readable, writable } = new TransformStream();
    if (res.body) res.body.pipeTo(writable);

    return new NextResponse(readable, {
      status: res.status,
      statusText: res.statusText,
      headers: responseHeaders,
    });
  } catch {
    return NextResponse.next();
  }
}