import { PassThrough } from "node:stream";

import type { AppLoadContext, EntryContext } from "@remix-run/node";
import { createReadableStreamFromReadable } from "@remix-run/node";
import { RemixServer } from "@remix-run/react";
import isbot from "isbot";
import { renderToPipeableStream } from "react-dom/server";
import { createSitemapGenerator } from "remix-sitemap";

const ABORT_DELAY = 5_000;

// Step 1. setup the generator
const { isSitemapUrl, sitemap } = createSitemapGenerator({
  siteUrl: "https://web3.news",
  generateRobotsTxt: true,
});

export default async function handleRequest(
  request: Request,
  responseStatusCode: number,
  responseHeaders: Headers,
  remixContext: EntryContext,
  loadContext: AppLoadContext
) {
  if (isSitemapUrl(request)) {
    return await sitemap(request, remixContext);
  }

  return isbot(request.headers.get("user-agent"))
    ? handleBotRequest(
        request,
        responseStatusCode,
        responseHeaders,
        remixContext
      )
    : handleBrowserRequest(
        request,
        responseStatusCode,
        responseHeaders,
        remixContext
      );
}

function handleBotRequest(
  request: Request,
  responseStatusCode: number,
  responseHeaders: Headers,
  remixContext: EntryContext
) {
  return new Promise((resolve, reject) => {
    let shellRendered = false;
    const { pipe, abort } = renderToPipeableStream(
      <RemixServer
        context={remixContext}
        url={request.url}
        abortDelay={ABORT_DELAY}
      />,
      {
        onAllReady() {
          shellRendered = true;
          const body = new PassThrough();
          const stream = createReadableStreamFromReadable(body);

          responseHeaders.set("Content-Type", "text/html");

          resolve(
            new Response(stream, {
              headers: responseHeaders,
              status: responseStatusCode,
            })
          );

          pipe(body);
        },
        onShellError(error: unknown) {
          reject(error);
        },
        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);
          }
        },
      }
    );

    setTimeout(abort, ABORT_DELAY);
  });
}

function handleBrowserRequest(
  request: Request,
  responseStatusCode: number,
  responseHeaders: Headers,
  remixContext: EntryContext
) {
  return new Promise((resolve, reject) => {
    let shellRendered = false;
    const { pipe, abort } = renderToPipeableStream(
      <RemixServer
        context={remixContext}
        url={request.url}
        abortDelay={ABORT_DELAY}
      />,
      {
        onShellReady() {
          shellRendered = true;
          const body = new PassThrough();
          const stream = createReadableStreamFromReadable(body);

          responseHeaders.set("Content-Type", "text/html");

          resolve(
            new Response(stream, {
              headers: responseHeaders,
              status: responseStatusCode,
            })
          );

          pipe(body);
        },
        onShellError(error: unknown) {
          reject(error);
        },
        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);
          }
        },
      }
    );

    setTimeout(abort, ABORT_DELAY);
  });
}