Index of ${url.pathname}

import { existsSync, readdirSync, statSync } from "node:fs";
import { join, normalize } from "node:path";

const rootDir = process.cwd();
const port = Number.parseInt(process.env.PORT ?? "3000", 10);

function resolveSafePath(urlPathname: string): string | null {
  let pathname = urlPathname;
  try {
    pathname = decodeURIComponent(pathname);
  } catch {
    return null;
  }

  if (pathname.endsWith("/")) pathname += "index.html";
  const rel = pathname.replace(/^\/+/, "");
  const normalized = normalize(rel);

  if (normalized.startsWith("..") || normalized.includes("/..") || normalized.includes("\\..")) {
    return null;
  }

  const parts = normalized.split(/[\\/]+/).filter(Boolean);
  if (parts.some((p) => p !== "." && p.startsWith("."))) return null;

  return join(rootDir, normalized);
}

Bun.serve({
  port,
  async fetch(req) {
    if (req.method !== "GET" && req.method !== "HEAD") {
      return new Response("Method Not Allowed", { status: 405 });
    }

    const url = new URL(req.url);
    const filePath = resolveSafePath(url.pathname);
    if (!filePath) return new Response("Bad Request", { status: 400 });

    // Redirect directory paths missing trailing slash.
    if (!url.pathname.endsWith("/") && existsSync(filePath) && statSync(filePath).isDirectory()) {
      return Response.redirect(`${url.pathname}/`, 308);
    }

    if (!existsSync(filePath)) {
      // If it's a directory URL but there's no index.html, show a tiny listing.
      if (url.pathname.endsWith("/")) {
        const dirPath = resolveSafePath(url.pathname.replace(/\/$/, ""));
        if (!dirPath) return new Response("Bad Request", { status: 400 });
        if (existsSync(dirPath) && statSync(dirPath).isDirectory()) {
          const entries = readdirSync(dirPath, { withFileTypes: true })
            .filter((d) => !d.name.startsWith("."))
            .map((d) => ({ name: d.name, isDir: d.isDirectory() }))
            .sort((a, b) => Number(b.isDir) - Number(a.isDir) || a.name.localeCompare(b.name));

          const items = [
            url.pathname !== "/" ? `<li><a href="../">../</a></li>` : "",
            ...entries.map(({ name, isDir }) => {
              const href = `${url.pathname}${encodeURIComponent(name)}${isDir ? "/" : ""}`;
              return `<li><a href="${href}">${name}${isDir ? "/" : ""}</a></li>`;
            }),
          ].join("");

          const html = `<!doctype html><meta charset="utf-8"><title>Index of ${url.pathname}</title><h1>Index of ${url.pathname}</h1><ul>${items}</ul>`;
          const headers = new Headers({ "Content-Type": "text/html; charset=utf-8" });
          headers.set("Content-Length", String(Buffer.byteLength(html)));
          return new Response(req.method === "HEAD" ? null : html, { status: 200, headers });
        }
      }

      return new Response("Not Found", { status: 404 });
    }

    const file = Bun.file(filePath);
    const headers = new Headers();
    if (file.type) headers.set("Content-Type", file.type);
    headers.set("Content-Length", String(file.size));

    return new Response(req.method === "HEAD" ? null : file, { status: 200, headers });
  },
});

console.log(`Serving ${rootDir} at http://localhost:${port}`);