server.js

const http = require("http");
const fs = require("fs");
const path = require("path");
const { URL } = require("url");

const root = __dirname;
const publicDir = path.join(root, "public");
const port = Number(process.env.PORT || 3000);

const mimeTypes = {
  ".html": "text/html; charset=utf-8",
  ".css": "text/css; charset=utf-8",
  ".js": "application/javascript; charset=utf-8",
  ".json": "application/json; charset=utf-8",
  ".svg": "image/svg+xml",
  ".png": "image/png",
  ".ico": "image/x-icon"
};

function send(res, status, body, type = "application/json; charset=utf-8") {
  res.writeHead(status, {
    "Content-Type": type,
    "Cache-Control": "no-store",
    "Access-Control-Allow-Origin": "*"
  });
  res.end(body);
}

function normalizeRedditUrl(input) {
  const url = new URL(input);
  if (!["www.reddit.com", "old.reddit.com", "reddit.com"].includes(url.hostname)) {
    throw new Error("Only reddit.com links are supported.");
  }
  url.hostname = "www.reddit.com";
  url.searchParams.set("limit", "500");
  url.searchParams.set("sort", "confidence");
  if (!url.pathname.endsWith(".json")) {
    url.pathname = url.pathname.replace(/\/?$/, ".json");
  }
  return url.toString();
}

async function fetchReddit(url) {
  const controller = new AbortController();
  const timeout = setTimeout(() => controller.abort(), 15000);
  try {
    const response = await fetch(url, {
      signal: controller.signal,
      headers: {
        "User-Agent": "RedditDebateAnalyzer/1.0 hackathon demo by local user",
        "Accept": "application/json"
      }
    });
    const text = await response.text();
    if (!response.ok) {
      throw new Error(`Reddit returned ${response.status}: ${text.slice(0, 160)}`);
    }
    JSON.parse(text);
    return text;
  } finally {
    clearTimeout(timeout);
  }
}

function serveStatic(req, res) {
  const requested = decodeURIComponent(new URL(req.url, `http://localhost:${port}`).pathname);
  const cleanPath = requested === "/" ? "/index.html" : requested;
  const filePath = path.normalize(path.join(publicDir, cleanPath));
  if (!filePath.startsWith(publicDir)) {
    send(res, 403, "Forbidden", "text/plain; charset=utf-8");
    return;
  }

  fs.readFile(filePath, (err, data) => {
    if (err) {
      send(res, 404, "Not found", "text/plain; charset=utf-8");
      return;
    }
    const type = mimeTypes[path.extname(filePath)] || "application/octet-stream";
    send(res, 200, data, type);
  });
}

const server = http.createServer(async (req, res) => {
  const requestUrl = new URL(req.url, `http://localhost:${port}`);

  if (requestUrl.pathname === "/api/reddit") {
    try {
      const target = requestUrl.searchParams.get("url");
      if (!target) {
        send(res, 400, JSON.stringify({ error: "Missing url parameter." }));
        return;
      }
      const redditUrl = normalizeRedditUrl(target);
      const body = await fetchReddit(redditUrl);
      send(res, 200, body);
    } catch (error) {
      send(res, 502, JSON.stringify({ error: error.message || "Unable to fetch Reddit thread." }));
    }
    return;
  }

  serveStatic(req, res);
});

server.listen(port, () => {
  console.log(`Reddit Debate Analyzer running at http://localhost:${port}`);
});