server.js

const express = require("express");
const cors = require("cors");
const fetch = require("node-fetch");

// NOTE: The original Firebase Admin + /summary endpoint has been removed
// because this server is now focused on proxying external APIs for the
// front-end (Code_Class) to avoid CORS issues.

const app = express();
app.use(cors());
app.use(express.json());

// Helper to mimic a browser
const fetchWithUA = async (url) => {
  return fetch(url, {
    headers: {
      "User-Agent":
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
      "Accept-Language": "en-US,en;q=0.9",
    },
  });
};

// ---------- Proxy endpoints for Code_Class ----------

// LeetCode proxy (uses public Lydia LeetCode API to simplify)
app.post("/code-class/leetcode", async (req, res) => {
  try {
    const { username } = req.body || {};
    if (!username) {
      return res.status(400).json({ error: "username is required" });
    }

    // Lydia's LeetCode API (no auth, community maintained)
    const upstream = await fetchWithUA(
      `https://leetcode-api.herokuapp.com/username/${encodeURIComponent(
        username
      )}`
    );

    if (!upstream.ok) {
      console.error("LeetCode upstream error:", upstream.status);
      return res
        .status(502)
        .json({ error: "Upstream LeetCode API error", status: upstream.status });
    }

    const data = await upstream.json();
    res.json(data);
  } catch (e) {
    console.error("LeetCode proxy error:", e);
    res.status(500).json({ error: "Failed to proxy LeetCode" });
  }
});

// CodeChef profile proxy
app.get("/code-class/codechef/:username", async (req, res) => {
  try {
    const { username } = req.params;
    const upstream = await fetchWithUA(
      `https://codechef-api.vercel.app/${encodeURIComponent(username)}`
    );
    const data = await upstream.json();
    res.json(data);
  } catch (e) {
    console.error("CodeChef proxy error:", e);
    res.status(500).json({ error: "Failed to proxy CodeChef" });
  }
});

// GeeksforGeeks profile page proxy (HTML)
app.get("/code-class/gfg/:username", async (req, res) => {
  try {
    const { username } = req.params;
    const upstream = await fetchWithUA(
      `https://www.geeksforgeeks.org/user/${encodeURIComponent(
        username
      )}`
    );
    // GFG profile URL is /user/USERNAME (sometimes /user/USERNAME/)

    if (!upstream.ok) {
      console.error("GFG upstream error:", upstream.status);
      if (upstream.status === 404) return res.status(404).send("GFG User not found");
      return res.status(upstream.status).send("GFG Upstream Error");
    }

    const text = await upstream.text();
    res.type("text/plain").send(text);
  } catch (e) {
    console.error("GFG proxy error:", e);
    res.status(500).send("Failed to proxy GFG");
  }
});

// HackerEarth profile page proxy (HTML)
app.get("/code-class/hackerearth/:username", async (req, res) => {
  try {
    const { username } = req.params;
    const upstream = await fetchWithUA(
      `https://www.hackerearth.com/@${encodeURIComponent(username)}`
    );

    if (!upstream.ok) {
      console.error("HackerEarth upstream error:", upstream.status);
      return res.status(upstream.status).send("HackerEarth Upstream Error");
    }

    const text = await upstream.text();
    res.type("text/plain").send(text);
  } catch (e) {
    console.error("HackerEarth proxy error:", e);
    res.status(500).send("Failed to proxy HackerEarth");
  }
});

const PORT = 4000;
app.listen(PORT, () => console.log(`Code_Class proxy server running on ${PORT}`));