const http = require("http");
const fs = require("fs");
const path = require("path");

const PORT = process.env.PORT || 3000;
const DATA = path.join(__dirname, "data.json");

function readData() {
  try { return JSON.parse(fs.readFileSync(DATA, "utf8")); } catch (_) { return { registrations: [] }; }
}
function writeData(d) {
  fs.writeFileSync(DATA, JSON.stringify(d, null, 2));
}
function body(req) {
  return new Promise((resolve) => {
    let s = "";
    req.on("data", (c) => (s += c));
    req.on("end", () => { try { resolve(JSON.parse(s || "{}")); } catch (_) { resolve({}); } });
  });
}
function clean(v, max) {
  return String(v == null ? "" : v).replace(/[<>]/g, "").trim().slice(0, max);
}

http.createServer(async (req, res) => {
  const url = req.url.split("?")[0];

  // API: список регистраций
  if (req.method === "GET" && url === "/api/registrations") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(readData().registrations));
  }
  // API: регистрация
  if (req.method === "POST" && url === "/api/registrations") {
    const b = await body(req);
    const name = clean(b.name, 120);
    const dept = clean(b.dept, 120);
    const email = clean(b.email, 120);
    const phone = clean(b.phone, 40);
    if (!name || !dept || !email || !phone) {
      res.writeHead(400, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: false, error: "Заполните все поля" }));
    }
    const rec = { name, dept, email, phone, createdAt: new Date().toISOString() };
    const d = readData();
    if (d.registrations.some((r) => r.email && r.email.toLowerCase() === email.toLowerCase())) {
      res.writeHead(409, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: false, error: "С таким e-mail вы уже зарегистрированы" }));
    }
    d.registrations.push({ id: Date.now(), ...rec });
    writeData(d);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // Статика
  let file = url === "/" ? "/index.html" : url;
  const full = path.join(__dirname, file);
  if (full.startsWith(__dirname) && fs.existsSync(full) && fs.statSync(full).isFile()) {
    const ext = path.extname(full);
    const type = ext === ".css" ? "text/css" : ext === ".js" ? "application/javascript" : "text/html";
    res.writeHead(200, { "Content-Type": type + "; charset=utf-8" });
    return res.end(fs.readFileSync(full));
  }
  res.writeHead(404); res.end("Not found");
}).listen(PORT, () => console.log("Сервер на порту " + PORT));