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 { apartments: [], log: [] }; }
}
function writeData(data) {
  fs.writeFileSync(DATA, JSON.stringify(data, 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({}); } });
  });
}

http.createServer(async (req, res) => {
  res.setHeader("Access-Control-Allow-Origin", "*");
  res.setHeader("Access-Control-Allow-Methods", "GET, POST, OPTIONS");
  res.setHeader("Access-Control-Allow-Headers", "Content-Type");
  
  if (req.method === "OPTIONS") {
    res.writeHead(200);
    return res.end();
  }

  const url = req.url.split("?")[0];

  if (req.method === "GET" && url === "/api/data") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(readData()));
  }

  if (req.method === "POST" && url === "/api/update-readings") {
    const data = readData();
    const { apartmentId, readings } = await body(req);
    const apt = data.apartments.find(a => a.id === parseInt(apartmentId));
    if (apt) {
      apt.lastReadings = { ...apt.currentReadings };
      apt.currentReadings = { ...apt.currentReadings, ...readings };
      data.log.push({
        when: new Date().toISOString(),
        what: `Обновлены показания для ${apt.name}`,
        who: "арендатор"
      });
      writeData(data);
    }
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  if (req.method === "POST" && url === "/api/mark-paid") {
    const data = readData();
    const { apartmentId } = await body(req);
    const apt = data.apartments.find(a => a.id === parseInt(apartmentId));
    if (apt) {
      apt.status = "оплачено";
      data.log.push({
        when: new Date().toISOString(),
        what: `Оплата отмечена для ${apt.name}`,
        who: "арендатор"
      });
      writeData(data);
    }
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  if (req.method === "POST" && url === "/api/update-apartment") {
    const data = readData();
    const update = await body(req);
    const idx = data.apartments.findIndex(a => a.id === parseInt(update.id));
    if (idx !== -1) {
      data.apartments[idx] = { ...data.apartments[idx], ...update };
      data.log.push({
        when: new Date().toISOString(),
        what: `Обновлены данные для квартиры ${update.id}`,
        who: "админ"
      });
      writeData(data);
    }
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  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 запущен на порту " + PORT));