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 { items: [], log: [], users: [] }; }
}
function writeData(data) {
  fs.writeFileSync(DATA, JSON.stringify(data, null, 2));
}

function parseBody(req) {
  return new Promise((resolve) => {
    let body = "";
    req.on("data", chunk => body += chunk);
    req.on("end", () => {
      try { resolve(JSON.parse(body || "{}")); } catch { resolve({}); }
    });
  });
}

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



  // ==================== API ПОЛЬЗОВАТЕЛЕЙ ====================
  if (url === "/api/users" && method === "GET") {
    const data = readData();
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(data.users.map(u => ({ login: u.login, role: u.role, createdAt: u.createdAt }))));
  }

  if (url === "/api/users" && method === "POST") {
    const body = await parseBody(req);
    const data = readData();
    if (data.users.find(u => u.login === body.login)) {
      res.writeHead(400, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ error: "Пользователь существует" }));
    }
    data.users.push({ login: body.login, password: body.password, role: body.role || "user", createdAt: new Date().toISOString() });
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  if (url.startsWith("/api/users/") && method === "DELETE") {
    const login = url.split("/")[3];
    const data = readData();
    const idx = data.users.findIndex(u => u.login === login);
    if (idx === -1 || (data.users[idx].role === "admin" && data.users.filter(u => u.role === "admin").length <= 1)) {
      res.writeHead(400, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ error: "Нельзя удалить" }));
    }
    data.users.splice(idx, 1);
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

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

  if (url === "/api/items" && method === "POST") {
    const body = await parseBody(req);
    const data = readData();
    const newItem = { id: Date.now(), ...body, createdAt: new Date().toISOString().slice(0, 10), updatedAt: new Date().toISOString().slice(0, 10) };
    delete newItem.id;
    data.items.push(newItem);
    data.log.push({ id: Date.now(), timestamp: new Date().toISOString(), action: "создана", itemId: newItem.id, itemName: newItem.name, user: 'system', changes: {} });
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  if (url.startsWith("/api/items/") && method === "PUT") {
    const id = parseInt(url.split("/")[3]);
    const body = await parseBody(req);
    const data = readData();
    const idx = data.items.findIndex(i => i.id === id);
    if (idx === -1) {
      res.writeHead(404, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ error: "Не найдено" }));
    }
    const changes = {};
    Object.keys(body).forEach(k => {
      if (k !== 'id' && data.items[idx][k] !== body[k]) changes[k] = `${data.items[idx][k]} → ${body[k]}`;
    });
    data.items[idx] = { ...data.items[idx], ...body, updatedAt: new Date().toISOString().slice(0, 10) };
    data.log.push({ id: Date.now(), timestamp: new Date().toISOString(), action: "изменена", itemId: id, itemName: data.items[idx].name, user: 'system', changes });
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  if (url.startsWith("/api/items/") && method === "DELETE") {
    const id = parseInt(url.split("/")[3]);
    const data = readData();
    const idx = data.items.findIndex(i => i.id === id);
    if (idx === -1) {
      res.writeHead(404, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ error: "Не найдено" }));
    }
    const removed = data.items.splice(idx, 1)[0];
    data.log.push({ id: Date.now(), timestamp: new Date().toISOString(), action: "удалена", itemId: id, itemName: removed.name, user: 'system', changes: {} });
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  if (url === "/api/log" && method === "GET") {
    const data = readData();
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(data.log.slice(-100).reverse()));
  }

  if (url === "/api/stats" && method === "GET") {
    const data = readData();
    const today = new Date().toISOString().slice(0, 10);
    const in30Days = new Date(Date.now() + 30 * 24 * 60 * 60 * 1000).toISOString().slice(0, 10);
    const stats = {
      total: data.items.length,
      byStatus: { "в эксплуатации": 0, "на складе": 0, "в ремонте": 0, "списано": 0 },
      requireCheck: 0,
      overdue: 0
    };
    data.items.forEach(i => {
      if (stats.byStatus[i.status] !== undefined) stats.byStatus[i.status]++;
      if (i.nextCheckDate && i.nextCheckDate < today) stats.overdue++;
      else if (i.nextCheckDate && i.nextCheckDate <= in30Days) stats.requireCheck++;
    });
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(stats));
  }

  // ==================== СТАТИКА ====================
  if (url === "/login.html" || url === "/style.css" || url.startsWith("/design-system/")) {
    const file = path.join(__dirname, url.split("?")[0]);
    if (fs.existsSync(file)) {
      const ext = path.extname(file);
      const type = ext === ".css" ? "text/css" : "text/html";
      res.writeHead(200, { "Content-Type": type + "; charset=utf-8" });
      return res.end(fs.readFileSync(file));
    }
  }

  if (url === "/" || url === "/index.html") {
    const file = path.join(__dirname, user ? "/index.html" : "/login.html");
    if (fs.existsSync(file)) {
      res.writeHead(200, { "Content-Type": "text/html; charset=utf-8" });
      return res.end(fs.readFileSync(file));
    }
  }

  if (url === "/script.js") {
    const file = path.join(__dirname, "/script.js");
    if (fs.existsSync(file)) {
      res.writeHead(200, { "Content-Type": "application/javascript; charset=utf-8" });
      return res.end(fs.readFileSync(file));
    }
  }

  res.writeHead(404); res.end("Not found");
}).listen(PORT, () => console.log("Сервер на порту " + PORT));