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");
const USERS = path.join(__dirname, "users.json");
const PERMISSIONS = path.join(__dirname, "permissions.json");

function readJSON(file, empty) {
  try { return JSON.parse(fs.readFileSync(file, "utf8")); } catch (_) { return empty; }
}
function writeJSON(file, data) {
  fs.writeFileSync(file, JSON.stringify(data, null, 2));
}

function loadRecords() {
  const data = readJSON(DATA, { records: [], sheets: [] });
  if (!data.records) data.records = [];
  if (!data.sheets) data.sheets = [];
  return data;
}
function saveRecords(data) {
  writeJSON(DATA, data);
}

function loadUsers() {
  return readJSON(USERS, { users: [] });
}
function saveUsers(data) {
  writeJSON(USERS, data);
}

function loadPermissions() {
  return readJSON(PERMISSIONS, { permissions: [] });
}
function savePermissions(data) {
  writeJSON(PERMISSIONS, data);
}

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({}); }
    });
  });
}

const mime = {
  ".html": "text/html; charset=utf-8",
  ".css": "text/css; charset=utf-8",
  ".js": "application/javascript; charset=utf-8",
  ".json": "application/json; charset=utf-8",
  ".png": "image/png",
  ".jpg": "image/jpeg",
  ".svg": "image/svg+xml",
};

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

  // API: Records
  if (method === "GET" && url === "/api/records") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(loadRecords()));
  }
  if (method === "POST" && url === "/api/records") {
    const rec = await body(req);
    const data = loadRecords();
    data.records.push({ id: Date.now(), ...rec });
    saveRecords(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }
  if (method === "PUT" && url === "/api/records") {
    const rec = await body(req);
    const data = loadRecords();
    const idx = data.records.findIndex(r => r.id === rec.id);
    if (idx >= 0) {
      data.records[idx] = { ...data.records[idx], ...rec };
      saveRecords(data);
    }
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }
  if (method === "DELETE" && url === "/api/records") {
    const { id } = await body(req);
    const data = loadRecords();
    data.records = data.records.filter(r => r.id !== id);
    saveRecords(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: Sheets (области, города, ДПБО, ДПКК)
  if (method === "GET" && url === "/api/sheets") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(loadRecords()));
  }
  if (method === "POST" && url === "/api/sheets") {
    const sheet = await body(req);
    const data = loadRecords();
    data.sheets.push({ id: Date.now(), ...sheet });
    saveRecords(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: Users
  if (method === "GET" && url === "/api/users") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(loadUsers()));
  }
  if (method === "POST" && url === "/api/users") {
    const user = await body(req);
    const data = loadUsers();
    data.users.push({ id: Date.now(), ...user });
    saveUsers(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }
  if (method === "PUT" && url === "/api/users") {
    const user = await body(req);
    const data = loadUsers();
    const idx = data.users.findIndex(u => u.id === user.id);
    if (idx >= 0) {
      data.users[idx] = { ...data.users[idx], ...user };
      saveUsers(data);
    }
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }
  if (method === "DELETE" && url === "/api/users") {
    const { id } = await body(req);
    const data = loadUsers();
    data.users = data.users.filter(u => u.id !== id);
    saveUsers(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: Permissions
  if (method === "GET" && url === "/api/permissions") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(loadPermissions()));
  }
  if (method === "POST" && url === "/api/permissions") {
    const perm = await body(req);
    const data = loadPermissions();
    data.permissions.push({ id: Date.now(), ...perm });
    savePermissions(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }
  if (method === "DELETE" && url === "/api/permissions") {
    const { id } = await body(req);
    const data = loadPermissions();
    data.permissions = data.permissions.filter(p => p.id !== id);
    savePermissions(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: Statistics
  if (method === "POST" && url === "/api/stats") {
    const { startDate, endDate, groupBy } = await body(req);
    const data = loadRecords();
    const start = startDate ? new Date(startDate) : null;
    const end = endDate ? new Date(endDate) : null;
    
    let filtered = data.records.filter(r => {
      if (!r.date) return true;
      const d = new Date(r.date);
      if (start && d < start) return false;
      if (end && d > end) return false;
      return true;
    });

    const stats = {};
    filtered.forEach(r => {
      const key = r[groupBy] || "Не указано";
      if (!stats[key]) stats[key] = 0;
      stats[key]++;
    });

    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ stats, total: filtered.length }));
  }

  // API: Export to Excel
  if (method === "GET" && url.startsWith("/api/export/excel")) {
    const XLSX = require("xlsx");
    const data = loadRecords();
    const wb = XLSX.utils.book_new();
    
    const ws = XLSX.utils.json_to_sheet(data.records.map(r => ({
      "№": r.num || "",
      "Сегмент": r.segment || "",
      "Область": r.region || "",
      "Район": r.district || "",
      "Населенный пункт": r.settlement || "",
      "Адрес": r.address || "",
      "Наименование клиента": r.clientName || "",
      "Вид деятельности": r.activity || "",
      "Тех. возможность": r.techPossibility || "",
      "Статус строительства": r.constructionStatus || "",
      "Начало строительства": r.constructionStart || "",
      "Сроки завершения": r.constructionEnd || "",
      "Примечание": r.note || "",
      "№ устройства": r.deviceNum || "",
      "Статус подключения": r.connectionStatus || "",
      "Дата подключения": r.connectionDate || "",
      "Тарифный план": r.tariff || "",
      "ARPU (тыс. тг)": r.arpu || ""
    })));
    
    XLSX.utils.book_append_sheet(wb, ws, "Все записи");
    
    const regions = [...new Set(data.records.map(r => r.region).filter(Boolean))];
    regions.forEach(region => {
      const regionData = data.records.filter(r => r.region === region);
      const regionWs = XLSX.utils.json_to_sheet(regionData.map(r => ({
        "№": r.num || "",
        "Сегмент": r.segment || "",
        "Район": r.district || "",
        "Населенный пункт": r.settlement || "",
        "Адрес": r.address || "",
        "Наименование клиента": r.clientName || "",
        "Вид деятельности": r.activity || "",
        "Тех. возможность": r.techPossibility || "",
        "Статус строительства": r.constructionStatus || "",
        "Начало строительства": r.constructionStart || "",
        "Сроки завершения": r.constructionEnd || "",
        "Примечание": r.note || "",
        "№ устройства": r.deviceNum || "",
        "Статус подключения": r.connectionStatus || "",
        "Дата подключения": r.connectionDate || "",
        "Тарифный план": r.tariff || "",
        "ARPU (тыс. тг)": r.arpu || ""
      })));
      XLSX.utils.book_append_sheet(wb, regionWs, region.slice(0, 31));
    });
    
    const buffer = XLSX.write(wb, { type: "buffer", bookType: "xlsx" });
    res.writeHead(200, {
      "Content-Type": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
      "Content-Disposition": "attachment; filename=clients.xlsx"
    });
    return res.end(buffer);
  }

  // Static files
  let file = url === "/" ? "/index.html" : url.split("?")[0];
  const full = path.join(__dirname, file);
  if (full.startsWith(__dirname) && fs.existsSync(full) && fs.statSync(full).isFile()) {
    const ext = path.extname(full);
    const type = mime[ext] || "text/plain";
    res.writeHead(200, { "Content-Type": type });
    return res.end(fs.readFileSync(full));
  }
  
  res.writeHead(404, { "Content-Type": "text/plain" });
  res.end("Not found");
}).listen(PORT, () => console.log("Сервер запущен на порту " + PORT));