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: [] }; }
}
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, PUT, DELETE, 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];

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

  // API: добавить заявку
  if (req.method === "POST" && url === "/api/items") {
    const item = await body(req);
    const data = readData();
    const newItem = {
      id: Date.now(),
      createdAt: new Date().toISOString(),
      status: "новая",
      ...item
    };
    data.items.push(newItem);
    data.log.push({ when: new Date().toISOString(), what: "Добавлена заявка #" + newItem.id, who: item.person || "anon" });
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true, item: newItem }));
  }

  // API: обновить заявку
  if (req.method === "PUT" && url.startsWith("/api/items/")) {
    const id = parseInt(url.split("/")[3]);
    const updates = await body(req);
    const data = readData();
    const idx = data.items.findIndex(i => i.id === id);
    if (idx !== -1) {
      const old = data.items[idx];
      data.items[idx] = { ...old, ...updates };
      data.log.push({ when: new Date().toISOString(), what: "Изменена заявка #" + id, who: updates.person || "anon" });
      writeData(data);
      res.writeHead(200, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: true }));
    }
    res.writeHead(404);
    return res.end(JSON.stringify({ error: "Не найдено" }));
  }

  // API: удалить заявку
  if (req.method === "DELETE" && url.startsWith("/api/items/")) {
    const id = parseInt(url.split("/")[3]);
    const data = readData();
    const item = data.items.find(i => i.id === id);
    data.items = data.items.filter(i => i.id !== id);
    if (item) {
      data.log.push({ when: new Date().toISOString(), what: "Удалена заявка #" + id + " (" + item.object + ")", who: "system" });
    }
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: лог действий
  if (req.method === "GET" && url === "/api/log") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(readData().log.slice(-50)));
  }

  // 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 заявок СТПК запущен на порту " + PORT));