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 readItems() {
  try { return JSON.parse(fs.readFileSync(DATA, "utf8")); } catch (_) { return []; }
}
function writeItems(items) {
  fs.writeFileSync(DATA, JSON.stringify(items, 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) => {
  const url = req.url.split("?")[0];
  
  // CORS headers
  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();
  }
  
  // API: get all items
  if (req.method === "GET" && url === "/api/items") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(readItems()));
  }
  
  // API: add single item
  if (req.method === "POST" && url === "/api/items") {
    const data = await body(req);
    const items = readItems();
    
    // If data is array, replace all items
    if (Array.isArray(data)) {
      writeItems(data);
    } else {
      // If data is single item, add it
      const newItem = { id: Date.now(), ...data };
      items.push(newItem);
      writeItems(items);
    }
    
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }
  
  // Static files
  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" : ext === ".svg" ? "image/svg+xml" : "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));