const http = require("http");
const fs = require("fs");
const path = require("path");

const PORT = process.env.PORT;
const DATA = path.join(__dirname, "data.json");

function readData() {
  try { return JSON.parse(fs.readFileSync(DATA, "utf8")); } catch (_) { return { classes: [], reminders: [] }; }
}
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: получить все кружки
  if (req.method === "GET" && url === "/api/classes") {
    const data = readData();
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(data.classes || []));
  }

  // API: добавить кружок
  if (req.method === "POST" && url === "/api/classes") {
    const item = await body(req);
    const data = readData();
    if (!data.classes) data.classes = [];
    data.classes.push({ id: Date.now(), ...item });
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: обновить кружок
  if (req.method === "PUT" && url === "/api/classes") {
    const item = await body(req);
    const data = readData();
    const idx = (data.classes || []).findIndex(c => c.id === item.id);
    if (idx >= 0) {
      data.classes[idx] = { ...data.classes[idx], ...item };
      writeData(data);
    }
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: удалить кружок
  if (req.method === "DELETE" && url === "/api/classes") {
    const { id } = await body(req);
    const data = readData();
    data.classes = (data.classes || []).filter(c => c.id !== id);
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

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

  // API: добавить напоминание
  if (req.method === "POST" && url === "/api/reminders") {
    const item = await body(req);
    const data = readData();
    if (!data.reminders) data.reminders = [];
    data.reminders.push({ id: Date.now(), ...item });
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: удалить напоминание
  if (req.method === "DELETE" && url === "/api/reminders") {
    const { id } = await body(req);
    const data = readData();
    data.reminders = (data.reminders || []).filter(r => r.id !== id);
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // 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 запущен на порту " + PORT));