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: [], stats: { total: 0, active: 0, completed: 0 } }; }
}
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");
  res.setHeader("Access-Control-Allow-Headers", "Content-Type");
  
  if (req.method === "OPTIONS") {
    res.writeHead(200);
    return res.end();
  }

  if (req.method === "GET" && req.url === "/api/data") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(readData()));
  }
  
  if (req.method === "POST" && req.url === "/api/data") {
    const data = readData();
    const item = await body(req);
    item.id = Date.now();
    item.createdAt = new Date().toISOString().slice(0, 10);
    data.items.push(item);
    data.stats.total = data.items.length;
    data.stats.active = data.items.filter(i => i.status === "active").length;
    data.stats.completed = data.items.filter(i => i.status === "completed").length;
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true, item }));
  }
  
  if (req.method === "PUT" && req.url.startsWith("/api/data/")) {
    const id = parseInt(req.url.split("/").pop());
    const data = readData();
    const idx = data.items.findIndex(i => i.id === id);
    if (idx !== -1) {
      const update = await body(req);
      data.items[idx] = { ...data.items[idx], ...update };
      data.stats.active = data.items.filter(i => i.status === "active").length;
      data.stats.completed = data.items.filter(i => i.status === "completed").length;
      writeData(data);
      res.writeHead(200, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: true }));
    }
    res.writeHead(404, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ error: "Not found" }));
  }
  
  if (req.method === "DELETE" && req.url.startsWith("/api/data/")) {
    const id = parseInt(req.url.split("/").pop());
    const data = readData();
    data.items = data.items.filter(i => i.id !== id);
    data.stats.total = data.items.length;
    data.stats.active = data.items.filter(i => i.status === "active").length;
    data.stats.completed = data.items.filter(i => i.status === "completed").length;
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  let file = req.url === "/" ? "/index.html" : req.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 = 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, { "Content-Type": "text/html" });
  res.end("Not found");
}).listen(PORT, () => console.log("Dashboard running on port " + PORT));