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 { instructions: [], users: [], 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({}); } });
  });
}

function updateStatuses(instructions) {
  const today = new Date().toISOString().slice(0, 10);
  let changed = false;
  instructions.forEach(inst => {
    if (inst.status !== "Выполнено" && inst.planDate < today) {
      inst.status = "Просрочено";
      changed = true;
    }
  });
  return changed;
}

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 поручения
  if (req.method === "GET" && url === "/api/instructions") {
    const data = readData();
    const changed = updateStatuses(data.instructions);
    if (changed) writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(data.instructions));
  }

  // API: Получить одно поручение по ID
  if (req.method === "GET" && url.startsWith("/api/instructions/")) {
    const id = parseInt(url.split("/")[3]);
    const data = readData();
    const inst = data.instructions.find(i => i.id === id);
    if (!inst) {
      res.writeHead(404);
      return res.end("Not found");
    }
    updateStatuses(data.instructions);
    if (data.instructions.find(i => i.id === id)?.status === "Просрочено" && inst.status !== "Просрочено") {
      inst.status = "Просрочено";
    }
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(inst));
  }

  // API: Создать поручение
  if (req.method === "POST" && url === "/api/instructions") {
    const data = readData();
    const inst = await body(req);
    inst.id = Date.now();
    inst.status = inst.status || "В работе";
    inst.answers = inst.answers || [];
    inst.history = inst.history || [{ date: new Date().toISOString().slice(0, 10), user: inst.rm || "Пользователь", field: "Создано", newValue: "-" }];
    inst.attachments = inst.attachments || [];
    data.instructions.push(inst);
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true, id: inst.id }));
  }

  // API: Обновить поручение
  if (req.method === "PUT" && url.startsWith("/api/instructions/")) {
    const id = parseInt(url.split("/")[3]);
    const data = readData();
    const idx = data.instructions.findIndex(i => i.id === id);
    if (idx === -1) {
      res.writeHead(404);
      return res.end("Not found");
    }
    const updates = await body(req);
    const old = data.instructions[idx];
    
    // Обновляем поля
    ["title", "status", "issueDate", "planDate", "factDate", "note", "rm", "delegate"].forEach(field => {
      if (updates[field] !== undefined && updates[field] !== old[field]) {
        data.instructions[idx][field] = updates[field];
        if (!updates._skipLog) {
          data.instructions[idx].history.push({
            date: new Date().toISOString().slice(0, 10),
            user: updates.user || "Пользователь",
            field: field === "rm" ? "РМ" : field === "delegate" ? "Исполнитель" : field,
            newValue: String(updates[field])
          });
        }
      }
    });

    if (updates.answer) {
      data.instructions[idx].answers.push({
        date: new Date().toISOString().slice(0, 10),
        text: updates.answer.text,
        author: updates.answer.author
      });
    }

    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: Удалить поручение
  if (req.method === "DELETE" && url.startsWith("/api/instructions/")) {
    const id = parseInt(url.split("/")[3]);
    const data = readData();
    const idx = data.instructions.findIndex(i => i.id === id);
    if (idx === -1) {
      res.writeHead(404);
      return res.end("Not found");
    }
    const removed = data.instructions.splice(idx, 1)[0];
    data.log.push({ date: new Date().toISOString(), action: "delete", instruction: removed.title, user: "Пользователь" });
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

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

  // API: Логин
  if (req.method === "POST" && url === "/api/login") {
    try {
      const data = readData();
      const creds = await body(req);
      const login = creds.login;
      const password = creds.password;
      const user = data.users.find(u => u.login === login && u.password === password);
      if (!user) {
        res.writeHead(401, { "Content-Type": "application/json" });
        return res.end(JSON.stringify({ ok: false, error: "Неверный логин или пароль" }));
      }
      res.writeHead(200, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: true, user: { login: user.login, name: user.name, role: user.role } }));
    } catch (e) {
      res.writeHead(500, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: false, error: "Ошибка сервера: " + e.message }));
    }
  }

  // API: Logout (просто для вида)
  if (req.method === "POST" && url === "/api/logout") {
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify({ ok: true }));
  }

  // API: Выгрузка в CSV (Excel)
  if (req.method === "GET" && url === "/api/export") {
    const data = readData();
    updateStatuses(data.instructions);
    const head = ["ID;Поручение;Статус;Дата выдачи;Плановый срок;Фактический срок;РМ;Исполнитель;Примечание"];
    const body = data.instructions.map(i => 
      [i.id, `"${(i.title||"").replace(/"/g, '""')}"`, i.status, i.issueDate, i.planDate, i.factDate || "", i.rm || "", i.delegate || "", `"${(i.note||"").replace(/"/g, '""')}"`].join(";")
    );
    const csv = "\uFEFF" + [head, ...body].join("\n");
    res.writeHead(200, { 
      "Content-Type": "text/csv; charset=utf-8",
      "Content-Disposition": "attachment; filename=otchet.csv"
    });
    return res.end(csv);
  }

  // Статика: index.html / registry.html / card.html / style.css / script.js
  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" : "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));