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

const PORT = process.env.PORT || 3000;
const DATA_FILE = path.join(__dirname, 'data.json');

function readData() {
  try { return JSON.parse(fs.readFileSync(DATA_FILE, 'utf8')); }
  catch (_) { return []; }
}
function writeData(arr) { fs.writeFileSync(DATA_FILE, JSON.stringify(arr, null, 2)); }

// Mock functions – replace with real integrations later
function extractRequest(reqBody) {
  // Expect fields: initiator, object, area, termMonths, price (optional)
  return reqBody;
}
function getTariffFromSAP(object) {
  // Mock: return 4800 per m2
  return 4800;
}
function generateContract(data) {
  const { initiator, object, area, termMonths, price } = data;
  const total = area * price * termMonths;
  return `Договор аренды\nСтороны: ${initiator} и ОЦО ЮС\nОбъект: ${object}\nПлощадь: ${area} м²\nСрок: ${termMonths} мес.\nТариф: ${price} ₸/м²\nСумма: ${total} ₸`;
}
function checkCompliance(contract, tariff) {
  const flags = [];
  // Simple rule: price must not be lower than tariff
  const priceMatch = contract.match(/Тариф: (\d+) /);
  if (priceMatch && Number(priceMatch[1]) < tariff) {
    flags.push({ type: 'tariff', message: `Тариф ниже актуального (${priceMatch[1]} < ${tariff})` });
  }
  // Add more checks later
  return flags;
}
function compareWithCounterparty(version) {
  // Mock: assume two deviations
  return [{ clause: 'Пункт 3', diff: 'Изменена площадь' }, { clause: 'Пункт 7', diff: 'Срок аренды 12 мес → 24 мес' }];
}

const server = http.createServer(async (req, res) => {
  const url = req.url.split('?')[0];
  // API: create contract from Lotus request (mocked POST /api/contract)
  if (req.method === 'POST' && url === '/api/contract') {
    let body = '';
    req.on('data', chunk => body += chunk);
    req.on('end', () => {
      try {
        const json = JSON.parse(body);
        const requestData = extractRequest(json);
        // validate required fields
        const missing = [];
        ['initiator','object','area','termMonths'].forEach(f => { if (!requestData[f]) missing.push(f); });
        if (missing.length) {
          res.writeHead(400, {'Content-Type':'application/json'});
          return res.end(JSON.stringify({error:'Missing fields', missing}));
        }
        // price from request or tariff
        const tariff = getTariffFromSAP(requestData.object);
        const price = requestData.price || tariff;
        const contract = generateContract({ ...requestData, price });
        const flags = checkCompliance(contract, tariff);
        const deviations = requestData.counterpartyVersion ? compareWithCounterparty(requestData.counterpartyVersion) : [];
        const record = { id: Date.now(), request: requestData, contract, tariff, price, flags, deviations };
        const data = readData();
        data.push(record);
        writeData(data);
        res.writeHead(200, {'Content-Type':'application/json'});
        res.end(JSON.stringify({ok:true, record}));
      } catch (e) {
        res.writeHead(500, {'Content-Type':'application/json'});
        res.end(JSON.stringify({error:e.message}));
      }
    });
    return;
  }
  // Serve static files
  let filePath = url === '/' ? '/index.html' : url;
  const fullPath = path.join(__dirname, filePath);
  if (fs.existsSync(fullPath) && fs.statSync(fullPath).isFile()) {
    const ext = path.extname(fullPath);
    const mime = {
      '.html':'text/html',
      '.css':'text/css',
      '.js':'application/javascript',
      '.json':'application/json'
    }[ext] || 'application/octet-stream';
    res.writeHead(200, {'Content-Type': mime + '; charset=utf-8'});
    res.end(fs.readFileSync(fullPath));
    return;
  }
  res.writeHead(404); res.end('Not found');
});

server.listen(PORT, () => console.log('Server listening on port ' + PORT));