'use strict';

const { serverTimestamp } = require('./seed');

function readBody(req) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    req.on('data', (chunk) => chunks.push(chunk));
    req.on('end', () => resolve(Buffer.concat(chunks)));
    req.on('error', reject);
  });
}

function sendJson(res, statusCode, body) {
  const responseBody = JSON.stringify(body);
  res.writeHead(statusCode, {
    'Content-Type': 'application/json; charset=utf-8',
    'Content-Length': Buffer.byteLength(responseBody),
  });
  res.end(responseBody);
}

function createJtlPosServer(store, config = {}) {
  const { authToken = process.env.AUTH_TOKEN || '9a2e3036ed9c47e389741d9dbb7590e9' } = config;
  const {
    certificateFingerprint = 'BC2114CF407A42724BEEF417960F76DCBF9DE879',
    certificateSerialNumber = '00BFC8BEACDB981B165210EF111CB9D3',
    serverFingerprint = '39-6D-BD-DE-F3-5C-5A-EA-C2-19-CF-EB-A7-A9-58-2F-20-3F-20-F7-3D-E6-CA-8E-AE-FD-28-30-37-A6-45-AE',
    mandantId = '1',
    mandantName = 'eB-Standard',
    mandantDatabase = 'eazybusiness',
  } = config;

  function buildClientStep1() {
    return {
      authCode: null,
      authToken,
      certificateFingerprint,
      certificateSerialNumber,
      mandantId,
      mandantName: null,
      mandantDatabase: null,
      serverFingerprint,
      name: null,
      serverTimestamp: serverTimestamp(),
    };
  }

  function buildClientStep2(authCode) {
    return {
      authCode,
      authToken,
      certificateFingerprint,
      certificateSerialNumber,
      mandantId,
      mandantName,
      mandantDatabase,
      serverFingerprint: null,
      name: null,
      serverTimestamp: serverTimestamp(),
    };
  }

  async function handle(req, res) {
    const url = new URL(req.url, 'https://localhost');

    const route = (method, pathname) => method === req.method && url.pathname === pathname;

    if (route('GET', '/api/v1/client')) {
      const authCode = url.searchParams.get('authCode') || '';
      const name = url.searchParams.get('name') || 'JTL-POS';
      const state = store.getState();

      // Step 1 — the first 4 digits of a pre-registered 6-digit pairing code.
      if (authCode.length <= 4 && authCode.length > 0) {
        return sendJson(res, 200, buildClientStep1());
      }

      // Step 2 — full 6-digit code must exist in the pending authCodes map.
      if (authCode.length === 6) {
        if (state.authCodes[authCode]) {
          store.dispatch({ type: 'REVOKE_PAIRING_CODE', payload: { code: authCode } });
          store.dispatch({ type: 'REGISTER_DEVICE', payload: { token: authToken, name } });
          return sendJson(res, 200, buildClientStep2(authCode));
        }
        return sendJson(res, 400, { Message: 'Der Authentifizierungscode ist falsch.' });
      }

      return sendJson(res, 400, { Message: 'Keinen passenden Authentifizierungscode gefunden.' });
    }

    if (route('GET', '/api/v1/init')) {
      const params = {
        lastChangedCategory: url.searchParams.get('lastChangedCategory') || '0',
        lastChangedCustomer: url.searchParams.get('lastChangedCustomer') || '0',
        lastChangedCustomerGroup: url.searchParams.get('lastChangedCustomerGroup') || '0',
        lastChangedProduct: url.searchParams.get('lastChangedProduct') || '0',
        lastChangedConfigurationGroup: url.searchParams.get('lastChangedConfigurationGroup') || '0',
        lastChangedConfigurationItem: url.searchParams.get('lastChangedConfigurationItem') || '0',
        lastChangedCompositeProduct: url.searchParams.get('lastChangedCompositeProduct') || '0',
        lastChangedDeletedEntity: url.searchParams.get('lastChangedDeletedEntity') || '0',
      };
      return sendJson(res, 200, store.getInitCounts(params));
    }

    const entityEndpoints = {
      '/api/v1/customergroup': { collection: 'customerGroups', param: 'lastChangedCustomerGroup', limit: '200' },
      '/api/v1/deletedentity': { collection: 'deletedEntities', param: 'lastChangedDeletedEntity', limit: '200' },
      '/api/v1/category': { collection: 'categories', param: 'lastChangedCategory', limit: '20' },
      '/api/v1/customer': { collection: 'customers', param: 'lastChangedCustomer', limit: '20' },
      '/api/v1/product': { collection: 'products', param: 'lastChangedProduct', limit: '20' },
      '/api/v1/productcomposite': { collection: 'productComposites', param: 'lastChangedCompositeProduct', limit: '20' },
    };

    for (const [pathname, { collection, param, limit: defaultLimit }] of Object.entries(entityEndpoints)) {
      if (route('GET', pathname)) {
        const cursor = url.searchParams.get(param) || '0';
        const limit = url.searchParams.get('limit') || defaultLimit;
        const response = store.selectFilteredListFromCollection(collection, cursor, limit);
        return sendJson(res, 200, response);
      }
    }

    return sendJson(res, 404, {
      Message: `No HTTP resource was found that matches the request URI '${url}'.`,
    });
  }

  return async function requestListener(req, res) {
    const body = await readBody(req);
    // Attach raw body for optional logging by the wrapper
    req.rawBody = body;
    try {
      await handle(req, res);
    } catch (err) {
      sendJson(res, 500, { Message: err.message });
    }
  };
}

module.exports = { createJtlPosServer };