/**
 * 认证工具 - 获取 MQTT 凭证
 */
const storage = require('./storage.js');

/**
 * 生成 MQTT clientId
 * 格式：S&{设备编号}&{产品ID}&{用户ID}
 * @param {string} serialNumber - 设备编号
 * @param {number|string} productId - 产品ID
 * @param {number|string} userId - 用户ID
 * @returns {string}
 */
function generateClientId(serialNumber, productId, userId) {
  return `S&${serialNumber}&${productId}&${userId}`;
}

/**
 * 获取 MQTT 连接凭证
 * @param {string} serialNumber - 设备编号
 * @param {number|string} productId - 产品ID
 * @param {string} productSecret - 产品密钥
 * @returns {Object|null} { clientId, username, password }
 */
function getMqttCredentials(serialNumber, productId, productSecret) {
  const userInfo = storage.getUserInfo();
  if (!userInfo || !userInfo.userId) {
    console.error('[Auth] 未登录，无法获取 MQTT 凭证');
    return null;
  }

  const userId = userInfo.userId;
  const clientId = generateClientId(serialNumber, productId, userId);

  return {
    clientId: clientId,
    username: serialNumber,
    password: productSecret,
  };
}

/**
 * 构建测点数据上报 Topic（蓝牙网关测点链路）
 * 格式：/{productId}/{serialNumber}/{measurePointId}/measure/post
 * @param {number|string} productId - 产品ID
 * @param {string} serialNumber - 设备编号
 * @param {string} measurePointId - 测点唯一识别号
 * @returns {string}
 */
function buildMeasurePostTopic(productId, serialNumber, measurePointId) {
  return `/${productId}/${serialNumber}/${measurePointId}/measure/post`;
}

/**
 * 构建属性上报 Topic
 * 格式：/{productId}/{serialNumber}/property/post
 * @param {number|string} productId - 产品ID
 * @param {string} serialNumber - 设备编号
 * @returns {string}
 */
function buildPropertyPostTopic(productId, serialNumber) {
  return `/${productId}/${serialNumber}/property/post`;
}

/**
 * 构建功能下发 Topic
 * 格式：/{productId}/{serialNumber}/function/get
 * @param {number|string} productId - 产品ID
 * @param {string} serialNumber - 设备编号
 * @returns {string}
 */
function buildFunctionGetTopic(productId, serialNumber) {
  return `/${productId}/${serialNumber}/function/get`;
}

/**
 * 构建属性读取 Topic
 * 格式：/{productId}/{serialNumber}/property/get
 * @param {number|string} productId - 产品ID
 * @param {string} serialNumber - 设备编号
 * @returns {string}
 */
function buildPropertyGetTopic(productId, serialNumber) {
  return `/${productId}/${serialNumber}/property/get`;
}

/**
 * 检查登录状态
 * @returns {boolean}
 */
function checkLoginStatus() {
  const token = storage.getToken();
  const userInfo = storage.getUserInfo();
  return !!(token && userInfo && userInfo.userId);
}

/**
 * 获取当前用户ID
 * @returns {number|null}
 */
function getCurrentUserId() {
  const userInfo = storage.getUserInfo();
  return userInfo ? userInfo.userId : null;
}

module.exports = {
  generateClientId,
  getMqttCredentials,
  buildMeasurePostTopic,
  buildPropertyPostTopic,
  buildFunctionGetTopic,
  buildPropertyGetTopic,
  checkLoginStatus,
  getCurrentUserId,
};