const mqtt = require('mqtt');

function formatUploadTime(date = new Date()) {
  const year = date.getFullYear();
  const month = String(date.getMonth() + 1).padStart(2, '0');
  const day = String(date.getDate()).padStart(2, '0');
  const hour = String(date.getHours()).padStart(2, '0');
  const minute = String(date.getMinutes()).padStart(2, '0');
  const second = String(date.getSeconds()).padStart(2, '0');
  return `${year}-${month}-${day} ${hour}:${minute}:${second}`;
}

class MqttService {
  constructor(config = {}, logger = console) {
    this.config = config;
    this.logger = logger;
    this.client = null;
    this.connected = false;
  }

  getBrokerUrl() {
    if (this.config.brokerUrl) {
      return this.config.brokerUrl;
    }

    return `${this.config.protocol || 'mqtt'}://${this.config.host}:${this.config.port}`;
  }

  getClientId() {
    if (this.config.clientId) {
      return this.config.clientId;
    }

    const hostName = String(this.config.host || 'broker').replace(/[^a-zA-Z0-9]/g, '_');
    return `jh2028_gateway_${hostName}`;
  }

  buildTopic(device) {
    if (this.config.topicTemplate) {
      return this.config.topicTemplate
        .replace('{deviceId}', device.deviceId)
        .replace('{ip}', device.ip)
        .replace('{name}', device.name || device.deviceId);
    }

    return `${this.config.defaultTopicPrefix || 'device'}/${device.deviceId}`;
  }

  buildPayload(message) {
    return {
      ...(message || {}),
      suedtime: formatUploadTime(),
    };
  }

  start() {
    const brokerUrl = this.getBrokerUrl();
    const clientId = this.getClientId();

    this.logger.info(`[MQTT] 正在连接 服务地址=${brokerUrl} 客户端ID=${clientId}`);
    this.client = mqtt.connect(brokerUrl, {
      clientId,
      username: this.config.username || undefined,
      password: this.config.password || undefined,
      reconnectPeriod: this.config.reconnectPeriod || 5000,
      connectTimeout: this.config.connectTimeoutMs || 30000,
    });

    this.client.on('connect', () => {
      this.connected = true;
      this.logger.info(`[MQTT] 已连接 服务地址=${brokerUrl}`);
    });

    this.client.on('reconnect', () => {
      this.connected = false;
      this.logger.warn('[MQTT] 正在重连');
    });

    this.client.on('close', () => {
      this.connected = false;
      this.logger.warn('[MQTT] 连接已关闭');
    });

    this.client.on('error', (error) => {
      this.logger.error(`[MQTT] 连接异常: ${error.message}`);
    });
  }

  publish(device, message) {
    if (!this.client) {
      return Promise.reject(new Error('MQTT service is not started'));
    }

    const topic = this.buildTopic(device);
    const payloadObject = this.buildPayload(message);
    const payload = JSON.stringify(payloadObject);

    if (!this.connected) {
      this.logger.warn(`[MQTT] 当前未连接，消息将进入客户端队列 主题=${topic}`);
    }

    return new Promise((resolve, reject) => {
      this.client.publish(topic, payload, {
        qos: this.config.qos || 0,
        retain: Boolean(this.config.retain),
      }, (error) => {
        if (error) {
          this.logger.error(`[MQTT] 发布失败 主题=${topic}: ${error.message}`);
          reject(error);
          return;
        }

        this.logger.info(`[MQTT] 发布成功 主题=${topic} 数据=${payload}`);
        resolve({ ok: true, topic, payload: payloadObject });
      });
    });
  }

  async stop() {
    if (!this.client) {
      return;
    }

    this.logger.info('[MQTT] 正在停止');
    await new Promise((resolve) => {
      this.client.end(false, resolve);
    });
    this.connected = false;
    this.client = null;
    this.logger.info('[MQTT] 已停止');
  }
}

module.exports = {
  MqttService,
  formatUploadTime,
};