const axios = require('axios');

let accessTokenCache = {
  token: null,
  expiresAt: null
};

class WechatSubscribeService {
  static async getAccessToken() {
    const now = Date.now();
    
    if (accessTokenCache.token && accessTokenCache.expiresAt && now < accessTokenCache.expiresAt) {
      return accessTokenCache.token;
    }
    
    const appId = process.env.WECHAT_APPID;
    const appSecret = process.env.WECHAT_APPSECRET;
    
    const url = `https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=${appId}&secret=${appSecret}`;
    
    try {
      const response = await axios.get(url);
      const { access_token, expires_in } = response.data;
      
      accessTokenCache = {
        token: access_token,
        expiresAt: now + (expires_in - 300) * 1000
      };
      
      return access_token;
    } catch (error) {
      console.error('获取微信 access_token 失败:', error.response?.data || error.message);
      throw new Error('获取微信 access_token 失败');
    }
  }
  
  static async sendSubscribeMessage({ touser, templateId, page, data }) {
    const accessToken = await this.getAccessToken();
    const url = `https://api.weixin.qq.com/cgi-bin/message/subscribe/send?access_token=${accessToken}`;
    
    const requestData = {
      touser,
      template_id: templateId,
      page: page || 'pages/index/index',
      data
    };
    
    try {
      const response = await axios.post(url, requestData);
      
      if (response.data.errcode === 0) {
        return { success: true, messageId: response.data.msgid };
      } else {
        console.error('发送订阅消息失败:', response.data);
        return { 
          success: false, 
          errcode: response.data.errcode, 
          errmsg: response.data.errmsg 
        };
      }
    } catch (error) {
      console.error('发送订阅消息异常:', error.response?.data || error.message);
      return { success: false, errmsg: error.message };
    }
  }
  
  static async sendVersionUpdateMessage({ openid, templateId, character_string1, thing3, thing6 }) {
    const data = {
      character_string1: { value: character_string1 },
      thing3: { value: thing3 }
    };
    
    if (thing6) {
      data.thing6 = { value: thing6 };
    }
    
    return this.sendSubscribeMessage({
      touser: openid,
      templateId,
      page: 'pages/index/index',
      data
    });
  }
  
  static async sendExpiryReminderMessage({ openid, templateId, thing1, thing2, phrase3 }) {
    const data = {
      thing1: { value: thing1 },
      thing2: { value: thing2 },
      phrase3: { value: phrase3 }
    };
    
    return this.sendSubscribeMessage({
      touser: openid,
      templateId,
      page: 'pages/profile/profile',
      data
    });
  }
}

module.exports = WechatSubscribeService;