Wechat.prototype.uploadTempMaterial = function(type,filepath){
  var that = this;
  var form = { //构造表单
    media:fs.createReadStream(filepath)
  }
  return new Promise(function(resolve,reject){
    that.fetchAccessToken().then(function(data){

      var url = api.uploadMaterial + 'access_token=' + data.access_token + '&type=' + type;
      request({url:url,method:'POST',formData:form,json:true}).then(function(response){
        var _data = response.body;
        if(_data){
          resolve(_data)
        }else{
          throw new Error('upload material failed!');
        }
      }).catch(function(err){
        reject(err);
      });
    });
  });
}

else if(content === '2'){
  var data = yield wechatApi.uploadTempMaterial('image',__dirname+'/public/king.jpg');
  reply = {
    type:'image',
    mediaId:data.media_id
  }
}

Wechat.prototype.uploadPermMaterial = function(type,material){
  var that = this;
  var form = {}
  var uploadUrl = '';
  if(type === 'pic') uploadUrl = api.uploadPermPics;
  if(type === 'other') uploadUrl = api.uploadPermOther;
  if(type === 'news'){
    uploadUrl = api.uploadPermNews;
    form = material
  }else{
    form.media = fs.createReadStream(material);
  }
  return new Promise(function(resolve,reject){
    that.fetchAccessToken().then(function(data){
      var url = uploadUrl + 'access_token=' + data.access_token;
      var opts = {
        method:'POST',
        url:url,
        json:true
      }
      (type == 'news') ? (opts.body = form) : (opts.formData = form); //上传数据的方式不同
      request(opts).then(function(response){
        var _data = response.body;
        if(_data){
          resolve(_data)
        }else{
          throw new Error('upload permanent material failed!');
        }
      }).catch(function(err){
        reject(err);
      });
    });
  });
}

Wechat.prototype.getMaterial = function(mediaId,permanent){
  var that = this;
  var getUrl = permanent ? api.getPermMaterial : api.getTempMaterial;
  return new Promise(function(resolve,reject){
    that.fetchAccessToken().then(function(data){
      var url = getUrl + 'access_token=' + data.access_token;
      if(!permanent) url += '&media_id=' + mediaId;
      resolve(url)
    });
  });
}

Wechat.prototype.delMaterial = function(mediaId){
  var that = this;
  return new Promise(function(resolve,reject){
    that.fetchAccessToken().then(function(data){
      var url = api.delPermMaterial + 'access_token=' + data.access_token;
      var form = {media_id:mediaId}
      request({url:url,method:'POST',formData:form,json:true}).then(function(response){
        var _data = response.body;
        if(_data.errcode === '0'){
          resolve();
        }else{
          throw new Error('delete permanent material failed!');
        }
      }).catch(function(err){
        reject(err);
      });
    });
  });
}