text: #
  # Copyright (c) 2019 Ryan Murray.
  #
  # This file is part of Dremio Client
  # (see https://github.com/rymurr/dremio_client).
  #
  # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #   http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing,
  # software distributed under the License is distributed on an
  # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, either express or implied.  See the License for the
  # specific language governing permissions and limitations
  # under the License.
  #
  
  
  try:
      import pyarrow as pa
      from pyarrow import flight
      from .flight_auth import HttpDremioClientAuthHandler
      from pyarrow.compat import tobytes
  
      def connect(hostname='localhost', port=47470,
                  username='dremio', password='dremio123', tls_root_certs_filename=None):
          """
          Connect to and authenticate against Dremio's arrow flight server. Auth is skipped if username is None
  
          :param hostname: Dremio coordinator hostname
          :param port: Dremio coordinator port
          :param username: Username on Dremio
          :param password: Password on Dremio
          :param tls_root_certs_filename: use ssl to connect with root certs from filename
          :return: arrow flight client
          """
          if tls_root_certs_filename:
              with open(tls_root_certs_filename) as f:
                  tls_root_certs = f.read()
              location = 'grpc+tls://{}:{}'.format(hostname, port)
              c = flight.FlightClient(location, tls_root_certs=tls_root_certs)
          else:
              location = 'grpc+tcp://{}:{}'.format(hostname, port)
              c = flight.FlightClient(location)
          if username:
              c.authenticate(HttpDremioClientAuthHandler(
                  username, password if password else ''))
          return c
  
      def query(sql, client=None, hostname='localhost', port=47470,
                username='dremio', password='dremio123', pandas=True, tls_root_certs_filename=False):
          """
          Run an sql query against Dremio and return a pandas dataframe or arrow table
  
          Either host,port,user,pass tuple or a pre-connected client should be supplied. Not both
  
          :param sql: sql query to execute on dremio
          :param client: pre-connected client (optional)
          :param hostname: Dremio coordinator hostname (optional)
          :param port: Dremio coordinator port (optional)
          :param username: Username on Dremio (optional)
          :param password: Password on Dremio (optional)
          :param pandas: return a pandas dataframe (default) or an arrow table
          :param tls_root_certs_filename: use ssl to connect with root certs from filename
          :return:
          """
          if not client:
              client = connect(hostname, port, username, password, tls_root_certs_filename)
  
          info = client.get_flight_info(flight.FlightDescriptor.for_command(tobytes(sql)))
          reader = client.do_get(info.endpoints[0].ticket)
          batches = []
          while True:
              try:
                  batch, _ = reader.read_chunk()
                  batches.append(batch)
              except StopIteration:
                  break
          data = pa.Table.from_batches(batches)
          if pandas:
              return data.to_pandas()
          else:
              return data
  
  except ImportError:
      def connect(*args, **kwargs):
          raise NotImplementedError("Python Flight bindings require Python 3 and pyarrow > 0.14.0")
  
      def query(*args, **kwargs):
          raise NotImplementedError("Python Flight bindings require Python 3 and pyarrow > 0.14.0")
  