# Copyright 2016 Google Inc.
#
# Licensed 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.

import shutil
from mobly.controllers import sniffer
from mobly.controllers.sniffer_lib.local import local_base


class Sniffer(local_base.SnifferLocalBase):
  """This class defines a sniffer which uses tshark as its back-end
    """

  def __init__(self, config_path, logger, base_configs=None):
    """See base class documentation
        """
    self._executable_path = None

    super().__init__(config_path, logger, base_configs=base_configs)

    self._executable_path = (shutil.which("tshark") or
                             shutil.which("/usr/local/bin/tshark"))
    if self._executable_path is None:
      raise sniffer.SnifferError("Cannot find a path to the 'tshark' "
                                 "executable (or to '/usr/local/bin/tshark')")

  def get_descriptor(self):
    """See base class documentation
        """
    return "local-tshark-{}-ch{}".format(self._interface)

  def get_subtype(self):
    """See base class documentation
        """
    return "tshark"

  def _get_command_line(self,
                        additional_args=None,
                        duration=None,
                        packet_count=None):
    cmd = "{} -i {} -w {}".format(self._executable_path, self._interface,
                                  self._temp_capture_file_path)
    if duration is not None:
      cmd = "{} -a duration:{}".format(cmd, duration)
    if packet_count is not None:
      cmd = "{} -c {}".format(cmd, packet_count)
    if additional_args is not None:
      cmd = "{} {}".format(cmd, additional_args)
    return cmd