# 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 tcpdump 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("tcpdump")
        if self._executable_path is None:
            raise sniffer.SnifferError(
                "Cannot find a path to the 'tcpdump' executable")

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

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

    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 packet_count is not None:
            cmd = "{} -c {}".format(cmd, packet_count)
        if additional_args is not None:
            cmd = "{} {}".format(cmd, additional_args)
        return cmd