"""
client.py: implementation of the VnodeClient class for issuing commands
over a control channel to the vnoded process running in a network namespace.
The control channel can be accessed via calls using the vcmd shell.
"""

from core import constants, utils


class VnodeClient(object):
    """
    Provides client functionality for interacting with a virtual node.
    """

    def __init__(self, name, ctrlchnlname):
        """
        Create a VnodeClient instance.

        :param str name: name for client
        :param str ctrlchnlname: control channel name
        """
        self.name = name
        self.ctrlchnlname = ctrlchnlname

    def _verify_connection(self):
        """
        Checks that the vcmd client is properly connected.

        :return: nothing
        :raises IOError: when not connected
        """
        if not self.connected():
            raise IOError("vcmd not connected")

    def connected(self):
        """
        Check if node is connected or not.

        :return: True if connected, False otherwise
        :rtype: bool
        """
        return True

    def close(self):
        """
        Close the client connection.

        :return: nothing
        """
        pass

    def _cmd_args(self):
        return [constants.VCMD_BIN, "-c", self.ctrlchnlname, "--"]

    def check_cmd(self, args, wait=True):
        """
        Run command and return exit status and combined stdout and stderr.

        :param list[str]|str args: command to run
        :param bool wait: True to wait for command status, False otherwise
        :return: combined stdout and stderr
        :rtype: str
        :raises core.CoreCommandError: when there is a non-zero exit status
        """
        self._verify_connection()
        args = utils.split_args(args)
        args = self._cmd_args() + args
        return utils.check_cmd(args, wait=wait)

    def termcmdstring(self, sh="/bin/sh"):
        """
        Create a terminal command string.

        :param str sh: shell to execute command in
        :return: str
        """
        return "%s -c %s -- %s" % (constants.VCMD_BIN, self.ctrlchnlname, sh)