from paramiko import SSHClient, AutoAddPolicy
from paramiko.ssh_exception import AuthenticationException
from getpass import getpass


class SshClient(object):
    '''
    The Sshclient class wraps some basic
    paramiko.SSHClient functionality

    Attributes:
        host(str): remote host name
        user(str): login user name
        password(str): login user password
        connection(object): the wrapped paramiko.SSHClient
            object or None if the connection is not successful
    '''


    def __init__(self, host, user, pword):
        '''
        The class constructor.
        self.connection is intialized to a paramiko.SSHClient
        instance or None if the connection is not successful.

        Args:
            host(str): remote host name
            user(str): login user name
            pword(str): login user password
        '''
        self.host = host
        self.user = user
        self.password = pword
        self.connection = None

        try:
            self.connection = SSHClient()
            self.connection.set_missing_host_key_policy(AutoAddPolicy())
            self.connection.connect(hostname=host, username=user, password=pword)

        except AuthenticationException as exception:
            print(exception.args)
            self.connection.close()
            self.connection = None


    def execute(self, cmd):
        '''
        Executes a command on the remote host.

        Args:
            cmd(str): the command to be executed

        Returns:
            a dictionary containing the out,
            err and retval keys.
        '''

        stdin, stdout, stderr = self.connection.exec_command(cmd)

        return {'out': stdout.readlines(),
                'err' : stderr.readlines(),
                'retval': stdout.channel.recv_exit_status()}


    def close(self):
        '''
        Closes the connection.
        '''

        if not self.connection is None:
            self.connection.close()
            self.connection = None



if __name__ == '__main__':

    host = input('Remote host name: ')
    user = input('User name: ')
    pword = getpass()

    # connects to the remote client
    # using the given credentials

    try:
        client = SshClient(host, user, pword)
    except exception:
        print(exception.args)

    # if the connection is successful
    # create a directory on the remote host
    # if it does not exist

    if not client.connection is None:

        dir_name = 'my-files'
        list_dirs = 'ls'
        mkdir = 'mkdir ' + dir_name
        msg_dir_exists = 'directory ' + dir_name + ' exists'

        ret = client.execute(list_dirs)

        success = ret['retval'] == 0
        dir_exists = any(dir_name in s for s in ret['out'])

        if success and not dir_exists:
            ret = client.execute(mkdir)
            print(ret['retval'])
        else:
            print(msg_dir_exists)

        client.close()