###############################################################################
# Copyright (c) 2017 Koren Lev (Cisco Systems), Yaron Yogev (Cisco Systems)   #
# and others                                                                  #
#                                                                             #
# All rights reserved. This program and the accompanying materials            #
# are made available under the terms of the Apache License, Version 2.0       #
# which accompanies this distribution, and is available at                    #
# http://www.apache.org/licenses/LICENSE-2.0                                  #
###############################################################################
import os

import paramiko

from utils.binary_converter import BinaryConverter
from discover.scan_error import ScanError

class SshError(Exception):
    pass

class SshConnection(BinaryConverter):
    connections = {}

    max_call_count_per_con = 100
    timeout = 15  # timeout for exec in seconds

    DEFAULT_PORT = 22

    def __init__(self, _host: str, _user: str, _pwd: str=None, _key: str = None,
                 _port: int = None,  _call_count_limit: int=None,
                 for_sftp: bool = False):
        super().__init__()
        self.host = _host
        self.ssh_client = None
        self.ftp = None
        self.for_sftp = for_sftp
        self.key = _key
        self.port = _port
        self.user = _user
        self.pwd = _pwd
        self.check_definitions()
        self.fetched_host_details = False
        self.call_count = 0
        self.call_count_limit = 0 if for_sftp \
            else (SshConnection.max_call_count_per_con
                  if _call_count_limit is None else _call_count_limit)
        self.connections[self.get_connection_key(_host, for_sftp)] = self

    def check_definitions(self):
        if not self.host:
            raise ValueError('Missing definition of host for CLI access')
        if not self.user:
            raise ValueError('Missing definition of user ' +
                             'for CLI access to host {}'.format(self.host))
        if self.key and not os.path.exists(self.key):
            raise ValueError('Key file not found: ' + self.key)
        if not self.key and not self.pwd:
            raise ValueError('Must specify key or password ' +
                             'for CLI access to host {}'.format(self.host))

    @staticmethod
    def get_ssh(host, _for_sftp=False):
        return SshConnection.get_connection(host, for_sftp=_for_sftp)

    @staticmethod
    def get_connection_key(host, for_sftp=False):
        key = ('sftp-' if for_sftp else '') + host
        return key

    @staticmethod
    def get_connection(host, for_sftp=False):
        key = SshConnection.get_connection_key(host, for_sftp)
        return SshConnection.connections.get(key)

    def disconnect(self):