import paramiko
from typing import Any, Dict


def open_ssh_client(dev):
    """
    This function is used to return a new paramiko SSH client that uses the same login method &
    credentials as the original Junos device instance.  The purpose of this function is to provide
    the caller with the complete paramiko library of functionality based on the returned SSH client.
    :param dev: jnpr.junos.Device instance
    :return: paramiko.SSHClient instance
    """

    # note, the following code was extracted from the scp module, and then the scp module
    # was refactored to use this function
    ssh_client = paramiko.SSHClient()
    ssh_client.load_system_host_keys()
    ssh_client.set_missing_host_key_policy(paramiko.AutoAddPolicy())

    # use junos._hostname since this will be correct if we are going
    # through a jumphost.

    config: Dict[str, Any] = {}
    kwargs: Dict[str, Any] = {}
    ssh_config = getattr(dev, "_sshconf_path")
    if ssh_config:
        ssh_cfg_obj = paramiko.SSHConfig()
        with open(ssh_config) as open_ssh_config:
            ssh_cfg_obj.parse(open_ssh_config)
        config = ssh_cfg_obj.lookup(dev._hostname)

    sock = None
    proxy_cmd = config.get("proxycommand")
    if proxy_cmd:
        sock = paramiko.proxy.ProxyCommand(proxy_cmd)

    if dev._ssh_private_key_file is not None:
        kwargs["key_filename"] = dev._ssh_private_key_file

    # pick hostname from .ssh config if any
    hostname = config.get("hostname", dev._hostname)

    # Assign the port value
    port = int(dev.port) if dev._port is not None else 22
    port = 22 if hostname == "localhost" or dev._port == 830 else port

    ssh_client.connect(
        hostname=hostname,
        port=port,
        username=dev._auth_user,
        password=dev._auth_password,
        sock=sock,
        **kwargs,
    )
    return ssh_client