#!/usr/bin/env python3

# build-in modules
import argparse
import getpass
import os
from io import StringIO

# opt-in modules
import paramiko
import yaml
from yaml.loader import SafeLoader
from cryptography.hazmat.primitives import serialization as crypto_serialization
from cryptography.hazmat.primitives.asymmetric import ed25519, dsa, rsa, ec
from scp import SCPClient
from paramiko import RSAKey, Ed25519Key, ECDSAKey, DSSKey, PKey, SSHClient


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--host", dest="hostname", required=True, type=str, help="SSH-Server")
    parser.add_argument("--port", dest="port", default=22, type=int, help="SSH-Port")
    parser.add_argument("--username", dest="username", default=getpass.getuser(), type=str, help="Remote Unix User")
    parser.add_argument("--password", dest="password", default=None, type=str, help="Remote password")
    parser.add_argument("--identity-file", dest="identity_file", default=None, type=str, help="Path to private SSH-Key")
    parser.add_argument("--identity-passphrase", dest="identity_passphrase", default=None, type=str, help="Passphrase of the SSH-Key")
    parser.add_argument("--remote-config", dest="remote_config", default="~/.kube/config", type=str, help="Remote kubectl config")
    parser.add_argument("--remote-cluster-name", dest="remote_cluster_name", default="kubernetes", type=str, help="Name of the cluster")
    parser.add_argument("--remote-user-name", dest="remote_user_name", default="kubernetes-admin", type=str, help="Name of the user")
    parser.add_argument("--local-config", dest="local_config", default="~/.kube/config", type=str, help="Local kubectl config")
    parser.add_argument("--local-cluster-name", dest="local_cluster_name", default="kubernetes", type=str, help="Name of the cluster")
    parser.add_argument("--local-user-name", dest="local_user_name", default="kubernetes-admin", type=str, help="Name of the user")
    args = parser.parse_args()

    ssh_client = create_ssh_client(args.hostname, args.port, args.username, args.identity_file, args.identity_passphrase)
    scp_client = SCPClient(ssh_client.get_transport())

    scp_client.get(args.remote_config, local_path="/tmp/admin.config")

    with open("/tmp/admin.config", 'r', encoding="UTF-8") as f:
        remote_config = yaml.load(f, Loader=SafeLoader)

    with open(args.local_config, 'r', encoding="UTF-8") as f:
        local_config = yaml.load(f, Loader=SafeLoader)


    # Remove old objects
    local_config["clusters"] = list(filter(lambda cluster: cluster["name"] != args.local_cluster_name, local_config["clusters"]))
    local_config["users"] = list(filter(lambda user: user["name"] != args.local_user_name, local_config["users"]))

    # Add new objects
    local_config["clusters"] = local_config["clusters"] + list(filter(lambda cluster: cluster["name"] == args.remote_cluster_name, remote_config["clusters"]))
    local_config["users"] = local_config["users"] + list(filter(lambda user: user["name"] == args.remote_user_name, remote_config["users"]))

    # Rename object attributes
    for cluster in list(filter(lambda cluster: cluster["name"] == args.remote_cluster_name, remote_config["clusters"])):
        cluster["name"] = args.local_cluster_name

    for user in list(filter(lambda user: user["name"] == args.remote_user_name, remote_config["users"])):
        user["name"] = args.local_user_name

    # Store new local_config
    with open(args.local_config, 'w', encoding="UTF-8") as f:
        yaml.dump(local_config, f)

def create_ssh_client(hostname: str, port: str, username: str, identity_file: str, identity_passphrase: str) -> SSHClient:
    ssh_client = paramiko.SSHClient()
    ssh_client.set_missing_host_key_policy(paramiko.AutoAddPolicy())

    ssh_private_key = PKey

    if identity_file != None and os.path.isfile(identity_file):
        ssh_private_key_file_obj = open(file=identity_file, mode="r", encoding="UTF-8")
        ssh_private_key = from_private_key(ssh_private_key_file_obj, identity_passphrase)

    ssh_client.connect(username=username, hostname = hostname, port = port, pkey=ssh_private_key, compress=True)

    return ssh_client


def from_private_key(file_obj, password=None) -> PKey:
    private_key = None
    file_bytes = bytes(file_obj.read(), "utf-8")
    try:
        key = crypto_serialization.load_ssh_private_key(
            file_bytes,
            password=password,
        )
        file_obj.seek(0)
    except ValueError:
        key = crypto_serialization.load_pem_private_key(
            file_bytes,
            password=password,
        )
        if password:
            encryption_algorithm = crypto_serialization.BestAvailableEncryption(
                password
            )
        else:
            encryption_algorithm = crypto_serialization.NoEncryption()

        file_obj = StringIO(
            key.private_bytes(
                crypto_serialization.Encoding.PEM,
                crypto_serialization.PrivateFormat.OpenSSH,
                encryption_algorithm,
            ).decode("utf-8")
        )
    if isinstance(key, rsa.RSAPrivateKey):
        private_key = RSAKey.from_private_key(file_obj, password)
    elif isinstance(key, ed25519.Ed25519PrivateKey):
        private_key = Ed25519Key.from_private_key(file_obj, password)
    elif isinstance(key, ec.EllipticCurvePrivateKey):
        private_key = ECDSAKey.from_private_key(file_obj, password)
    elif isinstance(key, dsa.DSAPrivateKey):
        private_key = DSSKey.from_private_key(file_obj, password)
    else:
        raise TypeError
    return private_key

if __name__ == "__main__":
    main()