# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2013 IBM Corp.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

import contextlib
import ftplib
import os
import uuid

import paramiko

from nova.openstack.common import log as logging
from nova.openstack.common import processutils
from nova.virt.powervm import constants
from nova.virt.powervm import exception

LOG = logging.getLogger(__name__)


class Connection(object):

    def __init__(self, host, username, password, port=22, keyfile=None):
        self.host = host
        self.username = username
        self.password = password
        self.port = port
        self.keyfile = keyfile


def ssh_connect(connection):
    """Method to connect to remote system using ssh protocol.

    :param connection: a Connection object.
    :returns: paramiko.SSHClient -- an active ssh connection.
    :raises: PowerVMConnectionFailed
    """
    try:
        ssh = paramiko.SSHClient()
        ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        ssh.connect(connection.host,
                    username=connection.username,
                    password=connection.password,
                    port=connection.port,
                    key_filename=connection.keyfile,
                    timeout=constants.POWERVM_CONNECTION_TIMEOUT)

        LOG.debug("SSH connection with %s established successfully." %
                  connection.host)

        # send TCP keepalive packets every 20 seconds
        ssh.get_transport().set_keepalive(20)

        return ssh
    except Exception:
        LOG.exception(_('Connection error connecting PowerVM manager'))
        raise exception.PowerVMConnectionFailed()


def check_connection(ssh, connection):
    """
    Checks the SSH connection to see if the transport is valid.
    If the connection is dead, a new connection is created and returned.

    :param ssh: an existing paramiko.SSHClient connection.
    :param connection: a Connection object.
    :returns: paramiko.SSHClient -- an active ssh connection.
    :raises: PowerVMConnectionFailed -- if the ssh connection fails.
    """
    # if the ssh client is not set or the transport is dead, re-connect
    if (ssh is None or
        ssh.get_transport() is None or
        not ssh.get_transport().is_active()):
            LOG.debug("Connection to host %s will be established." %
                      connection.host)
            ssh = ssh_connect(connection)

    return ssh


def ssh_command_as_root(ssh_connection, cmd, check_exit_code=True):
    """Method to execute remote command as root.

    :param connection: an active paramiko.SSHClient connection.
    :param command: string containing the command to run.
    :returns: Tuple -- a tuple of (stdout, stderr)
    :raises: processutils.ProcessExecutionError
    """
    LOG.debug(_('Running cmd (SSH-as-root): %s') % cmd)
    chan = ssh_connection._transport.open_session()
    # This command is required to be executed
    # in order to become root.
    chan.exec_command('ioscli oem_setup_env')
    bufsize = -1
    stdin = chan.makefile('wb', bufsize)
    stdout = chan.makefile('rb', bufsize)
    stderr = chan.makefile_stderr('rb', bufsize)
    # We run the command and then call 'exit' to exit from
    # super user environment.
    stdin.write('%s\n%s\n' % (cmd, 'exit'))
    stdin.flush()
    exit_status = chan.recv_exit_status()

    # Lets handle the error just like processutils.ssh_execute does.
    if exit_status != -1:
        LOG.debug(_('Result was %s') % exit_status)
        if check_exit_code and exit_status != 0:
            # TODO(mikal): I know this is weird, but it needs to be consistent
            # with processutils.execute. I will move this method to oslo in
            # a later commit.
            raise processutils.ProcessExecutionError(exit_code=exit_status,
                                                     stdout=stdout,
                                                     stderr=stderr,
                                                     cmd=''.join(cmd))

    return (stdout, stderr)


def ftp_put_command(connection, local_path, remote_dir):
    """Method to transfer a file via ftp.

    :param connection: a Connection object.
    :param local_path: path to the local file
    :param remote_dir: path to remote destination
    :raises: PowerVMFileTransferFailed
    """
    try:
        ftp = ftplib.FTP(host=connection.host,
                         user=connection.username,
                         passwd=connection.password)
        ftp.cwd(remote_dir)
        name = os.path.split(local_path)[1]
        f = open(local_path, "rb")
        ftp.storbinary("STOR " + name, f)
        f.close()
        ftp.close()
    except Exception:
        LOG.error(_('File transfer to PowerVM manager failed'))
        raise exception.PowerVMFTPTransferFailed(ftp_cmd='PUT',
                source_path=local_path, dest_path=remote_dir)


def ftp_get_command(connection, remote_path, local_path):
    """Retrieve a file via FTP

    :param connection: a Connection object.
    :param remote_path: path to the remote file
    :param local_path: path to local destination
    :raises: PowerVMFileTransferFailed
    """
    try:
        ftp = ftplib.FTP(host=connection.host,
                         user=connection.username,
                         passwd=connection.password)
        ftp.cwd(os.path.dirname(remote_path))
        name = os.path.basename(remote_path)
        LOG.debug(_("ftp GET %(remote_path)s to: %(local_path)s") % locals())
        with open(local_path, 'w') as ftpfile:
            ftpcmd = 'RETR %s' % name
            ftp.retrbinary(ftpcmd, ftpfile.write)
        ftp.close()
    except Exception:
        LOG.error(_("File transfer from PowerVM manager failed"))
        raise exception.PowerVMFTPTransferFailed(ftp_cmd='GET',
                source_path=remote_path, dest_path=local_path)


def aix_path_join(path_one, path_two):
    """Ensures file path is built correctly for remote UNIX system

    :param path_one: string of the first file path
    :param path_two: string of the second file path
    :returns: a uniform path constructed from both strings
    """
    if path_one.endswith('/'):
        path_one = path_one.rstrip('/')

    if path_two.startswith('/'):
        


    final_path = path_one + '/' + path_two
    return final_path


@contextlib.contextmanager
def vios_to_vios_auth(source, dest, conn_info):
    """Context allowing for SSH between VIOS partitions

    This context will build an SSH key on the source host, put the key
    into the authorized_keys on the destination host, and make the
    private key file name available within the context.
    The key files and key inserted into authorized_keys will be
    removed when the context exits.

    :param source: source IP or DNS name
    :param dest: destination IP or DNS name
    :param conn_info: dictionary object with SSH connection
                      information for both hosts
    """
    KEY_BASE_NAME = "os-%s" % uuid.uuid4().hex
    keypair_uuid = uuid.uuid4()
    src_conn_obj = ssh_connect(conn_info)

    dest_conn_info = Connection(dest, conn_info.username,
                                       conn_info.password)
    dest_conn_obj = ssh_connect(dest_conn_info)

    def run_command(conn_obj, cmd):
        stdout, stderr = processutils.ssh_execute(conn_obj, cmd)
        return stdout.strip().splitlines()

    def build_keypair_on_source():
        mkkey = ('ssh-keygen -f %s -N "" -C %s' %
                    (KEY_BASE_NAME, keypair_uuid.hex))
        ssh_command_as_root(src_conn_obj, mkkey)

        chown_key = ('chown %s %s*' % (conn_info.username, KEY_BASE_NAME))
        ssh_command_as_root(src_conn_obj, chown_key)

        cat_key = ('cat %s.pub' % KEY_BASE_NAME)
        pubkey = run_command(src_conn_obj, cat_key)

        return pubkey[0]

    def cleanup_key_on_source():
        rmkey = 'rm %s*' % KEY_BASE_NAME
        run_command(src_conn_obj, rmkey)

    def insert_into_authorized_keys(public_key):
        echo_key = 'echo "%s" >> .ssh/authorized_keys' % public_key
        ssh_command_as_root(dest_conn_obj, echo_key)

    def remove_from_authorized_keys():
        rmkey = ('sed /%s/d .ssh/authorized_keys > .ssh/authorized_keys' %
                 keypair_uuid.hex)
        ssh_command_as_root(dest_conn_obj, rmkey)

    public_key = build_keypair_on_source()
    insert_into_authorized_keys(public_key)

    try:
        yield KEY_BASE_NAME
    finally:
        remove_from_authorized_keys()
        cleanup_key_on_source()

path_two = path_two.lstrip('/')