# coding=utf-8

# Copyright 2014 International Business Machines Corporation
# All Rights Reserved.
#
#    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.

"""
Ironic console utilities.
"""

import os
import subprocess
import tempfile
import time

from oslo.concurrency import processutils
from oslo.config import cfg

from ironic.common import exception
from ironic.common.i18n import _
from ironic.common.i18n import _LW
from ironic.common import utils
from ironic.openstack.common import log as logging
from ironic.openstack.common import loopingcall


opts = [
    cfg.StrOpt('terminal',
               default='shellinaboxd',
               help='Path to serial console terminal program'),
    cfg.StrOpt('terminal_cert_dir',
               help='Directory containing the terminal SSL cert(PEM) for '
               'serial console access'),
    cfg.StrOpt('terminal_pid_dir',
               help='Directory for holding terminal pid files. '
               'If not specified, the temporary directory will be used.'),
    cfg.IntOpt('subprocess_checking_interval',
               default=1,
               help='Time interval (in seconds) for checking the status of '
               'console subprocess.'),
    cfg.IntOpt('subprocess_timeout',
               default=10,
               help='Time (in seconds) to wait for the console subprocess '
               'to start.'),
    ]

CONF = cfg.CONF
CONF.register_opts(opts, group='console')

LOG = logging.getLogger(__name__)


def _get_console_pid_dir():
    """Return the directory for the pid file."""

    if CONF.console.terminal_pid_dir:
        pid_dir = CONF.console.terminal_pid_dir
    else:
        pid_dir = tempfile.gettempdir()
    return pid_dir


def _ensure_console_pid_dir_exists():
    """Ensure that the console PID directory exists

    Checks that the directory for the console PID file exists
    and if not, creates it.

    :raises: ConsoleError if the directory doesn't exist and cannot be created
    """

    dir = _get_console_pid_dir()
    if not os.path.exists(dir):
        try:
            os.makedirs(dir)
        except OSError as exc:
            msg = (_("Cannot create directory '%(path)s' for console PID file."
                     " Reason: %(reason)s.") % {'path': dir, 'reason': exc})
            LOG.error(msg)
            raise exception.ConsoleError(message=msg)


def _get_console_pid_file(node_uuid):
    """Generate the pid file name to hold the terminal process id."""

    pid_dir = _get_console_pid_dir()
    name = "%s.pid" % node_uuid
    path = os.path.join(pid_dir, name)
    return path


def _get_console_pid(node_uuid):
    """Get the terminal process id from pid file."""

    pid_path = _get_console_pid_file(node_uuid)
    try:
        with open(pid_path, 'r') as f:
            pid_str = f.readline()
            return int(pid_str)
    except (IOError, ValueError):
        raise exception.NoConsolePid(pid_path=pid_path)


def _stop_console(node_uuid):
    """Close the serial console for a node

    Kills the console process and deletes the PID file.

    :param node_uuid: the UUID of the node
    :raises: NoConsolePid if no console PID was found
    :raises: processutils.ProcessExecutionError if unable to stop the process
    """

    try:
        console_pid = _get_console_pid(node_uuid)

        # Allow exitcode 99 (RC_UNAUTHORIZED)
        utils.execute('kill', str(console_pid), check_exit_code=[0, 99])
    finally:
        utils.unlink_without_raise(_get_console_pid_file(node_uuid))


def make_persistent_password_file(path, password):
    """Writes a file containing a password until deleted."""

    try:
        utils.delete_if_exists(path)
        with open(path, 'wb') as file:
            os.chmod(path, 0o600)
            file.write(password)
        return path
    except Exception as e:
        utils.delete_if_exists(path)
        raise exception.PasswordFileFailedToCreate(error=str(e))


def get_shellinabox_console_url(port):
    """Get a url to access the console via shellinaboxd.

    :param port: the terminal port for the node.
    """

    console_host = CONF.my_ip
    if utils.is_valid_ipv6(console_host):
        console_host = '[%s]' % console_host
    console_url = "http://%s:%s" % (console_host, port)
    return console_url


def start_shellinabox_console(node_uuid, port, console_cmd):
    """Open the serial console for a node.

    :param node_uuid: the uuid for the node.
    :param port: the terminal port for the node.
    :param console_cmd: the shell command that gets the console.
    :raises: ConsoleError if the directory for the PID file cannot be created.
    :raises: ConsoleSubprocessFailed when invoking the subprocess failed.
    """

    # make sure that the old console for this node is stopped
    # and the files are cleared
    try:
        _stop_console(node_uuid)
    except exception.NoConsolePid:
        pass
    except processutils.ProcessExecutionError as exc:
        LOG.warning(_LW("Failed to kill the old console process "
                "before starting a new shellinabox console "
                "for node %(node)s. Reason: %(err)s"),
                {'node': node_uuid, 'err': exc})

    _ensure_console_pid_dir_exists()
    pid_file = _get_console_pid_file(node_uuid)

    # put together the command and arguments for invoking the console
    args = []
    args.append(CONF.console.terminal)
    if CONF.console.terminal_cert_dir:
        args.append("-c")
        args.append(CONF.console.terminal_cert_dir)
    else:
        args.append("-t")
    args.append("-p")
    args.append(str(port))
    args.append("--background=%s" % pid_file)
    args.append("-s")
    args.append(console_cmd)

    # run the command as a subprocess
    try:
        LOG.debug('Running subprocess: %s', ' '.join(args))
        # use pipe here to catch the error in case shellinaboxd
        # failed to start.
        obj = subprocess.Popen(args,
                               stdout=subprocess.PIPE,
                               stderr=subprocess.PIPE)
    except (OSError, ValueError) as e:
        error = _("%(exec_error)s\n"
                  "Command: %(command)s") % {'exec_error': str(e),
                                             'command': ' '.join(args)}
        LOG.warning(error)
        raise exception.ConsoleSubprocessFailed(error=error)

    def _wait(node_uuid, popen_obj):
        locals['returncode'] = popen_obj.poll()

        # check if the console pid is created.
        # if it is, then the shellinaboxd is invoked successfully as a daemon.
        # otherwise check the error.
        if locals['returncode'] is not None:
            if locals['returncode'] == 0 and os.path.exists(pid_file):
                raise loopingcall.LoopingCallDone()
            else:
                (stdout, stderr) = popen_obj.communicate()
                locals['errstr'] = _("Command: %(command)s.\n"
                        "Exit code: %(return_code)s.\n"
                        "Stdout: %(stdout)r\n"
                        "Stderr: %(stderr)r") % {'command': ' '.join(args),
                                'return_code': locals['returncode'],
                                'stdout': stdout,
                                'stderr': stderr}
                LOG.warning(locals['errstr'])
                raise loopingcall.LoopingCallDone()

        if (time.time() > expiration):
            locals['errstr'] = _("Timeout while waiting for console"
                    " subprocess to start for node %s.") % node_uuid
            LOG.warning(locals['errstr'])
            raise loopingcall.LoopingCallDone()

    locals = {'returncode': None, 'errstr': ''}
    expiration = time.time() + CONF.console.subprocess_timeout
    timer = loopingcall.FixedIntervalLoopingCall(_wait, node_uuid, obj)
    timer.start(interval=CONF.console.subprocess_checking_interval).wait()

    if locals['errstr']:
        raise exception.ConsoleSubprocessFailed(error=locals['errstr'])


def stop_shellinabox_console(node_uuid):
    """Close the serial console for a node.

    :param node_uuid: the UUID of the node
    :raises: ConsoleError if unable to stop the console process
    """

    try:
        _stop_console(node_uuid)
    except exception.NoConsolePid:
        LOG.warning(_LW("No console pid found for node %s while trying to "
                        "stop shellinabox console."), node_uuid)
    except processutils.ProcessExecutionError as exc:
            msg = (_("Could not stop the console for node '%(node)s'. "
                     "Reason: %(err)s.") % {'node': node_uuid, 'err': exc})
            raise exception.ConsoleError(message=msg)
