# 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 errno
import os
import psutil
import signal
import subprocess
import time

from ironic_lib import utils as ironic_utils
from oslo_log import log as logging
from oslo_service import loopingcall
from oslo_utils import netutils

from ironic.common import exception
from ironic.common.i18n import _
from ironic.common.i18n import _LE
from ironic.common.i18n import _LW
from ironic.common import utils
from ironic.conf import CONF


LOG = logging.getLogger(__name__)


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

    return CONF.console.terminal_pid_dir or CONF.tempdir


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: ConsoleError if unable to stop the console process
    """

    try:
        console_pid = _get_console_pid(node_uuid)

        os.kill(console_pid, signal.SIGTERM)
    except OSError as exc:
        if exc.errno != errno.ESRCH:
            msg = (_("Could not stop the console for node '%(node)s'. "
                     "Reason: %(err)s.") % {'node': node_uuid, 'err': exc})
            raise exception.ConsoleError(message=msg)
        else:
            LOG.warning(_LW("Console process for node %s is not running "
                            "but pid file exists."), node_uuid)
    finally:
        ironic_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.encode())
        return path
    except Exception as e:
        utils.delete_if_exists(path)
        raise exception.PasswordFileFailedToCreate(error=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 netutils.is_valid_ipv6(console_host):
        console_host = '[%s]' % console_host
    scheme = 'https' if CONF.console.terminal_cert_dir else 'http'
    return '%(scheme)s://%(host)s:%(port)s' % {'scheme': scheme,
                                               'host': console_host,
                                               'port': port}


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
        or an old process cannot be stopped.
    :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

    _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 and the process is running.
        # 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) and
                psutil.pid_exists(_get_console_pid(node_uuid))):
                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)


def get_socat_console_url(port):
    """Get a URL to access the console via socat.

    :param port: the terminal port (integer) for the node
    :return: an access URL to the socat console of the node
    """
    console_host = CONF.my_ip
    if netutils.is_valid_ipv6(console_host):
        console_host = '[%s]' % console_host

    return 'tcp://%(host)s:%(port)s' % {'host': console_host,
                                        'port': port}


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

    :param node_uuid: the uuid of the node
    :param port: the terminal port for the node
    :param console_cmd: the shell command that will be executed by socat to
        establish console to the node
    :raises ConsoleError: if the directory for the PID file or the PID file
        cannot be created
    :raises ConsoleSubprocessFailed: when invoking the subprocess failed
    """
    # Make sure that the old console for this node is stopped.
    # If no console is running, we may get exception NoConsolePid.
    try:
        _stop_console(node_uuid)
    except exception.NoConsolePid:
        pass

    _ensure_console_pid_dir_exists()
    pid_file = _get_console_pid_file(node_uuid)

    # put together the command and arguments for invoking the console
    args = ['socat']
    args.append('-L%s' % pid_file)

    console_host = CONF.my_ip
    if netutils.is_valid_ipv6(console_host):
        arg = 'TCP6-LISTEN:%(port)s,bind=[%(host)s],reuseaddr,fork'
    else:
        arg = 'TCP4-LISTEN:%(port)s,bind=%(host)s,reuseaddr,fork'
    args.append(arg % {'host': console_host,
                       'port': port})

    args.append('EXEC:"%s",pty,stderr' % 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 socat
        # fails to start. Note that socat uses stdout as transferring
        # data, so we only capture stderr for checking if it fails.
        obj = subprocess.Popen(args, stderr=subprocess.PIPE)
    except (OSError, ValueError) as e:
        error = _("%(exec_error)s\n"
                  "Command: %(command)s") % {'exec_error': str(e),
                                             'command': ' '.join(args)}
        LOG.exception(_LE('Unable to start socat console'))
        raise exception.ConsoleSubprocessFailed(error=error)

    # NOTE: we need to check if socat fails to start here.
    # If it starts successfully, it will run in non-daemon mode and
    # will not return until the console session is stopped.

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

        # socat runs in non-daemon mode, so it should not return now
        if wait_state['returncode'] is None:
            # If the pid file is created and the process is running,
            # we stop checking it periodically.
            if (os.path.exists(pid_file) and
                    psutil.pid_exists(_get_console_pid(node_uuid))):
                raise loopingcall.LoopingCallDone()
        else:
            # socat returned, it failed to start.
            # We get the error (out should be None in this case).
            (_out, err) = popen_obj.communicate()
            wait_state['errstr'] = _(
                "Command: %(command)s.\n"
                "Exit code: %(return_code)s.\n"
                "Stderr: %(error)r") % {
                    'command': ' '.join(args),
                    'return_code': wait_state['returncode'],
                    'error': err}
            LOG.error(wait_state['errstr'])
            raise loopingcall.LoopingCallDone()

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

    wait_state = {'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 wait_state['errstr']:
        raise exception.ConsoleSubprocessFailed(error=wait_state['errstr'])


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

    :param node_uuid: the UUID of the node
    :raise 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 socat console."), node_uuid)
