# Copyright 2013 Rackspace, Inc.
#
# 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 copy
import errno
import glob
import io
import os
import re
import shutil
import subprocess
import tarfile
import tempfile
import time

from ironic_lib import utils as ironic_utils
from oslo_concurrency import processutils
from oslo_log import log as logging
from oslo_serialization import base64
from oslo_utils import units
from six.moves.urllib import parse

from ironic_python_agent import errors

LOG = logging.getLogger(__name__)


# Agent parameters can be passed by kernel command-line arguments and/or
# by virtual media. Virtual media parameters passed would be available
# when the agent is started, but might not be available for re-reading
# later on because:
# * Virtual media might be exposed from Swift and swift temp url might
#   expire.
# * Ironic might have removed the floppy image from Swift after starting
#   the deploy.
#
# Even if it's available, there is no need to re-read from the device and
# /proc/cmdline again, because it is never going to change.  So we cache the
# agent parameters that was passed (by proc/cmdline and/or virtual media)
# when we read it for the first time, and then use this cache.
AGENT_PARAMS_CACHED = dict()


COLLECT_LOGS_COMMANDS = {
    'ps': ['ps', 'au'],
    'df': ['df', '-a'],
    'iptables': ['iptables', '-L'],
    'ip_addr': ['ip', 'addr'],
    'lshw': ['lshw', '-quiet', '-json'],
}


DEVICE_EXTRACTOR = re.compile(r'^(?:(.*\d)p|(.*\D))(?:\d+)$')


def execute(*cmd, **kwargs):
    """Convenience wrapper around ironic_lib's execute() method.

    Executes and logs results from a system command.
    """
    return ironic_utils.execute(*cmd, **kwargs)


def try_execute(*cmd, **kwargs):
    """The same as execute but returns None on error.

    Executes and logs results from a system command. See docs for
    oslo_concurrency.processutils.execute for usage.

    Instead of raising an exception on failure, this method simply
    returns None in case of failure.

    :param cmd: positional arguments to pass to processutils.execute()
    :param kwargs: keyword arguments to pass to processutils.execute()
    :raises: UnknownArgumentError on receiving unknown arguments
    :returns: tuple of (stdout, stderr) or None in some error cases
    """
    try:
        return execute(*cmd, **kwargs)
    except (processutils.ProcessExecutionError, OSError) as e:
        LOG.debug('Command failed: %s', e)


def _read_params_from_file(filepath):
    """Extract key=value pairs from a file.

    :param filepath: path to a file containing key=value pairs separated by
                     whitespace or newlines.
    :returns: a dictionary representing the content of the file
    """
    with open(filepath) as f:
        cmdline = f.read()

    options = cmdline.split()
    params = {}
    for option in options:
        if '=' not in option:
            continue
        k, v = option.split('=', 1)
        params[k] = v

    return params


def _get_vmedia_device():
    """Finds the device filename of the virtual media device using sysfs.

    :returns: a string containing the filename of the virtual media device
    """
    sysfs_device_models = glob.glob("/sys/class/block/*/device/model")
    vmedia_device_model = "virtual media"
    for model_file in sysfs_device_models:
        try:
            with open(model_file) as model_file_fobj:
                if vmedia_device_model in model_file_fobj.read().lower():
                    vmedia_device = model_file.split('/')[4]
                    return vmedia_device
        except Exception:
            pass


def _get_vmedia_params():
    """This method returns the parameters passed through virtual media floppy.

    :returns: a partial dict of potential agent configuration parameters
    :raises: VirtualMediaBootError when it cannot find the virtual media device
    """
    parameters_file = "parameters.txt"

    vmedia_device_file_lower_case = "/dev/disk/by-label/ir-vfd-dev"
    vmedia_device_file_upper_case = "/dev/disk/by-label/IR-VFD-DEV"
    if os.path.exists(vmedia_device_file_lower_case):
        vmedia_device_file = vmedia_device_file_lower_case
    elif os.path.exists(vmedia_device_file_upper_case):
        vmedia_device_file = vmedia_device_file_upper_case
    else:

        # TODO(rameshg87): This block of code is there only for compatibility
        # reasons (so that newer agent can work with older Ironic). Remove
        # this after Liberty release.
        vmedia_device = _get_vmedia_device()
        if not vmedia_device:
            msg = "Unable to find virtual media device"
            raise errors.VirtualMediaBootError(msg)

        vmedia_device_file = os.path.join("/dev", vmedia_device)

    vmedia_mount_point = tempfile.mkdtemp()
    try:
        try:
            stdout, stderr = execute("mount", vmedia_device_file,
                                     vmedia_mount_point)
        except processutils.ProcessExecutionError as e:
            msg = ("Unable to mount virtual media device %(device)s: "
                   "%(error)s" % {'device': vmedia_device_file, 'error': e})
            raise errors.VirtualMediaBootError(msg)

        parameters_file_path = os.path.join(vmedia_mount_point,
                                            parameters_file)
        params = _read_params_from_file(parameters_file_path)

        try:
            stdout, stderr = execute("umount", vmedia_mount_point)
        except processutils.ProcessExecutionError as e:
            pass
    finally:
        try:
            shutil.rmtree(vmedia_mount_point)
        except Exception as e:
            pass

    return params


def _get_cached_params():
    """Helper method to get cached params to ease unit testing."""
    return AGENT_PARAMS_CACHED


def _set_cached_params(params):
    """Helper method to set cached params to ease unit testing."""
    global AGENT_PARAMS_CACHED
    AGENT_PARAMS_CACHED = params


def get_agent_params():
    """Gets parameters passed to the agent via kernel cmdline or vmedia.

    Parameters can be passed using either the kernel commandline or through
    virtual media. If boot_method is vmedia, merge params provided via vmedia
    with those read from the kernel command line.

    Although it should never happen, if a variable is both set by vmedia and
    kernel command line, the setting in vmedia will take precedence.

    :returns: a dict of potential configuration parameters for the agent
    """

    # Check if we have the parameters cached
    params = _get_cached_params()
    if not params:
        params = _read_params_from_file('/proc/cmdline')

        # If the node booted over virtual media, the parameters are passed
        # in a text file within the virtual media floppy.
        if params.get('boot_method') == 'vmedia':
            vmedia_params = _get_vmedia_params()
            params.update(vmedia_params)

        # Cache the parameters so that it can be used later on.
        _set_cached_params(params)

        # Check to see if any deprecated parameters have been used
        deprecated_params = {'lldp-timeout': 'ipa-lldp-timeout'}
        for old_param, new_param in deprecated_params.items():
            if params.get(old_param) is not None:
                LOG.warning("The parameter '%s' has been deprecated. Please "
                            "use %s instead.", old_param, new_param)

    return copy.deepcopy(params)


def normalize(string):
    """Return a normalized string.

    Take a urlencoded value from Ironic and urldecode it.

    :param string: a urlencoded string
    :returns: a normalized version of passed in string
    """
    return parse.unquote(string).lower().strip()


class AccumulatedFailures(object):
    """Object to accumulate failures without raising exception."""

    def __init__(self, exc_class=RuntimeError):
        self._failures = []
        self._exc_class = exc_class

    def add(self, fail, *fmt):
        """Add failure with optional formatting.

        :param fail: exception or error string
        :param fmt: formatting arguments (only if fail is a string)
        """
        if fmt:
            fail = fail % fmt
        LOG.error('%s', fail)
        self._failures.append(fail)

    def get_error(self):
        """Get error string or None."""
        if not self._failures:
            return

        msg = ('The following errors were encountered:\n%s'
               % '\n'.join('* %s' % item for item in self._failures))
        return msg

    def raise_if_needed(self):
        """Raise exception if error list is not empty.

        :raises: RuntimeError
        """
        if self._failures:
            raise self._exc_class(self.get_error())

    def __nonzero__(self):
        return bool(self._failures)

    __bool__ = __nonzero__

    def __repr__(self):  # pragma: no cover
        # This is for tests
        if self:
            return '<%s: %s>' % (self.__class__.__name__,
                                 ', '.join(self._failures))
        else:
            return '<%s: success>' % self.__class__.__name__


def guess_root_disk(block_devices, min_size_required=4 * units.Gi):
    """Find suitable disk provided that root device hints are not given.

    If no hints are passed, order the devices by size (primary key) and
    name (secondary key), and return the first device larger than
    min_size_required as the root disk.
    """
    # NOTE(arne_wiebalck): Order devices by size and name. Secondary
    # ordering by name is done to increase chances of successful
    # booting for BIOSes which try only one (the "first") disk.
    block_devices.sort(key=lambda device: (device.size, device.name))

    if not block_devices or block_devices[-1].size < min_size_required:
        raise errors.DeviceNotFound(
            "No suitable device was found "
            "for deployment - root device hints were not provided "
            "and all found block devices are smaller than %iB."
            % min_size_required)
    for device in block_devices:
        if device.size >= min_size_required:
            return device


def is_journalctl_present():
    """Check if the journalctl command is present.

    :returns: True if journalctl is present, False if not.
    """
    try:
        devnull = open(os.devnull, 'w')
        subprocess.check_call(['journalctl', '--version'], stdout=devnull,
                              stderr=devnull)
    except OSError as e:
        if e.errno == errno.ENOENT:
            return False
    return True


def get_command_output(command):
    """Return the output of a given command.

    :param command: The command to be executed.
    :raises: CommandExecutionError if the execution of the command fails.
    :returns: A BytesIO string with the output.
    """
    try:
        out, _ = execute(*command, binary=True, log_stdout=False)
    except (processutils.ProcessExecutionError, OSError) as e:
        error_msg = ('Failed to get the output of the command "%(command)s". '
                     'Error: %(error)s' % {'command': command, 'error': e})
        LOG.error(error_msg)
        raise errors.CommandExecutionError(error_msg)
    return io.BytesIO(out)


def get_journalctl_output(lines=None, units=None):
    """Query the contents of the systemd journal.

    :param lines: Maximum number of lines to retrieve from the
                  logs. If None, return everything.
    :param units: A list with the names of the units we should
                  retrieve the logs from. If None retrieve the logs
                  for everything.
    :returns: A log string.
    """
    cmd = ['journalctl', '--full', '--no-pager', '-b']
    if lines is not None:
        cmd.extend(['-n', str(lines)])
    if units is not None:
        [cmd.extend(['-u', u]) for u in units]

    return get_command_output(cmd)


def gzip_and_b64encode(io_dict=None, file_list=None):
    """Gzip and base64 encode files and BytesIO buffers.

    :param io_dict: A dictionary containing whose the keys are the file
        names and the value a BytesIO object.
    :param file_list: A list of file path.
    :returns: A gzipped and base64 encoded string.
    """
    io_dict = io_dict or {}
    file_list = file_list or []

    with io.BytesIO() as fp:
        with tarfile.open(fileobj=fp, mode='w:gz') as tar:
            for fname in io_dict:
                ioobj = io_dict[fname]
                tarinfo = tarfile.TarInfo(name=fname)
                tarinfo.size = ioobj.seek(0, 2)
                tarinfo.mtime = time.time()
                ioobj.seek(0)
                tar.addfile(tarinfo, ioobj)

            for f in file_list:
                tar.add(f)

        fp.seek(0)
        return base64.encode_as_text(fp.getvalue())


def collect_system_logs(journald_max_lines=None):
    """Collect system logs.

    Collect system logs, for distributions using systemd the logs will
    come from journald. On other distributions the logs will come from
    the /var/log directory and dmesg output.

    :param journald_max_lines: Maximum number of lines to retrieve from
                               the journald. if None, return everything.
    :returns: A tar, gzip base64 encoded string with the logs.
    """

    def try_get_command_output(io_dict, file_name, command):
        try:
            io_dict[file_name] = get_command_output(command)
        except errors.CommandExecutionError:
            pass

    io_dict = {}
    file_list = []
    if is_journalctl_present():
        io_dict['journal'] = get_journalctl_output(lines=journald_max_lines)
    else:
        try_get_command_output(io_dict, 'dmesg', ['dmesg'])
        file_list.append('/var/log')

    for name, cmd in COLLECT_LOGS_COMMANDS.items():
        try_get_command_output(io_dict, name, cmd)

    return gzip_and_b64encode(io_dict=io_dict, file_list=file_list)


def get_ssl_client_options(conf):
    """Format SSL-related requests options.

    :param conf: oslo_config CONF object
    :returns: tuple of 'verify' and 'cert' values to pass to requests
    """
    if conf.insecure:
        verify = False
    else:
        verify = conf.cafile or True
    if conf.certfile and conf.keyfile:
        cert = (conf.certfile, conf.keyfile)
    else:
        cert = None
    return verify, cert


def extract_device(part):
    """Extract the device from a partition name or path.

    :param part: the partition
    :return: a device if success, None otherwise
    """

    m = DEVICE_EXTRACTOR.match(part)
    if not m:
        return None
    return (m.group(1) or m.group(2))