# 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 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'],
}


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 log_stdout: keyword-only argument: whether to log the output
    :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 find the first device larger than min_size_required,
    assume it is the OS disk
    """
    # TODO(russellhaering): This isn't a valid assumption in
    # all cases, is there a more reasonable default behavior?
    block_devices.sort(key=lambda device: device.size)
    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)
        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_bytes(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