#!/usr/bin/python2 -O
# vim: fileencoding=utf-8

#
# The Qubes OS Project, https://www.qubes-os.org/
#
# Copyright (C) 2015  Joanna Rutkowska <joanna@invisiblethingslab.com>
# Copyright (C) 2015  Wojtek Porczyk <woju@invisiblethingslab.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#

'''Qubes' command line tools
'''

from __future__ import print_function

import argparse
import importlib
import logging
import os
import sys
import textwrap

import qubes.log

#: constant returned when some action should be performed on all qubes
VM_ALL = object()


class QubesAction(argparse.Action):
    ''' Interface providing a convinience method to be called, after
        `namespace.app` is instantiated.
    '''
    # pylint: disable=too-few-public-methods
    def parse_qubes_app(self, parser, namespace):
        ''' This method is called by :py:class:`qubes.tools.QubesArgumentParser`
            after the `namespace.app` is instantiated. Oerwrite this method when
            extending :py:class:`qubes.tools.QubesAction` to initialized values
            based on the `namespace.app`
        '''
        raise NotImplementedError


class PropertyAction(argparse.Action):
    '''Action for argument parser that stores a property.'''
    # pylint: disable=redefined-builtin,too-few-public-methods
    def __init__(self,
            option_strings,
            dest,
            metavar='NAME=VALUE',
            required=False,
            help='set property to a value'):
        super(PropertyAction, self).__init__(option_strings, 'properties',
            metavar=metavar, default={}, help=help)

    def __call__(self, parser, namespace, values, option_string=None):
        try:
            prop, value = values.split('=', 1)
        except ValueError:
            parser.error('invalid property token: {!r}'.format(values))

        getattr(namespace, self.dest)[prop] = value


class SinglePropertyAction(argparse.Action):
    '''Action for argument parser that stores a property.'''

    # pylint: disable=redefined-builtin,too-few-public-methods
    def __init__(self,
            option_strings,
            dest,
            metavar='VALUE',
            const=None,
            nargs=None,
            required=False,
            help=None):
        if help is None:
            help = 'set {!r} property to a value'.format(dest)
            if const is not None:
                help += ' {!r}'.format(const)

        if const is not None:
            nargs = 0

        super(SinglePropertyAction, self).__init__(option_strings, 'properties',
            metavar=metavar, help=help, default={}, const=const,
            nargs=nargs)

        self.name = dest


    def __call__(self, parser, namespace, values, option_string=None):
        getattr(namespace, self.dest)[self.name] = values \
            if self.const is None else self.const


class HelpPropertiesAction(argparse.Action):
    '''Action for argument parser that displays all properties and exits.'''
    # pylint: disable=redefined-builtin,too-few-public-methods
    def __init__(self,
            option_strings,
            klass=None,
            dest=argparse.SUPPRESS,
            default=argparse.SUPPRESS,
            help='list all available properties with short descriptions'
                ' and exit'):
        super(HelpPropertiesAction, self).__init__(
            option_strings=option_strings,
            dest=dest,
            default=default,
            nargs=0,
            help=help)

        # late import because of circular dependency
        import qubes # pylint: disable=redefined-outer-name
        self._klass = klass if klass is not None else qubes.Qubes


    def __call__(self, parser, namespace, values, option_string=None):
        # pylint: disable=redefined-outer-name
        properties = self._klass.property_list()
        width = max(len(prop.__name__) for prop in properties)
        wrapper = textwrap.TextWrapper(width=80,
            initial_indent='  ', subsequent_indent=' ' * (width + 6))

        text = 'Common properties:\n' + '\n'.join(
            wrapper.fill('{name:{width}s}  {doc}'.format(
                name=prop.__name__,
                doc=qubes.utils.format_doc(prop.__doc__) if prop.__doc__ else'',
                width=width))
            for prop in sorted(properties))
        if self._klass is not qubes.Qubes:
            text += '\n\n' \
                'There may be more properties in specific domain classes.\n'
        parser.exit(message=text)


class VmNameAction(QubesAction):
    ''' Action for parsing one ore multiple domains from provided VMNAMEs '''

    # pylint: disable=too-few-public-methods,redefined-builtin
    def __init__(self, option_strings, nargs=1, dest='vmnames', help=None,
                 **kwargs):
        if help is None:
            if nargs == argparse.OPTIONAL:
                help = 'at most one domain name'
            elif nargs == 1:
                help = 'a domain name'
            elif nargs == argparse.ZERO_OR_MORE:
                help = 'zero or more domain names'
            elif nargs == argparse.ONE_OR_MORE:
                help = 'one or more domain names'
            elif nargs > 1:
                help = '%s domain names' % nargs
            else:
                raise argparse.ArgumentError(
                    nargs, "Passed unexpected value {!s} as {!s} nargs ".format(
                        nargs, dest))

        super(VmNameAction, self).__init__(option_strings, dest=dest, help=help,
                                           nargs=nargs, **kwargs)

    def __call__(self, parser, namespace, values, option_string=None):
        ''' Set ``namespace.vmname`` to ``values`` '''
        setattr(namespace, self.dest, values)

    def parse_qubes_app(self, parser, namespace):
        assert hasattr(namespace, 'app')
        setattr(namespace, 'domains', [])
        app = namespace.app
        if hasattr(namespace, 'all_domains') and namespace.all_domains:
            namespace.domains = [
                vm
                for vm in app.domains
                if vm.qid != 0 and vm.name not in namespace.exclude
            ]
        else:
            if hasattr(namespace, 'exclude') and namespace.exclude:
                parser.error('--exclude can only be used with --all')

            for vm_name in getattr(namespace, self.dest):
                try:
                    namespace.domains += [app.domains[vm_name]]
                except KeyError:
                    parser.error('no such domain: {!r}'.format(vm_name))


class QubesArgumentParser(argparse.ArgumentParser):
    '''Parser preconfigured for use in most of the Qubes command-line tools.

    :param bool want_app: instantiate :py:class:`qubes.Qubes` object
    :param bool want_app_no_instance: don't actually instantiate \
        :py:class:`qubes.Qubes` object, just add argument for custom xml file
    :param bool want_force_root: add ``--force-root`` option
    :param mixed vmname_nargs: The number of ``VMNAME`` arguments that should be
            consumed. Values include:
                - N (an integer) consumes N arguments (and produces a list)
                - '?' consumes zero or one arguments
                - '*' consumes zero or more arguments (and produces a list)
                - '+' consumes one or more arguments (and produces a list)
    *kwargs* are passed to :py:class:`argparser.ArgumentParser`.

    Currenty supported options:
        ``--force-root`` (optional)
        ``--qubesxml`` location of :file:`qubes.xml` (help is suppressed)
        ``--verbose`` and ``--quiet``
    '''

    def __init__(self, want_app=True, want_app_no_instance=False,
                 want_force_root=False, vmname_nargs=None, **kwargs):

        super(QubesArgumentParser, self).__init__(**kwargs)

        self._want_app = want_app
        self._want_app_no_instance = want_app_no_instance
        self._want_force_root = want_force_root
        self._vmname_nargs = vmname_nargs
        if self._want_app:
            self.add_argument('--qubesxml', metavar='FILE', action='store',
                              dest='app', help=argparse.SUPPRESS)


        self.add_argument('--verbose', '-v', action='count',
                          help='increase verbosity')

        self.add_argument('--quiet', '-q', action='count',
                          help='decrease verbosity')

        if self._want_force_root:
            self.add_argument('--force-root', action='store_true',
                              default=False, help='force to run as root')

        if self._vmname_nargs in [argparse.ZERO_OR_MORE, argparse.ONE_OR_MORE]:
            vm_name_group = VmNameGroup(self, self._vmname_nargs)
            self._mutually_exclusive_groups.append(vm_name_group)
        elif self._vmname_nargs is not None:
            self.add_argument('VMNAME', nargs=self._vmname_nargs,
                              action=VmNameAction)

        self.set_defaults(verbose=1, quiet=0)

    def parse_args(self, *args, **kwargs):
        namespace = super(QubesArgumentParser, self).parse_args(*args, **kwargs)

        if self._want_app and not self._want_app_no_instance:
            self.set_qubes_verbosity(namespace)
            namespace.app = qubes.Qubes(namespace.app)

        if self._want_force_root:
            self.dont_run_as_root(namespace)

        for action in self._actions:
            if issubclass(action.__class__, QubesAction):
                action.parse_qubes_app(self, namespace)

        return namespace


    def error_runtime(self, message):
        '''Runtime error, without showing usage.

        :param str message: message to show
        '''
        self.exit(1, '{}: error: {}\n'.format(self.prog, message))


    def dont_run_as_root(self, namespace):
        '''Prevent running as root.

        :param argparse.Namespace args: if there is ``.force_root`` attribute \
            set to true, run anyway
        '''
        try:
            euid = os.geteuid()
        except AttributeError: # no geteuid(), probably NT
            return

        if euid == 0 and not namespace.force_root:
            self.error_runtime(
                'refusing to run as root; add --force-root to override')

    @staticmethod
    def get_loglevel_from_verbosity(namespace):
        ''' Return loglevel calculated from quiet and verbose arguments '''
        return (namespace.quiet - namespace.verbose) * 10 + logging.WARNING


    @staticmethod
    def set_qubes_verbosity(namespace):
        '''Apply a verbosity setting.

        This is done by configuring global logging.
        :param argparse.Namespace args: args as parsed by parser
        '''

        verbose = namespace.verbose - namespace.quiet

        if verbose >= 2:
            qubes.log.enable_debug()
        elif verbose >= 1:
            qubes.log.enable()

    # pylint: disable=no-self-use
    def print_error(self, *args, **kwargs):
        ''' Print to ``sys.stderr``'''
        print(*args, file=sys.stderr, **kwargs)


class AliasedSubParsersAction(argparse._SubParsersAction):
    # source https://gist.github.com/sampsyo/471779
    # pylint: disable=protected-access,too-few-public-methods
    class _AliasedPseudoAction(argparse.Action):
        # pylint: disable=redefined-builtin
        def __init__(self, name, aliases, help):
            dest = name
            if aliases:
                dest += ' (%s)' % ','.join(aliases)
            sup = super(AliasedSubParsersAction._AliasedPseudoAction, self)
            sup.__init__(option_strings=[], dest=dest, help=help)

        def __call__(self, **kwargs):
            super(AliasedSubParsersAction._AliasedPseudoAction, self).__call__(
                **kwargs)

    def add_parser(self, name, **kwargs):
        if 'aliases' in kwargs:
            aliases = kwargs['aliases']
            del kwargs['aliases']
        else:
            aliases = []

        local_parser = super(AliasedSubParsersAction, self).add_parser(
            name, **kwargs)

        # Make the aliases work.
        for alias in aliases:
            self._name_parser_map[alias] = local_parser
        # Make the help text reflect them, first removing old help entry.
        if 'help' in kwargs:
            self._choices_actions.pop()
            pseudo_action = self._AliasedPseudoAction(name, aliases,
                                                      kwargs.pop('help'))
            self._choices_actions.append(pseudo_action)

        return local_parser


def get_parser_for_command(command):
    '''Get parser for given qvm-tool.

    :param str command: command name
    :rtype: argparse.ArgumentParser
    :raises ImportError: when command's module is not found
    :raises AttributeError: when parser was not found
    '''

    module = importlib.import_module(
        '.' + command.replace('-', '_'), 'qubes.tools')

    try:
        parser = module.parser
    except AttributeError:
        try:
            parser = module.get_parser()
        except AttributeError:
            raise AttributeError('cannot find parser in module')

    return parser


# pylint: disable=protected-access
class VmNameGroup(argparse._MutuallyExclusiveGroup):
    ''' Adds an a VMNAME, --all & --exclude parameters to a
        :py:class:``argparse.ArgumentParser```.
    '''

    def __init__(self, container, required, vm_action=VmNameAction):
        super(VmNameGroup, self).__init__(container, required=required)
        self.add_argument('--all', action='store_true',
                          dest='all_domains',
                          help='perform the action on all qubes')
        container.add_argument('--exclude', action='append', default=[],
                               help='exclude the qube from --all')
        self.add_argument('VMNAME', action=vm_action, nargs='*',
                          default=[])  # the default parameter is important! see
                                # https://stackoverflow.com/questions/35044288
                                # and `argparse.ArgumentParser.parse_args()`