# Copyright 2017, David Wilson
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

import logging
import optparse
import os
import time

import mitogen.core
import mitogen.parent


LOG = logging.getLogger(__name__)
PASSWORD_PROMPT = 'password'
SUDO_OPTIONS = [
    #(False, 'bool', '--askpass', '-A')
    #(False, 'str', '--auth-type', '-a')
    #(False, 'bool', '--background', '-b')
    #(False, 'str', '--close-from', '-C')
    #(False, 'str', '--login-class', 'c')
    (True,  'bool', '--preserve-env', '-E'),
    #(False, 'bool', '--edit', '-e')
    #(False, 'str', '--group', '-g')
    (True,  'bool', '--set-home', '-H'),
    #(False, 'str', '--host', '-h')
    #(False, 'bool', '--login', '-i')
    #(False, 'bool', '--remove-timestamp', '-K')
    #(False, 'bool', '--reset-timestamp', '-k')
    #(False, 'bool', '--list', '-l')
    #(False, 'bool', '--preserve-groups', '-P')
    #(False, 'str', '--prompt', '-p')
    #(False, 'str', '--role', '-r')

    # These options are supplied by default by Ansible, but are ignored, as
    # sudo always runs under a TTY with Mitogen.
    (True, 'bool', '--stdin', '-S'),
    (True, 'bool', '--non-interactive', '-n'),

    #(False, 'str', '--shell', '-s')
    #(False, 'str', '--type', '-t')
    #(False, 'str', '--other-user', '-U')
    #(False, 'str', '--user', '-u')
    #(False, 'bool', '--version', '-V')
    #(False, 'bool', '--validate', '-v')
]


class OptionParser(optparse.OptionParser):
    def help(self):
        self.exit()
    def error(self, msg):
        self.exit(msg=msg)
    def exit(self, status=0, msg=None):
        msg = 'sudo: ' + (msg or 'unsupported option')
        raise mitogen.core.StreamError(msg)


def make_sudo_parser():
    parser = OptionParser()
    for supported, kind, longopt, shortopt in SUDO_OPTIONS:
        if kind == 'bool':
            parser.add_option(longopt, shortopt, action='store_true')
        else:
            parser.add_option(longopt, shortopt)
    return parser


def parse_sudo_flags(args):
    parser = make_sudo_parser()
    opts, args = parser.parse_args(args)
    if len(args):
        raise mitogen.core.StreamError('unsupported sudo arguments:'+str(args))
    return opts


class PasswordError(mitogen.core.Error):
    pass


class Stream(mitogen.parent.Stream):
    create_child = staticmethod(mitogen.parent.tty_create_child)
    sudo_path = 'sudo'
    username = 'root'
    password = None
    preserve_env = False
    set_home = False

    def construct(self, username=None, sudo_path=None, password=None,
                  preserve_env=None, set_home=None, sudo_args=None,
                  **kwargs):
        super(Stream, self).construct(**kwargs)
        opts = parse_sudo_flags(sudo_args or [])

        if username is not None:
            self.username = username
        if sudo_path is not None:
            self.sudo_path = sudo_path
        if password is not None:
            self.password = password
        if (preserve_env or opts.preserve_env) is not None:
            self.preserve_env = preserve_env or opts.preserve_env
        if (set_home or opts.set_home) is not None:
            self.set_home = set_home or opts.set_home

    def connect(self):
        super(Stream, self).connect()
        self.name = 'sudo.' + self.username

    def get_boot_command(self):
        bits = [self.sudo_path, '-u', self.username]
        if self.preserve_env:
            bits += ['--preserve-env']
        if self.set_home:
            bits += ['--set-home']
        bits = bits + super(Stream, self).get_boot_command()
        LOG.debug('sudo command line: %r', bits)
        return bits

    password_incorrect_msg = 'sudo password is incorrect'
    password_required_msg = 'sudo password is required'

    def _connect_bootstrap(self):
        password_sent = False
        for buf in mitogen.parent.iter_read(self.receive_side.fd,
                                            time.time() + 10.0):
            LOG.debug('%r: received %r', self, buf)
            if buf.endswith('EC0\n'):
                self._ec0_received()
                return
            elif PASSWORD_PROMPT in buf.lower():
                if self.password is None:
                    raise PasswordError(self.password_required_msg)
                if password_sent:
                    raise PasswordError(self.password_incorrect_msg)
                LOG.debug('sending password')
                os.write(self.transmit_side.fd, self.password + '\n')
                password_sent = True
        raise mitogen.core.StreamError('bootstrap failed')