# Copyright 2015 Canonical, Ltd.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import asyncio
import crypt
import logging
import os
import random
import subprocess
import pathlib

log = logging.getLogger("subiquitycore.utils")


def _clean_env(env):
    if env is None:
        env = os.environ.copy()
    else:
        env = env.copy()
    # Do we always want to do this?
    env['LC_ALL'] = 'C'
    # Maaaybe want to remove SNAP here too.
    return env


def run_command(cmd, *, input=None, stdout=subprocess.PIPE,
                stderr=subprocess.PIPE, encoding='utf-8', errors='replace',
                env=None, **kw):
    """A wrapper around subprocess.run with logging and different defaults.

    We never ever want a subprocess to inherit our file descriptors!
    """
    if input is None:
        kw['stdin'] = subprocess.DEVNULL
    else:
        input = input.encode(encoding)
    log.debug("run_command called: %s", cmd)
    try:
        cp = subprocess.run(cmd, input=input, stdout=stdout, stderr=stderr,
                            env=_clean_env(env), **kw)
        if encoding:
            if isinstance(cp.stdout, bytes):
                cp.stdout = cp.stdout.decode(encoding)
            if isinstance(cp.stderr, bytes):
                cp.stderr = cp.stderr.decode(encoding)
    except subprocess.CalledProcessError as e:
        log.debug("run_command %s", str(e))
        raise
    else:
        log.debug("run_command %s exited with code %s", cp.args, cp.returncode)
        return cp


async def arun_command(cmd, *, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                       encoding='utf-8', input=None, errors='replace',
                       env=None, check=False, **kw):
    if input is None:
        if 'stdin' not in kw:
            kw['stdin'] = subprocess.DEVNULL
    else:
        kw['stdin'] = subprocess.PIPE
        input = input.encode(encoding)
    log.debug("arun_command called: %s", cmd)
    proc = await asyncio.create_subprocess_exec(
        *cmd, stdout=stdout, stderr=stderr, env=_clean_env(env), **kw)
    stdout, stderr = await proc.communicate(input=input)
    if encoding:
        if stdout is not None:
            stdout = stdout.decode(encoding)
        if stderr is not None:
            stderr = stderr.decode(encoding)
    log.debug("arun_command %s exited with code %s", cmd, proc.returncode)
    if check and proc.returncode != 0:
        raise subprocess.CalledProcessError(proc.returncode, cmd)
    else:
        return subprocess.CompletedProcess(
            cmd, proc.returncode, stdout, stderr)


async def astart_command(cmd, *, stdout=subprocess.PIPE,
                         stderr=subprocess.PIPE, stdin=subprocess.DEVNULL,
                         env=None, **kw):
    log.debug("astart_command called: %s", cmd)
    return await asyncio.create_subprocess_exec(
        *cmd, stdout=stdout, stderr=stderr,
        env=_clean_env(env), **kw)


def start_command(cmd, *, stdin=subprocess.DEVNULL, stdout=subprocess.PIPE,
                  stderr=subprocess.PIPE, encoding='utf-8', errors='replace',
                  env=None, **kw):
    """A wrapper around subprocess.Popen with logging and different defaults.

    We never ever want a subprocess to inherit our file descriptors!
    """
    log.debug('start_command called: %s', cmd)
    return subprocess.Popen(cmd, stdin=stdin, stdout=stdout, stderr=stderr,
                            env=_clean_env(env), **kw)


# FIXME: replace with passlib and update package deps
def crypt_password(passwd, algo='SHA-512'):
    # encryption algo - id pairs for crypt()
    algos = {'SHA-512': '$6$', 'SHA-256': '$5$', 'MD5': '$1$', 'DES': ''}
    if algo not in algos:
        raise Exception('Invalid algo({}), must be one of: {}. '.format(
            algo, ','.join(algos.keys())))

    salt_set = ('abcdefghijklmnopqrstuvwxyz'
                'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
                '0123456789./')
    salt = 16 * ' '
    salt = ''.join([random.choice(salt_set) for c in salt])
    return crypt.crypt(passwd, algos[algo] + salt)


def disable_console_conf():
    """ Stop console-conf service; which also restores getty service """
    log.info('disabling console-conf service')
    run_command(["systemctl", "stop", "--no-block", "console-conf@*.service",
                 "serial-console-conf@*.service"])
    return


def disable_subiquity():
    """ Stop subiquity service; which also restores getty service """
    log.info('disabling subiquity service')
    run_command(["mkdir", "-p", "/run/subiquity"])
    run_command(["touch", "/run/subiquity/complete"])
    run_command(["systemctl", "start", "--no-block", "getty@tty1.service"])
    run_command(["systemctl", "stop", "--no-block",
                 "snap.subiquity.subiquity-service.service",
                 "serial-subiquity@*.service"])
    return


def is_wsl():
    """ Returns True if we are on a WSL system """
    return pathlib.Path("/proc/sys/fs/binfmt_misc/WSLInterop").is_file()