# Microsoft Azure Linux Agent
#
# Copyright 2014 Microsoft Corporation
#
# 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.
#
# Requires Python 2.4+ and Openssl 1.0+
#

import subprocess
import azurelinuxagent.common.logger as logger
from azurelinuxagent.common.future import ustr

if not hasattr(subprocess, 'check_output'):
    def check_output(*popenargs, **kwargs):
        r"""Backport from subprocess module from python 2.7"""
        if 'stdout' in kwargs:
            raise ValueError('stdout argument not allowed, '
                             'it will be overridden.')
        process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
        output, unused_err = process.communicate()
        retcode = process.poll()
        if retcode:
            cmd = kwargs.get("args")
            if cmd is None:
                cmd = popenargs[0]
            raise subprocess.CalledProcessError(retcode, cmd, output=output)
        return output


    # Exception classes used by this module.
    class CalledProcessError(Exception):
        def __init__(self, returncode, cmd, output=None):
            self.returncode = returncode
            self.cmd = cmd
            self.output = output

        def __str__(self):
            return ("Command '{0}' returned non-zero exit status {1}"
                    "").format(self.cmd, self.returncode)


    subprocess.check_output = check_output
    subprocess.CalledProcessError = CalledProcessError

"""
Shell command util functions
"""


def run(cmd, chk_err=True):
    """
    Calls run_get_output on 'cmd', returning only the return code.
    If chk_err=True then errors will be reported in the log.
    If chk_err=False then errors will be suppressed from the log.
    """
    retcode, out = run_get_output(cmd, chk_err)
    return retcode


def run_get_output(cmd, chk_err=True, log_cmd=True):
    """
    Wrapper for subprocess.check_output.
    Execute 'cmd'.  Returns return code and STDOUT, trapping expected
    exceptions.
    Reports exceptions to Error if chk_err parameter is True
    """
    if log_cmd:
        logger.verbose(u"Run '{0}'", cmd)
    try:
        output = subprocess.check_output(cmd,
                                         stderr=subprocess.STDOUT,
                                         shell=True)
        output = ustr(output,
                      encoding='utf-8',
                      errors="backslashreplace")
    except Exception as e:
        if type(e) is subprocess.CalledProcessError:
            output = ustr(e.output,
                        encoding='utf-8',
                        errors="backslashreplace")
            if chk_err:
                if log_cmd:
                    logger.error(u"Command: '{0}'", e.cmd)
                logger.error(u"Return code: {0}", e.returncode)
                logger.error(u"Result: {0}", output)
            return e.returncode, output
        else:
            logger.error(
                u"'{0}' raised unexpected exception: '{1}'".format(
                    cmd, ustr(e)))
            return -1, ustr(e)
    return 0, output


def quote(word_list):
    """
    Quote a list or tuple of strings for Unix Shell as words, using the
    byte-literal single quote.

    The resulting string is safe for use with ``shell=True`` in ``subprocess``,
    and in ``os.system``. ``assert shlex.split(ShellQuote(wordList)) == wordList``.

    See POSIX.1:2013 Vol 3, Chap 2, Sec 2.2.2:
    http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_02_02
    """
    if not isinstance(word_list, (tuple, list)):
        word_list = (word_list,)

    return " ".join(list("'{0}'".format(s.replace("'", "'\\''")) for s in word_list))

# End shell command util functions