# Copyright (C) 2012 Yahoo! Inc.

#

# Author: Joshua Harlow <harlowja@yahoo-inc.com>

#

# This file is part of cloud-init. See LICENSE file for license information.

import pipes

import re

from io import StringIO

# This library is used to parse/write

# out the various sysconfig files edited (best attempt effort)

#

# It has to be slightly modified though

# to ensure that all values are quoted/unquoted correctly

# since these configs are usually sourced into

# bash scripts...

import configobj

# See: http://pubs.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap08.html

# or look at the 'param_expand()' function in the subst.c file in the bash

# source tarball...

SHELL_VAR_RULE = r'[a-zA-Z_]+[a-zA-Z0-9_]*'

SHELL_VAR_REGEXES = [

    # Basic variables

    re.compile(r"\$" + SHELL_VAR_RULE),

    # Things like $?, $0, $-, $@

    re.compile(r"\$[0-9#\?\-@\*]"),

    # Things like ${blah:1} - but this one

    # gets very complex so just try the

    # simple path

    re.compile(r"\$\{.+\}"),

]

def _contains_shell_variable(text):

    for r in SHELL_VAR_REGEXES:

        if r.search(text):

            return True

    return False

class SysConf(configobj.ConfigObj):

    """A configobj.ConfigObj subclass specialised for sysconfig files.

    :param contents:

        The sysconfig file to parse, in a format accepted by

        ``configobj.ConfigObj.__init__`` (i.e. "a filename, file like object,

        or list of lines").

    """

    def __init__(self, contents):

        configobj.ConfigObj.__init__(self, contents,

                                     interpolation=False,

                                     write_empty_values=True)

    def __str__(self):

        contents = self.write()

        out_contents = StringIO()

        if isinstance(contents, (list, tuple)):

            out_contents.write("\n".join(contents))

        else:

            out_contents.write(str(contents))

        return out_contents.getvalue()

    def _quote(self, value, multiline=False):

        if not isinstance(value, str):

            raise ValueError('Value "%s" is not a string' % (value))

        if len(value) == 0:

            return ''

        quot_func = None

        if value[0] in ['"', "'"] and value[-1] in ['"', "'"]:

            if len(value) == 1:

                quot_func = (lambda x: self._get_single_quote(x) % x)

        else:

            # Quote whitespace if it isn't the start + end of a shell command

            if value.strip().startswith("$(") and value.strip().endswith(")"):

                pass

            else:

                if re.search(r"[\t\r\n ]", value):

                    if _contains_shell_variable(value):

                        # If it contains shell variables then we likely want to

                        # leave it alone since the pipes.quote function likes

                        # to use single quotes which won't get expanded...

                        if re.search(r"[\n\"']", value):

                            quot_func = (lambda x:

                                         self._get_triple_quote(x) % x)

                        else:

                            quot_func = (lambda x:

                                         self._get_single_quote(x) % x)

                    else:

                        quot_func = pipes.quote

        if not quot_func:

            return value

        return quot_func(value)

    def _write_line(self, indent_string, entry, this_entry, comment):

        # Ensure it is formatted fine for

        # how these sysconfig scripts are used

        val = self._decode_element(self._quote(this_entry))

        key = self._decode_element(self._quote(entry))

        cmnt = self._decode_element(comment)

        return '%s%s%s%s%s' % (indent_string,

                               key,

                               self._a_to_u('='),

                               val,

                               cmnt)

# vi: ts=4 expandtab