# (c) 2012-2014, Michael DeHaan <michael.dehaan@gmail.com>
#
# This file is part of Ansible
#
# Ansible 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 3 of the License, or
# (at your option) any later version.
#
# Ansible 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.

import errno
import sys
import re
import os
import shlex
import yaml
import copy
import optparse
import operator
from ansible import errors
from ansible import __version__
from ansible.utils.display_functions import *
from ansible.utils.plugins import *
from ansible.utils.su_prompts import *
from ansible.utils.hashing import secure_hash, secure_hash_s, checksum, checksum_s, md5, md5s
from ansible.callbacks import display
from ansible.module_utils.splitter import split_args, unquote
from ansible.module_utils.basic import heuristic_log_sanitize
from ansible.utils.unicode import to_bytes, to_unicode
import ansible.constants as C
import ast
import time
import StringIO
import stat
import termios
import tty
import pipes
import random
import difflib
import warnings
import traceback
import getpass
import sys
import subprocess
import contextlib

from vault import VaultLib

VERBOSITY=0

MAX_FILE_SIZE_FOR_DIFF=1*1024*1024

# caching the compilation of the regex used
# to check for lookup calls within data
LOOKUP_REGEX = re.compile(r'lookup\s*\(')
PRINT_CODE_REGEX = re.compile(r'(?:{[{%]|[%}]})')
CODE_REGEX = re.compile(r'(?:{%|%})')


try:
    # simplejson can be much faster if it's available
    import simplejson as json
except ImportError:
    import json

try:
    from yaml import CSafeLoader as Loader
except ImportError:
    from yaml import SafeLoader as Loader

PASSLIB_AVAILABLE = False
try:
    import passlib.hash
    PASSLIB_AVAILABLE = True
except:
    pass

try:
    import builtin
except ImportError:
    import __builtin__ as builtin

KEYCZAR_AVAILABLE=False
try:
    try:
        # some versions of pycrypto may not have this?
        from Crypto.pct_warnings import PowmInsecureWarning
    except ImportError:
        PowmInsecureWarning = RuntimeWarning

    with warnings.catch_warnings(record=True) as warning_handler:
        warnings.simplefilter("error", PowmInsecureWarning)
        try:
            import keyczar.errors as key_errors
            from keyczar.keys import AesKey
        except PowmInsecureWarning:
            system_warning(
                "The version of gmp you have installed has a known issue regarding " + \
                "timing vulnerabilities when used with pycrypto. " + \
                "If possible, you should update it (i.e. yum update gmp)."
            )
            warnings.resetwarnings()
            warnings.simplefilter("ignore")
            import keyczar.errors as key_errors
            from keyczar.keys import AesKey
        KEYCZAR_AVAILABLE=True
except ImportError:
    pass


###############################################################
# Abstractions around keyczar
###############################################################

def key_for_hostname(hostname):
    # fireball mode is an implementation of ansible firing up zeromq via SSH
    # to use no persistent daemons or key management

    if not KEYCZAR_AVAILABLE:
        raise errors.AnsibleError("python-keyczar must be installed on the control machine to use accelerated modes")

    key_path = os.path.expanduser(C.ACCELERATE_KEYS_DIR)
    if not os.path.exists(key_path):
        os.makedirs(key_path, mode=0700)
        os.chmod(key_path, int(C.ACCELERATE_KEYS_DIR_PERMS, 8))
    elif not os.path.isdir(key_path):
        raise errors.AnsibleError('ACCELERATE_KEYS_DIR is not a directory.')

    if stat.S_IMODE(os.stat(key_path).st_mode) != int(C.ACCELERATE_KEYS_DIR_PERMS, 8):
        raise errors.AnsibleError('Incorrect permissions on the private key directory. Use `chmod 0%o %s` to correct this issue, and make sure any of the keys files contained within that directory are set to 0%o' % (int(C.ACCELERATE_KEYS_DIR_PERMS, 8), C.ACCELERATE_KEYS_DIR, int(C.ACCELERATE_KEYS_FILE_PERMS, 8)))

    key_path = os.path.join(key_path, hostname)

    # use new AES keys every 2 hours, which means fireball must not allow running for longer either
    if not os.path.exists(key_path) or (time.time() - os.path.getmtime(key_path) > 60*60*2):
        key = AesKey.Generate(size=256)
        fd = os.open(key_path, os.O_WRONLY | os.O_CREAT, int(C.ACCELERATE_KEYS_FILE_PERMS, 8))
        fh = os.fdopen(fd, 'w')
        fh.write(str(key))
        fh.close()
        return key
    else:
        if stat.S_IMODE(os.stat(key_path).st_mode) != int(C.ACCELERATE_KEYS_FILE_PERMS, 8):
            raise errors.AnsibleError('Incorrect permissions on the key file for this host. Use `chmod 0%o %s` to correct this issue.' % (int(C.ACCELERATE_KEYS_FILE_PERMS, 8), key_path))
        fh = open(key_path)
        key = AesKey.Read(fh.read())
        fh.close()
        return key

def encrypt(key, msg):
    return key.Encrypt(msg.encode('utf-8'))

def decrypt(key, msg):
    try:
        return key.Decrypt(msg)
    except key_errors.InvalidSignatureError:
        raise errors.AnsibleError("decryption failed")

###############################################################
# UTILITY FUNCTIONS FOR COMMAND LINE TOOLS
###############################################################

def read_vault_file(vault_password_file):
    """Read a vault password from a file or if executable, execute the script and
    retrieve password from STDOUT
    """
    if vault_password_file:
        this_path = os.path.realpath(os.path.expanduser(vault_password_file))
        if is_executable(this_path):
            try:
                # STDERR not captured to make it easier for users to prompt for input in their scripts
                p = subprocess.Popen(this_path, stdout=subprocess.PIPE)
            except OSError, e:
                raise errors.AnsibleError("problem running %s (%s)" % (' '.join(this_path), e))
            stdout, stderr = p.communicate()
            vault_pass = stdout.strip('\r\n')
        else:
            try:
                f = open(this_path, "rb")
                vault_pass=f.read().strip()
                f.close()
            except (OSError, IOError), e:
                raise errors.AnsibleError("Could not read %s: %s" % (this_path, e))

        return vault_pass
    else:
        return None

def err(msg):
    ''' print an error message to stderr '''

    print >> sys.stderr, msg

def exit(msg, rc=1):
    ''' quit with an error to stdout and a failure code '''

    err(msg)
    sys.exit(rc)

def jsonify(result, format=False):
    ''' format JSON output (uncompressed or uncompressed) '''

    if result is None:
        return "{}"
    result2 = result.copy()
    for key, value in result2.items():
        if type(value) is str:
            result2[key] = value.decode('utf-8', 'ignore')

    indent = None
    if format:
        indent = 4

    try:
        return json.dumps(result2, sort_keys=True, indent=indent, ensure_ascii=False)
    except UnicodeDecodeError:
        return json.dumps(result2, sort_keys=True, indent=indent)

def write_tree_file(tree, hostname, buf):
    ''' write something into treedir/hostname '''

    # TODO: might be nice to append playbook runs per host in a similar way
    # in which case, we'd want append mode.
    path = os.path.join(tree, hostname)
    buf = to_bytes(buf)
    with open(path, 'wb+') as fd:
        fd.write(buf)

def is_failed(result):
    ''' is a given JSON result a failed result? '''

    return ((result.get('rc', 0) != 0) or (result.get('failed', False) in [ True, 'True', 'true']))

def is_changed(result):
    ''' is a given JSON result a changed result? '''

    return (result.get('changed', False) in [ True, 'True', 'true'])

def check_conditional(conditional, basedir, inject, fail_on_undefined=False):
    from ansible.utils import template

    if conditional is None or conditional == '':
        return True

    if isinstance(conditional, list):
        for x in conditional:
            if not check_conditional(x, basedir, inject, fail_on_undefined=fail_on_undefined):
                return False
        return True

    if not isinstance(conditional, basestring):
        return conditional

    conditional = conditional.replace("jinja2_compare ","")
    # allow variable names
    if conditional in inject and '-' not in to_unicode(inject[conditional], nonstring='simplerepr'):
        conditional = to_unicode(inject[conditional], nonstring='simplerepr')
    conditional = template.template(basedir, conditional, inject, fail_on_undefined=fail_on_undefined)
    original = to_unicode(conditional, nonstring='simplerepr').replace("jinja2_compare ","")
    # a Jinja2 evaluation that results in something Python can eval!
    presented = "{%% if %s %%} True {%% else %%} False {%% endif %%}" % conditional
    conditional = template.template(basedir, presented, inject)
    val = conditional.strip()
    if val == presented:
        # the templating failed, meaning most likely a
        # variable was undefined. If we happened to be
        # looking for an undefined variable, return True,
        # otherwise fail
        if "is undefined" in conditional:
            return True
        elif "is defined" in conditional:
            return False
        else:
            raise errors.AnsibleError("error while evaluating conditional: %s" % original)
    elif val == "True":
        return True
    elif val == "False":
        return False
    else:
        raise errors.AnsibleError("unable to evaluate conditional: %s" % original)

def is_executable(path):
    '''is the given path executable?'''
    return (stat.S_IXUSR & os.stat(path)[stat.ST_MODE]
            or stat.S_IXGRP & os.stat(path)[stat.ST_MODE]
            or stat.S_IXOTH & os.stat(path)[stat.ST_MODE])

def unfrackpath(path):
    '''
    returns a path that is free of symlinks, environment
    variables, relative path traversals and symbols (~)
    example:
    '$HOME/../../var/mail' becomes '/var/spool/mail'
    '''
    return os.path.normpath(os.path.realpath(os.path.expandvars(os.path.expanduser(path))))

def prepare_writeable_dir(tree,mode=0777):
    ''' make sure a directory exists and is writeable '''

    # modify the mode to ensure the owner at least
    # has read/write access to this directory
    mode |= 0700

    # make sure the tree path is always expanded
    # and normalized and free of symlinks
    tree = unfrackpath(tree)

    if not os.path.exists(tree):
        try:
            os.makedirs(tree, mode)
        except (IOError, OSError), e:
            raise errors.AnsibleError("Could not make dir %s: %s" % (tree, e))
    if not os.access(tree, os.W_OK):
        raise errors.AnsibleError("Cannot write to path %s" % tree)
    return tree

def path_dwim(basedir, given):
    '''
    make relative paths work like folks expect.
    '''

    if given.startswith("'"):
        given = given[1:-1]

    if given.startswith("/"):
        return os.path.abspath(given)
    elif given.startswith("~"):
        return os.path.abspath(os.path.expanduser(given))
    else:
        if basedir is None:
            basedir = "."
        return os.path.abspath(os.path.join(basedir, given))

def path_dwim_relative(original, dirname, source, playbook_base, check=True):
    ''' find one file in a directory one level up in a dir named dirname relative to current '''
    # (used by roles code)

    from ansible.utils import template


    basedir = os.path.dirname(original)
    if os.path.islink(basedir):
        basedir = unfrackpath(basedir)
        template2 = os.path.join(basedir, dirname, source)
    else:
        template2 = os.path.join(basedir, '..', dirname, source)
    source2 = path_dwim(basedir, template2)
    if os.path.exists(source2):
        return source2
    obvious_local_path = path_dwim(playbook_base, source)
    if os.path.exists(obvious_local_path):
        return obvious_local_path
    if check:
        raise errors.AnsibleError("input file not found at %s or %s" % (source2, obvious_local_path))
    return source2 # which does not exist

def repo_url_to_role_name(repo_url):
    # gets the role name out of a repo like 
    # http://git.example.com/repos/repo.git" => "repo"

    if '://' not in repo_url and '@' not in repo_url:
        return repo_url
    trailing_path = repo_url.split('/')[-1]
    if trailing_path.endswith('.git'):
        trailing_path = trailing_path[:-4]
    if trailing_path.endswith('.tar.gz'):
        trailing_path = trailing_path[:-7]
    if ',' in trailing_path:
        trailing_path = trailing_path.split(',')[0]
    return trailing_path


def role_spec_parse(role_spec):
    # takes a repo and a version like 
    # git+http://git.example.com/repos/repo.git,v1.0 
    # and returns a list of properties such as:
    # {
    #   'scm': 'git', 
    #   'src': 'http://git.example.com/repos/repo.git', 
    #   'version': 'v1.0', 
    #   'name': 'repo'
    # }
  
    role_spec = role_spec.strip()
    role_version = ''
    default_role_versions = dict(git='master', hg='tip')
    if role_spec == "" or role_spec.startswith("#"):
        return (None, None, None, None)

    tokens = [s.strip() for s in role_spec.split(',')]
    
    # assume https://github.com URLs are git+https:// URLs and not
    # tarballs unless they end in '.zip'
    if 'github.com/' in tokens[0] and not tokens[0].startswith("git+") and not tokens[0].endswith('.tar.gz'):
        tokens[0] = 'git+' + tokens[0]

    if '+' in tokens[0]:
        (scm, role_url) = tokens[0].split('+')
    else:
        scm = None
        role_url = tokens[0]
    if len(tokens) >= 2:
        role_version = tokens[1]
    if len(tokens) == 3:
        role_name = tokens[2]
    else:
        role_name = repo_url_to_role_name(tokens[0])
    if scm and not role_version:
        role_version = default_role_versions.get(scm, '')
    return dict(scm=scm, src=role_url, version=role_version, name=role_name)


def role_yaml_parse(role):
    if 'role' in role:
        # Old style: {role: "galaxy.role,version,name", other_vars: "here" }
        role_info = role_spec_parse(role['role'])
        if isinstance(role_info, dict):
            # Warning: Slight change in behaviour here.  name may be being
            # overloaded.  Previously, name was only a parameter to the role.
            # Now it is both a parameter to the role and the name that
            # ansible-galaxy will install under on the local system.
            if 'name' in role and 'name' in role_info:
                del role_info['name']
            role.update(role_info)
    else:
        # New style: { src: 'galaxy.role,version,name', other_vars: "here" }
        if 'github.com' in role["src"] and 'http' in role["src"] and '+' not in role["src"] and not role["src"].endswith('.tar.gz'):
            role["src"] = "git+" + role["src"]

        if '+' in role["src"]:
            (scm, src) = role["src"].split('+')
            role["scm"] = scm
            role["src"] = src

        if 'name' not in role:
            role["name"] = repo_url_to_role_name(role["src"])

        if 'version' not in role:
            role['version'] = ''

        if 'scm' not in role:
            role['scm'] = None

    return role


def json_loads(data):
    ''' parse a JSON string and return a data structure '''
    try:
        loaded = json.loads(data)
    except ValueError,e:
        raise errors.AnsibleError("Unable to read provided data as JSON: %s" % str(e))

    return loaded

def _clean_data(orig_data, from_remote=False, from_inventory=False):
    ''' remove jinja2 template tags from a string '''

    if not isinstance(orig_data, basestring):
        return orig_data

    # when the data is marked as having come from a remote, we always
    # replace any print blocks (ie. {{var}}), however when marked as coming
    # from inventory we only replace print blocks that contain a call to
    # a lookup plugin (ie. {{lookup('foo','bar'))}})
    replace_prints = from_remote or (from_inventory and '{{' in orig_data and LOOKUP_REGEX.search(orig_data) is not None)

    regex = PRINT_CODE_REGEX if replace_prints else CODE_REGEX

    with contextlib.closing(StringIO.StringIO(orig_data)) as data:
        # these variables keep track of opening block locations, as we only
        # want to replace matched pairs of print/block tags
        print_openings = []
        block_openings = []
        for mo in regex.finditer(orig_data):
            token = mo.group(0)
            token_start = mo.start(0)

            if token[0] == '{':
                if token == '{%':
                    block_openings.append(token_start)
                elif token == '{{':
                    print_openings.append(token_start)

            elif token[1] == '}':
                prev_idx = None
                if token == '%}' and block_openings:
                    prev_idx = block_openings.pop()
                elif token == '}}' and print_openings:
                    prev_idx = print_openings.pop()

                if prev_idx is not None:
                    # replace the opening
                    data.seek(prev_idx, os.SEEK_SET)
                    data.write('{#')
                    # replace the closing
                    data.seek(token_start, os.SEEK_SET)
                    data.write('#}')

            else:
                assert False, 'Unhandled regex match'

        return data.getvalue()

def _clean_data_struct(orig_data, from_remote=False, from_inventory=False):
    '''
    walk a complex data structure, and use _clean_data() to
    remove any template tags that may exist
    '''
    if not from_remote and not from_inventory:
        raise errors.AnsibleErrors("when cleaning data, you must specify either from_remote or from_inventory")
    if isinstance(orig_data, dict):
        data = orig_data.copy()
        for key in data:
            new_key = _clean_data_struct(key, from_remote, from_inventory)
            new_val = _clean_data_struct(data[key], from_remote, from_inventory)
            if key != new_key:
                del data[key]
            data[new_key] = new_val
    elif isinstance(orig_data, list):
        data = orig_data[:]
        for i in range(0, len(data)):
            data[i] = _clean_data_struct(data[i], from_remote, from_inventory)
    elif isinstance(orig_data, basestring):
        data = _clean_data(orig_data, from_remote, from_inventory)
    else:
        data = orig_data
    return data

def parse_json(raw_data, from_remote=False, from_inventory=False, no_exceptions=False):
    ''' this version for module return data only '''

    orig_data = raw_data

    # ignore stuff like tcgetattr spewage or other warnings
    data = filter_leading_non_json_lines(raw_data)

    try:
        results = json.loads(data)
    except:
        if no_exceptions:
            return dict(failed=True, parsed=False, msg=raw_data)
        else:
            raise

    if from_remote:
        results = _clean_data_struct(results, from_remote, from_inventory)

    return results

def serialize_args(args):
    '''
    Flattens a dictionary args to a k=v string
    '''
    module_args = ""
    for (k,v) in args.iteritems():
        if isinstance(v, basestring):
            module_args = "%s=%s %s" % (k, pipes.quote(v), module_args)
        elif isinstance(v, bool):
            module_args = "%s=%s %s" % (k, str(v), module_args)
    return module_args.strip()

def merge_module_args(current_args, new_args):
    '''
    merges either a dictionary or string of k=v pairs with another string of k=v pairs,
    and returns a new k=v string without duplicates.
    '''
    if not isinstance(current_args, basestring):
        raise errors.AnsibleError("expected current_args to be a basestring")
    # we use parse_kv to split up the current args into a dictionary
    final_args = parse_kv(current_args)
    if isinstance(new_args, dict):
        final_args.update(new_args)
    elif isinstance(new_args, basestring):
        new_args_kv = parse_kv(new_args)
        final_args.update(new_args_kv)
    return serialize_args(final_args)

def parse_yaml(data, path_hint=None):
    ''' convert a yaml string to a data structure.  Also supports JSON, ssssssh!!!'''

    stripped_data = data.lstrip()
    loaded = None
    if stripped_data.startswith("{") or stripped_data.startswith("["):
        # since the line starts with { or [ we can infer this is a JSON document.
        try:
            loaded = json.loads(data)
        except ValueError, ve:
            if path_hint:
                raise errors.AnsibleError(path_hint + ": " + str(ve))
            else:
                raise errors.AnsibleError(str(ve))
    else:
        # else this is pretty sure to be a YAML document
        loaded = yaml.load(data, Loader=Loader)

    return loaded

def process_common_errors(msg, probline, column):
    replaced = probline.replace(" ","")

    if ":{{" in replaced and "}}" in replaced:
        msg = msg + """
This one looks easy to fix.  YAML thought it was looking for the start of a
hash/dictionary and was confused to see a second "{".  Most likely this was
meant to be an ansible template evaluation instead, so we have to give the
parser a small hint that we wanted a string instead. The solution here is to
just quote the entire value.

For instance, if the original line was:

    app_path: {{ base_path }}/foo

It should be written as:

    app_path: "{{ base_path }}/foo"
"""
        return msg

    elif len(probline) and len(probline) > 1 and len(probline) > column and probline[column] == ":" and probline.count(':') > 1:
        msg = msg + """
This one looks easy to fix.  There seems to be an extra unquoted colon in the line
and this is confusing the parser. It was only expecting to find one free
colon. The solution is just add some quotes around the colon, or quote the
entire line after the first colon.

For instance, if the original line was:

    copy: src=file.txt dest=/path/filename:with_colon.txt

It can be written as:

    copy: src=file.txt dest='/path/filename:with_colon.txt'

Or:

    copy: 'src=file.txt dest=/path/filename:with_colon.txt'


"""
        return msg
    else:
        parts = probline.split(":")
        if len(parts) > 1:
            middle = parts[1].strip()
            match = False
            unbalanced = False
            if middle.startswith("'") and not middle.endswith("'"):
                match = True
            elif middle.startswith('"') and not middle.endswith('"'):
                match = True
            if len(middle) > 0 and middle[0] in [ '"', "'" ] and middle[-1] in [ '"', "'" ] and probline.count("'") > 2 or probline.count('"') > 2:
                unbalanced = True
            if match:
                msg = msg + """
This one looks easy to fix.  It seems that there is a value started
with a quote, and the YAML parser is expecting to see the line ended
with the same kind of quote.  For instance:

    when: "ok" in result.stdout

Could be written as:

   when: '"ok" in result.stdout'

or equivalently:

   when: "'ok' in result.stdout"

"""
                return msg

            if unbalanced:
                msg = msg + """
We could be wrong, but this one looks like it might be an issue with
unbalanced quotes.  If starting a value with a quote, make sure the
line ends with the same set of quotes.  For instance this arbitrary
example:

    foo: "bad" "wolf"

Could be written as:

    foo: '"bad" "wolf"'

"""
                return msg

    return msg

def process_yaml_error(exc, data, path=None, show_content=True):
    if hasattr(exc, 'problem_mark'):
        mark = exc.problem_mark
        if show_content:
            if mark.line -1 >= 0:
                before_probline = data.split("\n")[mark.line-1]
            else:
                before_probline = ''
            probline = data.split("\n")[mark.line]
            arrow = " " * mark.column + "^"
            msg = """Syntax Error while loading YAML script, %s
Note: The error may actually appear before this position: line %s, column %s

%s
%s
%s""" % (path, mark.line + 1, mark.column + 1, before_probline, probline, arrow)

            unquoted_var = None
            if '{{' in probline and '}}' in probline:
                if '"{{' not in probline or "'{{" not in probline:
                    unquoted_var = True

            if not unquoted_var:
                msg = process_common_errors(msg, probline, mark.column)
            else:
                msg = msg + """
We could be wrong, but this one looks like it might be an issue with
missing quotes.  Always quote template expression brackets when they
start a value. For instance:

    with_items:
      - {{ foo }}

Should be written as:

    with_items:
      - "{{ foo }}"

"""
        else:
            # most likely displaying a file with sensitive content,
            # so don't show any of the actual lines of yaml just the
            # line number itself
            msg = """Syntax error while loading YAML script, %s
The error appears to have been on line %s, column %s, but may actually
be before there depending on the exact syntax problem.
""" % (path, mark.line + 1, mark.column + 1)

    else:
        # No problem markers means we have to throw a generic
        # "stuff messed up" type message. Sry bud.
        if path:
            msg = "Could not parse YAML. Check over %s again." % path
        else:
            msg = "Could not parse YAML."
    raise errors.AnsibleYAMLValidationFailed(msg)


def parse_yaml_from_file(path, vault_password=None):
    ''' convert a yaml file to a data structure '''

    data = None
    show_content = True

    try:
        data = open(path).read()
    except IOError:
        raise errors.AnsibleError("file could not read: %s" % path)

    vault = VaultLib(password=vault_password)
    if vault.is_encrypted(data):
        # if the file is encrypted and no password was specified,
        # the decrypt call would throw an error, but we check first
        # since the decrypt function doesn't know the file name
        if vault_password is None:
            raise errors.AnsibleError("A vault password must be specified to decrypt %s" % path)
        data = vault.decrypt(data)
        show_content = False

    try:
        return parse_yaml(data, path_hint=path)
    except yaml.YAMLError, exc:
        process_yaml_error(exc, data, path, show_content)

def parse_kv(args):
    ''' convert a string of key/value items to a dict '''
    options = {}
    if args is not None:
        try:
            vargs = split_args(args)
        except ValueError, ve:
            if 'no closing quotation' in str(ve).lower():
                raise errors.AnsibleError("error parsing argument string, try quoting the entire line.")
            else:
                raise
        for x in vargs:
            if "=" in x:
                k, v = x.split("=",1)
                options[k.strip()] = unquote(v.strip())
    return options

def _validate_both_dicts(a, b):

    if not (isinstance(a, dict) and isinstance(b, dict)):
        raise errors.AnsibleError(
            "failed to combine variables, expected dicts but got a '%s' and a '%s'" % (type(a).__name__, type(b).__name__)
        )

def merge_hash(a, b):
    ''' recursively merges hash b into a
    keys from b take precedence over keys from a '''

    result = {}

    # we check here as well as in combine_vars() since this
    # function can work recursively with nested dicts
    _validate_both_dicts(a, b)

    for dicts in a, b:
        # next, iterate over b keys and values
        for k, v in dicts.iteritems():
            # if there's already such key in a
            # and that key contains dict
            if k in result and isinstance(result[k], dict):
                # merge those dicts recursively
                result[k] = merge_hash(a[k], v)
            else:
                # otherwise, just copy a value from b to a
                result[k] = v

    return result

def default(value, function):
    ''' syntactic sugar around lazy evaluation of defaults '''
    if value is None:
        return function()
    return value


def _git_repo_info(repo_path):
    ''' returns a string containing git branch, commit id and commit date '''
    result = None
    if os.path.exists(repo_path):
        # Check if the .git is a file. If it is a file, it means that we are in a submodule structure.
        if os.path.isfile(repo_path):
            try:
                gitdir = yaml.safe_load(open(repo_path)).get('gitdir')
                # There is a possibility the .git file to have an absolute path.
                if os.path.isabs(gitdir):
                    repo_path = gitdir
                else:
                    repo_path = os.path.join(repo_path[:-4], gitdir)
            except (IOError, AttributeError):
                return ''
        f = open(os.path.join(repo_path, "HEAD"))
        branch = f.readline().split('/')[-1].rstrip("\n")
        f.close()
        branch_path = os.path.join(repo_path, "refs", "heads", branch)
        if os.path.exists(branch_path):
            f = open(branch_path)
            commit = f.readline()[:10]
            f.close()
        else:
            # detached HEAD
            commit = branch[:10]
            branch = 'detached HEAD'
            branch_path = os.path.join(repo_path, "HEAD")

        date = time.localtime(os.stat(branch_path).st_mtime)
        if time.daylight == 0:
            offset = time.timezone
        else:
            offset = time.altzone
        result = "({0} {1}) last updated {2} (GMT {3:+04d})".format(branch, commit,
            time.strftime("%Y/%m/%d %H:%M:%S", date), offset / -36)
    else:
        result = ''
    return result


def _gitinfo():
    basedir = os.path.join(os.path.dirname(__file__), '..', '..', '..')
    repo_path = os.path.join(basedir, '.git')
    result = _git_repo_info(repo_path)
    submodules = os.path.join(basedir, '.gitmodules')
    if not os.path.exists(submodules):
       return result
    f = open(submodules)
    for line in f:
        tokens = line.strip().split(' ')
        if tokens[0] == 'path':
            submodule_path = tokens[2]
            submodule_info =_git_repo_info(os.path.join(basedir, submodule_path, '.git'))
            if not submodule_info:
                submodule_info = ' not found - use git submodule update --init ' + submodule_path
            result += "\n  {0}: {1}".format(submodule_path, submodule_info)
    f.close()
    return result


def version(prog):
    result = "{0} {1}".format(prog, __version__)
    gitinfo = _gitinfo()
    if gitinfo:
        result = result + " {0}".format(gitinfo)
    result = result + "\n  configured module search path = %s" % C.DEFAULT_MODULE_PATH
    return result

def version_info(gitinfo=False):
    if gitinfo:
        # expensive call, user with care
        ansible_version_string = version('')
    else:
        ansible_version_string = __version__
    ansible_version = ansible_version_string.split()[0]
    ansible_versions = ansible_version.split('.')
    for counter in range(len(ansible_versions)):
        if ansible_versions[counter] == "":
            ansible_versions[counter] = 0
        try:
            ansible_versions[counter] = int(ansible_versions[counter])
        except:
            pass
    if len(ansible_versions) < 3:
        for counter in range(len(ansible_versions), 3):
            ansible_versions.append(0)
    return {'string':      ansible_version_string.strip(),
            'full':        ansible_version,
            'major':       ansible_versions[0],
            'minor':       ansible_versions[1],
            'revision':    ansible_versions[2]}

def getch():
    ''' read in a single character '''
    fd = sys.stdin.fileno()
    old_settings = termios.tcgetattr(fd)
    try:
        tty.setraw(sys.stdin.fileno())
        ch = sys.stdin.read(1)
    finally:
        termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
    return ch

def sanitize_output(arg_string):
    ''' strips private info out of a string '''

    private_keys = ('password', 'login_password')

    output = []
    for part in arg_string.split():
        try:
            (k, v) = part.split('=', 1)
        except ValueError:
            v = heuristic_log_sanitize(part)
            output.append(v)
            continue

        if k in private_keys:
            v = 'VALUE_HIDDEN'
        else:
            v = heuristic_log_sanitize(v)
        output.append('%s=%s' % (k, v))

    output = ' '.join(output)
    return output


####################################################################
# option handling code for /usr/bin/ansible and ansible-playbook
# below this line

class SortedOptParser(optparse.OptionParser):
    '''Optparser which sorts the options by opt before outputting --help'''

    def format_help(self, formatter=None):
        self.option_list.sort(key=operator.methodcaller('get_opt_string'))
        return optparse.OptionParser.format_help(self, formatter=None)

def increment_debug(option, opt, value, parser):
    global VERBOSITY
    VERBOSITY += 1

def base_parser(constants=C, usage="", output_opts=False, runas_opts=False,
    async_opts=False, connect_opts=False, subset_opts=False, check_opts=False, diff_opts=False):
    ''' create an options parser for any ansible script '''

    parser = SortedOptParser(usage, version=version("%prog"))
    parser.add_option('-v','--verbose', default=False, action="callback",
        callback=increment_debug, help="verbose mode (-vvv for more, -vvvv to enable connection debugging)")

    parser.add_option('-f','--forks', dest='forks', default=constants.DEFAULT_FORKS, type='int',
        help="specify number of parallel processes to use (default=%s)" % constants.DEFAULT_FORKS)
    parser.add_option('-i', '--inventory-file', dest='inventory',
        help="specify inventory host file (default=%s)" % constants.DEFAULT_HOST_LIST,
        default=constants.DEFAULT_HOST_LIST)
    parser.add_option('-e', '--extra-vars', dest="extra_vars", action="append",
        help="set additional variables as key=value or YAML/JSON", default=[])
    parser.add_option('-u', '--user', default=constants.DEFAULT_REMOTE_USER, dest='remote_user',
        help='connect as this user (default=%s)' % constants.DEFAULT_REMOTE_USER)
    parser.add_option('-k', '--ask-pass', default=False, dest='ask_pass', action='store_true',
        help='ask for SSH password')
    parser.add_option('--private-key', default=constants.DEFAULT_PRIVATE_KEY_FILE, dest='private_key_file',
        help='use this file to authenticate the connection')
    parser.add_option('--ask-vault-pass', default=False, dest='ask_vault_pass', action='store_true',
        help='ask for vault password')
    parser.add_option('--vault-password-file', default=constants.DEFAULT_VAULT_PASSWORD_FILE,
        dest='vault_password_file', help="vault password file")
    parser.add_option('--list-hosts', dest='listhosts', action='store_true',
        help='outputs a list of matching hosts; does not execute anything else')
    parser.add_option('-M', '--module-path', dest='module_path',
        help="specify path(s) to module library (default=%s)" % constants.DEFAULT_MODULE_PATH,
        default=None)

    if subset_opts:
        parser.add_option('-l', '--limit', default=constants.DEFAULT_SUBSET, dest='subset',
            help='further limit selected hosts to an additional pattern')

    parser.add_option('-T', '--timeout', default=constants.DEFAULT_TIMEOUT, type='int',
        dest='timeout',
        help="override the SSH timeout in seconds (default=%s)" % constants.DEFAULT_TIMEOUT)

    if output_opts:
        parser.add_option('-o', '--one-line', dest='one_line', action='store_true',
            help='condense output')
        parser.add_option('-t', '--tree', dest='tree', default=None,
            help='log output to this directory')

    if runas_opts:
        # priv user defaults to root later on to enable detecting when this option was given here
        parser.add_option('-K', '--ask-sudo-pass', default=constants.DEFAULT_ASK_SUDO_PASS, dest='ask_sudo_pass', action='store_true',
            help='ask for sudo password (deprecated, use become)')
        parser.add_option('--ask-su-pass', default=constants.DEFAULT_ASK_SU_PASS, dest='ask_su_pass', action='store_true',
            help='ask for su password (deprecated, use become)')
        parser.add_option("-s", "--sudo", default=constants.DEFAULT_SUDO, action="store_true", dest='sudo',
            help="run operations with sudo (nopasswd) (deprecated, use become)")
        parser.add_option('-U', '--sudo-user', dest='sudo_user', default=None,
                          help='desired sudo user (default=root) (deprecated, use become)')
        parser.add_option('-S', '--su', default=constants.DEFAULT_SU, action='store_true',
            help='run operations with su (deprecated, use become)')
        parser.add_option('-R', '--su-user', default=None,
            help='run operations with su as this user (default=%s) (deprecated, use become)' % constants.DEFAULT_SU_USER)

        # consolidated privilege escalation (become)
        parser.add_option("-b", "--become", default=constants.DEFAULT_BECOME, action="store_true", dest='become',
            help="run operations with become (nopasswd implied)")
        parser.add_option('--become-method', dest='become_method', default=constants.DEFAULT_BECOME_METHOD, type='string',
            help="privilege escalation method to use (default=%s), valid choices: [ %s ]" % (constants.DEFAULT_BECOME_METHOD, ' | '.join(constants.BECOME_METHODS)))
        parser.add_option('--become-user', default=None, dest='become_user', type='string',
            help='run operations as this user (default=%s)' % constants.DEFAULT_BECOME_USER)
        parser.add_option('--ask-become-pass', default=False, dest='become_ask_pass', action='store_true',
            help='ask for privilege escalation password')


    if connect_opts:
        parser.add_option('-c', '--connection', dest='connection',
                          default=constants.DEFAULT_TRANSPORT,
                          help="connection type to use (default=%s)" % constants.DEFAULT_TRANSPORT)

    if async_opts:
        parser.add_option('-P', '--poll', default=constants.DEFAULT_POLL_INTERVAL, type='int',
            dest='poll_interval',
            help="set the poll interval if using -B (default=%s)" % constants.DEFAULT_POLL_INTERVAL)
        parser.add_option('-B', '--background', dest='seconds', type='int', default=0,
            help='run asynchronously, failing after X seconds (default=N/A)')

    if check_opts:
        parser.add_option("-C", "--check", default=False, dest='check', action='store_true',
            help="don't make any changes; instead, try to predict some of the changes that may occur"
        )

    if diff_opts:
        parser.add_option("-D", "--diff", default=False, dest='diff', action='store_true',
            help="when changing (small) files and templates, show the differences in those files; works great with --check"
        )

    return parser

def parse_extra_vars(extra_vars_opts, vault_pass):
    extra_vars = {}
    for extra_vars_opt in extra_vars_opts:
        extra_vars_opt = to_unicode(extra_vars_opt)
        if extra_vars_opt.startswith(u"@"):
            # Argument is a YAML file (JSON is a subset of YAML)
            extra_vars = combine_vars(extra_vars, parse_yaml_from_file(extra_vars_opt[1:], vault_password=vault_pass))
        elif extra_vars_opt and extra_vars_opt[0] in u'[{':
            # Arguments as YAML
            extra_vars = combine_vars(extra_vars, parse_yaml(extra_vars_opt))
        else:
            # Arguments as Key-value
            extra_vars = combine_vars(extra_vars, parse_kv(extra_vars_opt))
    return extra_vars

def ask_vault_passwords(ask_vault_pass=False, ask_new_vault_pass=False, confirm_vault=False, confirm_new=False):

    vault_pass = None
    new_vault_pass = None

    if ask_vault_pass:
        vault_pass = getpass.getpass(prompt="Vault password: ")

    if ask_vault_pass and confirm_vault:
        vault_pass2 = getpass.getpass(prompt="Confirm Vault password: ")
        if vault_pass != vault_pass2:
            raise errors.AnsibleError("Passwords do not match")

    if ask_new_vault_pass:
        new_vault_pass = getpass.getpass(prompt="New Vault password: ")

    if ask_new_vault_pass and confirm_new:
        new_vault_pass2 = getpass.getpass(prompt="Confirm New Vault password: ")
        if new_vault_pass != new_vault_pass2:
            raise errors.AnsibleError("Passwords do not match")

    # enforce no newline chars at the end of passwords
    if vault_pass:
        vault_pass = to_bytes(vault_pass, errors='strict', nonstring='simplerepr').strip()
    if new_vault_pass:
        new_vault_pass = to_bytes(new_vault_pass, errors='strict', nonstring='simplerepr').strip()

    return vault_pass, new_vault_pass

def ask_passwords(ask_pass=False, become_ask_pass=False, ask_vault_pass=False, become_method=C.DEFAULT_BECOME_METHOD):
    sshpass = None
    becomepass = None
    vaultpass = None
    become_prompt = ''

    if ask_pass:
        sshpass = getpass.getpass(prompt="SSH password: ")
        become_prompt = "%s password[defaults to SSH password]: " % become_method.upper()
        if sshpass:
            sshpass = to_bytes(sshpass, errors='strict', nonstring='simplerepr')
    else:
        become_prompt = "%s password: " % become_method.upper()

    if become_ask_pass:
        becomepass = getpass.getpass(prompt=become_prompt)
        if ask_pass and becomepass == '':
            becomepass = sshpass
        if becomepass:
            becomepass = to_bytes(becomepass)

    if ask_vault_pass:
        vaultpass = getpass.getpass(prompt="Vault password: ")
        if vaultpass:
            vaultpass = to_bytes(vaultpass, errors='strict', nonstring='simplerepr').strip()

    return (sshpass, becomepass, vaultpass)


def choose_pass_prompt(options):

    if options.ask_su_pass:
        return 'su'
    elif options.ask_sudo_pass:
        return 'sudo'

    return options.become_method

def normalize_become_options(options):

    options.become_ask_pass = options.become_ask_pass or options.ask_sudo_pass or options.ask_su_pass or C.DEFAULT_BECOME_ASK_PASS
    options.become_user = options.become_user or options.sudo_user or options.su_user or C.DEFAULT_BECOME_USER

    if options.become:
        pass
    elif options.sudo:
        options.become = True
        options.become_method = 'sudo'
    elif options.su:
        options.become = True
        options.become_method = 'su'


def do_encrypt(result, encrypt, salt_size=None, salt=None):
    if PASSLIB_AVAILABLE:
        try:
            crypt = getattr(passlib.hash, encrypt)
        except:
            raise errors.AnsibleError("passlib does not support '%s' algorithm" % encrypt)

        if salt_size:
            result = crypt.encrypt(result, salt_size=salt_size)
        elif salt:
            result = crypt.encrypt(result, salt=salt)
        else:
            result = crypt.encrypt(result)
    else:
        raise errors.AnsibleError("passlib must be installed to encrypt vars_prompt values")

    return result

def last_non_blank_line(buf):

    all_lines = buf.splitlines()
    all_lines.reverse()
    for line in all_lines:
        if (len(line) > 0):
            return line
    # shouldn't occur unless there's no output
    return ""

def filter_leading_non_json_lines(buf):
    '''
    used to avoid random output from SSH at the top of JSON output, like messages from
    tcagetattr, or where dropbear spews MOTD on every single command (which is nuts).

    need to filter anything which starts not with '{', '[', ', '=' or is an empty line.
    filter only leading lines since multiline JSON is valid.
    '''

    filtered_lines = StringIO.StringIO()
    stop_filtering = False
    for line in buf.splitlines():
        if stop_filtering or line.startswith('{') or line.startswith('['):
            stop_filtering = True
            filtered_lines.write(line + '\n')
    return filtered_lines.getvalue()

def boolean(value):
    val = str(value)
    if val.lower() in [ "true", "t", "y", "1", "yes" ]:
        return True
    else:
        return False

def make_become_cmd(cmd, user, shell, method, flags=None, exe=None):
    """
    helper function for connection plugins to create privilege escalation commands
    """

    randbits = ''.join(chr(random.randint(ord('a'), ord('z'))) for x in xrange(32))
    success_key = 'BECOME-SUCCESS-%s' % randbits
    prompt = None
    becomecmd = None

    shell = shell or '$SHELL'

    if method == 'sudo':
        # Rather than detect if sudo wants a password this time, -k makes sudo always ask for
        # a password if one is required. Passing a quoted compound command to sudo (or sudo -s)
        # directly doesn't work, so we shellquote it with pipes.quote() and pass the quoted
        # string to the user's shell.  We loop reading output until we see the randomly-generated
        # sudo prompt set with the -p option.
        prompt = '[sudo via ansible, key=%s] password: ' % randbits
        exe = exe or C.DEFAULT_SUDO_EXE
        becomecmd = '%s -k && %s %s -S -p "%s" -u %s %s -c %s' % \
            (exe, exe, flags or C.DEFAULT_SUDO_FLAGS, prompt, user, shell, pipes.quote('echo %s; %s' % (success_key, cmd)))

    elif method == 'su':
        exe = exe or C.DEFAULT_SU_EXE
        flags = flags or C.DEFAULT_SU_FLAGS
        becomecmd = '%s %s %s -c "%s -c %s"' % (exe, flags, user, shell, pipes.quote('echo %s; %s' % (success_key, cmd)))

    elif method == 'pbrun':
        prompt = 'assword:'
        exe = exe or 'pbrun'
        flags = flags or ''
        becomecmd = '%s -b %s -u %s "%s"' % (exe, flags, user, pipes.quote('echo %s; %s' % (success_key,cmd)))

    elif method == 'pfexec':
        exe = exe or 'pfexec'
        flags = flags or ''
        # No user as it uses it's own exec_attr to figure it out
        becomecmd = '%s %s "%s"' % (exe, flags, pipes.quote('echo %s; %s' % (success_key,cmd)))

    if becomecmd is None:
        raise errors.AnsibleError("Privilege escalation method not found: %s" % method)

    return (('%s -c ' % shell) + pipes.quote(becomecmd), prompt, success_key)


def make_sudo_cmd(sudo_exe, sudo_user, executable, cmd):
    """
    helper function for connection plugins to create sudo commands
    """
    return make_become_cmd(cmd, sudo_user, executable, 'sudo', C.DEFAULT_SUDO_FLAGS, sudo_exe)


def make_su_cmd(su_user, executable, cmd):
    """
    Helper function for connection plugins to create direct su commands
    """
    return make_become_cmd(cmd, su_user, executable, 'su', C.DEFAULT_SU_FLAGS, C.DEFAULT_SU_EXE)

def get_diff(diff):
    # called by --diff usage in playbook and runner via callbacks
    # include names in diffs 'before' and 'after' and do diff -U 10

    try:
        with warnings.catch_warnings():
            warnings.simplefilter('ignore')
            ret = []
            if 'dst_binary' in diff:
                ret.append("diff skipped: destination file appears to be binary\n")
            if 'src_binary' in diff:
                ret.append("diff skipped: source file appears to be binary\n")
            if 'dst_larger' in diff:
                ret.append("diff skipped: destination file size is greater than %d\n" % diff['dst_larger'])
            if 'src_larger' in diff:
                ret.append("diff skipped: source file size is greater than %d\n" % diff['src_larger'])
            if 'before' in diff and 'after' in diff:
                if 'before_header' in diff:
                    before_header = "before: %s" % diff['before_header']
                else:
                    before_header = 'before'
                if 'after_header' in diff:
                    after_header = "after: %s" % diff['after_header']
                else:
                    after_header = 'after'
                differ = difflib.unified_diff(to_unicode(diff['before']).splitlines(True), to_unicode(diff['after']).splitlines(True), before_header, after_header, '', '', 10)
                for line in list(differ):
                    ret.append(line)
            return u"".join(ret)
    except UnicodeDecodeError:
        return ">> the files are different, but the diff library cannot compare unicode strings"

def is_list_of_strings(items):
    for x in items:
        if not isinstance(x, basestring):
            return False
    return True

def list_union(a, b):
    result = []
    for x in a:
        if x not in result:
            result.append(x)
    for x in b:
        if x not in result:
            result.append(x)
    return result

def list_intersection(a, b):
    result = []
    for x in a:
        if x in b and x not in result:
            result.append(x)
    return result

def list_difference(a, b):
    result = []
    for x in a:
        if x not in b and x not in result:
            result.append(x)
    for x in b:
        if x not in a and x not in result:
            result.append(x)
    return result

def contains_vars(data):
    '''
    returns True if the data contains a variable pattern
    '''
    return "$" in data or "{{" in data

def safe_eval(expr, locals={}, include_exceptions=False):
    '''
    This is intended for allowing things like:
    with_items: a_list_variable

    Where Jinja2 would return a string but we do not want to allow it to
    call functions (outside of Jinja2, where the env is constrained). If
    the input data to this function came from an untrusted (remote) source,
    it should first be run through _clean_data_struct() to ensure the data
    is further sanitized prior to evaluation.

    Based on:
    http://stackoverflow.com/questions/12523516/using-ast-and-whitelists-to-make-pythons-eval-safe
    '''

    # this is the whitelist of AST nodes we are going to
    # allow in the evaluation. Any node type other than
    # those listed here will raise an exception in our custom
    # visitor class defined below.
    SAFE_NODES = set(
        (
            ast.Add,
            ast.BinOp,
            ast.Call,
            ast.Compare,
            ast.Dict,
            ast.Div,
            ast.Expression,
            ast.List,
            ast.Load,
            ast.Mult,
            ast.Num,
            ast.Name,
            ast.Str,
            ast.Sub,
            ast.Tuple,
            ast.UnaryOp,
        )
    )

    # AST node types were expanded after 2.6
    if not sys.version.startswith('2.6'):
        SAFE_NODES.union(
            set(
                (ast.Set,)
            )
        )

    filter_list = []
    for filter in filter_loader.all():
        filter_list.extend(filter.filters().keys())

    CALL_WHITELIST = C.DEFAULT_CALLABLE_WHITELIST + filter_list

    class CleansingNodeVisitor(ast.NodeVisitor):
        def generic_visit(self, node, inside_call=False):
            if type(node) not in SAFE_NODES:
                raise Exception("invalid expression (%s)" % expr)
            elif isinstance(node, ast.Call):
                inside_call = True
            elif isinstance(node, ast.Name) and inside_call:
                if hasattr(builtin, node.id) and node.id not in CALL_WHITELIST:
                    raise Exception("invalid function: %s" % node.id)
            # iterate over all child nodes
            for child_node in ast.iter_child_nodes(node):
                self.generic_visit(child_node, inside_call)

    if not isinstance(expr, basestring):
        # already templated to a datastructure, perhaps?
        if include_exceptions:
            return (expr, None)
        return expr

    cnv = CleansingNodeVisitor()
    try:
        parsed_tree = ast.parse(expr, mode='eval')
        cnv.visit(parsed_tree)
        compiled = compile(parsed_tree, expr, 'eval')
        result = eval(compiled, {}, locals)

        if include_exceptions:
            return (result, None)
        else:
            return result
    except SyntaxError, e:
        # special handling for syntax errors, we just return
        # the expression string back as-is
        if include_exceptions:
            return (expr, None)
        return expr
    except Exception, e:
        if include_exceptions:
            return (expr, e)
        return expr


def listify_lookup_plugin_terms(terms, basedir, inject):

    from ansible.utils import template

    if isinstance(terms, basestring):
        # someone did:
        #    with_items: alist
        # OR
        #    with_items: {{ alist }}

        stripped = terms.strip()
        if not (stripped.startswith('{') or stripped.startswith('[')) and \
           not stripped.startswith("/") and \
           not stripped.startswith('set([') and \
           not LOOKUP_REGEX.search(terms):
            # if not already a list, get ready to evaluate with Jinja2
            # not sure why the "/" is in above code :)
            try:
                new_terms = template.template(basedir, "{{ %s }}" % terms, inject)
                if isinstance(new_terms, basestring) and "{{" in new_terms:
                    pass
                else:
                    terms = new_terms
            except:
                pass

        if '{' in terms or '[' in terms:
            # Jinja2 already evaluated a variable to a list.
            # Jinja2-ified list needs to be converted back to a real type
            # TODO: something a bit less heavy than eval
            return safe_eval(terms)

        if isinstance(terms, basestring):
            terms = [ terms ]

    return terms

def combine_vars(a, b):

    _validate_both_dicts(a, b)

    if C.DEFAULT_HASH_BEHAVIOUR == "merge":
        return merge_hash(a, b)
    else:
        return dict(a.items() + b.items())

def random_password(length=20, chars=C.DEFAULT_PASSWORD_CHARS):
    '''Return a random password string of length containing only chars.'''

    password = []
    while len(password) < length:
        new_char = os.urandom(1)
        if new_char in chars:
            password.append(new_char)

    return ''.join(password)

def before_comment(msg):
    ''' what's the part of a string before a comment? '''
    msg = msg.replace("\#","**NOT_A_COMMENT**")
    msg = msg.split("#")[0]
    msg = msg.replace("**NOT_A_COMMENT**","#")
    return msg

def load_vars(basepath, results, vault_password=None):
    """
    Load variables from any potential yaml filename combinations of basepath,
    returning result.
    """

    paths_to_check = [ "".join([basepath, ext])
                       for ext in C.YAML_FILENAME_EXTENSIONS ]

    found_paths = []

    for path in paths_to_check:
        found, results = _load_vars_from_path(path, results, vault_password=vault_password)
        if found:
            found_paths.append(path)


    # disallow the potentially confusing situation that there are multiple
    # variable files for the same name. For example if both group_vars/all.yml
    # and group_vars/all.yaml
    if len(found_paths) > 1:
        raise errors.AnsibleError("Multiple variable files found. "
            "There should only be one. %s" % ( found_paths, ))

    return results

## load variables from yaml files/dirs
#  e.g. host/group_vars
#
def _load_vars_from_path(path, results, vault_password=None):
    """
    Robustly access the file at path and load variables, carefully reporting
    errors in a friendly/informative way.

    Return the tuple (found, new_results, )
    """

    try:
        # in the case of a symbolic link, we want the stat of the link itself,
        # not its target
        pathstat = os.lstat(path)
    except os.error, err:
        # most common case is that nothing exists at that path.
        if err.errno == errno.ENOENT:
            return False, results
        # otherwise this is a condition we should report to the user
        raise errors.AnsibleError(
            "%s is not accessible: %s."
            " Please check its permissions." % ( path, err.strerror))

    # symbolic link
    if stat.S_ISLNK(pathstat.st_mode):
        try:
            target = os.path.realpath(path)
        except os.error, err2:
            raise errors.AnsibleError("The symbolic link at %s "
                "is not readable: %s.  Please check its permissions."
                % (path, err2.strerror, ))
        # follow symbolic link chains by recursing, so we repeat the same
        # permissions checks above and provide useful errors.
        return _load_vars_from_path(target, results, vault_password)

    # directory
    if stat.S_ISDIR(pathstat.st_mode):

        # support organizing variables across multiple files in a directory
        return True, _load_vars_from_folder(path, results, vault_password=vault_password)

    # regular file
    elif stat.S_ISREG(pathstat.st_mode):
        data = parse_yaml_from_file(path, vault_password=vault_password)
        if data and type(data) != dict:
            raise errors.AnsibleError(
                "%s must be stored as a dictionary/hash" % path)
        elif data is None:
            data = {}

        # combine vars overrides by default but can be configured to do a
        # hash merge in settings
        results = combine_vars(results, data)
        return True, results

    # something else? could be a fifo, socket, device, etc.
    else:
        raise errors.AnsibleError("Expected a variable file or directory "
            "but found a non-file object at path %s" % (path, ))

def _load_vars_from_folder(folder_path, results, vault_password=None):
    """
    Load all variables within a folder recursively.
    """

    # this function and _load_vars_from_path are mutually recursive

    try:
        names = os.listdir(folder_path)
    except os.error, err:
        raise errors.AnsibleError(
            "This folder cannot be listed: %s: %s."
             % ( folder_path, err.strerror))

    # evaluate files in a stable order rather than whatever order the
    # filesystem lists them.
    names.sort()

    # do not parse hidden files or dirs, e.g. .svn/
    paths = [os.path.join(folder_path, name) for name in names if not name.startswith('.')]
    for path in paths:
        _found, results = _load_vars_from_path(path, results, vault_password=vault_password)
    return results

def update_hash(hash, key, new_value):
    ''' used to avoid nested .update calls on the parent '''

    value = hash.get(key, {})
    value.update(new_value)
    hash[key] = value

def censor_unlogged_data(data):
    '''
    used when the no_log: True attribute is passed to a task to keep data from a callback.
    NOT intended to prevent variable registration, but only things from showing up on
    screen
    '''
    new_data = {}
    for (x,y) in data.iteritems():
       if x in [ 'skipped', 'changed', 'failed', 'rc' ]:
           new_data[x] = y
    new_data['censored'] = 'results hidden due to no_log parameter'
    return new_data

def check_mutually_exclusive_privilege(options, parser):

    # privilege escalation command line arguments need to be mutually exclusive
    if (options.su or options.su_user or options.ask_su_pass) and \
                (options.sudo or options.sudo_user or options.ask_sudo_pass) or \
        (options.su or options.su_user or options.ask_su_pass) and \
                (options.become or options.become_user or options.become_ask_pass) or \
        (options.sudo or options.sudo_user or options.ask_sudo_pass) and \
                (options.become or options.become_user or options.become_ask_pass):

            parser.error("Sudo arguments ('--sudo', '--sudo-user', and '--ask-sudo-pass') "
                         "and su arguments ('-su', '--su-user', and '--ask-su-pass') "
                         "and become arguments ('--become', '--become-user', and '--ask-become-pass')"
                         " are exclusive of each other")


