# Copyright (c) 2015 Ansible, Inc.
# All Rights Reserved.

# Python
import base64
import json
import yaml
import logging
import os
import re
import subprocess
import stat
import sys
import urllib
import urlparse
import threading
import contextlib
import tempfile

# Decorator
from decorator import decorator

# Django
from django.utils.translation import ugettext_lazy as _
from django.db.models.fields.related import ForeignObjectRel, ManyToManyField

# Django REST Framework
from rest_framework.exceptions import ParseError, PermissionDenied
from django.utils.encoding import smart_str
from django.utils.text import slugify
from django.apps import apps

logger = logging.getLogger('awx.main.utils')

__all__ = ['get_object_or_400', 'get_object_or_403', 'camelcase_to_underscore', 'memoize',
           'get_ansible_version', 'get_ssh_version', 'get_awx_version', 'update_scm_url',
           'get_type_for_model', 'get_model_for_type', 'copy_model_by_class',
           'copy_m2m_relationships' ,'cache_list_capabilities', 'to_python_boolean',
           'ignore_inventory_computed_fields', 'ignore_inventory_group_removal',
           '_inventory_updates', 'get_pk_from_dict', 'getattrd', 'NoDefaultProvided',
           'get_current_apps', 'set_current_apps', 'OutputEventFilter',
           'callback_filter_out_ansible_extra_vars', 'get_search_fields', 'get_system_task_capacity',
           'wrap_args_with_proot', 'build_proot_temp_dir', 'check_proot_installed', 'model_to_dict',
           'model_instance_diff', 'timestamp_apiformat', 'parse_yaml_or_json', 'RequireDebugTrueOrTest',
           'has_model_field_prefetched']


def get_object_or_400(klass, *args, **kwargs):
    '''
    Return a single object from the given model or queryset based on the query
    params, otherwise raise an exception that will return in a 400 response.
    '''
    from django.shortcuts import _get_queryset
    queryset = _get_queryset(klass)
    try:
        return queryset.get(*args, **kwargs)
    except queryset.model.DoesNotExist as e:
        raise ParseError(*e.args)
    except queryset.model.MultipleObjectsReturned as e:
        raise ParseError(*e.args)


def get_object_or_403(klass, *args, **kwargs):
    '''
    Return a single object from the given model or queryset based on the query
    params, otherwise raise an exception that will return in a 403 response.
    '''
    from django.shortcuts import _get_queryset
    queryset = _get_queryset(klass)
    try:
        return queryset.get(*args, **kwargs)
    except queryset.model.DoesNotExist as e:
        raise PermissionDenied(*e.args)
    except queryset.model.MultipleObjectsReturned as e:
        raise PermissionDenied(*e.args)


def to_python_boolean(value, allow_none=False):
    value = unicode(value)
    if value.lower() in ('true', '1', 't'):
        return True
    elif value.lower() in ('false', '0', 'f'):
        return False
    elif allow_none and value.lower() in ('none', 'null'):
        return None
    else:
        raise ValueError(_(u'Unable to convert "%s" to boolean') % unicode(value))


def camelcase_to_underscore(s):
    '''
    Convert CamelCase names to lowercase_with_underscore.
    '''
    s = re.sub(r'(((?<=[a-z])[A-Z])|([A-Z](?![A-Z]|$)))', '_\\1', s)
    return s.lower().strip('_')


class RequireDebugTrueOrTest(logging.Filter):
    '''
    Logging filter to output when in DEBUG mode or running tests.
    '''

    def filter(self, record):
        from django.conf import settings
        return settings.DEBUG or 'test' in sys.argv


def memoize(ttl=60, cache_key=None):
    '''
    Decorator to wrap a function and cache its result.
    '''
    from django.core.cache import cache

    def _memoizer(f, *args, **kwargs):
        key = cache_key or slugify('%s %r %r' % (f.__name__, args, kwargs))
        value = cache.get(key)
        if value is None:
            value = f(*args, **kwargs)
            cache.set(key, value, ttl)
        return value
    return decorator(_memoizer)


@memoize()
def get_ansible_version():
    '''
    Return Ansible version installed.
    '''
    try:
        proc = subprocess.Popen(['ansible', '--version'],
                                stdout=subprocess.PIPE)
        result = proc.communicate()[0]
        return result.split('\n')[0].replace('ansible', '').strip()
    except:
        return 'unknown'


@memoize()
def get_ssh_version():
    '''
    Return SSH version installed.
    '''
    try:
        proc = subprocess.Popen(['ssh', '-V'],
                                stderr=subprocess.PIPE)
        result = proc.communicate()[1]
        return result.split(" ")[0].split("_")[1]
    except:
        return 'unknown'


def get_awx_version():
    '''
    Return Ansible Tower version as reported by setuptools.
    '''
    from awx import __version__
    try:
        import pkg_resources
        return pkg_resources.require('ansible_tower')[0].version
    except:
        return __version__


def update_scm_url(scm_type, url, username=True, password=True,
                   check_special_cases=True, scp_format=False):
    '''
    Update the given SCM URL to add/replace/remove the username/password. When
    username/password is True, preserve existing username/password, when
    False (None, '', etc.), remove any existing username/password, otherwise
    replace username/password. Also validates the given URL.
    '''
    # Handle all of the URL formats supported by the SCM systems:
    # git: https://www.kernel.org/pub/software/scm/git/docs/git-clone.html#URLS
    # hg: http://www.selenic.com/mercurial/hg.1.html#url-paths
    # svn: http://svnbook.red-bean.com/en/1.7/svn-book.html#svn.advanced.reposurls
    if scm_type not in ('git', 'hg', 'svn', 'insights'):
        raise ValueError(_('Unsupported SCM type "%s"') % str(scm_type))
    if not url.strip():
        return ''
    parts = urlparse.urlsplit(url)
    try:
        parts.port
    except ValueError:
        raise ValueError(_('Invalid %s URL') % scm_type)
    if parts.scheme == 'git+ssh' and not scp_format:
        raise ValueError(_('Unsupported %s URL') % scm_type)

    if '://' not in url:
        # Handle SCP-style URLs for git (e.g. [user@]host.xz:path/to/repo.git/).
        if scm_type == 'git' and ':' in url:
            if '@' in url:
                userpass, hostpath = url.split('@', 1)
            else:
                userpass, hostpath = '', url
            if hostpath.count(':') > 1:
                raise ValueError(_('Invalid %s URL') % scm_type)
            host, path = hostpath.split(':', 1)
            #if not path.startswith('/') and not path.startswith('~/'):
            #    path = '~/%s' % path
            #if path.startswith('/'):
            #    path = path.lstrip('/')
            hostpath = '/'.join([host, path])
            modified_url = '@'.join(filter(None, [userpass, hostpath]))
            # git+ssh scheme identifies URLs that should be converted back to
            # SCP style before passed to git module.
            parts = urlparse.urlsplit('git+ssh://%s' % modified_url)
        # Handle local paths specified without file scheme (e.g. /path/to/foo).
        # Only supported by git and hg.
        elif scm_type in ('git', 'hg'):
            if not url.startswith('/'):
                parts = urlparse.urlsplit('file:///%s' % url)
            else:
                parts = urlparse.urlsplit('file://%s' % url)
        else:
            raise ValueError(_('Invalid %s URL') % scm_type)

    # Validate that scheme is valid for given scm_type.
    scm_type_schemes = {
        'git': ('ssh', 'git', 'git+ssh', 'http', 'https', 'ftp', 'ftps', 'file'),
        'hg': ('http', 'https', 'ssh', 'file'),
        'svn': ('http', 'https', 'svn', 'svn+ssh', 'file'),
        'insights': ('http', 'https')
    }
    if parts.scheme not in scm_type_schemes.get(scm_type, ()):
        raise ValueError(_('Unsupported %s URL') % scm_type)
    if parts.scheme == 'file' and parts.netloc not in ('', 'localhost'):
        raise ValueError(_('Unsupported host "%s" for file:// URL') % (parts.netloc))
    elif parts.scheme != 'file' and not parts.netloc:
        raise ValueError(_('Host is required for %s URL') % parts.scheme)
    if username is True:
        netloc_username = parts.username or ''
    elif username:
        netloc_username = username
    else:
        netloc_username = ''
    if password is True:
        netloc_password = parts.password or ''
    elif password:
        netloc_password = password
    else:
        netloc_password = ''

    # Special handling for github/bitbucket SSH URLs.
    if check_special_cases:
        special_git_hosts = ('github.com', 'bitbucket.org', 'altssh.bitbucket.org')
        if scm_type == 'git' and parts.scheme.endswith('ssh') and parts.hostname in special_git_hosts and netloc_username != 'git':
            raise ValueError(_('Username must be "git" for SSH access to %s.') % parts.hostname)
        if scm_type == 'git' and parts.scheme.endswith('ssh') and parts.hostname in special_git_hosts and netloc_password:
            #raise ValueError('Password not allowed for SSH access to %s.' % parts.hostname)
            netloc_password = ''
        special_hg_hosts = ('bitbucket.org', 'altssh.bitbucket.org')
        if scm_type == 'hg' and parts.scheme == 'ssh' and parts.hostname in special_hg_hosts and netloc_username != 'hg':
            raise ValueError(_('Username must be "hg" for SSH access to %s.') % parts.hostname)
        if scm_type == 'hg' and parts.scheme == 'ssh' and netloc_password:
            #raise ValueError('Password not supported for SSH with Mercurial.')
            netloc_password = ''

    if netloc_username and parts.scheme != 'file' and scm_type != "insights":
        netloc = u':'.join([urllib.quote(x) for x in (netloc_username, netloc_password) if x])
    else:
        netloc = u''
    netloc = u'@'.join(filter(None, [netloc, parts.hostname]))
    if parts.port:
        netloc = u':'.join([netloc, unicode(parts.port)])
    new_url = urlparse.urlunsplit([parts.scheme, netloc, parts.path,
                                   parts.query, parts.fragment])
    if scp_format and parts.scheme == 'git+ssh':
        new_url = new_url.replace('git+ssh://', '', 1).replace('/', ':', 1)
    return new_url


def get_allowed_fields(obj, serializer_mapping):
    from django.contrib.auth.models import User

    if serializer_mapping is not None and obj.__class__ in serializer_mapping:
        serializer_actual = serializer_mapping[obj.__class__]()
        allowed_fields = [x for x in serializer_actual.fields if not serializer_actual.fields[x].read_only] + ['id']
    else:
        allowed_fields = [x.name for x in obj._meta.fields]

    if isinstance(obj, User):
        field_blacklist = ['last_login']
        allowed_fields = [f for f in allowed_fields if f not in field_blacklist]

    return allowed_fields


def _convert_model_field_for_display(obj, field_name, password_fields=None):
    # NOTE: Careful modifying the value of field_val, as it could modify
    # underlying model object field value also.
    field_val = getattr(obj, field_name, None)
    if password_fields is None:
        password_fields = set(getattr(type(obj), 'PASSWORD_FIELDS', [])) | set(['password'])
    if field_name in password_fields:
        return u'hidden'
    if hasattr(obj, 'display_%s' % field_name):
        field_val = getattr(obj, 'display_%s' % field_name)()
    if isinstance(field_val, (list, dict)):
        try:
            field_val = json.dumps(field_val, ensure_ascii=False)
        except Exception:
            pass
    if type(field_val) not in (bool, int, type(None)):
        field_val = smart_str(field_val)
    return field_val


def model_instance_diff(old, new, serializer_mapping=None):
    """
    Calculate the differences between two model instances. One of the instances may be None (i.e., a newly
    created model or deleted model). This will cause all fields with a value to have changed (from None).
    serializer_mapping are used to determine read-only fields.
    When provided, read-only fields will not be included in the resulting dictionary
    """
    from django.db.models import Model

    if not(old is None or isinstance(old, Model)):
        raise TypeError('The supplied old instance is not a valid model instance.')
    if not(new is None or isinstance(new, Model)):
        raise TypeError('The supplied new instance is not a valid model instance.')
    old_password_fields = set(getattr(type(old), 'PASSWORD_FIELDS', [])) | set(['password'])
    new_password_fields = set(getattr(type(new), 'PASSWORD_FIELDS', [])) | set(['password'])

    diff = {}

    allowed_fields = get_allowed_fields(new, serializer_mapping)

    for field in allowed_fields:
        old_value = getattr(old, field, None)
        new_value = getattr(new, field, None)
        if old_value != new_value:
            diff[field] = (
                _convert_model_field_for_display(old, field, password_fields=old_password_fields),
                _convert_model_field_for_display(new, field, password_fields=new_password_fields),
            )

    if len(diff) == 0:
        diff = None

    return diff


def model_to_dict(obj, serializer_mapping=None):
    """
    Serialize a model instance to a dictionary as best as possible
    serializer_mapping are used to determine read-only fields.
    When provided, read-only fields will not be included in the resulting dictionary
    """
    password_fields = set(getattr(type(obj), 'PASSWORD_FIELDS', [])) | set(['password'])
    attr_d = {}

    allowed_fields = get_allowed_fields(obj, serializer_mapping)

    for field in obj._meta.fields:
        if field.name not in allowed_fields:
            continue
        attr_d[field.name] = _convert_model_field_for_display(obj, field.name, password_fields=password_fields)

    return attr_d


def copy_model_by_class(obj1, Class2, fields, kwargs):
    '''
    Creates a new unsaved object of type Class2 using the fields from obj1
    values in kwargs can override obj1
    '''
    create_kwargs = {}
    for field_name in fields:
        # Foreign keys can be specified as field_name or field_name_id.
        id_field_name = '%s_id' % field_name
        if hasattr(obj1, id_field_name):
            if field_name in kwargs:
                value = kwargs[field_name]
            elif id_field_name in kwargs:
                value = kwargs[id_field_name]
            else:
                value = getattr(obj1, id_field_name)
            if hasattr(value, 'id'):
                value = value.id
            create_kwargs[id_field_name] = value
        elif field_name in kwargs:
            if field_name == 'extra_vars' and isinstance(kwargs[field_name], dict):
                create_kwargs[field_name] = json.dumps(kwargs['extra_vars'])
            elif not isinstance(Class2._meta.get_field(field_name), (ForeignObjectRel, ManyToManyField)):
                create_kwargs[field_name] = kwargs[field_name]
        elif hasattr(obj1, field_name):
            field_obj = obj1._meta.get_field_by_name(field_name)[0]
            if not isinstance(field_obj, ManyToManyField):
                create_kwargs[field_name] = getattr(obj1, field_name)

    # Apply class-specific extra processing for origination of unified jobs
    if hasattr(obj1, '_update_unified_job_kwargs') and obj1.__class__ != Class2:
        new_kwargs = obj1._update_unified_job_kwargs(**create_kwargs)
    else:
        new_kwargs = create_kwargs

    return Class2(**new_kwargs)


def copy_m2m_relationships(obj1, obj2, fields, kwargs=None):
    '''
    In-place operation.
    Given two saved objects, copies related objects from obj1
    to obj2 to field of same name, if field occurs in `fields`
    '''
    for field_name in fields:
        if hasattr(obj1, field_name):
            field_obj = obj1._meta.get_field_by_name(field_name)[0]
            if isinstance(field_obj, ManyToManyField):
                # Many to Many can be specified as field_name
                src_field_value = getattr(obj1, field_name)
                if kwargs and field_name in kwargs:
                    override_field_val = kwargs[field_name]
                    if isinstance(override_field_val, list):
                        getattr(obj2, field_name).add(*override_field_val)
                        continue
                    if override_field_val.__class__.__name__ is 'ManyRelatedManager':
                        src_field_value = override_field_val
                dest_field = getattr(obj2, field_name)
                dest_field.add(*list(src_field_value.all().values_list('id', flat=True)))


def get_type_for_model(model):
    '''
    Return type name for a given model class.
    '''
    opts = model._meta.concrete_model._meta
    return camelcase_to_underscore(opts.object_name)


def get_model_for_type(type):
    '''
    Return model class for a given type name.
    '''
    from django.db.models import Q
    from django.contrib.contenttypes.models import ContentType
    for ct in ContentType.objects.filter(Q(app_label='main') | Q(app_label='auth', model='user')):
        ct_model = ct.model_class()
        if not ct_model:
            continue
        ct_type = get_type_for_model(ct_model)
        if type == ct_type:
            return ct_model


def cache_list_capabilities(page, prefetch_list, model, user):
    '''
    Given a `page` list of objects, the specified roles for the specified user
    are save on each object in the list, using 1 query for each role type

    Examples:
    capabilities_prefetch = ['admin', 'execute']
      --> prefetch the admin (edit) and execute (start) permissions for
          items in list for current user
    capabilities_prefetch = ['inventory.admin']
      --> prefetch the related inventory FK permissions for current user,
          and put it into the object's cache
    capabilities_prefetch = [{'copy': ['inventory.admin', 'project.admin']}]
      --> prefetch logical combination of admin permission to inventory AND
          project, put into cache dictionary as "copy"
    '''
    from django.db.models import Q
    page_ids = [obj.id for obj in page]
    for obj in page:
        obj.capabilities_cache = {}

    skip_models = []
    if hasattr(model, 'invalid_user_capabilities_prefetch_models'):
        skip_models = model.invalid_user_capabilities_prefetch_models()

    for prefetch_entry in prefetch_list:

        display_method = None
        if type(prefetch_entry) is dict:
            display_method = prefetch_entry.keys()[0]
            paths = prefetch_entry[display_method]
        else:
            paths = prefetch_entry

        if type(paths) is not list:
            paths = [paths]

        # Build the query for accessible_objects according the user & role(s)
        filter_args = []
        for role_path in paths:
            if '.' in role_path:
                res_path = '__'.join(role_path.split('.')[:-1])
                role_type = role_path.split('.')[-1]
                parent_model = model
                for subpath in role_path.split('.')[:-1]:
                    parent_model = parent_model._meta.get_field(subpath).related_model
                filter_args.append(Q(
                    Q(**{'%s__pk__in' % res_path: parent_model.accessible_pk_qs(user, '%s_role' % role_type)}) |
                    Q(**{'%s__isnull' % res_path: True})))
            else:
                role_type = role_path
                filter_args.append(Q(**{'pk__in': model.accessible_pk_qs(user, '%s_role' % role_type)}))

        if display_method is None:
            # Role name translation to UI names for methods
            display_method = role_type
            if role_type == 'admin':
                display_method = 'edit'
            elif role_type in ['execute', 'update']:
                display_method = 'start'

        # Union that query with the list of items on page
        filter_args.append(Q(pk__in=page_ids))
        ids_with_role = set(model.objects.filter(*filter_args).values_list('pk', flat=True))

        # Save data item-by-item
        for obj in page:
            if skip_models and obj.__class__.__name__.lower() in skip_models:
                continue
            obj.capabilities_cache[display_method] = False
            if obj.pk in ids_with_role:
                obj.capabilities_cache[display_method] = True


def parse_yaml_or_json(vars_str):
    '''
    Attempt to parse a string with variables, and if attempt fails,
    return an empty dictionary.
    '''
    if isinstance(vars_str, dict):
        return vars_str
    try:
        vars_dict = json.loads(vars_str)
    except (ValueError, TypeError):
        try:
            vars_dict = yaml.safe_load(vars_str)
            assert isinstance(vars_dict, dict)
        except (yaml.YAMLError, TypeError, AttributeError, AssertionError):
            vars_dict = {}
    return vars_dict


@memoize()
def get_system_task_capacity():
    '''
    Measure system memory and use it as a baseline for determining the system's capacity
    '''
    from django.conf import settings
    if hasattr(settings, 'SYSTEM_TASK_CAPACITY'):
        return settings.SYSTEM_TASK_CAPACITY
    try:
        out = subprocess.check_output(['free', '-m'])
    except subprocess.CalledProcessError:
        logger.exception('Problem obtaining capacity from system.')
        return 0
    total_mem_value = out.split()[7]
    if int(total_mem_value) <= 2048:
        return 50
    return 50 + ((int(total_mem_value) / 1024) - 2) * 75


_inventory_updates = threading.local()


@contextlib.contextmanager
def ignore_inventory_computed_fields():
    '''
    Context manager to ignore updating inventory computed fields.
    '''
    try:
        previous_value = getattr(_inventory_updates, 'is_updating', False)
        _inventory_updates.is_updating = True
        yield
    finally:
        _inventory_updates.is_updating = previous_value


@contextlib.contextmanager
def ignore_inventory_group_removal():
    '''
    Context manager to ignore moving groups/hosts when group is deleted.
    '''
    try:
        previous_value = getattr(_inventory_updates, 'is_removing', False)
        _inventory_updates.is_removing = True
        yield
    finally:
        _inventory_updates.is_removing = previous_value


@memoize()
def check_proot_installed():
    '''
    Check that proot is installed.
    '''
    from django.conf import settings
    cmd = [getattr(settings, 'AWX_PROOT_CMD', 'bwrap'), '--version']
    try:
        proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE)
        proc.communicate()
        return bool(proc.returncode == 0)
    except (OSError, ValueError):
        return False


def build_proot_temp_dir():
    '''
    Create a temporary directory for proot to use.
    '''
    from django.conf import settings
    path = tempfile.mkdtemp(prefix='ansible_tower_proot_', dir=settings.AWX_PROOT_BASE_PATH)
    os.chmod(path, stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR)
    return path


def wrap_args_with_proot(args, cwd, **kwargs):
    '''
    Wrap existing command line with proot to restrict access to:
     - /tmp (except for own tmp files)
    For non-isolated nodes:
     - /etc/tower (to prevent obtaining db info or secret key)
     - /var/lib/awx (except for current project)
     - /var/log/tower
     - /var/log/supervisor
    '''
    from django.conf import settings
    new_args = [getattr(settings, 'AWX_PROOT_CMD', 'bwrap'), '--unshare-pid', '--dev-bind', '/', '/']
    hide_paths = [tempfile.gettempdir()]
    if not kwargs.get('isolated'):
        hide_paths.extend(['/etc/tower', '/var/lib/awx', '/var/log',
                           settings.PROJECTS_ROOT, settings.JOBOUTPUT_ROOT])
    hide_paths.extend(getattr(settings, 'AWX_PROOT_HIDE_PATHS', None) or [])
    for path in sorted(set(hide_paths)):
        if not os.path.exists(path):
            continue
        path = os.path.realpath(path)
        if os.path.isdir(path):
            new_path = tempfile.mkdtemp(dir=kwargs['proot_temp_dir'])
            os.chmod(new_path, stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR)
        else:
            handle, new_path = tempfile.mkstemp(dir=kwargs['proot_temp_dir'])
            os.close(handle)
            os.chmod(new_path, stat.S_IRUSR | stat.S_IWUSR)
        new_args.extend(['--bind', '%s' %(new_path,), '%s' % (path,)])
    if kwargs.get('isolated'):
        show_paths = [kwargs['private_data_dir']]
    elif 'private_data_dir' in kwargs:
        show_paths = [cwd, kwargs['private_data_dir']]
    else:
        show_paths = [cwd]
    if settings.ANSIBLE_USE_VENV:
        show_paths.append(settings.ANSIBLE_VENV_PATH)
    if settings.TOWER_USE_VENV:
        show_paths.append(settings.TOWER_VENV_PATH)
    show_paths.extend(getattr(settings, 'AWX_PROOT_SHOW_PATHS', None) or [])
    for path in sorted(set(show_paths)):
        if not os.path.exists(path):
            continue
        path = os.path.realpath(path)
        new_args.extend(['--bind', '%s' % (path,), '%s' % (path,)])
    if kwargs.get('isolated'):
        if 'ansible-playbook' in args:
            # playbook runs should cwd to the SCM checkout dir
            new_args.extend(['--chdir', os.path.join(kwargs['private_data_dir'], 'project')])
        else:
            # ad-hoc runs should cwd to the root of the private data dir
            new_args.extend(['--chdir', kwargs['private_data_dir']])
    else:
        new_args.extend(['--chdir', cwd])
    new_args.extend(args)
    return new_args


def get_pk_from_dict(_dict, key):
    '''
    Helper for obtaining a pk from user data dict or None if not present.
    '''
    try:
        return int(_dict[key])
    except (TypeError, KeyError, ValueError):
        return None


def timestamp_apiformat(timestamp):
    timestamp = timestamp.isoformat()
    if timestamp.endswith('+00:00'):
        timestamp = timestamp[:-6] + 'Z'
    return timestamp


# damn you python 2.6
def timedelta_total_seconds(timedelta):
    return (
        timedelta.microseconds + 0.0 +
        (timedelta.seconds + timedelta.days * 24 * 3600) * 10 ** 6) / 10 ** 6


class NoDefaultProvided(object):
    pass


def getattrd(obj, name, default=NoDefaultProvided):
    """
    Same as getattr(), but allows dot notation lookup
    Discussed in:
    http://stackoverflow.com/questions/11975781
    """

    try:
        return reduce(getattr, name.split("."), obj)
    except AttributeError:
        if default != NoDefaultProvided:
            return default
        raise


current_apps = apps


def set_current_apps(apps):
    global current_apps
    current_apps = apps


def get_current_apps():
    global current_apps
    return current_apps


class OutputEventFilter(object):
    '''
    File-like object that looks for encoded job events in stdout data.
    '''

    EVENT_DATA_RE = re.compile(r'\x1b\[K((?:[A-Za-z0-9+/=]+\x1b\[\d+D)+)\x1b\[K')

    def __init__(self, fileobj=None, event_callback=None, raw_callback=None):
        self._fileobj = fileobj
        self._event_callback = event_callback
        self._raw_callback = raw_callback
        self._counter = 1
        self._start_line = 0
        self._buffer = ''
        self._current_event_data = None

    def __getattr__(self, attr):
        return getattr(self._fileobj, attr)

    def write(self, data):
        if self._fileobj:
            self._fileobj.write(data)
        self._buffer += data
        if self._raw_callback:
            self._raw_callback(data)
        while True:
            match = self.EVENT_DATA_RE.search(self._buffer)
            if not match:
                break
            try:
                base64_data = re.sub(r'\x1b\[\d+D', '', match.group(1))
                event_data = json.loads(base64.b64decode(base64_data))
            except ValueError:
                event_data = {}
            self._emit_event(self._buffer[:match.start()], event_data)
            self._buffer = self._buffer[match.end():]

    def close(self):
        if self._fileobj:
            self._fileobj.close()
        if self._buffer:
            self._emit_event(self._buffer)
            self._buffer = ''

    def _emit_event(self, buffered_stdout, next_event_data=None):
        if self._current_event_data:
            event_data = self._current_event_data
            stdout_chunks = [buffered_stdout]
        elif buffered_stdout:
            event_data = dict(event='verbose')
            stdout_chunks = buffered_stdout.splitlines(True)
        else:
            stdout_chunks = []

        for stdout_chunk in stdout_chunks:
            event_data['counter'] = self._counter
            self._counter += 1
            event_data['stdout'] = stdout_chunk[:-2] if len(stdout_chunk) > 2 else ""
            n_lines = stdout_chunk.count('\n')
            event_data['start_line'] = self._start_line
            event_data['end_line'] = self._start_line + n_lines
            self._start_line += n_lines
            if self._event_callback:
                self._event_callback(event_data)

        if next_event_data.get('uuid', None):
            self._current_event_data = next_event_data
        else:
            self._current_event_data = None


def callback_filter_out_ansible_extra_vars(extra_vars):
    extra_vars_redacted = {}
    extra_vars = parse_yaml_or_json(extra_vars)
    for key, value in extra_vars.iteritems():
        if not key.startswith('ansible_'):
            extra_vars_redacted[key] = value
    return extra_vars_redacted


def get_search_fields(model):
    fields = []
    for field in model._meta.fields:
        if field.name in ('username', 'first_name', 'last_name', 'email',
                          'name', 'description'):
            fields.append(field.name)
    return fields


def has_model_field_prefetched(model_obj, field_name):
    # NOTE: Update this function if django internal implementation changes.
    return getattr(getattr(model_obj, field_name, None),
                   'prefetch_cache_name', '') in getattr(model_obj, '_prefetched_objects_cache', {})