Synnefo

# Copyright 2011 GRNET S.A. All rights reserved.

#

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# without modification, are permitted provided that the following

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#

#   1. Redistributions of source code must retain the above

#      copyright notice, this list of conditions and the following

#      disclaimer.

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#   2. Redistributions in binary form must reproduce the above

#      copyright notice, this list of conditions and the following

#      disclaimer in the documentation and/or other materials

#      provided with the distribution.

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# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

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import sys

import pkg_resources

import types

import os

from collections import defaultdict

# List of python distribution names which entry points will get excluded

# from snf-common settings extension mechanism

EXCLUDED_PACKAGES = os.environ.get('SYNNEFO_EXCLUDE_PACKAGES', '').split(":")

def get_entry_points(ns, name):

    for entry_point in pkg_resources.iter_entry_points(group=ns):

        if entry_point.name == name and \

                not entry_point.dist.project_name in EXCLUDED_PACKAGES:

            yield entry_point

def extend_module(module_name, attrs):

    module = sys.modules[module_name]

    for k, v in attrs.iteritems():

        setattr(module, k, v)

def entry_point_to_object(ep):

    object_or_func = ep.load()

    # user defined entry point is a function

    # get the return value

    obj = object_or_func

    if hasattr(object_or_func, '__call__'):

        obj = object_or_func()

    if isinstance(obj, types.ModuleType):

        dct = {}

        for k in dir(obj):

            if k.startswith("__"):

                continue

            dct[k] = getattr(obj, k)

        obj = dct

    return obj

def extend_module_from_entry_point(module_name, ns):

    """

    Extend a settings module from entry_point hooks

    """

    for e in get_entry_points(ns, 'default_settings'):

        extend_module(module_name, entry_point_to_object(e))

def extend_dict_from_entry_point(settings_object, ns, entry_point_name):

    for e in get_entry_points(ns, entry_point_name):

        settings_object.update(entry_point_to_object(e))

    return settings_object

def extend_list_from_entry_point(settings_object, ns, entry_point_name,

                                 unique=True):

    settings_object = list(settings_object)

    for e in get_entry_points(ns, entry_point_name):

        obj = entry_point_to_object(e)

        for row in obj:

            # skip duplicate entries

            if row in settings_object:

                continue

            if type(row) == dict and (row.get('before', False) or

                                      row.get('after', False)):

                insert_at = len(settings_object)

                if row.get('before', False):

                    try:

                        position = settings_object.index(row.get('before'))

                        insert_at = position - 1

                    except ValueError:

                        pass

                else:

                    try:

                        position = settings_object.index(row.get('after'))

                        insert_at = position + 1

                    except ValueError:

                        pass

                if insert_at < 0:

                    insert_at = 0

                inserts = row.get('insert', [])

                if not type(inserts) == list:

                    inserts = [inserts]

                for entry in inserts:

                    if not entry in settings_object:

                        settings_object.insert(insert_at, entry)

                        insert_at = insert_at + 1

            else:

                settings_object.append(row)

    return settings_object

def collect_defaults(ns):

    settings = defaultdict(lambda: [])

    for e in get_entry_points('synnefo', 'default_settings'):

        attrs = dir(e.load())

        settings[e.dist.key] = settings[e.dist.key] + attrs

    return settings

def extend_settings(mname, ns):

    extend_module_from_entry_point(mname, ns)

def extend_urls(patterns, ns):

    for e in get_entry_points(ns, 'urls'):

        patterns += e.load()

    return patterns