def delete(cls, users_group_id):

        try:

            # check if this group is not assigned to repo

            assigned_groups = UsersGroupRepoToPerm.query()\

                .filter(UsersGroupRepoToPerm.users_group_id ==

                        users_group_id).all()

            if assigned_groups:

                raise UsersGroupsAssignedException('RepoGroup assigned to %s' %

                                                   assigned_groups)

            users_group = cls.get(users_group_id, cache=False)

            Session.delete(users_group)

            Session.commit()

        except:

            log.error(traceback.format_exc())

            Session.rollback()

            raise

class UsersGroupMember(Base, BaseModel):

    __tablename__ = 'users_groups_members'

    __table_args__ = {'extend_existing':True}

    users_group_member_id = Column("users_group_member_id", Integer(), nullable=False, unique=True, default=None, primary_key=True)

    users_group_id = Column("users_group_id", Integer(), ForeignKey('users_groups.users_group_id'), nullable=False, unique=None, default=None)

    user_id = Column("user_id", Integer(), ForeignKey('users.user_id'), nullable=False, unique=None, default=None)

    user = relationship('User', lazy='joined')

    users_group = relationship('UsersGroup')

    def __init__(self, gr_id='', u_id=''):

        self.users_group_id = gr_id

        self.user_id = u_id

    @staticmethod

    def add_user_to_group(group, user):

        ugm = UsersGroupMember()

        ugm.users_group = group

        ugm.user = user

        Session.add(ugm)

        Session.commit()

        return ugm

class Repository(Base, BaseModel):

    __tablename__ = 'repositories'

    __table_args__ = (UniqueConstraint('repo_name'), {'extend_existing':True},)

    repo_id = Column("repo_id", Integer(), nullable=False, unique=True, default=None, primary_key=True)

    repo_name = Column("repo_name", String(length=255, convert_unicode=False, assert_unicode=None), nullable=False, unique=True, default=None)

    clone_uri = Column("clone_uri", String(length=255, convert_unicode=False, assert_unicode=None), nullable=True, unique=False, default=None)

    repo_type = Column("repo_type", String(length=255, convert_unicode=False, assert_unicode=None), nullable=False, unique=False, default='hg')

    user_id = Column("user_id", Integer(), ForeignKey('users.user_id'), nullable=False, unique=False, default=None)

    private = Column("private", Boolean(), nullable=True, unique=None, default=None)

    enable_statistics = Column("statistics", Boolean(), nullable=True, unique=None, default=True)

    enable_downloads = Column("downloads", Boolean(), nullable=True, unique=None, default=True)

    description = Column("description", String(length=10000, convert_unicode=False, assert_unicode=None), nullable=True, unique=None, default=None)

    created_on = Column('created_on', DateTime(timezone=False), nullable=True, unique=None, default=datetime.datetime.now)

    fork_id = Column("fork_id", Integer(), ForeignKey('repositories.repo_id'), nullable=True, unique=False, default=None)

    group_id = Column("group_id", Integer(), ForeignKey('groups.group_id'), nullable=True, unique=False, default=None)

    user = relationship('User')

    fork = relationship('Repository', remote_side=repo_id)

    group = relationship('RepoGroup')

    repo_to_perm = relationship('UserRepoToPerm', cascade='all', order_by='UserRepoToPerm.repo_to_perm_id')

    users_group_to_perm = relationship('UsersGroupRepoToPerm', cascade='all')

    stats = relationship('Statistics', cascade='all', uselist=False)

    followers = relationship('UserFollowing', primaryjoin='UserFollowing.follows_repo_id==Repository.repo_id', cascade='all')

    logs = relationship('UserLog', cascade='all')

    def __repr__(self):

        return "<%s('%s:%s')>" % (self.__class__.__name__,

                                  self.repo_id, self.repo_name)

    @classmethod

    def url_sep(cls):

        return '/'

    @classmethod

    def get_by_repo_name(cls, repo_name):

        q = Session.query(cls).filter(cls.repo_name == repo_name)

        q = q.options(joinedload(Repository.fork))\

                .options(joinedload(Repository.user))\

                .options(joinedload(Repository.group))

        return q.one()

    @classmethod

    def get_repo_forks(cls, repo_id):

        return cls.query().filter(Repository.fork_id == repo_id)

    @classmethod

    def base_path(cls):

        """

        Returns base path when all repos are stored

        :param cls:

        """

        q = Session.query(RhodeCodeUi).filter(RhodeCodeUi.ui_key ==

                                              cls.url_sep())

        q.options(FromCache("sql_cache_short", "repository_repo_path"))

        return q.one().ui_value

    @property

    def just_name(self):

        return self.repo_name.split(Repository.url_sep())[-1]

    @property

    def groups_with_parents(self):

        groups = []

        if self.group is None:

            return groups

        cur_gr = self.group

        groups.insert(0, cur_gr)

        while 1:

            gr = getattr(cur_gr, 'parent_group', None)

            cur_gr = cur_gr.parent_group

            if gr is None:

                break

            groups.insert(0, gr)

        return groups

    @property

    def groups_and_repo(self):

        return self.groups_with_parents, self.just_name

    @LazyProperty

    def repo_path(self):

        """

        Returns base full path for that repository means where it actually

        exists on a filesystem

        """

        q = Session.query(RhodeCodeUi).filter(RhodeCodeUi.ui_key ==

                                              Repository.url_sep())

        q.options(FromCache("sql_cache_short", "repository_repo_path"))

        return q.one().ui_value

    @property

    def repo_full_path(self):

        p = [self.repo_path]

        # we need to split the name by / since this is how we store the

        # names in the database, but that eventually needs to be converted

        # into a valid system path

        p += self.repo_name.split(Repository.url_sep())

        return os.path.join(*p)

    def get_new_name(self, repo_name):

        """

        returns new full repository name based on assigned group and new new

        :param group_name:

        """

        path_prefix = self.group.full_path_splitted if self.group else []

        return Repository.url_sep().join(path_prefix + [repo_name])

    @property

    def _ui(self):

        """

        Creates an db based ui object for this repository

        """

        from mercurial import ui

        from mercurial import config

        baseui = ui.ui()

        #clean the baseui object

        baseui._ocfg = config.config()

        baseui._ucfg = config.config()

        baseui._tcfg = config.config()

        ret = RhodeCodeUi.query()\

            .options(FromCache("sql_cache_short", "repository_repo_ui")).all()

        hg_ui = ret

        for ui_ in hg_ui:

            if ui_.ui_active:

                log.debug('settings ui from db[%s]%s:%s', ui_.ui_section,

                          ui_.ui_key, ui_.ui_value)

                baseui.setconfig(ui_.ui_section, ui_.ui_key, ui_.ui_value)

        return baseui

    @classmethod

    def is_valid(cls, repo_name):

        """

        returns True if given repo name is a valid filesystem repository

        """

        from rhodecode.lib.utils import is_valid_repo

        return is_valid_repo(repo_name, cls.base_path())

    #==========================================================================

    # SCM PROPERTIES

    #==========================================================================

    def get_changeset(self, rev):

        return get_changeset_safe(self.scm_instance, rev)

    @property

    def tip(self):

        return self.get_changeset('tip')

    @property

    def author(self):

        return self.tip.author

    @property

    def last_change(self):

        return self.scm_instance.last_change

    #==========================================================================

    # SCM CACHE INSTANCE

    #==========================================================================

    @property

    def invalidate(self):

        return CacheInvalidation.invalidate(self.repo_name)

    def set_invalidate(self):

        """

        set a cache for invalidation for this instance

        """

        CacheInvalidation.set_invalidate(self.repo_name)

    @LazyProperty

    def scm_instance(self):

        return self.__get_instance()

    @property

    def scm_instance_cached(self):

        @cache_region('long_term')

        def _c(repo_name):

            return self.__get_instance()

        rn = self.repo_name

        inv = self.invalidate

        if inv is not None:

            region_invalidate(_c, None, rn)

            # update our cache

            CacheInvalidation.set_valid(inv.cache_key)

        return _c(rn)

    def __get_instance(self):

        repo_full_path = self.repo_full_path

        try:

            alias = get_scm(repo_full_path)[0]

            log.debug('Creating instance of %s repository', alias)

            backend = get_backend(alias)

        except VCSError:

            log.error(traceback.format_exc())

            log.error('Perhaps this repository is in db and not in '

                      'filesystem run rescan repositories with '

                      '"destroy old data " option from admin panel')

            return

        if alias == 'hg':

            repo = backend(safe_str(repo_full_path), create=False,

                           baseui=self._ui)

            # skip hidden web repository

            if repo._get_hidden():

                return

        else:

            repo = backend(repo_full_path, create=False)

        return repo

class RepoGroup(Base, BaseModel):

    __tablename__ = 'groups'

    __table_args__ = (UniqueConstraint('group_name', 'group_parent_id'),

                      CheckConstraint('group_id != group_parent_id'), {'extend_existing':True},)

    __mapper_args__ = {'order_by':'group_name'}

    group_id = Column("group_id", Integer(), nullable=False, unique=True, default=None, primary_key=True)

    group_name = Column("group_name", String(length=255, convert_unicode=False, assert_unicode=None), nullable=False, unique=True, default=None)

    group_parent_id = Column("group_parent_id", Integer(), ForeignKey('groups.group_id'), nullable=True, unique=None, default=None)

    group_description = Column("group_description", String(length=10000, convert_unicode=False, assert_unicode=None), nullable=True, unique=None, default=None)

    parent_group = relationship('RepoGroup', remote_side=group_id)

    def __init__(self, group_name='', parent_group=None):

        self.group_name = group_name

        self.parent_group = parent_group

    def __repr__(self):

        return "<%s('%s:%s')>" % (self.__class__.__name__, self.group_id,

                                  self.group_name)

    @classmethod

    def groups_choices(cls):

        from webhelpers.html import literal as _literal

        repo_groups = [('', '')]

        sep = ' » '

        _name = lambda k: _literal(sep.join(k))

        repo_groups.extend([(x.group_id, _name(x.full_path_splitted))

                              for x in cls.query().all()])

        repo_groups = sorted(repo_groups, key=lambda t: t[1].split(sep)[0])

        return repo_groups

    @classmethod

    def url_sep(cls):

        return '/'

    @classmethod

    def get_by_group_name(cls, group_name, cache=False, case_insensitive=False):

        if case_insensitive:

            gr = cls.query()\

                .filter(cls.group_name.ilike(group_name))

        else:

            gr = cls.query()\

                .filter(cls.group_name == group_name)

        if cache:

            gr = gr.options(FromCache("sql_cache_short",

                                          "get_group_%s" % group_name))

        return gr.scalar()

    @property

    def parents(self):

        parents_recursion_limit = 5

        groups = []

        if self.parent_group is None:

            return groups

        cur_gr = self.parent_group

        groups.insert(0, cur_gr)

        cnt = 0

        while 1:

            cnt += 1

            gr = getattr(cur_gr, 'parent_group', None)

            cur_gr = cur_gr.parent_group

            if gr is None:

                break

            if cnt == parents_recursion_limit:

                # this will prevent accidental infinit loops

                log.error('group nested more than %s' %

                          parents_recursion_limit)

                break

            groups.insert(0, gr)

        return groups

    @property

    def children(self):

        return Group.query().filter(Group.parent_group == self)

    @property

    def name(self):

        return self.group_name.split(Group.url_sep())[-1]

    @property

    def full_path(self):

        return self.group_name

    @property

    def full_path_splitted(self):

        return self.group_name.split(Group.url_sep())

    @property

    def repositories(self):

        return Repository.query().filter(Repository.group == self)

    @property

    def repositories_recursive_count(self):

        cnt = self.repositories.count()

        def children_count(group):

            cnt = 0

            for child in group.children:

                cnt += child.repositories.count()

                cnt += children_count(child)

            return cnt

    @classmethod

    def get_by_group_name(cls, group_name, cache=False,

                          case_insensitive=False):

        if case_insensitive:

            q = cls.query().filter(cls.users_group_name.ilike(group_name))

        else:

            q = cls.query().filter(cls.users_group_name == group_name)

        if cache:

            q = q.options(FromCache("sql_cache_short",

                                    "get_user_%s" % group_name))

        return q.scalar()

    @classmethod

    def get(cls, users_group_id, cache=False):

        users_group = cls.query()

        if cache:

            users_group = users_group.options(FromCache("sql_cache_short",

                                    "get_users_group_%s" % users_group_id))

        return users_group.get(users_group_id)

class UsersGroupMember(Base, BaseModel):

    __tablename__ = 'users_groups_members'

    __table_args__ = {'extend_existing':True}

    users_group_member_id = Column("users_group_member_id", Integer(), nullable=False, unique=True, default=None, primary_key=True)

    users_group_id = Column("users_group_id", Integer(), ForeignKey('users_groups.users_group_id'), nullable=False, unique=None, default=None)

    user_id = Column("user_id", Integer(), ForeignKey('users.user_id'), nullable=False, unique=None, default=None)

    user = relationship('User', lazy='joined')

    users_group = relationship('UsersGroup')

    def __init__(self, gr_id='', u_id=''):

        self.users_group_id = gr_id

        self.user_id = u_id

    @staticmethod

    def add_user_to_group(group, user):

        ugm = UsersGroupMember()

        ugm.users_group = group

        ugm.user = user

        Session.add(ugm)

        Session.commit()

        return ugm

class Repository(Base, BaseModel):

    __tablename__ = 'repositories'

    __table_args__ = (UniqueConstraint('repo_name'), {'extend_existing':True},)

    repo_id = Column("repo_id", Integer(), nullable=False, unique=True, default=None, primary_key=True)

    repo_name = Column("repo_name", String(length=255, convert_unicode=False, assert_unicode=None), nullable=False, unique=True, default=None)

    clone_uri = Column("clone_uri", String(length=255, convert_unicode=False, assert_unicode=None), nullable=True, unique=False, default=None)

    repo_type = Column("repo_type", String(length=255, convert_unicode=False, assert_unicode=None), nullable=False, unique=False, default='hg')

    user_id = Column("user_id", Integer(), ForeignKey('users.user_id'), nullable=False, unique=False, default=None)

    private = Column("private", Boolean(), nullable=True, unique=None, default=None)

    enable_statistics = Column("statistics", Boolean(), nullable=True, unique=None, default=True)

    enable_downloads = Column("downloads", Boolean(), nullable=True, unique=None, default=True)

    description = Column("description", String(length=10000, convert_unicode=False, assert_unicode=None), nullable=True, unique=None, default=None)

    created_on = Column('created_on', DateTime(timezone=False), nullable=True, unique=None, default=datetime.datetime.now)

    fork_id = Column("fork_id", Integer(), ForeignKey('repositories.repo_id'), nullable=True, unique=False, default=None)

    group_id = Column("group_id", Integer(), ForeignKey('groups.group_id'), nullable=True, unique=False, default=None)

    user = relationship('User')

    fork = relationship('Repository', remote_side=repo_id)

    group = relationship('RepoGroup')

    repo_to_perm = relationship('UserRepoToPerm', cascade='all', order_by='UserRepoToPerm.repo_to_perm_id')

    users_group_to_perm = relationship('UsersGroupRepoToPerm', cascade='all')

    stats = relationship('Statistics', cascade='all', uselist=False)

    followers = relationship('UserFollowing', primaryjoin='UserFollowing.follows_repo_id==Repository.repo_id', cascade='all')

    logs = relationship('UserLog')

    def __repr__(self):

        return "<%s('%s:%s')>" % (self.__class__.__name__,

                                  self.repo_id, self.repo_name)

    @classmethod

    def url_sep(cls):

        return '/'

    @classmethod

    def get_by_repo_name(cls, repo_name):

        q = Session.query(cls).filter(cls.repo_name == repo_name)

        q = q.options(joinedload(Repository.fork))\

                .options(joinedload(Repository.user))\

                .options(joinedload(Repository.group))

        return q.scalar()

    @classmethod

    def get_repo_forks(cls, repo_id):

        return cls.query().filter(Repository.fork_id == repo_id)

    @classmethod

    def base_path(cls):

        """

        Returns base path when all repos are stored

        :param cls:

        """

        q = Session.query(RhodeCodeUi)\

            .filter(RhodeCodeUi.ui_key == cls.url_sep())

        q = q.options(FromCache("sql_cache_short", "repository_repo_path"))

        return q.one().ui_value

    @property

    def just_name(self):

        return self.repo_name.split(Repository.url_sep())[-1]

    @property

    def groups_with_parents(self):

        groups = []

        if self.group is None:

            return groups

        cur_gr = self.group

        groups.insert(0, cur_gr)

        while 1:

            gr = getattr(cur_gr, 'parent_group', None)

            cur_gr = cur_gr.parent_group

            if gr is None:

                break

            groups.insert(0, gr)

        return groups

    @property

    def groups_and_repo(self):

        return self.groups_with_parents, self.just_name

    @LazyProperty

    def repo_path(self):

        """

        Returns base full path for that repository means where it actually

        exists on a filesystem

        """

        q = Session.query(RhodeCodeUi).filter(RhodeCodeUi.ui_key ==

                                              Repository.url_sep())

        q = q.options(FromCache("sql_cache_short", "repository_repo_path"))

        return q.one().ui_value

    @property

    def repo_full_path(self):

        p = [self.repo_path]

        # we need to split the name by / since this is how we store the

        # names in the database, but that eventually needs to be converted

        # into a valid system path

        p += self.repo_name.split(Repository.url_sep())

        return os.path.join(*p)

    def get_new_name(self, repo_name):

        """

        returns new full repository name based on assigned group and new new

        :param group_name:

        """

        path_prefix = self.group.full_path_splitted if self.group else []

        return Repository.url_sep().join(path_prefix + [repo_name])

    @property

    def _ui(self):

        """

        Creates an db based ui object for this repository

        """

        from mercurial import ui

        from mercurial import config

        baseui = ui.ui()

        #clean the baseui object

        baseui._ocfg = config.config()

        baseui._ucfg = config.config()

        baseui._tcfg = config.config()

        ret = RhodeCodeUi.query()\

            .options(FromCache("sql_cache_short", "repository_repo_ui")).all()

        hg_ui = ret

        for ui_ in hg_ui:

            if ui_.ui_active:

                log.debug('settings ui from db[%s]%s:%s', ui_.ui_section,

                          ui_.ui_key, ui_.ui_value)

                baseui.setconfig(ui_.ui_section, ui_.ui_key, ui_.ui_value)

        return baseui

    @classmethod

    def is_valid(cls, repo_name):

        """

        returns True if given repo name is a valid filesystem repository

        """

        from rhodecode.lib.utils import is_valid_repo

        return is_valid_repo(repo_name, cls.base_path())

    #==========================================================================

    # SCM PROPERTIES

    #==========================================================================

    def get_changeset(self, rev):

        return get_changeset_safe(self.scm_instance, rev)

    @property

    def tip(self):

        return self.get_changeset('tip')

    @property

    def author(self):

        return self.tip.author

    @property

    def last_change(self):

        return self.scm_instance.last_change

    #==========================================================================

    # SCM CACHE INSTANCE

    #==========================================================================

    @property

    def invalidate(self):

        return CacheInvalidation.invalidate(self.repo_name)

    def set_invalidate(self):

        """

        set a cache for invalidation for this instance

        """

        CacheInvalidation.set_invalidate(self.repo_name)

    @LazyProperty

    def scm_instance(self):

        return self.__get_instance()

    @property

    def scm_instance_cached(self):

        @cache_region('long_term')

        def _c(repo_name):

            return self.__get_instance()

        rn = self.repo_name

        log.debug('Getting cached instance of repo')

        inv = self.invalidate

        if inv is not None:

            region_invalidate(_c, None, rn)

            # update our cache

            CacheInvalidation.set_valid(inv.cache_key)

        return _c(rn)

    def __get_instance(self):

        repo_full_path = self.repo_full_path

        try:

            alias = get_scm(repo_full_path)[0]

            log.debug('Creating instance of %s repository', alias)

            backend = get_backend(alias)

        except VCSError:

            log.error(traceback.format_exc())

            log.error('Perhaps this repository is in db and not in '

                      'filesystem run rescan repositories with '

                      '"destroy old data " option from admin panel')

            return

        if alias == 'hg':

            repo = backend(safe_str(repo_full_path), create=False,

                           baseui=self._ui)

            # skip hidden web repository

            if repo._get_hidden():

                return

        else:

            repo = backend(repo_full_path, create=False)

        return repo

class RepoGroup(Base, BaseModel):

    __tablename__ = 'groups'

    __table_args__ = (UniqueConstraint('group_name', 'group_parent_id'),

                      CheckConstraint('group_id != group_parent_id'), {'extend_existing':True},)

    __mapper_args__ = {'order_by':'group_name'}

    group_id = Column("group_id", Integer(), nullable=False, unique=True, default=None, primary_key=True)

    group_name = Column("group_name", String(length=255, convert_unicode=False, assert_unicode=None), nullable=False, unique=True, default=None)

    group_parent_id = Column("group_parent_id", Integer(), ForeignKey('groups.group_id'), nullable=True, unique=None, default=None)

    group_description = Column("group_description", String(length=10000, convert_unicode=False, assert_unicode=None), nullable=True, unique=None, default=None)

    parent_group = relationship('RepoGroup', remote_side=group_id)

    def __init__(self, group_name='', parent_group=None):

        self.group_name = group_name

        self.parent_group = parent_group

    def __repr__(self):

        return "<%s('%s:%s')>" % (self.__class__.__name__, self.group_id,

                                  self.group_name)

    @classmethod

    def groups_choices(cls):

        from webhelpers.html import literal as _literal

        repo_groups = [('', '')]

        sep = ' » '

        _name = lambda k: _literal(sep.join(k))

        repo_groups.extend([(x.group_id, _name(x.full_path_splitted))

                              for x in cls.query().all()])

        repo_groups = sorted(repo_groups, key=lambda t: t[1].split(sep)[0])

        return repo_groups

    @classmethod

    def url_sep(cls):

        return '/'

    @classmethod

    def get_by_group_name(cls, group_name, cache=False, case_insensitive=False):

        if case_insensitive:

            gr = cls.query()\

                .filter(cls.group_name.ilike(group_name))

        else:

            gr = cls.query()\

                .filter(cls.group_name == group_name)

        if cache:

            gr = gr.options(FromCache("sql_cache_short",

                                          "get_group_%s" % group_name))

        return gr.scalar()

    @property

    def parents(self):

        parents_recursion_limit = 5

        groups = []

        if self.parent_group is None:

            return groups

        cur_gr = self.parent_group

        groups.insert(0, cur_gr)

        cnt = 0

        while 1:

            cnt += 1

            gr = getattr(cur_gr, 'parent_group', None)

            cur_gr = cur_gr.parent_group

            if gr is None:

                break

            if cnt == parents_recursion_limit:

                # this will prevent accidental infinit loops

                log.error('group nested more than %s' %

                          parents_recursion_limit)

                break

            groups.insert(0, gr)

        return groups

    @property

    def children(self):

        return RepoGroup.query().filter(RepoGroup.parent_group == self)

    @property

    def name(self):

        return self.group_name.split(RepoGroup.url_sep())[-1]

    @property

    def full_path(self):

        return self.group_name

    @property

    def full_path_splitted(self):

        return self.group_name.split(RepoGroup.url_sep())

    @property

    def repositories(self):

        return Repository.query().filter(Repository.group == self)

    @property

    def repositories_recursive_count(self):

        cnt = self.repositories.count()

        def children_count(group):

            cnt = 0

            for child in group.children:

                cnt += child.repositories.count()

                cnt += children_count(child)

            return cnt

        return cnt + children_count(self)

    def get_new_name(self, group_name):

        """