"""

        _rev_type, _rev = self.landing_rev

        cs = self.get_changeset(_rev)

        if isinstance(cs, EmptyChangeset):

            return self.get_changeset()

        return cs

    def update_changeset_cache(self, cs_cache=None):

        """

        Update cache of last changeset for repository, keys should be::

            short_id

            raw_id

            revision

            message

            date

            author

        :param cs_cache:

        """

        from kallithea.lib.vcs.backends.base import BaseChangeset

        if cs_cache is None:

            cs_cache = EmptyChangeset()

            # use no-cache version here

            scm_repo = self.scm_instance_no_cache()

            if scm_repo:

                cs_cache = scm_repo.get_changeset()

        if isinstance(cs_cache, BaseChangeset):

            cs_cache = cs_cache.__json__()

        if (not self.changeset_cache or cs_cache['raw_id'] != self.changeset_cache['raw_id']):

            _default = datetime.datetime.fromtimestamp(0)

            last_change = cs_cache.get('date') or _default

            log.debug('updated repo %s with new cs cache %s',

                      self.repo_name, cs_cache)

            self.updated_on = last_change

            self.changeset_cache = cs_cache

            Session().commit()

        else:

            log.debug('changeset_cache for %s already up to date with %s',

                      self.repo_name, cs_cache['raw_id'])

    @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

    def get_comments(self, revisions=None):

        """

        Returns comments for this repository grouped by revisions

        :param revisions: filter query by revisions only

        """

        cmts = ChangesetComment.query() \

            .filter(ChangesetComment.repo == self)

        if revisions is not None:

            if not revisions:

                return {} # don't use sql 'in' on empty set

            cmts = cmts.filter(ChangesetComment.revision.in_(revisions))

        grouped = collections.defaultdict(list)

        for cmt in cmts.all():

            grouped[cmt.revision].append(cmt)

        return grouped

    def statuses(self, revisions):

        """

        Returns statuses for this repository.

        PRs without any votes do _not_ show up as unreviewed.

        :param revisions: list of revisions to get statuses for

        """

        if not revisions:

            return {}

        statuses = ChangesetStatus.query() \

            .filter(ChangesetStatus.repo == self) \

            .filter(ChangesetStatus.version == 0) \

            .filter(ChangesetStatus.revision.in_(revisions))

        grouped = {}

        for stat in statuses.all():

            pr_id = pr_nice_id = pr_repo = None

            if stat.pull_request:

                pr_id = stat.pull_request.pull_request_id

                pr_nice_id = PullRequest.make_nice_id(pr_id)

                pr_repo = stat.pull_request.other_repo.repo_name

            grouped[stat.revision] = [str(stat.status), stat.status_lbl,

                                      pr_id, pr_repo, pr_nice_id,

                                      stat.author]

        return grouped

    def _repo_size(self):

        from kallithea.lib import helpers as h

        log.debug('calculating repository size...')

        return h.format_byte_size(self.scm_instance.size)

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

    # SCM CACHE INSTANCE

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

    def set_invalidate(self):

        """

        Flush SA session caches of instances of on disk repo.

        """

        try:

            del self._scm_instance

        except AttributeError:

            pass

    _scm_instance = None  # caching inside lifetime of SA session

    @property

    def scm_instance(self):

        if self._scm_instance is None:

            return self.scm_instance_no_cache()  # will populate self._scm_instance

        return self._scm_instance

    def scm_instance_no_cache(self):

        repo_full_path = self.repo_full_path

        alias = get_scm(repo_full_path)[0]

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

                  alias, self.repo_full_path)

        backend = get_backend(alias)

        if alias == 'hg':

            self._scm_instance = backend(repo_full_path, create=False, baseui=self._ui)

        else:

            self._scm_instance = backend(repo_full_path, create=False)

        return self._scm_instance

    def __json__(self):

        return dict(

            repo_id=self.repo_id,

            repo_name=self.repo_name,

            landing_rev=self.landing_rev,

        )

class RepoGroup(Base, BaseDbModel):

    __tablename__ = 'groups'

    __table_args__ = (

        _table_args_default_dict,

    )

    SEP = ' » '

    group_id = Column(Integer(), primary_key=True)

    group_name = Column(Unicode(255), nullable=False, unique=True) # full path

    parent_group_id = Column('group_parent_id', Integer(), ForeignKey('groups.group_id'), nullable=True)

    group_description = Column(Unicode(10000), nullable=False)

    owner_id = Column('user_id', Integer(), ForeignKey('users.user_id'), nullable=False)

    created_on = Column(DateTime(timezone=False), nullable=False, default=datetime.datetime.now)

    repo_group_to_perm = relationship('UserRepoGroupToPerm', cascade='all', order_by='UserRepoGroupToPerm.group_to_perm_id')

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

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

    owner = relationship('User')

    @classmethod

    def query(cls, sorted=False):

        """Add RepoGroup-specific helpers for common query constructs.

        sorted: if True, apply the default ordering (name, case insensitive).

        """

        q = super(RepoGroup, cls).query()

        if sorted:

            q = q.order_by(sqlalchemy.func.lower(RepoGroup.group_name))

        return q

    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 _generate_choice(cls, repo_group):

        """Return tuple with group_id and name as html literal"""

        from webhelpers2.html import literal

        if repo_group is None:

            return (-1, '-- %s --' % _('top level'))

    @classmethod

    def groups_choices(cls, groups):

        """Return tuples with group_id and name as html literal."""

        return sorted((cls._generate_choice(g) for g in groups),

                      key=lambda c: c[1].split(cls.SEP))

    @classmethod

    def guess_instance(cls, value):

        return super(RepoGroup, cls).guess_instance(value, RepoGroup.get_by_group_name)

    @classmethod

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

        group_name = group_name.rstrip('/')

        if case_insensitive:

            gr = cls.query() \

                .filter(sqlalchemy.func.lower(cls.group_name) == sqlalchemy.func.lower(group_name))

        else:

            gr = cls.query() \

                .filter(cls.group_name == group_name)

        return gr.scalar()

    @property

    def parents(self):

        groups = []

        group = self.parent_group

        while group is not None:

            groups.append(group)

            group = group.parent_group

            assert group not in groups, group # avoid recursion on bad db content

        groups.reverse()

        return groups

    @property

    def children(self):

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

    @property

    def name(self):

        return self.group_name.split(URL_SEP)[-1]

    @property

    def full_path(self):

        return self.group_name

    @property

    def full_path_splitted(self):

        return self.group_name.split(URL_SEP)

    @property

    def repositories(self):

        return Repository.query(sorted=True).filter_by(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 _recursive_objects(self, include_repos=True):

        all_ = []

        def _get_members(root_gr):

            if include_repos:

                for r in root_gr.repositories:

                    all_.append(r)

            childs = root_gr.children.all()

            if childs:

                for gr in childs:

                    all_.append(gr)

                    _get_members(gr)

        _get_members(self)

        return [self] + all_

    def recursive_groups_and_repos(self):

        """

        Recursive return all groups, with repositories in those groups

        """

        return self._recursive_objects()

    def recursive_groups(self):

        """

        Returns all children groups for this group including children of children

        """

        return self._recursive_objects(include_repos=False)

    def get_new_name(self, group_name):

        """

        returns new full group name based on parent and new name

        :param group_name:

        """

        path_prefix = (self.parent_group.full_path_splitted if

                       self.parent_group else [])

        return URL_SEP.join(path_prefix + [group_name])

    def get_api_data(self):

        """

        Common function for generating api data

        """

        group = self

        data = dict(

            group_id=group.group_id,

            group_name=group.group_name,

            group_description=group.group_description,

            parent_group=group.parent_group.group_name if group.parent_group else None,

            repositories=[x.repo_name for x in group.repositories],

            owner=group.owner.username

        )

        return data

class Permission(Base, BaseDbModel):

    __tablename__ = 'permissions'

    __table_args__ = (

        Index('p_perm_name_idx', 'permission_name'),

        _table_args_default_dict,

    )

    PERMS = (

        ('hg.admin', _('Kallithea Administrator')),

        ('repository.none', _('Default user has no access to new repositories')),

        ('repository.read', _('Default user has read access to new repositories')),

        ('repository.write', _('Default user has write access to new repositories')),

        ('repository.admin', _('Default user has admin access to new repositories')),

        ('group.none', _('Default user has no access to new repository groups')),

        ('group.read', _('Default user has read access to new repository groups')),

        ('group.write', _('Default user has write access to new repository groups')),

        ('group.admin', _('Default user has admin access to new repository groups')),

        ('usergroup.none', _('Default user has no access to new user groups')),

        ('usergroup.read', _('Default user has read access to new user groups')),

        ('usergroup.write', _('Default user has write access to new user groups')),

        ('usergroup.admin', _('Default user has admin access to new user groups')),

        ('hg.repogroup.create.false', _('Only admins can create repository groups')),

        ('hg.repogroup.create.true', _('Non-admins can create repository groups')),

        ('hg.usergroup.create.false', _('Only admins can create user groups')),

        ('hg.usergroup.create.true', _('Non-admins can create user groups')),

        ('hg.create.none', _('Only admins can create top level repositories')),

        ('hg.create.repository', _('Non-admins can create top level repositories')),

        ('hg.create.write_on_repogroup.true', _('Repository creation enabled with write permission to a repository group')),

        ('hg.create.write_on_repogroup.false', _('Repository creation disabled with write permission to a repository group')),

        ('hg.fork.none', _('Only admins can fork repositories')),

        ('hg.fork.repository', _('Non-admins can fork repositories')),

        ('hg.register.none', _('Registration disabled')),

        ('hg.register.manual_activate', _('User registration with manual account activation')),

        ('hg.register.auto_activate', _('User registration with automatic account activation')),

        ('hg.extern_activate.manual', _('Manual activation of external account')),

        ('hg.extern_activate.auto', _('Automatic activation of external account')),

    )

    # definition of system default permissions for DEFAULT user

    DEFAULT_USER_PERMISSIONS = (

        'repository.read',

        'group.read',

        'usergroup.read',

        'hg.create.repository',

        'hg.create.write_on_repogroup.true',

        'hg.fork.repository',

        'hg.register.manual_activate',

        'hg.extern_activate.auto',

    )

    # defines which permissions are more important higher the more important

    # Weight defines which permissions are more important.

    # The higher number the more important.

    PERM_WEIGHTS = {

        'repository.none': 0,

        'repository.read': 1,

        'repository.write': 3,

        'repository.admin': 4,

        'group.none': 0,

        'group.read': 1,