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):

    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):

        """

        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 RepoGroup.url_sep().join(path_prefix + [group_name])

class Permission(Base, BaseModel):

    __tablename__ = 'permissions'

    __table_args__ = {'extend_existing':True}

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

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

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

    def __repr__(self):

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

                                  self.permission_id, self.permission_name)

    @classmethod

    def get_by_key(cls, key):

        return cls.query().filter(cls.permission_name == key).scalar()

    @classmethod

        q = Session().query(UserRepoToPerm, Repository, cls)\

            .join((Repository, UserRepoToPerm.repository_id == Repository.repo_id))\

            .join((cls, UserRepoToPerm.permission_id == cls.permission_id))\

            .filter(UserRepoToPerm.user_id == default_user_id)

        return q.all()

class UserRepoToPerm(Base, BaseModel):

    __tablename__ = 'repo_to_perm'

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

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

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

    permission_id = Column("permission_id", Integer(), ForeignKey('permissions.permission_id'), nullable=False, unique=None, default=None)

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

    user = relationship('User')

    permission = relationship('Permission')

    repository = relationship('Repository')

    @classmethod

    def create(cls, user, repository, permission):

        n = cls()

        n.user = user

        n.repository = repository

        n.permission = permission

        Session().add(n)

        return n

    def __repr__(self):

        return '<user:%s => %s >' % (self.user, self.repository)

class UserToPerm(Base, BaseModel):

    __tablename__ = 'user_to_perm'

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

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

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

    permission_id = Column("permission_id", Integer(), ForeignKey('permissions.permission_id'), nullable=False, unique=None, default=None)

    user = relationship('User')

    permission = relationship('Permission', lazy='joined')

    @classmethod

    def has_perm(cls, user_id, perm):

        if not isinstance(perm, Permission):

            raise Exception('perm needs to be an instance of Permission class')

        return cls.query().filter(cls.user_id == user_id)\

            .filter(cls.permission == perm).scalar() is not None

    @classmethod

    def grant_perm(cls, user_id, perm):