:param rev1: Entry point from which diff is shown. Can be

          ``self.EMPTY_CHANGESET`` - in this case, patch showing all

          the changes since empty state of the repository until ``rev2``

        :param rev2: Until which revision changes should be shown.

        :param ignore_whitespace: If set to ``True``, would not show whitespace

          changes. Defaults to ``False``.

        :param context: How many lines before/after changed lines should be

          shown. Defaults to ``3``.

        """

        if hasattr(rev1, 'raw_id'):

            rev1 = getattr(rev1, 'raw_id')

        if hasattr(rev2, 'raw_id'):

            rev2 = getattr(rev2, 'raw_id')

        # Check if given revisions are present at repository (may raise

        # ChangesetDoesNotExistError)

        if rev1 != self.EMPTY_CHANGESET:

            self.get_changeset(rev1)

        self.get_changeset(rev2)

        file_filter = match(self.path, '', [path])

        return ''.join(patch.diff(self._repo, rev1, rev2, match=file_filter,

                          opts=diffopts(git=True,

                                        ignorews=ignore_whitespace,

                                        context=context)))

    def _check_url(self, url):

        """

        Function will check given url and try to verify if it's a valid

        link. Sometimes it may happened that mercurial will issue basic

        auth request that can cause whole API to hang when used from python

        or other external calls.

        On failures it'll raise urllib2.HTTPError, return code 200 if url

        is valid or True if it's a local path

        """

        from mercurial.util import url as Url

        # those authnadlers are patched for python 2.6.5 bug an

        # infinit looping when given invalid resources

        from mercurial.url import httpbasicauthhandler, httpdigestauthhandler

        # check first if it's not an local url

        if os.path.isdir(url) or url.startswith('file:'):

            return True

        handlers = []

        test_uri, authinfo = Url(url).authinfo()

        if authinfo:

            #create a password manager

            passmgr = urllib2.HTTPPasswordMgrWithDefaultRealm()

            passmgr.add_password(*authinfo)

            handlers.extend((httpbasicauthhandler(passmgr),

                             httpdigestauthhandler(passmgr)))

        o = urllib2.build_opener(*handlers)

        o.addheaders = [('Content-Type', 'application/mercurial-0.1'),

                        ('Accept', 'application/mercurial-0.1')]

        q = {"cmd": 'between'}

        q.update({'pairs': "%s-%s" % ('0' * 40, '0' * 40)})

        qs = '?%s' % urllib.urlencode(q)

        cu = "%s%s" % (test_uri, qs)

        req = urllib2.Request(cu, None, {})

        try:

            resp = o.open(req)

            return resp.code == 200

        except Exception, e:

            # means it cannot be cloned

            raise urllib2.URLError(e)

    def _get_repo(self, create, src_url=None, update_after_clone=False):

        """

        Function will check for mercurial repository in given path and return

        a localrepo object. If there is no repository in that path it will

        raise an exception unless ``create`` parameter is set to True - in

        that case repository would be created and returned.

        If ``src_url`` is given, would try to clone repository from the

        location at given clone_point. Additionally it'll make update to

        working copy accordingly to ``update_after_clone`` flag

        """

        try:

            if src_url:

                url = str(self._get_url(src_url))

                opts = {}

                if not update_after_clone:

                    opts.update({'noupdate': True})

                try:

                    self._check_url(url)

                    clone(self.baseui, url, self.path, **opts)

#                except urllib2.URLError:

            rename = old_data.get('repo_name') != repo_name_full

            create = not edit

            if rename or create:

                if group_path != '':

                    if Repository.get_by_repo_name(repo_name_full):

                        msg = M(self, 'repository_in_group_exists', state,

                                repo=repo_name, group=group_name)

                        raise formencode.Invalid(msg, value, state,

                            error_dict=dict(repo_name=msg)

                        )

                elif RepoGroup.get_by_group_name(repo_name_full):

                        msg = M(self, 'same_group_exists', state,

                                repo=repo_name)

                        raise formencode.Invalid(msg, value, state,

                            error_dict=dict(repo_name=msg)

                        )

                elif Repository.get_by_repo_name(repo_name_full):

                        msg = M(self, 'repository_exists', state,

                                repo=repo_name)

                        raise formencode.Invalid(msg, value, state,

                            error_dict=dict(repo_name=msg)

                        )

            return value

    return _validator

def ValidForkName(*args, **kwargs):

    return ValidRepoName(*args, **kwargs)

def SlugifyName():

    class _validator(formencode.validators.FancyValidator):

        def _to_python(self, value, state):

            return repo_name_slug(value)

        def validate_python(self, value, state):

            pass

    return _validator

def ValidCloneUri():

    from rhodecode.lib.utils import make_ui

        if repo_type == 'hg':

            from mercurial.httprepo import httprepository, httpsrepository

                httpsrepository(make_ui('db'), url).capabilities

                httprepository(make_ui('db'), url).capabilities

        elif repo_type == 'git':

            #TODO: write a git url validator

            pass

    class _validator(formencode.validators.FancyValidator):

        messages = {

            'clone_uri': _(u'invalid clone url'),

            'invalid_clone_uri': _(u'Invalid clone url, provide a '

        }

        def validate_python(self, value, state):

            repo_type = value.get('repo_type')

            url = value.get('clone_uri')

            if not url:

                pass

                try:

                except Exception:

                    log.exception('Url validation failed')

                    msg = M(self, 'clone_uri')

                    raise formencode.Invalid(msg, value, state,

                        error_dict=dict(clone_uri=msg)

                    )

    return _validator

def ValidForkType(old_data={}):

    class _validator(formencode.validators.FancyValidator):

        messages = {

            'invalid_fork_type': _(u'Fork have to be the same type as parent')

        }

        def validate_python(self, value, state):

            if old_data['repo_type'] != value:

                msg = M(self, 'invalid_fork_type', state)

                raise formencode.Invalid(msg, value, state,

                    error_dict=dict(repo_type=msg)

                )

    return _validator

def ValidPerms(type_='repo'):

    if type_ == 'group':

        EMPTY_PERM = 'group.none'

    elif type_ == 'repo':

        EMPTY_PERM = 'repository.none'

    class _validator(formencode.validators.FancyValidator):

        messages = {

            'perm_new_member_name':

                _(u'This username or users group name is not valid')

        }

        def to_python(self, value, state):

            perms_update = []

            perms_new = []

            # build a list of permission to update and new permission to create

            for k, v in value.items():

                # means new added member to permissions

                if k.startswith('perm_new_member'):

                    new_perm = value.get('perm_new_member', False)

                    new_member = value.get('perm_new_member_name', False)

                    new_type = value.get('perm_new_member_type')

                    if new_member and new_perm:

                        if (new_member, new_perm, new_type) not in perms_new:

                            perms_new.append((new_member, new_perm, new_type))

                elif k.startswith('u_perm_') or k.startswith('g_perm_'):

                    member = k[7:]

                    t = {'u': 'user',

                         'g': 'users_group'