pr: Unify clone url generation of shadow repository.

rhodecode/lib/middleware/simplevcs.py

@@ -1,513 +1,510 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2014-2016  RhodeCode GmbH
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License, version 3
 # (only), as published by the Free Software Foundation.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 # This program is dual-licensed. If you wish to learn more about the
 # RhodeCode Enterprise Edition, including its added features, Support services,
 # and proprietary license terms, please see https://rhodecode.com/licenses/
 
 """
 SimpleVCS middleware for handling protocol request (push/clone etc.)
 It's implemented with basic auth function
 """
 
 import os
 import logging
 import importlib
 import re
 from functools import wraps
 
 from paste.httpheaders import REMOTE_USER, AUTH_TYPE
 from webob.exc import (
     HTTPNotFound, HTTPForbidden, HTTPNotAcceptable, HTTPInternalServerError)
 
 import rhodecode
 from rhodecode.authentication.base import authenticate, VCS_TYPE
 from rhodecode.lib.auth import AuthUser, HasPermissionAnyMiddleware
 from rhodecode.lib.base import BasicAuth, get_ip_addr, vcs_operation_context
 from rhodecode.lib.exceptions import (
     HTTPLockedRC, HTTPRequirementError, UserCreationError,
     NotAllowedToCreateUserError)
 from rhodecode.lib.hooks_daemon import prepare_callback_daemon
 from rhodecode.lib.middleware import appenlight
 from rhodecode.lib.middleware.utils import scm_app
 from rhodecode.lib.utils import (
     is_valid_repo, get_rhodecode_realm, get_rhodecode_base_path)
 from rhodecode.lib.utils2 import safe_str, fix_PATH, str2bool
 from rhodecode.lib.vcs.conf import settings as vcs_settings
 from rhodecode.lib.vcs.backends import base
 from rhodecode.model import meta
 from rhodecode.model.db import User, Repository, PullRequest
 from rhodecode.model.scm import ScmModel
 from rhodecode.model.pull_request import PullRequestModel
 
 
 log = logging.getLogger(__name__)
 
 
 def initialize_generator(factory):
     """
     Initializes the returned generator by draining its first element.
 
     This can be used to give a generator an initializer, which is the code
     up to the first yield statement. This decorator enforces that the first
     produced element has the value ``"__init__"`` to make its special
     purpose very explicit in the using code.
     """
 
     @wraps(factory)
     def wrapper(*args, **kwargs):
         gen = factory(*args, **kwargs)
         try:
             init = gen.next()
         except StopIteration:
             raise ValueError('Generator must yield at least one element.')
         if init != "__init__":
             raise ValueError('First yielded element must be "__init__".')
         return gen
     return wrapper
 
 
 class SimpleVCS(object):
     """Common functionality for SCM HTTP handlers."""
 
     SCM = 'unknown'
 
     acl_repo_name = None
     url_repo_name = None
     vcs_repo_name = None
 
     def __init__(self, application, config, registry):
         self.registry = registry
         self.application = application
         self.config = config
         # re-populated by specialized middleware
         self.repo_vcs_config = base.Config()
 
         # base path of repo locations
         self.basepath = get_rhodecode_base_path()
         # authenticate this VCS request using authfunc
         auth_ret_code_detection = \
             str2bool(self.config.get('auth_ret_code_detection', False))
         self.authenticate = BasicAuth(
             '', authenticate, registry, config.get('auth_ret_code'),
             auth_ret_code_detection)
         self.ip_addr = '0.0.0.0'
 
     def set_repo_names(self, environ):
         """
         This will populate the attributes acl_repo_name, url_repo_name,
         vcs_repo_name and pr_id on the current instance.
         """
-        # TODO: martinb: Unify generation/suffix of clone url. It is currently
-        #       used here in the regex, in PullRequest in get_api_data() and
-        #       indirectly in routing configuration.
         # TODO: martinb: Move to class or module scope.
         # TODO: martinb: Check if we have to use re.UNICODE.
         # TODO: martinb: Check which chars are allowed for repo/group names.
         #       These chars are excluded: '`?=[]\;\'"<>,/~!@#$%^&*()+{}|: '
         #       Code from: rhodecode/lib/utils.py:repo_name_slug()
         pr_regex = re.compile(
             '(?P<base_name>(?:[\w-]+)(?:/[\w-]+)*)/'    # repo groups
             '(?P<repo_name>[\w-]+)'                     # target repo name
             '/pull-request/(?P<pr_id>\d+)/repository')  # pr suffix
 
         # Get url repo name from environment.
         self.url_repo_name = self._get_repository_name(environ)
 
         # Check if this is a request to a shadow repository. In case of a
         # shadow repo set vcs_repo_name to the file system path pointing to the
         # shadow repo. And set acl_repo_name to the pull request target repo
         # because we use the target repo for permission checks. Otherwise all
         # names are equal.
         match = pr_regex.match(self.url_repo_name)
         if match:
             # Get pull request instance.
             match_dict = match.groupdict()
             pr_id = match_dict['pr_id']
             pull_request = PullRequest.get(pr_id)
 
             # Get file system path to shadow repository.
             workspace_id = PullRequestModel()._workspace_id(pull_request)
             target_vcs = pull_request.target_repo.scm_instance()
             vcs_repo_name = target_vcs._get_shadow_repository_path(
                 workspace_id)
 
             # Store names for later usage.
             self.pr_id = pr_id
             self.vcs_repo_name = vcs_repo_name
             self.acl_repo_name = pull_request.target_repo.repo_name
         else:
             # All names are equal for normal (non shadow) repositories.
             self.acl_repo_name = self.url_repo_name
             self.vcs_repo_name = self.url_repo_name
             self.pr_id = None
 
     @property
     def repo_name(self):
         # TODO: johbo: Remove, switch to correct repo name attribute
         return self.acl_repo_name
 
     @property
     def scm_app(self):
         custom_implementation = self.config.get('vcs.scm_app_implementation')
         if custom_implementation and custom_implementation != 'pyro4':
             log.info(
                 "Using custom implementation of scm_app: %s",
                 custom_implementation)
             scm_app_impl = importlib.import_module(custom_implementation)
         else:
             scm_app_impl = scm_app
         return scm_app_impl
 
     def _get_by_id(self, repo_name):
         """
         Gets a special pattern _<ID> from clone url and tries to replace it
         with a repository_name for support of _<ID> non changeable urls
         """
 
         data = repo_name.split('/')
         if len(data) >= 2:
             from rhodecode.model.repo import RepoModel
             by_id_match = RepoModel().get_repo_by_id(repo_name)
             if by_id_match:
                 data[1] = by_id_match.repo_name
 
         return safe_str('/'.join(data))
 
     def _invalidate_cache(self, repo_name):
         """
         Set's cache for this repository for invalidation on next access
 
         :param repo_name: full repo name, also a cache key
         """
         ScmModel().mark_for_invalidation(repo_name)
 
     def is_valid_and_existing_repo(self, repo_name, base_path, scm_type):
         db_repo = Repository.get_by_repo_name(repo_name)
         if not db_repo:
             log.debug('Repository `%s` not found inside the database.',
                       repo_name)
             return False
 
         if db_repo.repo_type != scm_type:
             log.warning(
                 'Repository `%s` have incorrect scm_type, expected %s got %s',
                 repo_name, db_repo.repo_type, scm_type)
             return False
 
         return is_valid_repo(repo_name, base_path, expect_scm=scm_type)
 
     def valid_and_active_user(self, user):
         """
         Checks if that user is not empty, and if it's actually object it checks
         if he's active.
 
         :param user: user object or None
         :return: boolean
         """
         if user is None:
             return False
 
         elif user.active:
             return True
 
         return False
 
     def _check_permission(self, action, user, repo_name, ip_addr=None):
         """
         Checks permissions using action (push/pull) user and repository
         name
 
         :param action: push or pull action
         :param user: user instance
         :param repo_name: repository name
         """
         # check IP
         inherit = user.inherit_default_permissions
         ip_allowed = AuthUser.check_ip_allowed(user.user_id, ip_addr,
                                                inherit_from_default=inherit)
         if ip_allowed:
             log.info('Access for IP:%s allowed', ip_addr)
         else:
             return False
 
         if action == 'push':
             if not HasPermissionAnyMiddleware('repository.write',
                                               'repository.admin')(user,
                                                                   repo_name):
                 return False
 
         else:
             # any other action need at least read permission
             if not HasPermissionAnyMiddleware('repository.read',
                                               'repository.write',
                                               'repository.admin')(user,
                                                                   repo_name):
                 return False
 
         return True
 
     def _check_ssl(self, environ, start_response):
         """
         Checks the SSL check flag and returns False if SSL is not present
         and required True otherwise
         """
         org_proto = environ['wsgi._org_proto']
         # check if we have SSL required  ! if not it's a bad request !
         require_ssl = str2bool(self.repo_vcs_config.get('web', 'push_ssl'))
         if require_ssl and org_proto == 'http':
             log.debug('proto is %s and SSL is required BAD REQUEST !',
                       org_proto)
             return False
         return True
 
     def __call__(self, environ, start_response):
         try:
             return self._handle_request(environ, start_response)
         except Exception:
             log.exception("Exception while handling request")
             appenlight.track_exception(environ)
             return HTTPInternalServerError()(environ, start_response)
         finally:
             meta.Session.remove()
 
     def _handle_request(self, environ, start_response):
 
         if not self._check_ssl(environ, start_response):
             reason = ('SSL required, while RhodeCode was unable '
                       'to detect this as SSL request')
             log.debug('User not allowed to proceed, %s', reason)
             return HTTPNotAcceptable(reason)(environ, start_response)
 
         if not self.repo_name:
             log.warning('Repository name is empty: %s', self.repo_name)
             # failed to get repo name, we fail now
             return HTTPNotFound()(environ, start_response)
         log.debug('Extracted repo name is %s', self.repo_name)
 
         ip_addr = get_ip_addr(environ)
         username = None
 
         # skip passing error to error controller
         environ['pylons.status_code_redirect'] = True
 
         # ======================================================================
         # GET ACTION PULL or PUSH
         # ======================================================================
         action = self._get_action(environ)
 
         # ======================================================================
         # Check if this is a request to a shadow repository of a pull request.
         # In this case only pull action is allowed.
         # ======================================================================
         if self.pr_id is not None and action != 'pull':
             reason = 'Only pull action is allowed for shadow repositories.'
             log.debug('User not allowed to proceed, %s', reason)
             return HTTPNotAcceptable(reason)(environ, start_response)
 
         # ======================================================================
         # CHECK ANONYMOUS PERMISSION
         # ======================================================================
         if action in ['pull', 'push']:
             anonymous_user = User.get_default_user()
             username = anonymous_user.username
             if anonymous_user.active:
                 # ONLY check permissions if the user is activated
                 anonymous_perm = self._check_permission(
                     action, anonymous_user, self.repo_name, ip_addr)
             else:
                 anonymous_perm = False
 
             if not anonymous_user.active or not anonymous_perm:
                 if not anonymous_user.active:
                     log.debug('Anonymous access is disabled, running '
                               'authentication')
 
                 if not anonymous_perm:
                     log.debug('Not enough credentials to access this '
                               'repository as anonymous user')
 
                 username = None
                 # ==============================================================
                 # DEFAULT PERM FAILED OR ANONYMOUS ACCESS IS DISABLED SO WE
                 # NEED TO AUTHENTICATE AND ASK FOR AUTH USER PERMISSIONS
                 # ==============================================================
 
                 # try to auth based on environ, container auth methods
                 log.debug('Running PRE-AUTH for container based authentication')
                 pre_auth = authenticate(
                     '', '', environ, VCS_TYPE, registry=self.registry)
                 if pre_auth and pre_auth.get('username'):
                     username = pre_auth['username']
                 log.debug('PRE-AUTH got %s as username', username)
 
                 # If not authenticated by the container, running basic auth
                 if not username:
                     self.authenticate.realm = get_rhodecode_realm()
 
                     try:
                         result = self.authenticate(environ)
                     except (UserCreationError, NotAllowedToCreateUserError) as e:
                         log.error(e)
                         reason = safe_str(e)
                         return HTTPNotAcceptable(reason)(environ, start_response)
 
                     if isinstance(result, str):
                         AUTH_TYPE.update(environ, 'basic')
                         REMOTE_USER.update(environ, result)
                         username = result
                     else:
                         return result.wsgi_application(environ, start_response)
 
                 # ==============================================================
                 # CHECK PERMISSIONS FOR THIS REQUEST USING GIVEN USERNAME
                 # ==============================================================
                 user = User.get_by_username(username)
                 if not self.valid_and_active_user(user):
                     return HTTPForbidden()(environ, start_response)
                 username = user.username
                 user.update_lastactivity()
                 meta.Session().commit()
 
                 # check user attributes for password change flag
                 user_obj = user
                 if user_obj and user_obj.username != User.DEFAULT_USER and \
                         user_obj.user_data.get('force_password_change'):
                     reason = 'password change required'
                     log.debug('User not allowed to authenticate, %s', reason)
                     return HTTPNotAcceptable(reason)(environ, start_response)
 
                 # check permissions for this repository
                 perm = self._check_permission(
                     action, user, self.repo_name, ip_addr)
                 if not perm:
                     return HTTPForbidden()(environ, start_response)
 
         # extras are injected into UI object and later available
         # in hooks executed by rhodecode
         check_locking = _should_check_locking(environ.get('QUERY_STRING'))
         extras = vcs_operation_context(
             environ, repo_name=self.repo_name, username=username,
             action=action, scm=self.SCM,
             check_locking=check_locking)
 
         # ======================================================================
         # REQUEST HANDLING
         # ======================================================================
         str_repo_name = safe_str(self.repo_name)
         repo_path = os.path.join(
             safe_str(self.basepath), safe_str(self.vcs_repo_name))
         log.debug('Repository path is %s', repo_path)
 
         fix_PATH()
 
         log.info(
             '%s action on %s repo "%s" by "%s" from %s',
             action, self.SCM, str_repo_name, safe_str(username), ip_addr)
 
         return self._generate_vcs_response(
             environ, start_response, repo_path, self.url_repo_name, extras, action)
 
     @initialize_generator
     def _generate_vcs_response(
             self, environ, start_response, repo_path, repo_name, extras,
             action):
         """
         Returns a generator for the response content.
 
         This method is implemented as a generator, so that it can trigger
         the cache validation after all content sent back to the client. It
         also handles the locking exceptions which will be triggered when
         the first chunk is produced by the underlying WSGI application.
         """
         callback_daemon, extras = self._prepare_callback_daemon(extras)
         config = self._create_config(extras, self.acl_repo_name)
         log.debug('HOOKS extras is %s', extras)
         app = self._create_wsgi_app(repo_path, repo_name, config)
 
         try:
             with callback_daemon:
                 try:
                     response = app(environ, start_response)
                 finally:
                     # This statement works together with the decorator
                     # "initialize_generator" above. The decorator ensures that
                     # we hit the first yield statement before the generator is
                     # returned back to the WSGI server. This is needed to
                     # ensure that the call to "app" above triggers the
                     # needed callback to "start_response" before the
                     # generator is actually used.
                     yield "__init__"
 
                 for chunk in response:
                     yield chunk
         except Exception as exc:
             # TODO: johbo: Improve "translating" back the exception.
             if getattr(exc, '_vcs_kind', None) == 'repo_locked':
                 exc = HTTPLockedRC(*exc.args)
                 _code = rhodecode.CONFIG.get('lock_ret_code')
                 log.debug('Repository LOCKED ret code %s!', (_code,))
             elif getattr(exc, '_vcs_kind', None) == 'requirement':
                 log.debug(
                     'Repository requires features unknown to this Mercurial')
                 exc = HTTPRequirementError(*exc.args)
             else:
                 raise
 
             for chunk in exc(environ, start_response):
                 yield chunk
         finally:
             # invalidate cache on push
             try:
                 if action == 'push':
                     self._invalidate_cache(repo_name)
             finally:
                 meta.Session.remove()
 
     def _get_repository_name(self, environ):
         """Get repository name out of the environmnent
 
         :param environ: WSGI environment
         """
         raise NotImplementedError()
 
     def _get_action(self, environ):
         """Map request commands into a pull or push command.
 
         :param environ: WSGI environment
         """
         raise NotImplementedError()
 
     def _create_wsgi_app(self, repo_path, repo_name, config):
         """Return the WSGI app that will finally handle the request."""
         raise NotImplementedError()
 
     def _create_config(self, extras, repo_name):
         """Create a Pyro safe config representation."""
         raise NotImplementedError()
 
     def _prepare_callback_daemon(self, extras):
         return prepare_callback_daemon(
             extras, protocol=vcs_settings.HOOKS_PROTOCOL,
             use_direct_calls=vcs_settings.HOOKS_DIRECT_CALLS)
 
 
 def _should_check_locking(query_string):
     # this is kind of hacky, but due to how mercurial handles client-server
     # server see all operation on commit; bookmarks, phases and
     # obsolescence marker in different transaction, we don't want to check
     # locking on those
     return query_string not in ['cmd=listkeys']

rhodecode/model/pull_request.py

@@ -1,1180 +1,1188 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2012-2016  RhodeCode GmbH
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License, version 3
 # (only), as published by the Free Software Foundation.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 # This program is dual-licensed. If you wish to learn more about the
 # RhodeCode Enterprise Edition, including its added features, Support services,
 # and proprietary license terms, please see https://rhodecode.com/licenses/
 
 
 """
 pull request model for RhodeCode
 """
 
 from collections import namedtuple
 import json
 import logging
 import datetime
 
 from pylons.i18n.translation import _
 from pylons.i18n.translation import lazy_ugettext
 
 from rhodecode.lib import helpers as h, hooks_utils, diffs
 from rhodecode.lib.compat import OrderedDict
 from rhodecode.lib.hooks_daemon import prepare_callback_daemon
 from rhodecode.lib.markup_renderer import (
     DEFAULT_COMMENTS_RENDERER, RstTemplateRenderer)
 from rhodecode.lib.utils import action_logger
 from rhodecode.lib.utils2 import safe_unicode, safe_str, md5_safe
 from rhodecode.lib.vcs.backends.base import (
     Reference, MergeResponse, MergeFailureReason)
 from rhodecode.lib.vcs.conf import settings as vcs_settings
 from rhodecode.lib.vcs.exceptions import (
     CommitDoesNotExistError, EmptyRepositoryError)
 from rhodecode.model import BaseModel
 from rhodecode.model.changeset_status import ChangesetStatusModel
 from rhodecode.model.comment import ChangesetCommentsModel
 from rhodecode.model.db import (
     PullRequest, PullRequestReviewers, ChangesetStatus,
     PullRequestVersion, ChangesetComment)
 from rhodecode.model.meta import Session
 from rhodecode.model.notification import NotificationModel, \
     EmailNotificationModel
 from rhodecode.model.scm import ScmModel
 from rhodecode.model.settings import VcsSettingsModel
 
 
 log = logging.getLogger(__name__)
 
 
 class PullRequestModel(BaseModel):
 
     cls = PullRequest
 
     DIFF_CONTEXT = 3
 
     MERGE_STATUS_MESSAGES = {
         MergeFailureReason.NONE: lazy_ugettext(
             'This pull request can be automatically merged.'),
         MergeFailureReason.UNKNOWN: lazy_ugettext(
             'This pull request cannot be merged because of an unhandled'
             ' exception.'),
         MergeFailureReason.MERGE_FAILED: lazy_ugettext(
             'This pull request cannot be merged because of conflicts.'),
         MergeFailureReason.PUSH_FAILED: lazy_ugettext(
             'This pull request could not be merged because push to target'
             ' failed.'),
         MergeFailureReason.TARGET_IS_NOT_HEAD: lazy_ugettext(
             'This pull request cannot be merged because the target is not a'
             ' head.'),
         MergeFailureReason.HG_SOURCE_HAS_MORE_BRANCHES: lazy_ugettext(
             'This pull request cannot be merged because the source contains'
             ' more branches than the target.'),
         MergeFailureReason.HG_TARGET_HAS_MULTIPLE_HEADS: lazy_ugettext(
             'This pull request cannot be merged because the target has'
             ' multiple heads.'),
         MergeFailureReason.TARGET_IS_LOCKED: lazy_ugettext(
             'This pull request cannot be merged because the target repository'
             ' is locked.'),
         MergeFailureReason.MISSING_COMMIT: lazy_ugettext(
             'This pull request cannot be merged because the target or the '
             'source reference is missing.'),
     }
 
     def __get_pull_request(self, pull_request):
         return self._get_instance(PullRequest, pull_request)
 
     def _check_perms(self, perms, pull_request, user, api=False):
         if not api:
             return h.HasRepoPermissionAny(*perms)(
                 user=user, repo_name=pull_request.target_repo.repo_name)
         else:
             return h.HasRepoPermissionAnyApi(*perms)(
                 user=user, repo_name=pull_request.target_repo.repo_name)
 
     def check_user_read(self, pull_request, user, api=False):
         _perms = ('repository.admin', 'repository.write', 'repository.read',)
         return self._check_perms(_perms, pull_request, user, api)
 
     def check_user_merge(self, pull_request, user, api=False):
         _perms = ('repository.admin', 'repository.write', 'hg.admin',)
         return self._check_perms(_perms, pull_request, user, api)
 
     def check_user_update(self, pull_request, user, api=False):
         owner = user.user_id == pull_request.user_id
         return self.check_user_merge(pull_request, user, api) or owner
 
     def check_user_change_status(self, pull_request, user, api=False):
         reviewer = user.user_id in [x.user_id for x in
                                     pull_request.reviewers]
         return self.check_user_update(pull_request, user, api) or reviewer
 
     def get(self, pull_request):
         return self.__get_pull_request(pull_request)
 
     def _prepare_get_all_query(self, repo_name, source=False, statuses=None,
                                opened_by=None, order_by=None,
                                order_dir='desc'):
         repo = self._get_repo(repo_name)
         q = PullRequest.query()
         # source or target
         if source:
             q = q.filter(PullRequest.source_repo == repo)
         else:
             q = q.filter(PullRequest.target_repo == repo)
 
         # closed,opened
         if statuses:
             q = q.filter(PullRequest.status.in_(statuses))
 
         # opened by filter
         if opened_by:
             q = q.filter(PullRequest.user_id.in_(opened_by))
 
         if order_by:
             order_map = {
                 'name_raw': PullRequest.pull_request_id,
                 'title': PullRequest.title,
                 'updated_on_raw': PullRequest.updated_on
             }
             if order_dir == 'asc':
                 q = q.order_by(order_map[order_by].asc())
             else:
                 q = q.order_by(order_map[order_by].desc())
 
         return q
 
     def count_all(self, repo_name, source=False, statuses=None,
                   opened_by=None):
         """
         Count the number of pull requests for a specific repository.
 
         :param repo_name: target or source repo
         :param source: boolean flag to specify if repo_name refers to source
         :param statuses: list of pull request statuses
         :param opened_by: author user of the pull request
         :returns: int number of pull requests
         """
         q = self._prepare_get_all_query(
             repo_name, source=source, statuses=statuses, opened_by=opened_by)
 
         return q.count()
 
     def get_all(self, repo_name, source=False, statuses=None, opened_by=None,
                 offset=0, length=None, order_by=None, order_dir='desc'):
         """
         Get all pull requests for a specific repository.
 
         :param repo_name: target or source repo
         :param source: boolean flag to specify if repo_name refers to source
         :param statuses: list of pull request statuses
         :param opened_by: author user of the pull request
         :param offset: pagination offset
         :param length: length of returned list
         :param order_by: order of the returned list
         :param order_dir: 'asc' or 'desc' ordering direction
         :returns: list of pull requests
         """
         q = self._prepare_get_all_query(
             repo_name, source=source, statuses=statuses, opened_by=opened_by,
             order_by=order_by, order_dir=order_dir)
 
         if length:
             pull_requests = q.limit(length).offset(offset).all()
         else:
             pull_requests = q.all()
 
         return pull_requests
 
     def count_awaiting_review(self, repo_name, source=False, statuses=None,
                               opened_by=None):
         """
         Count the number of pull requests for a specific repository that are
         awaiting review.
 
         :param repo_name: target or source repo
         :param source: boolean flag to specify if repo_name refers to source
         :param statuses: list of pull request statuses
         :param opened_by: author user of the pull request
         :returns: int number of pull requests
         """
         pull_requests = self.get_awaiting_review(
             repo_name, source=source, statuses=statuses, opened_by=opened_by)
 
         return len(pull_requests)
 
     def get_awaiting_review(self, repo_name, source=False, statuses=None,
                             opened_by=None, offset=0, length=None,
                             order_by=None, order_dir='desc'):
         """
         Get all pull requests for a specific repository that are awaiting
         review.
 
         :param repo_name: target or source repo
         :param source: boolean flag to specify if repo_name refers to source
         :param statuses: list of pull request statuses
         :param opened_by: author user of the pull request
         :param offset: pagination offset
         :param length: length of returned list
         :param order_by: order of the returned list
         :param order_dir: 'asc' or 'desc' ordering direction
         :returns: list of pull requests
         """
         pull_requests = self.get_all(
             repo_name, source=source, statuses=statuses, opened_by=opened_by,
             order_by=order_by, order_dir=order_dir)
 
         _filtered_pull_requests = []
         for pr in pull_requests:
             status = pr.calculated_review_status()
             if status in [ChangesetStatus.STATUS_NOT_REVIEWED,
                           ChangesetStatus.STATUS_UNDER_REVIEW]:
                 _filtered_pull_requests.append(pr)
         if length:
             return _filtered_pull_requests[offset:offset+length]
         else:
             return _filtered_pull_requests
 
     def count_awaiting_my_review(self, repo_name, source=False, statuses=None,
                                  opened_by=None, user_id=None):
         """
         Count the number of pull requests for a specific repository that are
         awaiting review from a specific user.
 
         :param repo_name: target or source repo
         :param source: boolean flag to specify if repo_name refers to source
         :param statuses: list of pull request statuses
         :param opened_by: author user of the pull request
         :param user_id: reviewer user of the pull request
         :returns: int number of pull requests
         """
         pull_requests = self.get_awaiting_my_review(
             repo_name, source=source, statuses=statuses, opened_by=opened_by,
             user_id=user_id)
 
         return len(pull_requests)
 
     def get_awaiting_my_review(self, repo_name, source=False, statuses=None,
                                opened_by=None, user_id=None, offset=0,
                                length=None, order_by=None, order_dir='desc'):
         """
         Get all pull requests for a specific repository that are awaiting
         review from a specific user.
 
         :param repo_name: target or source repo
         :param source: boolean flag to specify if repo_name refers to source
         :param statuses: list of pull request statuses
         :param opened_by: author user of the pull request
         :param user_id: reviewer user of the pull request
         :param offset: pagination offset
         :param length: length of returned list
         :param order_by: order of the returned list
         :param order_dir: 'asc' or 'desc' ordering direction
         :returns: list of pull requests
         """
         pull_requests = self.get_all(
             repo_name, source=source, statuses=statuses, opened_by=opened_by,
             order_by=order_by, order_dir=order_dir)
 
         _my = PullRequestModel().get_not_reviewed(user_id)
         my_participation = []
         for pr in pull_requests:
             if pr in _my:
                 my_participation.append(pr)
         _filtered_pull_requests = my_participation
         if length:
             return _filtered_pull_requests[offset:offset+length]
         else:
             return _filtered_pull_requests
 
     def get_not_reviewed(self, user_id):
         return [
             x.pull_request for x in PullRequestReviewers.query().filter(
                 PullRequestReviewers.user_id == user_id).all()
         ]
 
     def get_versions(self, pull_request):
         """
         returns version of pull request sorted by ID descending
         """
         return PullRequestVersion.query()\
             .filter(PullRequestVersion.pull_request == pull_request)\
             .order_by(PullRequestVersion.pull_request_version_id.asc())\
             .all()
 
     def create(self, created_by, source_repo, source_ref, target_repo,
         target_ref, revisions, reviewers, title, description=None):
         created_by_user = self._get_user(created_by)
         source_repo = self._get_repo(source_repo)
         target_repo = self._get_repo(target_repo)
 
         pull_request = PullRequest()
         pull_request.source_repo = source_repo
         pull_request.source_ref = source_ref
         pull_request.target_repo = target_repo
         pull_request.target_ref = target_ref
         pull_request.revisions = revisions
         pull_request.title = title
         pull_request.description = description
         pull_request.author = created_by_user
 
         Session().add(pull_request)
         Session().flush()
 
         reviewer_ids = set()
         # members / reviewers
         for reviewer_object in reviewers:
             if isinstance(reviewer_object, tuple):
                 user_id, reasons = reviewer_object
             else:
                 user_id, reasons = reviewer_object, []
 
             user = self._get_user(user_id)
             reviewer_ids.add(user.user_id)
 
             reviewer = PullRequestReviewers(user, pull_request, reasons)
             Session().add(reviewer)
 
         # Set approval status to "Under Review" for all commits which are
         # part of this pull request.
         ChangesetStatusModel().set_status(
             repo=target_repo,
             status=ChangesetStatus.STATUS_UNDER_REVIEW,
             user=created_by_user,
             pull_request=pull_request
         )
 
         self.notify_reviewers(pull_request, reviewer_ids)
         self._trigger_pull_request_hook(
             pull_request, created_by_user, 'create')
 
         return pull_request
 
     def _trigger_pull_request_hook(self, pull_request, user, action):
         pull_request = self.__get_pull_request(pull_request)
         target_scm = pull_request.target_repo.scm_instance()
         if action == 'create':
             trigger_hook = hooks_utils.trigger_log_create_pull_request_hook
         elif action == 'merge':
             trigger_hook = hooks_utils.trigger_log_merge_pull_request_hook
         elif action == 'close':
             trigger_hook = hooks_utils.trigger_log_close_pull_request_hook
         elif action == 'review_status_change':
             trigger_hook = hooks_utils.trigger_log_review_pull_request_hook
         elif action == 'update':
             trigger_hook = hooks_utils.trigger_log_update_pull_request_hook
         else:
             return
 
         trigger_hook(
             username=user.username,
             repo_name=pull_request.target_repo.repo_name,
             repo_alias=target_scm.alias,
             pull_request=pull_request)
 
     def _get_commit_ids(self, pull_request):
         """
         Return the commit ids of the merged pull request.
 
         This method is not dealing correctly yet with the lack of autoupdates
         nor with the implicit target updates.
         For example: if a commit in the source repo is already in the target it
         will be reported anyways.
         """
         merge_rev = pull_request.merge_rev
         if merge_rev is None:
             raise ValueError('This pull request was not merged yet')
 
         commit_ids = list(pull_request.revisions)
         if merge_rev not in commit_ids:
             commit_ids.append(merge_rev)
 
         return commit_ids
 
     def merge(self, pull_request, user, extras):
         log.debug("Merging pull request %s", pull_request.pull_request_id)
         merge_state = self._merge_pull_request(pull_request, user, extras)
         if merge_state.executed:
             log.debug(
                 "Merge was successful, updating the pull request comments.")
             self._comment_and_close_pr(pull_request, user, merge_state)
             self._log_action('user_merged_pull_request', user, pull_request)
         else:
             log.warn("Merge failed, not updating the pull request.")
         return merge_state
 
     def _merge_pull_request(self, pull_request, user, extras):
         target_vcs = pull_request.target_repo.scm_instance()
         source_vcs = pull_request.source_repo.scm_instance()
         target_ref = self._refresh_reference(
             pull_request.target_ref_parts, target_vcs)
 
         message = _(
             'Merge pull request #%(pr_id)s from '
             '%(source_repo)s %(source_ref_name)s\n\n %(pr_title)s') % {
                 'pr_id': pull_request.pull_request_id,
                 'source_repo': source_vcs.name,
                 'source_ref_name': pull_request.source_ref_parts.name,
                 'pr_title': pull_request.title
             }
 
         workspace_id = self._workspace_id(pull_request)
         use_rebase = self._use_rebase_for_merging(pull_request)
 
         callback_daemon, extras = prepare_callback_daemon(
             extras, protocol=vcs_settings.HOOKS_PROTOCOL,
             use_direct_calls=vcs_settings.HOOKS_DIRECT_CALLS)
 
         with callback_daemon:
             # TODO: johbo: Implement a clean way to run a config_override
             # for a single call.
             target_vcs.config.set(
                 'rhodecode', 'RC_SCM_DATA', json.dumps(extras))
             merge_state = target_vcs.merge(
                 target_ref, source_vcs, pull_request.source_ref_parts,
                 workspace_id, user_name=user.username,
                 user_email=user.email, message=message, use_rebase=use_rebase)
         return merge_state
 
     def _comment_and_close_pr(self, pull_request, user, merge_state):
         pull_request.merge_rev = merge_state.merge_commit_id
         pull_request.updated_on = datetime.datetime.now()
 
         ChangesetCommentsModel().create(
             text=unicode(_('Pull request merged and closed')),
             repo=pull_request.target_repo.repo_id,
             user=user.user_id,
             pull_request=pull_request.pull_request_id,
             f_path=None,
             line_no=None,
             closing_pr=True
         )
 
         Session().add(pull_request)
         Session().flush()
         # TODO: paris: replace invalidation with less radical solution
         ScmModel().mark_for_invalidation(
             pull_request.target_repo.repo_name)
         self._trigger_pull_request_hook(pull_request, user, 'merge')
 
     def has_valid_update_type(self, pull_request):
         source_ref_type = pull_request.source_ref_parts.type
         return source_ref_type in ['book', 'branch', 'tag']
 
     def update_commits(self, pull_request):
         """
         Get the updated list of commits for the pull request
         and return the new pull request version and the list
         of commits processed by this update action
         """
 
         pull_request = self.__get_pull_request(pull_request)
         source_ref_type = pull_request.source_ref_parts.type
         source_ref_name = pull_request.source_ref_parts.name
         source_ref_id = pull_request.source_ref_parts.commit_id
 
         if not self.has_valid_update_type(pull_request):
             log.debug(
                 "Skipping update of pull request %s due to ref type: %s",
                 pull_request, source_ref_type)
             return (None, None)
 
         source_repo = pull_request.source_repo.scm_instance()
         source_commit = source_repo.get_commit(commit_id=source_ref_name)
         if source_ref_id == source_commit.raw_id:
             log.debug("Nothing changed in pull request %s", pull_request)
             return (None, None)
 
         # Finally there is a need for an update
         pull_request_version = self._create_version_from_snapshot(pull_request)
         self._link_comments_to_version(pull_request_version)
 
         target_ref_type = pull_request.target_ref_parts.type
         target_ref_name = pull_request.target_ref_parts.name
         target_ref_id = pull_request.target_ref_parts.commit_id
         target_repo = pull_request.target_repo.scm_instance()
 
         if target_ref_type in ('tag', 'branch', 'book'):
             target_commit = target_repo.get_commit(target_ref_name)
         else:
             target_commit = target_repo.get_commit(target_ref_id)
 
         # re-compute commit ids
         old_commit_ids = set(pull_request.revisions)
         pre_load = ["author", "branch", "date", "message"]
         commit_ranges = target_repo.compare(
             target_commit.raw_id, source_commit.raw_id, source_repo, merge=True,
             pre_load=pre_load)
 
         ancestor = target_repo.get_common_ancestor(
             target_commit.raw_id, source_commit.raw_id, source_repo)
 
         pull_request.source_ref = '%s:%s:%s' % (
             source_ref_type, source_ref_name, source_commit.raw_id)
         pull_request.target_ref = '%s:%s:%s' % (
             target_ref_type, target_ref_name, ancestor)
         pull_request.revisions = [
             commit.raw_id for commit in reversed(commit_ranges)]
         pull_request.updated_on = datetime.datetime.now()
         Session().add(pull_request)
         new_commit_ids = set(pull_request.revisions)
 
         changes = self._calculate_commit_id_changes(
             old_commit_ids, new_commit_ids)
 
         old_diff_data, new_diff_data = self._generate_update_diffs(
             pull_request, pull_request_version)
 
         ChangesetCommentsModel().outdate_comments(
             pull_request, old_diff_data=old_diff_data,
             new_diff_data=new_diff_data)
 
         file_changes = self._calculate_file_changes(
             old_diff_data, new_diff_data)
 
         # Add an automatic comment to the pull request
         update_comment = ChangesetCommentsModel().create(
             text=self._render_update_message(changes, file_changes),
             repo=pull_request.target_repo,
             user=pull_request.author,
             pull_request=pull_request,
             send_email=False, renderer=DEFAULT_COMMENTS_RENDERER)
 
         # Update status to "Under Review" for added commits
         for commit_id in changes.added:
             ChangesetStatusModel().set_status(
                 repo=pull_request.source_repo,
                 status=ChangesetStatus.STATUS_UNDER_REVIEW,
                 comment=update_comment,
                 user=pull_request.author,
                 pull_request=pull_request,
                 revision=commit_id)
 
         log.debug(
             'Updated pull request %s, added_ids: %s, common_ids: %s, '
             'removed_ids: %s', pull_request.pull_request_id,
             changes.added, changes.common, changes.removed)
         log.debug('Updated pull request with the following file changes: %s',
                   file_changes)
 
         log.info(
             "Updated pull request %s from commit %s to commit %s, "
             "stored new version %s of this pull request.",
             pull_request.pull_request_id, source_ref_id,
             pull_request.source_ref_parts.commit_id,
             pull_request_version.pull_request_version_id)
         Session().commit()
         self._trigger_pull_request_hook(pull_request, pull_request.author,
                                         'update')
 
         return (pull_request_version, changes)
 
     def _create_version_from_snapshot(self, pull_request):
         version = PullRequestVersion()
         version.title = pull_request.title
         version.description = pull_request.description
         version.status = pull_request.status
         version.created_on = pull_request.created_on
         version.updated_on = pull_request.updated_on
         version.user_id = pull_request.user_id
         version.source_repo = pull_request.source_repo
         version.source_ref = pull_request.source_ref
         version.target_repo = pull_request.target_repo
         version.target_ref = pull_request.target_ref
 
         version._last_merge_source_rev = pull_request._last_merge_source_rev
         version._last_merge_target_rev = pull_request._last_merge_target_rev
         version._last_merge_status = pull_request._last_merge_status
         version.merge_rev = pull_request.merge_rev
 
         version.revisions = pull_request.revisions
         version.pull_request = pull_request
         Session().add(version)
         Session().flush()
 
         return version
 
     def _generate_update_diffs(self, pull_request, pull_request_version):
         diff_context = (
             self.DIFF_CONTEXT +
             ChangesetCommentsModel.needed_extra_diff_context())
         old_diff = self._get_diff_from_pr_or_version(
             pull_request_version, context=diff_context)
         new_diff = self._get_diff_from_pr_or_version(
             pull_request, context=diff_context)
 
         old_diff_data = diffs.DiffProcessor(old_diff)
         old_diff_data.prepare()
         new_diff_data = diffs.DiffProcessor(new_diff)
         new_diff_data.prepare()
 
         return old_diff_data, new_diff_data
 
     def _link_comments_to_version(self, pull_request_version):
         """
         Link all unlinked comments of this pull request to the given version.
 
         :param pull_request_version: The `PullRequestVersion` to which
             the comments shall be linked.
 
         """
         pull_request = pull_request_version.pull_request
         comments = ChangesetComment.query().filter(
             # TODO: johbo: Should we query for the repo at all here?
             # Pending decision on how comments of PRs are to be related
             # to either the source repo, the target repo or no repo at all.
             ChangesetComment.repo_id == pull_request.target_repo.repo_id,
             ChangesetComment.pull_request == pull_request,
             ChangesetComment.pull_request_version == None)
 
         # TODO: johbo: Find out why this breaks if it is done in a bulk
         # operation.
         for comment in comments:
             comment.pull_request_version_id = (
                 pull_request_version.pull_request_version_id)
             Session().add(comment)
 
     def _calculate_commit_id_changes(self, old_ids, new_ids):
         added = new_ids.difference(old_ids)
         common = old_ids.intersection(new_ids)
         removed = old_ids.difference(new_ids)
         return ChangeTuple(added, common, removed)
 
     def _calculate_file_changes(self, old_diff_data, new_diff_data):
 
         old_files = OrderedDict()
         for diff_data in old_diff_data.parsed_diff:
             old_files[diff_data['filename']] = md5_safe(diff_data['raw_diff'])
 
         added_files = []
         modified_files = []
         removed_files = []
         for diff_data in new_diff_data.parsed_diff:
             new_filename = diff_data['filename']
             new_hash = md5_safe(diff_data['raw_diff'])
 
             old_hash = old_files.get(new_filename)
             if not old_hash:
                 # file is not present in old diff, means it's added
                 added_files.append(new_filename)
             else:
                 if new_hash != old_hash:
                     modified_files.append(new_filename)
                 # now remove a file from old, since we have seen it already
                 del old_files[new_filename]
 
         # removed files is when there are present in old, but not in NEW,
         # since we remove old files that are present in new diff, left-overs
         # if any should be the removed files
         removed_files.extend(old_files.keys())
 
         return FileChangeTuple(added_files, modified_files, removed_files)
 
     def _render_update_message(self, changes, file_changes):
         """
         render the message using DEFAULT_COMMENTS_RENDERER (RST renderer),
         so it's always looking the same disregarding on which default
         renderer system is using.
 
         :param changes: changes named tuple
         :param file_changes: file changes named tuple
 
         """
         new_status = ChangesetStatus.get_status_lbl(
             ChangesetStatus.STATUS_UNDER_REVIEW)
 
         changed_files = (
             file_changes.added + file_changes.modified + file_changes.removed)
 
         params = {
             'under_review_label': new_status,
             'added_commits': changes.added,
             'removed_commits': changes.removed,
             'changed_files': changed_files,
             'added_files': file_changes.added,
             'modified_files': file_changes.modified,
             'removed_files': file_changes.removed,
         }
         renderer = RstTemplateRenderer()
         return renderer.render('pull_request_update.mako', **params)
 
     def edit(self, pull_request, title, description):
         pull_request = self.__get_pull_request(pull_request)
         if pull_request.is_closed():
             raise ValueError('This pull request is closed')
         if title:
             pull_request.title = title
         pull_request.description = description
         pull_request.updated_on = datetime.datetime.now()
         Session().add(pull_request)
 
     def update_reviewers(self, pull_request, reviewer_data):
         """
         Update the reviewers in the pull request
 
         :param pull_request: the pr to update
         :param reviewer_data: list of tuples [(user, ['reason1', 'reason2'])]
         """
 
         reviewers_reasons = {}
         for user_id, reasons in reviewer_data:
             if isinstance(user_id, (int, basestring)):
                 user_id = self._get_user(user_id).user_id
             reviewers_reasons[user_id] = reasons
 
         reviewers_ids = set(reviewers_reasons.keys())
         pull_request = self.__get_pull_request(pull_request)
         current_reviewers = PullRequestReviewers.query()\
             .filter(PullRequestReviewers.pull_request ==
                     pull_request).all()
         current_reviewers_ids = set([x.user.user_id for x in current_reviewers])
 
         ids_to_add = reviewers_ids.difference(current_reviewers_ids)
         ids_to_remove = current_reviewers_ids.difference(reviewers_ids)
 
         log.debug("Adding %s reviewers", ids_to_add)
         log.debug("Removing %s reviewers", ids_to_remove)
         changed = False
         for uid in ids_to_add:
             changed = True
             _usr = self._get_user(uid)
             reasons = reviewers_reasons[uid]
             reviewer = PullRequestReviewers(_usr, pull_request, reasons)
             Session().add(reviewer)
 
         self.notify_reviewers(pull_request, ids_to_add)
 
         for uid in ids_to_remove:
             changed = True
             reviewer = PullRequestReviewers.query()\
                 .filter(PullRequestReviewers.user_id == uid,
                         PullRequestReviewers.pull_request == pull_request)\
                 .scalar()
             if reviewer:
                 Session().delete(reviewer)
         if changed:
             pull_request.updated_on = datetime.datetime.now()
             Session().add(pull_request)
 
         return ids_to_add, ids_to_remove
 
     def get_url(self, pull_request):
         return h.url('pullrequest_show',
                      repo_name=safe_str(pull_request.target_repo.repo_name),
                      pull_request_id=pull_request.pull_request_id,
                      qualified=True)
 
     def get_shadow_clone_url(self, pull_request):
-        return u'{url}/repository'.format(url=self.get_url(pull_request))
+        """
+        Returns qualified url pointing to the shadow repository. If this pull
+        request is closed there is no shadow repository and ``None`` will be
+        returned.
+        """
+        if pull_request.is_closed():
+            return None
+        else:
+            return u'{url}/repository'.format(url=self.get_url(pull_request))
 
     def notify_reviewers(self, pull_request, reviewers_ids):
         # notification to reviewers
         if not reviewers_ids:
             return
 
         pull_request_obj = pull_request
         # get the current participants of this pull request
         recipients = reviewers_ids
         notification_type = EmailNotificationModel.TYPE_PULL_REQUEST
 
         pr_source_repo = pull_request_obj.source_repo
         pr_target_repo = pull_request_obj.target_repo
 
         pr_url = h.url(
             'pullrequest_show',
             repo_name=pr_target_repo.repo_name,
             pull_request_id=pull_request_obj.pull_request_id,
             qualified=True,)
 
         # set some variables for email notification
         pr_target_repo_url = h.url(
             'summary_home',
             repo_name=pr_target_repo.repo_name,
             qualified=True)
 
         pr_source_repo_url = h.url(
             'summary_home',
             repo_name=pr_source_repo.repo_name,
             qualified=True)
 
         # pull request specifics
         pull_request_commits = [
             (x.raw_id, x.message)
             for x in map(pr_source_repo.get_commit, pull_request.revisions)]
 
         kwargs = {
             'user': pull_request.author,
             'pull_request': pull_request_obj,
             'pull_request_commits': pull_request_commits,
 
             'pull_request_target_repo': pr_target_repo,
             'pull_request_target_repo_url': pr_target_repo_url,
 
             'pull_request_source_repo': pr_source_repo,
             'pull_request_source_repo_url': pr_source_repo_url,
 
             'pull_request_url': pr_url,
         }
 
         # pre-generate the subject for notification itself
         (subject,
          _h, _e,  # we don't care about those
          body_plaintext) = EmailNotificationModel().render_email(
             notification_type, **kwargs)
 
         # create notification objects, and emails
         NotificationModel().create(
             created_by=pull_request.author,
             notification_subject=subject,
             notification_body=body_plaintext,
             notification_type=notification_type,
             recipients=recipients,
             email_kwargs=kwargs,
         )
 
     def delete(self, pull_request):
         pull_request = self.__get_pull_request(pull_request)
         self._cleanup_merge_workspace(pull_request)
         Session().delete(pull_request)
 
     def close_pull_request(self, pull_request, user):
         pull_request = self.__get_pull_request(pull_request)
         self._cleanup_merge_workspace(pull_request)
         pull_request.status = PullRequest.STATUS_CLOSED
         pull_request.updated_on = datetime.datetime.now()
         Session().add(pull_request)
         self._trigger_pull_request_hook(
             pull_request, pull_request.author, 'close')
         self._log_action('user_closed_pull_request', user, pull_request)
 
     def close_pull_request_with_comment(self, pull_request, user, repo,
                                         message=None):
         status = ChangesetStatus.STATUS_REJECTED
 
         if not message:
             message = (
                 _('Status change %(transition_icon)s %(status)s') % {
                     'transition_icon': '>',
                     'status': ChangesetStatus.get_status_lbl(status)})
 
         internal_message = _('Closing with') + ' ' + message
 
         comm = ChangesetCommentsModel().create(
             text=internal_message,
             repo=repo.repo_id,
             user=user.user_id,
             pull_request=pull_request.pull_request_id,
             f_path=None,
             line_no=None,
             status_change=ChangesetStatus.get_status_lbl(status),
             status_change_type=status,
             closing_pr=True
         )
 
         ChangesetStatusModel().set_status(
             repo.repo_id,
             status,
             user.user_id,
             comm,
             pull_request=pull_request.pull_request_id
         )
         Session().flush()
 
         PullRequestModel().close_pull_request(
             pull_request.pull_request_id, user)
 
     def merge_status(self, pull_request):
         if not self._is_merge_enabled(pull_request):
             return False, _('Server-side pull request merging is disabled.')
         if pull_request.is_closed():
             return False, _('This pull request is closed.')
         merge_possible, msg = self._check_repo_requirements(
             target=pull_request.target_repo, source=pull_request.source_repo)
         if not merge_possible:
             return merge_possible, msg
 
         try:
             resp = self._try_merge(pull_request)
             status = resp.possible, self.merge_status_message(
                 resp.failure_reason)
         except NotImplementedError:
             status = False, _('Pull request merging is not supported.')
 
         return status
 
     def _check_repo_requirements(self, target, source):
         """
         Check if `target` and `source` have compatible requirements.
 
         Currently this is just checking for largefiles.
         """
         target_has_largefiles = self._has_largefiles(target)
         source_has_largefiles = self._has_largefiles(source)
         merge_possible = True
         message = u''
 
         if target_has_largefiles != source_has_largefiles:
             merge_possible = False
             if source_has_largefiles:
                 message = _(
                     'Target repository large files support is disabled.')
             else:
                 message = _(
                     'Source repository large files support is disabled.')
 
         return merge_possible, message
 
     def _has_largefiles(self, repo):
         largefiles_ui = VcsSettingsModel(repo=repo).get_ui_settings(
             'extensions', 'largefiles')
         return largefiles_ui and largefiles_ui[0].active
 
     def _try_merge(self, pull_request):
         """
         Try to merge the pull request and return the merge status.
         """
         log.debug(
             "Trying out if the pull request %s can be merged.",
             pull_request.pull_request_id)
         target_vcs = pull_request.target_repo.scm_instance()
         target_ref = self._refresh_reference(
             pull_request.target_ref_parts, target_vcs)
 
         target_locked = pull_request.target_repo.locked
         if target_locked and target_locked[0]:
             log.debug("The target repository is locked.")
             merge_state = MergeResponse(
                 False, False, None, MergeFailureReason.TARGET_IS_LOCKED)
         elif self._needs_merge_state_refresh(pull_request, target_ref):
             log.debug("Refreshing the merge status of the repository.")
             merge_state = self._refresh_merge_state(
                 pull_request, target_vcs, target_ref)
         else:
             possible = pull_request.\
                 _last_merge_status == MergeFailureReason.NONE
             merge_state = MergeResponse(
                 possible, False, None, pull_request._last_merge_status)
         log.debug("Merge response: %s", merge_state)
         return merge_state
 
     def _refresh_reference(self, reference, vcs_repository):
         if reference.type in ('branch', 'book'):
             name_or_id = reference.name
         else:
             name_or_id = reference.commit_id
         refreshed_commit = vcs_repository.get_commit(name_or_id)
         refreshed_reference = Reference(
             reference.type, reference.name, refreshed_commit.raw_id)
         return refreshed_reference
 
     def _needs_merge_state_refresh(self, pull_request, target_reference):
         return not(
             pull_request.revisions and
             pull_request.revisions[0] == pull_request._last_merge_source_rev and
             target_reference.commit_id == pull_request._last_merge_target_rev)
 
     def _refresh_merge_state(self, pull_request, target_vcs, target_reference):
         workspace_id = self._workspace_id(pull_request)
         source_vcs = pull_request.source_repo.scm_instance()
         use_rebase = self._use_rebase_for_merging(pull_request)
         merge_state = target_vcs.merge(
             target_reference, source_vcs, pull_request.source_ref_parts,
             workspace_id, dry_run=True, use_rebase=use_rebase)
 
         # Do not store the response if there was an unknown error.
         if merge_state.failure_reason != MergeFailureReason.UNKNOWN:
             pull_request._last_merge_source_rev = pull_request.\
                 source_ref_parts.commit_id
             pull_request._last_merge_target_rev = target_reference.commit_id
             pull_request._last_merge_status = (
                 merge_state.failure_reason)
             Session().add(pull_request)
             Session().flush()
 
         return merge_state
 
     def _workspace_id(self, pull_request):
         workspace_id = 'pr-%s' % pull_request.pull_request_id
         return workspace_id
 
     def merge_status_message(self, status_code):
         """
         Return a human friendly error message for the given merge status code.
         """
         return self.MERGE_STATUS_MESSAGES[status_code]
 
     def generate_repo_data(self, repo, commit_id=None, branch=None,
                            bookmark=None):
         all_refs, selected_ref = \
             self._get_repo_pullrequest_sources(
                 repo.scm_instance(), commit_id=commit_id,
                 branch=branch, bookmark=bookmark)
 
         refs_select2 = []
         for element in all_refs:
             children = [{'id': x[0], 'text': x[1]} for x in element[0]]
             refs_select2.append({'text': element[1], 'children': children})
 
         return {
             'user': {
                 'user_id': repo.user.user_id,
                 'username': repo.user.username,
                 'firstname': repo.user.firstname,
                 'lastname': repo.user.lastname,
                 'gravatar_link': h.gravatar_url(repo.user.email, 14),
             },
             'description': h.chop_at_smart(repo.description, '\n'),
             'refs': {
                 'all_refs': all_refs,
                 'selected_ref': selected_ref,
                 'select2_refs': refs_select2
             }
         }
 
     def generate_pullrequest_title(self, source, source_ref, target):
         return u'{source}#{at_ref} to {target}'.format(
             source=source,
             at_ref=source_ref,
             target=target,
         )
 
     def _cleanup_merge_workspace(self, pull_request):
         # Merging related cleanup
         target_scm = pull_request.target_repo.scm_instance()
         workspace_id = 'pr-%s' % pull_request.pull_request_id
 
         try:
             target_scm.cleanup_merge_workspace(workspace_id)
         except NotImplementedError:
             pass
 
     def _get_repo_pullrequest_sources(
             self, repo, commit_id=None, branch=None, bookmark=None):
         """
         Return a structure with repo's interesting commits, suitable for
         the selectors in pullrequest controller
 
         :param commit_id: a commit that must be in the list somehow
             and selected by default
         :param branch: a branch that must be in the list and selected
             by default - even if closed
         :param bookmark: a bookmark that must be in the list and selected
         """
 
         commit_id = safe_str(commit_id) if commit_id else None
         branch = safe_str(branch) if branch else None
         bookmark = safe_str(bookmark) if bookmark else None
 
         selected = None
 
         # order matters: first source that has commit_id in it will be selected
         sources = []
         sources.append(('book', repo.bookmarks.items(), _('Bookmarks'), bookmark))
         sources.append(('branch', repo.branches.items(), _('Branches'), branch))
 
         if commit_id:
             ref_commit = (h.short_id(commit_id), commit_id)
             sources.append(('rev', [ref_commit], _('Commit IDs'), commit_id))
 
         sources.append(
             ('branch', repo.branches_closed.items(), _('Closed Branches'), branch),
         )
 
         groups = []
         for group_key, ref_list, group_name, match in sources:
             group_refs = []
             for ref_name, ref_id in ref_list:
                 ref_key = '%s:%s:%s' % (group_key, ref_name, ref_id)
                 group_refs.append((ref_key, ref_name))
 
                 if not selected:
                     if set([commit_id, match]) & set([ref_id, ref_name]):
                         selected = ref_key
 
             if group_refs:
                 groups.append((group_refs, group_name))
 
         if not selected:
             ref = commit_id or branch or bookmark
             if ref:
                 raise CommitDoesNotExistError(
                     'No commit refs could be found matching: %s' % ref)
             elif repo.DEFAULT_BRANCH_NAME in repo.branches:
                 selected = 'branch:%s:%s' % (
                     repo.DEFAULT_BRANCH_NAME,
                     repo.branches[repo.DEFAULT_BRANCH_NAME]
                 )
             elif repo.commit_ids:
                 rev = repo.commit_ids[0]
                 selected = 'rev:%s:%s' % (rev, rev)
             else:
                 raise EmptyRepositoryError()
         return groups, selected
 
     def get_diff(self, pull_request, context=DIFF_CONTEXT):
         pull_request = self.__get_pull_request(pull_request)
         return self._get_diff_from_pr_or_version(pull_request, context=context)
 
     def _get_diff_from_pr_or_version(self, pr_or_version, context):
         source_repo = pr_or_version.source_repo
 
         # we swap org/other ref since we run a simple diff on one repo
         target_ref_id = pr_or_version.target_ref_parts.commit_id
         source_ref_id = pr_or_version.source_ref_parts.commit_id
         target_commit = source_repo.get_commit(
             commit_id=safe_str(target_ref_id))
         source_commit = source_repo.get_commit(commit_id=safe_str(source_ref_id))
         vcs_repo = source_repo.scm_instance()
 
         # TODO: johbo: In the context of an update, we cannot reach
         # the old commit anymore with our normal mechanisms. It needs
         # some sort of special support in the vcs layer to avoid this
         # workaround.
         if (source_commit.raw_id == vcs_repo.EMPTY_COMMIT_ID and
                 vcs_repo.alias == 'git'):
             source_commit.raw_id = safe_str(source_ref_id)
 
         log.debug('calculating diff between '
                   'source_ref:%s and target_ref:%s for repo `%s`',
                   target_ref_id, source_ref_id,
                   safe_unicode(vcs_repo.path))
 
         vcs_diff = vcs_repo.get_diff(
             commit1=target_commit, commit2=source_commit, context=context)
         return vcs_diff
 
     def _is_merge_enabled(self, pull_request):
         settings_model = VcsSettingsModel(repo=pull_request.target_repo)
         settings = settings_model.get_general_settings()
         return settings.get('rhodecode_pr_merge_enabled', False)
 
     def _use_rebase_for_merging(self, pull_request):
         settings_model = VcsSettingsModel(repo=pull_request.target_repo)
         settings = settings_model.get_general_settings()
         return settings.get('rhodecode_hg_use_rebase_for_merging', False)
 
     def _log_action(self, action, user, pull_request):
         action_logger(
             user,
             '{action}:{pr_id}'.format(
                 action=action, pr_id=pull_request.pull_request_id),
             pull_request.target_repo)
 
 
 ChangeTuple = namedtuple('ChangeTuple',
                          ['added', 'common', 'removed'])
 
 FileChangeTuple = namedtuple('FileChangeTuple',
                              ['added', 'modified', 'removed'])