#   List changesets that are ancestors of other but not of org.

        #   New changesets in org is thus ignored.

        #   Diff will be from common ancestor, and merges of org to other will thus be ignored.

        # If merge is False:

        #   Make a raw diff from org to other, no matter if related or not.

        #   Changesets in one and not in the other will be ignored

        merge = bool(request.GET.get('merge'))

        # fulldiff disables cut_off_limit

        c.fulldiff = request.GET.get('fulldiff')

        # partial uses compare_cs.html template directly

        partial = request.environ.get('HTTP_X_PARTIAL_XHR')

        # as_form puts hidden input field with changeset revisions

        c.as_form = partial and request.GET.get('as_form')

        # swap url for compare_diff page - never partial and never as_form

        c.swap_url = h.url('compare_url',

            repo_name=other_repo,

            org_ref_type=other_ref_type, org_ref_name=other_ref_name,

            other_repo=org_repo,

            other_ref_type=org_ref_type, other_ref_name=org_ref_name,

            merge=merge or '')

        # set callbacks for generating markup for icons

        c.ignorews_url = _ignorews_url

        c.context_url = _context_url

        ignore_whitespace = request.GET.get('ignorews') == '1'

        line_context = request.GET.get('context', 3)

        org_repo = Repository.get_by_repo_name(org_repo)

        other_repo = Repository.get_by_repo_name(other_repo)

        if org_repo is None:

            msg = 'Could not find org repo %s' % org_repo

            log.error(msg)

            h.flash(msg, category='error')

            return redirect(url('compare_home', repo_name=c.repo_name))

        if other_repo is None:

            msg = 'Could not find other repo %s' % other_repo

            log.error(msg)

            h.flash(msg, category='error')

            return redirect(url('compare_home', repo_name=c.repo_name))

        if org_repo.scm_instance.alias != other_repo.scm_instance.alias:

            msg = 'compare of two different kind of remote repos not available'

            log.error(msg)

            h.flash(msg, category='error')

            return redirect(url('compare_home', repo_name=c.repo_name))

        c.cs_rev = self._get_ref_rev(other_repo, other_ref_type, other_ref_name)

        c.compare_home = False

        c.a_repo = org_repo

        c.a_ref_name = org_ref_name

        c.a_ref_type = org_ref_type

        c.cs_repo = other_repo

        c.cs_ref_name = other_ref_name

        c.cs_ref_type = other_ref_type

        c.cs_ranges, c.cs_ranges_org, c.ancestor = self._get_changesets(

            org_repo.scm_instance.alias, org_repo.scm_instance, c.a_rev,

            other_repo.scm_instance, c.cs_rev)

        raw_ids = [x.raw_id for x in c.cs_ranges]

        c.cs_comments = other_repo.get_comments(raw_ids)

        c.statuses = other_repo.statuses(raw_ids)

        revs = [ctx.revision for ctx in reversed(c.cs_ranges)]

        c.jsdata = json.dumps(graph_data(c.cs_repo.scm_instance, revs))

        if partial:

            return render('compare/compare_cs.html')

        if merge and c.ancestor:

            # case we want a simple diff without incoming changesets,

            # previewing what will be merged.

            # Make the diff on the other repo (which is known to have other_rev)

            log.debug('Using ancestor %s as rev1 instead of %s'

                      % (c.ancestor, c.a_rev))

            rev1 = c.ancestor

            org_repo = other_repo

        else: # comparing tips, not necessarily linearly related

            if merge:

                log.error('Unable to find ancestor revision')

            if org_repo != other_repo:

                # TODO: we could do this by using hg unionrepo

                log.error('cannot compare across repos %s and %s', org_repo, other_repo)

                h.flash(_('Cannot compare repositories without using common ancestor'), category='error')

                raise HTTPBadRequest

            rev1 = c.a_rev

        diff_limit = self.cut_off_limit if not c.fulldiff else None

        log.debug('running diff between %s and %s in %s'

                  % (rev1, c.cs_rev, org_repo.scm_instance.path))

        txtdiff = org_repo.scm_instance.get_diff(rev1=rev1, rev2=c.cs_rev,

                                      ignore_whitespace=ignore_whitespace,

                                      context=line_context)

            return redirect(url('my_pullrequests'))

        raise HTTPForbidden()

    @LoginRequired()

    @HasRepoPermissionAnyDecorator('repository.read', 'repository.write',

                                   'repository.admin')

    def show(self, repo_name, pull_request_id, extra=None):

        repo_model = RepoModel()

        c.users_array = repo_model.get_users_js()

        c.user_groups_array = repo_model.get_user_groups_js()

        c.pull_request = PullRequest.get_or_404(pull_request_id)

        c.allowed_to_change_status = self._get_is_allowed_change_status(c.pull_request)

        cc_model = ChangesetCommentsModel()

        cs_model = ChangesetStatusModel()

        # pull_requests repo_name we opened it against

        # ie. other_repo must match

        if repo_name != c.pull_request.other_repo.repo_name:

            raise HTTPNotFound

        # load compare data into template context

        c.cs_repo = c.pull_request.org_repo

        (c.cs_ref_type,

         c.cs_ref_name,

         c.cs_rev) = c.pull_request.org_ref.split(':')

        c.a_repo = c.pull_request.other_repo

        (c.a_ref_type,

         c.a_ref_name,

         c.a_rev) = c.pull_request.other_ref.split(':') # other_rev is ancestor

        org_scm_instance = c.cs_repo.scm_instance # property with expensive cache invalidation check!!!

        c.cs_repo = c.cs_repo

        c.cs_ranges = [org_scm_instance.get_changeset(x) for x in c.pull_request.revisions]

        c.cs_ranges_org = None # not stored and not important and moving target - could be calculated ...

        revs = [ctx.revision for ctx in reversed(c.cs_ranges)]

        c.jsdata = json.dumps(graph_data(org_scm_instance, revs))

        c.available = []

        c.cs_branch_name = c.cs_ref_name

        other_scm_instance = c.a_repo.scm_instance

        c.update_msg = ""

        c.update_msg_other = ""

        if org_scm_instance.alias == 'hg' and c.a_ref_name != 'ancestor':

            if c.cs_ref_type != 'branch':

                c.cs_branch_name = org_scm_instance.get_changeset(c.cs_ref_name).branch # use ref_type ?

            other_branch_name = c.a_ref_name

            if c.a_ref_type != 'branch':

            # candidates: descendants of old head that are on the right branch

            #             and not are the old head itself ...

            #             and nothing at all if old head is a descendent of target ref name

            if other_scm_instance._repo.revs('present(%s)::&%s', c.cs_ranges[-1].raw_id, other_branch_name):

                c.update_msg = _('This pull request has already been merged to %s.') % other_branch_name

            else: # look for children of PR head on source branch in org repo

                arevs = org_scm_instance._repo.revs('%s:: & branch(%s) - %s',

                                                    revs[0], c.cs_branch_name, revs[0])

                if arevs:

                    if c.pull_request.is_closed():

                        c.update_msg = _('This pull request has been closed and can not be updated with descendent changes on %s:') % c.cs_branch_name

                    else:

                        c.update_msg = _('This pull request can be updated with descendent changes on %s:') % c.cs_branch_name

                    c.available = [org_scm_instance.get_changeset(x) for x in arevs]

                else:

                    c.update_msg = _('No changesets found for updating this pull request.')

            revs = org_scm_instance._repo.revs('head() & not (%s::) & branch(%s) & !closed()', revs[0], c.cs_branch_name)

            if revs:

                c.update_msg_other = _('Note: Branch %s also contains unrelated changes, such as %s.') % (c.cs_branch_name,

                    h.short_id(org_scm_instance.get_changeset((max(revs))).raw_id))

            else:

                c.update_msg_other = _('Branch %s does not contain other changes.') % c.cs_branch_name

        elif org_scm_instance.alias == 'git':

            c.update_msg = _("Git pull requests don't support updates yet.")

        raw_ids = [x.raw_id for x in c.cs_ranges]

        c.cs_comments = c.cs_repo.get_comments(raw_ids)

        c.statuses = c.cs_repo.statuses(raw_ids)

        ignore_whitespace = request.GET.get('ignorews') == '1'

        line_context = request.GET.get('context', 3)

        c.ignorews_url = _ignorews_url

        c.context_url = _context_url

        c.fulldiff = request.GET.get('fulldiff')

        diff_limit = self.cut_off_limit if not c.fulldiff else None

        # we swap org/other ref since we run a simple diff on one repo

        log.debug('running diff between %s and %s in %s'

                  % (c.a_rev, c.cs_rev, org_scm_instance.path))

        txtdiff = org_scm_instance.get_diff(rev1=safe_str(c.a_rev), rev2=safe_str(c.cs_rev),

                                      ignore_whitespace=ignore_whitespace,

                                      context=line_context)

        diff_processor = diffs.DiffProcessor(txtdiff or '', format='gitdiff',

                                             diff_limit=diff_limit)

        _parsed = diff_processor.prepare()

    repository loaded items are

    c.db_repo_scm_instance: instance of scm repository

    c.db_repo: instance of db

    c.repository_followers: number of followers

    c.repository_forks: number of forks

    c.repository_following: weather the current user is following the current repo

    """

    def __before__(self):

        super(BaseRepoController, self).__before__()

        if c.repo_name:  # extracted from routes

            _dbr = Repository.get_by_repo_name(c.repo_name)

            if not _dbr:

                return

            log.debug('Found repository in database %s with state `%s`'

                      % (safe_unicode(_dbr), safe_unicode(_dbr.repo_state)))

            route = getattr(request.environ.get('routes.route'), 'name', '')

            # allow to delete repos that are somehow damages in filesystem

            if route in ['delete_repo']:

                return

            if _dbr.repo_state in [Repository.STATE_PENDING]:

                if route in ['repo_creating_home']:

                    return

                check_url = url('repo_creating_home', repo_name=c.repo_name)

                return redirect(check_url)

            dbr = c.db_repo = _dbr

            c.db_repo_scm_instance = c.db_repo.scm_instance

            if c.db_repo_scm_instance is None:

                log.error('%s this repository is present in database but it '

                          'cannot be created as an scm instance', c.repo_name)

                from kallithea.lib import helpers as h

                h.flash(h.literal(_('Repository not found in the filesystem')),

                        category='error')

                raise paste.httpexceptions.HTTPNotFound()

            # some globals counter for menu

            c.repository_followers = self.scm_model.get_followers(dbr)

            c.repository_forks = self.scm_model.get_forks(dbr)

            c.repository_pull_requests = self.scm_model.get_pull_requests(dbr)

            c.repository_following = self.scm_model.is_following_repo(

                                    c.repo_name, self.authuser.user_id)

    @staticmethod

        """

        Safe way to get changeset. If error occurs show error.

        """

        from kallithea.lib import helpers as h

        try:

            return repo.scm_instance.get_ref_revision(ref_type, ref_name)

        except EmptyRepositoryError as e:

            h.flash(h.literal(_('There are no changesets yet')),

                    category='error')

            raise webob.exc.HTTPNotFound()

        except ChangesetDoesNotExistError as e:

            h.flash(h.literal(_('Changeset not found')),

                    category='error')

            raise webob.exc.HTTPNotFound()

        except RepositoryError as e:

            log.error(traceback.format_exc())

            h.flash(safe_str(e), category='error')

            raise webob.exc.HTTPBadRequest()