#no remote compare do it on the same repository

            else:

                hgrepo = other_repo._repo

            ancestors = hgrepo.revs("ancestor(id(%s), id(%s))", org_rev, other_rev)

            if ancestors:

                # pick arbitrary ancestor - but there is usually only one

                ancestor = hgrepo[ancestors[0]].hex()

            other_revs = hgrepo.revs("ancestors(id(%s)) and not ancestors(id(%s)) and not id(%s)",

                                     other_rev, org_rev, org_rev)

            other_changesets = [other_repo.get_changeset(rev) for rev in other_revs]

            org_revs = hgrepo.revs("ancestors(id(%s)) and not ancestors(id(%s)) and not id(%s)",

                                   org_rev, other_rev, other_rev)

            org_changesets = [org_repo.get_changeset(hgrepo[rev].hex()) for rev in org_revs]

        elif alias == 'git':

            if org_repo != other_repo:

                from dulwich.repo import Repo

                from dulwich.client import SubprocessGitClient

                gitrepo = Repo(org_repo.path)

                SubprocessGitClient(thin_packs=False).fetch(other_repo.path, gitrepo)

                gitrepo_remote = Repo(other_repo.path)

                SubprocessGitClient(thin_packs=False).fetch(org_repo.path, gitrepo_remote)

                revs = []

                for x in gitrepo_remote.get_walker(include=[other_rev],

                                                   exclude=[org_rev]):

                    revs.append(x.commit.id)

                other_changesets = [other_repo.get_changeset(rev) for rev in reversed(revs)]

                if other_changesets:

                    ancestor = other_changesets[0].parents[0].raw_id

                else:

                    # no changesets from other repo, ancestor is the other_rev

                    ancestor = other_rev

            else:

                so, se = org_repo.run_git_command(

                    'log --reverse --pretty="format: %%H" -s %s..%s'

                        % (org_rev, other_rev)

                )

                other_changesets = [org_repo.get_changeset(cs)

                              for cs in re.findall(r'[0-9a-fA-F]{40}', so)]

            org_changesets = []

        else:

            raise Exception('Bad alias only git and hg is allowed')

        return other_changesets, org_changesets, ancestor

    @LoginRequired()

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

                                   'repository.admin')

    def index(self, repo_name):

        c.compare_home = True

        org_repo = c.db_repo.repo_name

        other_repo = request.GET.get('other_repo', org_repo)

        c.org_repo = Repository.get_by_repo_name(org_repo)

        c.other_repo = Repository.get_by_repo_name(other_repo)

        c.org_ref_name = c.other_ref_name = _('Select changeset')

        return render('compare/compare_diff.html')

    @LoginRequired()

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

                                   'repository.admin')

    def compare(self, repo_name, org_ref_type, org_ref_name, other_ref_type, other_ref_name):

        org_repo = c.db_repo.repo_name

        other_repo = request.GET.get('other_repo', org_repo)

        # If merge is True:

        #   Show what org would get if merged with other:

        #   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 '')

        response.mustcontain('%s@master' % (GIT_REPO))

        # branch are equal

        response.mustcontain('<span class="empty_data">No files</span>')

        response.mustcontain('<span class="empty_data">No changesets</span>')

    def test_compare_revisions_hg(self):

        self.log_user()

        rev1 = 'b986218ba1c9'

        rev2 = '3d8f361e72ab'

        response = self.app.get(url('compare_url',

                                    repo_name=HG_REPO,

                                    org_ref_type="rev",

                                    org_ref_name=rev1,

                                    other_ref_type="rev",

                                    other_ref_name=rev2,

                                    ))

        response.mustcontain('%s@%s' % (HG_REPO, rev1))

        response.mustcontain('%s@%s' % (HG_REPO, rev2))

        ## outgoing changesets between those revisions

        response.mustcontain("""<a href="/%s/changeset/3d8f361e72ab303da48d799ff1ac40d5ac37c67e">r1:%s</a>""" % (HG_REPO, rev2))

        response.mustcontain('1 file changed with 7 insertions and 0 deletions')

        ## files

        response.mustcontain("""<a href="#C--c8e92ef85cd1">.hgignore</a>""")

    def test_compare_revisions_git(self):

        self.log_user()

        rev1 = 'c1214f7e79e02fc37156ff215cd71275450cffc3'

        rev2 = '38b5fe81f109cb111f549bfe9bb6b267e10bc557'

        response = self.app.get(url('compare_url',

                                    repo_name=GIT_REPO,

                                    org_ref_type="rev",

                                    org_ref_name=rev1,

                                    other_ref_type="rev",

                                    other_ref_name=rev2,

                                    ))

        response.mustcontain('%s@%s' % (GIT_REPO, rev1))

        response.mustcontain('%s@%s' % (GIT_REPO, rev2))

        ## outgoing changesets between those revisions

        response.mustcontain("""<a href="/%s/changeset/38b5fe81f109cb111f549bfe9bb6b267e10bc557">r1:%s</a>""" % (GIT_REPO, rev2[:12]))

        response.mustcontain('1 file changed with 7 insertions and 0 deletions')

        ## files

        response.mustcontain("""<a href="#C--c8e92ef85cd1">.hgignore</a>""")