# Copyright 2020 Joerg Sonnenberger <joerg@bec.de>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

"""reject_new_heads is a hook to check that branches touched by new changesets

have at most one open head. It can be used to enforce policies for

merge-before-push or rebase-before-push. It does not handle pre-existing

hydras.

Usage:

  [hooks]

  pretxnclose.reject_new_heads = \

    python:hgext.hooklib.reject_new_heads.hook

"""

from mercurial.i18n import _

from mercurial import (

    error,

    pycompat,

)

def hook(ui, repo, hooktype, node=None, **kwargs):

    if hooktype != b"pretxnclose":

        raise error.Abort(

            _(b'Unsupported hook type %r') % pycompat.bytestr(hooktype)

        )

    ctx = repo.unfiltered()[node]

    branches = set()

    for rev in repo.changelog.revs(start=ctx.rev()):

        rev = repo[rev]

        branches.add(rev.branch())

    for branch in branches:

        if len(repo.revs("head() and not closed() and branch(%s)", branch)) > 1:

            raise error.Abort(

                _(b'Changes on branch %r resulted in multiple heads')

                % pycompat.bytestr(branch)

            )