# rewriteutil.py - utility functions for rewriting changesets

#

# Copyright 2017 Octobus <contact@octobus.net>

#

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

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

from __future__ import absolute_import

from .i18n import _

from . import (

    error,

    node,

    obsolete,

    revset,

)

def precheck(repo, revs, action=b'rewrite'):

    """check if revs can be rewritten

    action is used to control the error message.

    Make sure this function is called after taking the lock.

    """

    if node.nullrev in revs:

        msg = _(b"cannot %s null changeset") % action

        hint = _(b"no changeset checked out")

        raise error.Abort(msg, hint=hint)

    if len(repo[None].parents()) > 1:

        raise error.Abort(_(b"cannot %s while merging") % action)

    publicrevs = repo.revs(b'%ld and public()', revs)

    if publicrevs:

        msg = _(b"cannot %s public changesets") % action

        hint = _(b"see 'hg help phases' for details")

        raise error.Abort(msg, hint=hint)

    newunstable = disallowednewunstable(repo, revs)

    if newunstable:

        raise error.Abort(_(b"cannot %s changeset with children") % action)

def disallowednewunstable(repo, revs):

    """Checks whether editing the revs will create new unstable changesets and

    are we allowed to create them.

    To allow new unstable changesets, set the config:

        `experimental.evolution.allowunstable=True`

    """

    allowunstable = obsolete.isenabled(repo, obsolete.allowunstableopt)

    if allowunstable:

        return revset.baseset()

    return repo.revs(b"(%ld::) - %ld", revs, revs)

def skip_empty_successor(ui, command):

    empty_successor = ui.config(b'rewrite', b'empty-successor')

    if empty_successor == b'skip':

        return True

    elif empty_successor == b'keep':

        return False

    else:

        raise error.ConfigError(

            _(

                b"%s doesn't know how to handle config "

                b"rewrite.empty-successor=%s (only 'skip' and 'keep' are "

                b"supported)"

            )

            % (command, empty_successor)

        )