# split.py - split a changeset into smaller parts
#
# Copyright 2011 Peter Arrenbrecht <peter.arrenbrecht@gmail.com>
#                Logilab SA        <contact@logilab.fr>
#                Pierre-Yves David <pierre-yves.david@ens-lyon.org>
#                Patrick Mezard <patrick@mezard.eu>
# Copyright 2017 Facebook, Inc.
#
# 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 mercurial import (
    bookmarks,
    cmdutil,
    commands,
    error,
    hg,
    lock as lockmod,
    obsolete,
    registrar,
    scmutil,
)
from mercurial.i18n import _

from . import common

cmdtable = {}
command = registrar.command(cmdtable)

@command('^split',
         [('r', 'rev', [], _("revision to split")),
          ('', 'no-rebase', False, _("don't rebase descendants after split")),
         ] + commands.commitopts + commands.commitopts2,
         _('hg split [OPTION]... [-r] [REV]'))
def split(ui, repo, *revs, **opts):
    """split a changeset into smaller changesets

    By default, split the current revision by prompting for all its hunks to be
    redistributed into new changesets.

    Use --rev to split a given changeset instead.
    """
    tr = wlock = lock = None
    newcommits = []

    revarg = (list(revs) + opts.get('rev')) or ['.']
    if len(revarg) != 1:
        msg = _("more than one revset is given")
        hnt = _("use either `hg split <rs>` or `hg split --rev <rs>`, not both")
        raise error.Abort(msg, hint=hnt)

    rev = scmutil.revsingle(repo, revarg[0])
    if opts.get('no_rebase'):
        torebase = ()
    else:
        torebase = repo.revs('descendants(%d) - (%d)', rev, rev)
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        cmdutil.bailifchanged(repo)
        if torebase:
            cmdutil.checkunfinished(repo)
        tr = repo.transaction('split')
        ctx = repo[rev]
        r = ctx.rev()
        disallowunstable = not obsolete.isenabled(repo,
                                                  obsolete.allowunstableopt)
        if disallowunstable:
            # XXX We should check head revs
            if repo.revs("(%d::) - %d", rev, rev):
                raise error.Abort(_("cannot split commit: %s not a head") % ctx)

        if len(ctx.parents()) > 1:
            raise error.Abort(_("cannot split merge commits"))
        prev = ctx.p1()
        bmupdate = common.bookmarksupdater(repo, ctx.node(), tr)
        bookactive = repo._activebookmark
        if bookactive is not None:
            repo.ui.status(_("(leaving bookmark %s)\n") % repo._activebookmark)
        bookmarks.deactivate(repo)
        hg.update(repo, prev)

        commands.revert(ui, repo, rev=r, all=True)

        def haschanges():
            modified, added, removed, deleted = repo.status()[:4]
            return modified or added or removed or deleted
        msg = ("HG: This is the original pre-split commit message. "
               "Edit it as appropriate.\n\n")
        msg += ctx.description()
        opts['message'] = msg
        opts['edit'] = True
        while haschanges():
            pats = ()
            cmdutil.dorecord(ui, repo, commands.commit, 'commit', False,
                             cmdutil.recordfilter, *pats, **opts)
            # TODO: Does no seem like the best way to do this
            # We should make dorecord return the newly created commit
            newcommits.append(repo['.'])
            if haschanges():
                if ui.prompt('Done splitting? [yN]', default='n') == 'y':
                    commands.commit(ui, repo, **opts)
                    newcommits.append(repo['.'])
                    break
            else:
                ui.status(_("no more change to split\n"))

        if newcommits:
            tip = repo[newcommits[-1]]
            bmupdate(tip.node())
            if bookactive is not None:
                bookmarks.activate(repo, bookactive)
            obsolete.createmarkers(repo, [(repo[r], newcommits)],
                                   operation='split')

            if torebase:
                top = repo.revs('allsuccessors(%d)', rev).last()
                common.restackonce(ui, repo, top)
        tr.close()
    finally:
        lockmod.release(tr, lock, wlock)