from __future__ import absolute_import

import hashlib

from mercurial import (

    error,

    obsolete,

    scmutil,

)

from mercurial.i18n import _

from . import (

    exthelper,

    rewriteutil,

    compat,

)

eh = exthelper.exthelper()

# flag in obsolescence markers to link to identical version

identicalflag = 4

@eh.command(

    '^rewind',

    [('', 'to', [], _("rewind to these revision")),

    ],

    _(''))

def rewind(ui, repo, **opts):

    """rewind stacks of changeset to a previous content

    """

    unfi = repo.unfiltered()

    if not opts.get('to'):

        raise error.Abort('no revision to rewind to')

    rewinded = scmutil.revrange(repo, opts.get('to'))

    with repo.wlock(), repo.lock():

        # Check that we can rewind these changesets

        with repo.transaction('rewind'):

            for rev in rewinded:

                _revive_revision(unfi, rev)

def _revive_revision(unfi, rev):

    """rewind a single revision rev.

    """

    ctx = unfi[rev]

    extra = ctx.extra().copy()

    # rewind hash should be unique over multiple rewind.

    user = unfi.ui.config('devel', 'user.obsmarker')

    if not user:

        user = unfi.ui.username()

    date = unfi.ui.configdate('devel', 'default-date')

    if date is None:

        date = compat.makedate()

    noise = "%s\0%s\0%d\0%d" % (ctx.node(), user, date[0], date[1])

    extra['__rewind-hash__'] = hashlib.sha256(noise).hexdigest()

    p1 = ctx.p1().node()

    p2 = ctx.p2().node()

    extradict = {'extra': extra}

    new, unusedvariable = rewriteutil.rewrite(unfi, ctx, [], ctx,

                                              [p1, p2],

                                              commitopts=extradict)

    obsolete.createmarkers(unfi, [(ctx, (unfi[new],))],

                           flag=identicalflag, operation='rewind')

    return new