# repair.py - functions for repository repair for mercurial

#

# Copyright 2005, 2006 Chris Mason <mason@suse.com>

# Copyright 2007 Matt Mackall

#

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

# GNU General Public License version 2, incorporated herein by reference.

import changegroup

from node import nullrev, short

from i18n import _

import os

def _bundle(repo, bases, heads, node, suffix, extranodes=None):

    """create a bundle with the specified revisions as a backup"""

    cg = repo.changegroupsubset(bases, heads, 'strip', extranodes)

    backupdir = repo.join("strip-backup")

    if not os.path.isdir(backupdir):

        os.mkdir(backupdir)

    name = os.path.join(backupdir, "%s-%s" % (short(node), suffix))

    repo.ui.warn(_("saving bundle to %s\n") % name)

    return changegroup.writebundle(cg, name, "HG10BZ")

def _collectfiles(repo, striprev):

    """find out the filelogs affected by the strip"""

    files = {}

    for x in xrange(striprev, len(repo)):

        for name in repo[x].files():

            if name in files:

                continue

            files[name] = 1

    files = files.keys()

    files.sort()

    return files

def _collectextranodes(repo, files, link):

    """return the nodes that have to be saved before the strip"""

    def collectone(revlog):

        extra = []

        startrev = count = len(revlog)

        # find the truncation point of the revlog

        for i in xrange(0, count):

            lrev = revlog.linkrev(i)

            if lrev >= link:

                startrev = i + 1

                break

        # see if any revision after that point has a linkrev less than link

        # (we have to manually save these guys)

        for i in xrange(startrev, count):

            node = revlog.node(i)

            lrev = revlog.linkrev(i)

            if lrev < link:

                extra.append((node, cl.node(lrev)))

        return extra

    extranodes = {}

    cl = repo.changelog

    extra = collectone(repo.manifest)

    if extra:

        extranodes[1] = extra

    for fname in files:

        f = repo.file(fname)

        extra = collectone(f)

        if extra:

            extranodes[fname] = extra

    return extranodes

def strip(ui, repo, node, backup="all"):

    cl = repo.changelog

    # TODO delete the undo files, and handle undo of merge sets

    striprev = cl.rev(node)

    # Some revisions with rev > striprev may not be descendants of striprev.

    # We have to find these revisions and put them in a bundle, so that

    # we can restore them after the truncations.

    # To create the bundle we use repo.changegroupsubset which requires

    # the list of heads and bases of the set of interesting revisions.

    # (head = revision in the set that has no descendant in the set;

    #  base = revision in the set that has no ancestor in the set)

    tostrip = {striprev: 1}

    saveheads = {}

    savebases = []

    for r in xrange(striprev + 1, len(cl)):

        parents = cl.parentrevs(r)

        if parents[0] in tostrip or parents[1] in tostrip:

            # r is a descendant of striprev

            tostrip[r] = 1

            # if this is a merge and one of the parents does not descend

            # from striprev, mark that parent as a savehead.

            if parents[1] != nullrev:

                for p in parents:

                    if p not in tostrip and p > striprev:

                        saveheads[p] = 1

        else:

            # if no parents of this revision will be stripped, mark it as

            # a savebase

            if parents[0] < striprev and parents[1] < striprev:

                savebases.append(cl.node(r))

            for p in parents:

                if p in saveheads:

                    del saveheads[p]

            saveheads[r] = 1

    saveheads = [cl.node(r) for r in saveheads]

    files = _collectfiles(repo, striprev)

    extranodes = _collectextranodes(repo, files, striprev)

    # create a changegroup for all the branches we need to keep

    if backup == "all":

        _bundle(repo, [node], cl.heads(), node, 'backup')

    if saveheads or extranodes:

        chgrpfile = _bundle(repo, savebases, saveheads, node, 'temp',

                            extranodes)

    fs = [repo.file(name) for name in files]

    mfst = repo.manifest

    tr = repo.transaction()

    offset = len(tr.entries)

    cl.strip(striprev, tr)

    mfst.strip(striprev, tr)

    for f in fs:

        f.strip(striprev, tr)

    try:

        for i in xrange(offset, len(tr.entries)):

            file, troffset, ignore = tr.entries[i]

            repo.sopener(file, 'a').truncate(troffset)

        tr.close()

    except:

        tr.abort()

        raise

    if saveheads or extranodes:

        ui.status(_("adding branch\n"))

        f = open(chgrpfile, "rb")

        gen = changegroup.readbundle(f, chgrpfile)

        repo.addchangegroup(gen, 'strip', 'bundle:' + chgrpfile, True)

        f.close()

        if backup != "strip":

            os.unlink(chgrpfile)