# 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 or any later version.

import changegroup

from node import nullrev, short

from i18n import _

import os

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

    """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.hg" % (short(node), suffix))

    if compress:

        bundletype = "HG10BZ"

    else:

        bundletype = "HG10UN"

    return changegroup.writebundle(cg, name, bundletype)

def _collectfiles(repo, striprev):

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

    files = set()

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

        files.update(repo[x].files())

    return sorted(files)

def _collectextranodes(repo, files, link):

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

    def collectone(cl, revlog):

        extra = []

        startrev = count = len(revlog)

        # find the truncation point of the revlog

        for i in xrange(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(cl, repo.manifest)

    if extra:

        extranodes[1] = extra

    for fname in files:

        f = repo.file(fname)

        extra = collectone(cl, 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)

    keeppartialbundle = backup == 'strip'

    # 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 = set((striprev,))

    saveheads = set()

    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.add(r)

            # 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.add(p)

        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))

            saveheads.difference_update(parents)

            saveheads.add(r)

    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

    backupfile = None

    if backup == "all":

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

        repo.ui.status(_("saved backup bundle to %s\n") % backupfile)

    if saveheads or extranodes:

        # do not compress partial bundle if we remove it from disk later

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

                            extranodes=extranodes, compress=keeppartialbundle)

    mfst = repo.manifest

    tr = repo.transaction("strip")

    offset = len(tr.entries)

    try:

        tr.startgroup()

        cl.strip(striprev, tr)

        mfst.strip(striprev, tr)

        for fn in files:

            repo.file(fn).strip(striprev, tr)

        tr.endgroup()

        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.note(_("adding branch\n"))

            f = open(chgrpfile, "rb")

            gen = changegroup.readbundle(f, chgrpfile)

            if not repo.ui.verbose:

                # silence internal shuffling chatter

                repo.ui.pushbuffer()

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

            if not repo.ui.verbose:

                repo.ui.popbuffer()

            f.close()

            if not keeppartialbundle:

                os.unlink(chgrpfile)

    except:

        if backupfile:

            ui.warn(_("strip failed, full bundle stored in '%s'\n")

                    % backupfile)

        elif saveheads:

            ui.warn(_("strip failed, partial bundle stored in '%s'\n")

                    % chgrpfile)

        raise

    repo.destroyed()