# 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, incorporated herein by reference.

import changegroup, revlog, os, commands

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

    def limitheads(chlog, stop):

        """return the list of all nodes that have no children"""

        p = {}

        h = []

        stoprev = 0

        if stop in chlog.nodemap:

            stoprev = chlog.rev(stop)

        for r in xrange(chlog.count() - 1, -1, -1):

            n = chlog.node(r)

            if n not in p:

                h.append(n)

            if n == stop:

                break

            if r < stoprev:

                break

            for pn in chlog.parents(n):

                p[pn] = 1

        return h

    def bundle(repo, bases, heads, rev, suffix):

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

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

        if not os.path.isdir(backupdir):

            os.mkdir(backupdir)

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

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

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

    def stripall(revnum):

        mm = repo.changectx(rev).manifest()

        seen = {}

        for x in xrange(revnum, repo.changelog.count()):

            for f in repo.changectx(x).files():

                if f in seen:

                    continue

                seen[f] = 1

                if f in mm:

                    filerev = mm[f]

                else:

                    filerev = 0

                seen[f] = filerev

        # we go in two steps here so the strip loop happens in a

        # sensible order.  When stripping many files, this helps keep

        # our disk access patterns under control.

        seen_list = seen.keys()

        seen_list.sort()

        for f in seen_list:

            ff = repo.file(f)

            filerev = seen[f]

            if filerev != 0:

                if filerev in ff.nodemap:

                    filerev = ff.rev(filerev)

                else:

                    filerev = 0

            ff.strip(filerev, revnum)

    chlog = repo.changelog

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

    pp = chlog.parents(rev)

    revnum = chlog.rev(rev)

    # save is a list of all the branches we are truncating away

    # that we actually want to keep.  changegroup will be used

    # to preserve them and add them back after the truncate

    saveheads = []

    savebases = {}

    heads = limitheads(chlog, rev)

    seen = {}

    # search through all the heads, finding those where the revision

    # we want to strip away is an ancestor.  Also look for merges

    # that might be turned into new heads by the strip.

    while heads:

        h = heads.pop()

        n = h

        while True:

            seen[n] = 1

            pp = chlog.parents(n)

            if pp[1] != revlog.nullid:

                for p in pp:

                    if chlog.rev(p) > revnum and p not in seen:

                        heads.append(p)

            if pp[0] == revlog.nullid:

                break

            if chlog.rev(pp[0]) < revnum:

                break

            n = pp[0]

            if n == rev:

                break

        r = chlog.reachable(h, rev)

        if rev not in r:

            saveheads.append(h)

            for x in r:

                if chlog.rev(x) > revnum:

                    savebases[x] = 1

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

    if backup == "all":

        bundle(repo, [rev], chlog.heads(), rev, 'backup')

    if saveheads:

        chgrpfile = bundle(repo, savebases.keys(), saveheads, rev, 'temp')

    stripall(revnum)

    change = chlog.read(rev)

    chlog.strip(revnum, revnum)

    repo.manifest.strip(repo.manifest.rev(change[0]), revnum)

    if saveheads:

        ui.status("adding branch\n")

        commands.unbundle(ui, repo, "file:%s" % chgrpfile, update=False)

        if backup != "strip":

            os.unlink(chgrpfile)