# 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.

from mercurial import changegroup, branchmap

from mercurial.node import short

from mercurial.i18n import _

import os

import errno

def _bundle(repo, bases, heads, node, suffix, compress=True):

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

    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.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 _collectbrokencsets(repo, files, striprev):

    """return the changesets which will be broken by the truncation"""

    s = set()

    def collectone(revlog):

        linkgen = (revlog.linkrev(i) for i in revlog)

        # find the truncation point of the revlog

        for lrev in linkgen:

            if lrev >= striprev:

                break

        # see if any revision after this point has a linkrev

        # less than striprev (those will be broken by strip)

        for lrev in linkgen:

            if lrev < striprev:

                s.add(lrev)

    collectone(repo.manifest)

    for fname in files:

        collectone(repo.file(fname))

    return s

def strip(ui, repo, nodelist, backup="all", topic='backup'):

    repo = repo.unfiltered()

    # It simplifies the logic around updating the branchheads cache if we only

    # have to consider the effect of the stripped revisions and not revisions

    # missing because the cache is out-of-date.

    branchmap.updatecache(repo)

    cl = repo.changelog

    # TODO handle undo of merge sets

    if isinstance(nodelist, str):

        nodelist = [nodelist]

    striplist = [cl.rev(node) for node in nodelist]

    striprev = min(striplist)

    # Generate set of branches who will have nodes stripped.

    striprevs = repo.revs("%ld::", striplist)

    stripbranches = set([repo[rev].branch() for rev in striprevs])

    # Set of potential new heads resulting from the strip.  The parents of any

    # node removed could be a new head because the node to be removed could have

    # been the only child of the parent.

    newheadrevs = repo.revs("parents(%ld::) - %ld::", striprevs, striprevs)

    newheadnodes = set([cl.node(rev) for rev in newheadrevs])

    newheadbranches = set([repo[rev].branch() for rev in newheadrevs])

    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(striplist)

    for rev in striplist:

        for desc in cl.descendants([rev]):

            tostrip.add(desc)

    files = _collectfiles(repo, striprev)

    saverevs = _collectbrokencsets(repo, files, striprev)

    # compute heads

    saveheads = set(saverevs)

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

        if r not in tostrip:

            saverevs.add(r)

            saveheads.difference_update(cl.parentrevs(r))

            saveheads.add(r)

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

    # compute base nodes

    if saverevs:

        descendants = set(cl.descendants(saverevs))

        saverevs.difference_update(descendants)

    savebases = [cl.node(r) for r in saverevs]

    stripbases = [cl.node(r) for r in tostrip]

    # For a set s, max(parents(s) - s) is the same as max(heads(::s - s)), but

    # is much faster

    newbmtarget = repo.revs('max(parents(%ld) - (%ld))', tostrip, tostrip)

    if newbmtarget:

        newbmtarget = repo[newbmtarget[0]].node()

    else:

        newbmtarget = '.'

    bm = repo._bookmarks

    updatebm = []

    for m in bm:

        rev = repo[bm[m]].rev()

        if rev in tostrip:

            updatebm.append(m)

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

    backupfile = None

    if backup == "all":

        backupfile = _bundle(repo, stripbases, cl.heads(), node, topic)

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

    if saveheads or savebases:

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

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

                            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: # re-raises

            tr.abort()

            raise

        if saveheads or savebases:

            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)

        # remove undo files

        for undofile in repo.undofiles():

            try:

                os.unlink(undofile)

            except OSError, e:

                if e.errno != errno.ENOENT:

                    ui.warn(_('error removing %s: %s\n') % (undofile, str(e)))

        for m in updatebm:

            bm[m] = repo[newbmtarget].node()

        bm.write()

    except: # re-raises

        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

    if len(stripbranches) == 1 and len(newheadbranches) == 1 \

            and stripbranches == newheadbranches:

        repo.destroyed(newheadnodes)

    else:

        # Multiple branches involved in strip. Will allow branchcache to become

        # invalid and later on rebuilt from scratch

        repo.destroyed()