# 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, exchange

from mercurial.node import short

from mercurial.i18n import _

import errno

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

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

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

    backupdir = "strip-backup"

    vfs = repo.vfs

    if not vfs.isdir(backupdir):

        vfs.mkdir(backupdir)

    name = "%s/%s-%s.hg" % (backupdir, short(node), suffix)

    if compress:

        bundletype = "HG10BZ"

    else:

        bundletype = "HG10UN"

    return changegroup.writebundle(cg, name, bundletype, vfs)

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):

        _, brokenset = revlog.getstrippoint(striprev)

        s.update([revlog.linkrev(r) for r in brokenset])

    collectone(repo.manifest)

    for fname in files:

        collectone(repo.file(fname))

    return s

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

    # Simple way to maintain backwards compatibility for this

    # argument.

    if backup in ['none', 'strip']:

        backup = False

    repo = repo.unfiltered()

    repo.destroying()

    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)

    # 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.first()].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

    vfs = repo.vfs

    if backup:

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

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

                       vfs.join(backupfile))

        repo.ui.log("backupbundle", "saved backup bundle to %s\n",

                    vfs.join(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=False)

    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)

                if troffset == 0:

                    repo.store.markremoved(file)

            tr.close()

        except: # re-raises

            tr.abort()

            raise

        if saveheads or savebases:

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

            f = vfs.open(chgrpfile, "rb")

            gen = exchange.readbundle(ui, f, chgrpfile, vfs)

            if not repo.ui.verbose:

                # silence internal shuffling chatter

                repo.ui.pushbuffer()

            changegroup.addchangegroup(repo, gen, 'strip',

                                       'bundle:' + vfs.join(chgrpfile), True)

            if not repo.ui.verbose:

                repo.ui.popbuffer()

            f.close()

        # remove undo files

        for undovfs, undofile in repo.undofiles():

            try:

                undovfs.unlink(undofile)

            except OSError, e:

                if e.errno != errno.ENOENT:

                    ui.warn(_('error removing %s: %s\n') %

                            (undovfs.join(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")

                    % vfs.join(backupfile))

        elif saveheads:

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

                    % vfs.join(chgrpfile))

        raise

    else:

        if saveheads or savebases:

            # Remove partial backup only if there were no exceptions

            vfs.unlink(chgrpfile)

    repo.destroyed()