import os

from mercurial.node import nullid

from mercurial.i18n import _

from mercurial import util, mdiff, cmdutil, scmutil

from mercurial import localrepo, changelog, manifest, filelog, revlog

class unionrevlog(revlog.revlog):

    def __init__(self, opener, indexfile, revlog2, linkmapper):

        # How it works:

        # To retrieve a revision, we just need to know the node id so we can

        # look it up in revlog2.

        #

            text = revlog.revlog.revision(self, rev)

            # already cached

        return text

    def addrevision(self, text, transaction, link, p1=None, p2=None, d=None):

        raise NotImplementedError

    def addgroup(self, revs, linkmapper, transaction):

        raise NotImplementedError

    def strip(self, rev, minlink):

        raise NotImplementedError

    def checksize(self):

        raise NotImplementedError

class unionchangelog(unionrevlog, changelog.changelog):

    def __init__(self, opener, opener2):

        changelog.changelog.__init__(self, opener)

        linkmapper = None

        changelog2 = changelog.changelog(opener2)

        unionrevlog.__init__(self, opener, self.indexfile, changelog2,

                             linkmapper)

class unionmanifest(unionrevlog, manifest.manifest):

    def __init__(self, opener, opener2, linkmapper):

        manifest.manifest.__init__(self, opener)

        manifest2 = manifest.manifest(opener2)

        unionrevlog.__init__(self, opener, self.indexfile, manifest2,

                             linkmapper)

class unionfilelog(unionrevlog, filelog.filelog):

    def __init__(self, opener, path, opener2, linkmapper, repo):

        filelog.filelog.__init__(self, opener, path)

        filelog2 = filelog.filelog(opener2, path)

        unionrevlog.__init__(self, opener, self.indexfile, filelog2,

                             linkmapper)

        self._repo = repo

    def _file(self, f):

        self._repo.file(f)

class unionpeer(localrepo.localpeer):

    def canpush(self):

        return False

class unionrepository(localrepo.localrepository):

    def __init__(self, ui, path, path2):

        localrepo.localrepository.__init__(self, ui, path)

        self.ui.setconfig('phases', 'publish', False)

        self._url = 'union:%s+%s' % (util.expandpath(path),

    def peer(self):

        return unionpeer(self)

    def getcwd(self):

        return os.getcwd() # always outside the repo

def instance(ui, path, create):

    if create:

        raise util.Abort(_('cannot create new union repository'))

    parentpath = ui.config("bundle", "mainreporoot", "")

    if not parentpath:

        # try to find the correct path to the working directory repo