# Mercurial phases support code

#

# Copyright 2011 Pierre-Yves David <pierre-yves.david@ens-lyon.org>

#                Logilab SA        <contact@logilab.fr>

#                Augie Fackler     <durin42@gmail.com>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

import errno

from node import nullid, bin, hex, short

from i18n import _

allphases = range(2)

trackedphases = allphases[1:]

def readroots(repo):

    """Read phase roots from disk"""

    roots = [set() for i in allphases]

    roots[0].add(nullid)

    try:

        f = repo.sopener('phaseroots')

        try:

            for line in f:

                phase, nh = line.strip().split()

                roots[int(phase)].add(bin(nh))

        finally:

            f.close()

    except IOError, inst:

        if inst.errno != errno.ENOENT:

            raise

    return roots

def writeroots(repo):

    """Write phase roots from disk"""

    f = repo.sopener('phaseroots', 'w', atomictemp=True)

    try:

        for phase, roots in enumerate(repo._phaseroots):

            for h in roots:

                f.write('%i %s\n' % (phase, hex(h)))

        repo._dirtyphases = False

    finally:

        f.close()

def filterunknown(repo, phaseroots=None):

    """remove unknown nodes from the phase boundary

    no data is lost as unknown node only old data for their descentants

    """

    if phaseroots is None:

        phaseroots = repo._phaseroots

    for phase, nodes in enumerate(phaseroots):

        missing = [node for node in nodes if node not in repo]

        if missing:

            for mnode in missing:

                msg = _('Removing unknown node %(n)s from %(p)i-phase boundary')

                repo.ui.debug(msg, {'n': short(mnode), 'p': phase})

            nodes.symmetric_difference_update(missing)

            repo._dirtyphases = True

    """Add nodes to a phase changing other nodes phases if necessary.

    Simplify boundary to contains phase roots only."""

    # move roots of lower states

    for phase in xrange(targetphase + 1, len(allphases)):

        # filter nodes that are not in a compatible phase already

        # XXX rev phase cache might have been invalidated by a previous loop

        # XXX we need to be smarter here

        nodes = [n for n in nodes if repo[n].phase() >= phase]

        if not nodes:

            break # no roots to move anymore

        roots = repo._phaseroots[phase]

        olds = roots.copy()

        ctxs = list(repo.set('roots((%ln::) - (%ln::%ln))', olds, olds, nodes))

        roots.clear()

        roots.update(ctx.node() for ctx in ctxs)

        if olds != roots:

            # invalidate cache (we probably could be smarter here

            if '_phaserev' in vars(repo):

                del repo._phaserev

            repo._dirtyphases = True