# 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

def advanceboundary(repo, targetphase, nodes):
    """Add nodes to a phase changing other nodes phases if necessary.

    This function move boundary *forward* this means that all nodes are set
    in the target phase or kept in a *lower* phase.

    Simplify boundary to contains phase roots only."""
    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

def retractboundary(repo, targetphase, nodes):
    """Set nodes back to a phase changing other nodes phases if necessary.

    This function move boundary *backward* this means that all nodes are set
    in the target phase or kept in a *higher* phase.

    Simplify boundary to contains phase roots only."""
    currentroots = repo._phaseroots[targetphase]
    newroots = [n for n in nodes if repo[n].phase() < targetphase]
    if newroots:
        currentroots.update(newroots)
        ctxs = repo.set('roots(%ln::)', currentroots)
        currentroots.intersection_update(ctx.node() for ctx in ctxs)
        if '_phaserev' in vars(repo):
            del repo._phaserev
        repo._dirtyphases = True