"""Reduce the changesets evolution feature scope for early and noob friendly UI

The full scale changeset evolution have some massive bleeding edge and it is

very easy for people not very intimate with the concept to end up in intricate

situation. In order to get some of the benefit sooner, this extension is

disabling some of the less polished aspect of evolution. It should gradually

get thinner and thinner as changeset evolution will get more polished. This

extension is only recommended for large scale organisations. Individual user

should probably stick on using Evolution in its current state, understand its

concept and provide feedback

The first feature provided by this extension is the ability to "inhibit"

obsolescence markers. Obsolete revision can be cheaply brought back to life

that way. However as the inhibitor are not fitting in an append only model,

this is incompatible with sharing mutable history.

"""

from mercurial import localrepo

from mercurial import obsolete

from mercurial import extensions

from mercurial import cmdutil

from mercurial import scmutil

cmdtable = {}

command = cmdutil.command(cmdtable)

def reposetup(ui, repo):

    class obsinhibitedrepo(repo.__class__):

        @localrepo.storecache('obsinhibit')

        def _obsinhibit(self):

            # XXX we should make sure it is invalidated by transaction failure

            obsinhibit = set()

            raw = self.sopener.tryread('obsinhibit')

            for i in xrange(0, len(raw), 20):

                obsinhibit.add(raw[i:i+20])

            return obsinhibit

    repo.__class__ = obsinhibitedrepo

# obsolescence inhibitor

########################

def _schedulewrite(tr, obsinhibit):

    """Make sure on disk content will be updated on transaction commit"""

    def writer(fp):

        """Serialize the inhibited list to disk.

        """

        raw = ''.join(obsinhibit)

        fp.write(raw)

    tr.addfilegenerator('obsinhibit', ('obsinhibit',), writer)

    tr.hookargs['obs_inbihited'] = '1'

def _inhibitmarkers(repo, nodes):

    """add marker inhibitor for all obsolete revision under <nodes>

    Content of <nodes> and all mutable ancestors are considered. Marker for

    obsolete revision only are created.

    """

    newinhibit = repo.set('::%ln and obsolete()', nodes)

    if newinhibit:

        tr = repo.transaction('obsinhibit')

        try:

            repo._obsinhibit.update(c.node() for c in newinhibit)

            _schedulewrite(tr, repo._obsinhibit)

            repo.invalidatevolatilesets()

            tr.close()

        finally:

            tr.release()

def _deinhibitmarkers(repo, nodes):

    """lift obsolescence inhibition on a set of nodes

    This will be triggered when inhibited nodes received new obsolescence

    markers. Otherwise the new obsolescence markers would also be inhibited.

    """

    deinhibited = repo._obsinhibit & set(nodes)

    if deinhibited:

        tr = repo.transaction('obsinhibit')

        try:

            repo._obsinhibit -= deinhibited

            _schedulewrite(tr, repo._obsinhibit)

            repo.invalidatevolatilesets()

            tr.close()

        finally:

            tr.release()

def _createmarkers(orig, repo, relations, flag=0, date=None, metadata=None):

    """wrap markers create to make sure we de-inhibit target nodes"""

    # wrapping transactio to unify the one in each function

    tr = repo.transaction('add-obsolescence-marker')

    try:

        orig(repo, relations, flag, date, metadata)

        precs = (r[0].node() for r in relations)

        _deinhibitmarkers(repo, precs)

        tr.close()

    finally:

        tr.release()

def extsetup(ui):

    # lets wrap the computation of the obsolete set

    # We apply inhibition there

    obsfunc = obsolete.cachefuncs['obsolete']

    def _computeobsoleteset(repo):

        """remove any inhibited nodes from the obsolete set

        This will trickle down to other part of mercurial (hidden, log, etc)"""

        obs = obsfunc(repo)

        getrev = repo.changelog.nodemap.get

        for n in repo._obsinhibit:

            obs.discard(getrev(n))

        return obs

    obsolete.cachefuncs['obsolete'] = _computeobsoleteset

    # drop divergence computation since it is incompatible with "light revive"

    obsolete.cachefuncs['divergent'] = lambda repo: set()

    # drop bumped computation since it is incompatible with "light revive"

    obsolete.cachefuncs['bumped'] = lambda repo: set()

    # wrap create marker to make it able to lift the inhibition

    extensions.wrapfunction(obsolete, 'createmarkers', _createmarkers)

@command('debugobsinhibit', [], '')

def cmddebugobsinhibit(ui, repo, *revs):

    """inhibit obsolescence markers effect on a set of revs"""

    nodes = (repo[r].node() for r in scmutil.revrange(repo, revs))

    _inhibitmarkers(repo, nodes)