import contextlib

import hashlib

from mercurial.i18n import _

from mercurial.node import nullid

from mercurial import (

    branchmap,

    changegroup,

    cmdutil,

    extensions,

    repoview,

    util,

)

from . import (

    common,

)

basefilter = set(['base', 'immutable'])

def topicfilter(name):

    """return a "topic" version of a filter level"""

    if name in basefilter:

        return name

    elif name is None:

        return None

    elif name.endswith('-topic'):

        return name

    else:

        return name + '-topic'

def istopicfilter(filtername):

    if filtername is None:

        return False

    return filtername.endswith('-topic')

def gettopicrepo(repo):

    if not common.hastopicext(repo):

        return repo

    filtername = topicfilter(repo.filtername)

    if filtername == repo.filtername:

        return repo

    return repo.filtered(filtername)

def _setuptopicfilter(ui):

    """extend the filter related mapping with topic related one"""

    funcmap = repoview.filtertable

    partialmap = branchmap.subsettable

    # filter level not affected by topic that we should not override

    for plainname in list(funcmap):

        newfilter = topicfilter(plainname)

        if newfilter == plainname:

            continue

        def revsfunc(repo, name=plainname):

            return repoview.filterrevs(repo, name)

        base = topicfilter(partialmap[plainname])

        if newfilter not in funcmap:

            funcmap[newfilter] = revsfunc

            partialmap[newfilter] = base

    funcmap['unfiltered-topic'] = lambda repo: frozenset()

    partialmap['unfiltered-topic'] = 'visible-topic'

def _phaseshash(repo, maxrev):

    """uniq ID for a phase matching a set of rev"""

    revs = set()

    cl = repo.changelog

    fr = cl.filteredrevs

    nm = cl.nodemap

    for roots in repo._phasecache.phaseroots[1:]:

        for n in roots:

            r = nm.get(n)

            if r not in fr and r < maxrev:

                revs.add(r)

    key = nullid

    revs = sorted(revs)

    if revs:

        s = hashlib.sha1()

        for rev in revs:

        key = s.digest()

    return key

def modsetup(ui):

    """call at uisetup time to install various wrappings"""

    _setuptopicfilter(ui)

    _wrapbmcache(ui)

    extensions.wrapfunction(changegroup.cg1unpacker, 'apply', cgapply)

    extensions.wrapfunction(cmdutil, 'commitstatus', commitstatus)

def cgapply(orig, self, repo, *args, **kwargs):

    """make sure a topicmap is used when applying a changegroup"""

    other = repo.filtered(topicfilter(repo.filtername))

    return orig(self, other, *args, **kwargs)

def commitstatus(orig, repo, node, branch, bheads=None, opts=None):

    # wrap commit status use the topic branch heads

    ctx = repo[node]

    if ctx.topic() and ctx.branch() == branch:

        bheads = repo.branchheads("%s:%s" % (branch, ctx.topic()))

    ret = orig(repo, node, branch, bheads=bheads, opts=opts)

    # logic copy-pasted from cmdutil.commitstatus()

    if opts is None:

        opts = {}

    if ctx.topic():

        return ret

    parents = ctx.parents()

    if (not opts.get('amend') and bheads and node not in bheads and not

        [x for x in parents if x.node() in bheads and x.branch() == branch]):

        repo.ui.status(_("(consider using topic for lightweight branches."

                         " See 'hg help topic')\n"))

    return ret

def _wrapbmcache(ui):

    class topiccache(_topiccache, branchmap.branchcache):

        pass

    branchmap.branchcache = topiccache

    try:

        # Mercurial 4.9

        class remotetopiccache(_topiccache, branchmap.remotebranchcache):

            pass

        branchmap.remotebranchcache = remotetopiccache

        def _wrapupdatebmcachemethod(orig, self, repo):

            # pass in the bound method as the original

            return _wrapupdatebmcache(orig.__get__(self), repo)

        extensions.wrapfunction(branchmap.BranchMapCache, 'updatecache', _wrapupdatebmcachemethod)

    except AttributeError:

        # Mercurial 4.8 and before

        extensions.wrapfunction(branchmap, 'updatecache', _wrapupdatebmcache)

def _wrapupdatebmcache(orig, repo):

    previous = getattr(repo, '_autobranchmaptopic', False)

    try:

        repo._autobranchmaptopic = False

        return orig(repo)

    finally:

        repo._autobranchmaptopic = previous

# needed to prevent reference used for 'super()' call using in branchmap.py to

# no go into cycle. (yes, URG)

_oldbranchmap = branchmap.branchcache

@contextlib.contextmanager

def oldbranchmap():

    previous = branchmap.branchcache

    try:

        branchmap.branchcache = _oldbranchmap

        yield

    finally:

        branchmap.branchcache = previous

class _topiccache(object): # combine me with branchmap.branchcache

    def __init__(self, *args, **kwargs):

        # super() call may fail otherwise

        with oldbranchmap():

            super(_topiccache, self).__init__(*args, **kwargs)

        self.phaseshash = None

    def copy(self):

        """return an deep copy of the branchcache object"""

        if util.safehasattr(self, '_entries'):

            _entries = self._entries

        else:

            # hg <= 4.9 (624d6683c705, b137a6793c51)

            _entries = self

        new = self.__class__(_entries, self.tipnode, self.tiprev,

                             self.filteredhash, self._closednodes)

        new.phaseshash = self.phaseshash

        return new

    def branchtip(self, branch, topic=''):

        '''Return the tipmost open head on branch head, otherwise return the

        tipmost closed head on branch.

        Raise KeyError for unknown branch.'''

        if topic:

            branch = '%s:%s' % (branch, topic)

        return super(_topiccache, self).branchtip(branch)

    def branchheads(self, branch, closed=False, topic=''):

        if topic:

            branch = '%s:%s' % (branch, topic)

        return super(_topiccache, self).branchheads(branch, closed=closed)

    def validfor(self, repo):

        """Is the cache content valid regarding a repo

        - False when cached tipnode is unknown or if we detect a strip.

        - True when cache is up to date or a subset of current repo."""

        valid = super(_topiccache, self).validfor(repo)

        if not valid:

            return False

        elif not istopicfilter(repo.filtername) or self.phaseshash is None:

            # phasehash at None means this is a branchmap

            # come from non topic thing

            return True

        else:

            try:

                valid = self.phaseshash == _phaseshash(repo, self.tiprev)

                return valid

            except IndexError:

                return False

    def write(self, repo):

        # we expect mutable set to be small enough to be that computing it all

        # the time will be fast enough

        if not istopicfilter(repo.filtername):

            super(_topiccache, self).write(repo)

    def update(self, repo, revgen):

        """Given a branchhead cache, self, that may have extra nodes or be

        missing heads, and a generator of nodes that are strictly a superset of

        heads missing, this function updates self to be correct.

        """

        if not istopicfilter(repo.filtername):

            return super(_topiccache, self).update(repo, revgen)

        unfi = repo.unfiltered()

        oldgetbranchinfo = unfi.revbranchcache().branchinfo

        def branchinfo(r, changelog=None):

            info = oldgetbranchinfo(r)

            topic = ''

            ctx = unfi[r]

            if ctx.mutable():

                topic = ctx.topic()

            branch = info[0]

            if topic:

                branch = '%s:%s' % (branch, topic)

            return (branch, info[1])

        try:

            unfi.revbranchcache().branchinfo = branchinfo

            super(_topiccache, self).update(repo, revgen)

            self.phaseshash = _phaseshash(repo, self.tiprev)

        finally:

            unfi.revbranchcache().branchinfo = oldgetbranchinfo