from __future__ import absolute_import

from mercurial import (
    error,
    registrar,
    revset,
    util,
)

from . import (
    destination,
    stack,
)

try:
    mkmatcher = revset._stringmatcher
except AttributeError:
    try:
        from mercurial.utils import stringutil
        mkmatcher = stringutil.stringmatcher
    except (ImportError, AttributeError):
        mkmatcher = util.stringmatcher

revsetpredicate = registrar.revsetpredicate()

def getstringstrict(x, err):
    if x and x[0] == 'string':
        return x[1]
    raise error.ParseError(err)

@revsetpredicate('topic([string or set])')
def topicset(repo, subset, x):
    """All changesets with the specified topic or the topics of the given
    changesets. Without the argument, all changesets with any topic specified.

    If `string` starts with `re:` the remainder of the name is treated
    as a regular expression.
    """
    args = revset.getargs(x, 0, 1, 'topic takes one or no arguments')

    mutable = revset._notpublic(repo, revset.fullreposet(repo), ())

    if not args:
        return (subset & mutable).filter(lambda r: bool(repo[r].topic()))

    try:
        topic = getstringstrict(args[0], '')
    except error.ParseError:
        # not a string, but another revset
        pass
    else:
        kind, pattern, matcher = mkmatcher(topic)

        if topic.startswith('literal:') and pattern not in repo.topics:
            raise error.RepoLookupError("topic '%s' does not exist" % pattern)

        def matches(r):
            topic = repo[r].topic()
            if not topic:
                return False
            return matcher(topic)

        return (subset & mutable).filter(matches)

    s = revset.getset(repo, revset.fullreposet(repo), x)
    topics = {repo[r].topic() for r in s}
    topics.discard('')

    def matches(r):
        if r in s:
            return True
        topic = repo[r].topic()
        if not topic:
            return False
        return topic in topics

    return (subset & mutable).filter(matches)

@revsetpredicate('ngtip([branch])')
def ngtipset(repo, subset, x):
    """The untopiced tip.

    Name is horrible so that people change it.
    """
    args = revset.getargs(x, 1, 1, 'topic takes one')
    # match a specific topic
    branch = revset.getstring(args[0], 'ngtip() argument must be a string')
    if branch == '.':
        branch = repo['.'].branch()
    return subset & revset.baseset(destination.ngtip(repo, branch))

@revsetpredicate('stack()')
def stackset(repo, subset, x):
    """All relevant changes in the current topic,

    This is roughly equivalent to 'topic(.) - obsolete' with a sorting moving
    unstable changeset after there future parent (as if evolve where already
    run)."""
    err = 'stack() takes no argument, it works on current topic'
    revset.getargs(x, 0, 0, err)
    topic = None
    branch = None
    if repo.currenttopic:
        topic = repo.currenttopic
    else:
        branch = repo[None].branch()
    return revset.baseset(stack.stack(repo, branch=branch, topic=topic)[1:]) & subset