# Copyright 2010-2012 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

__all__ = (
    "ordered_by_atom_specificity",
    "prune_incremental",
)

from _emerge.Package import Package
from portage.dep import best_match_to_list, _repo_separator


def ordered_by_atom_specificity(cpdict, pkg, repo=None):
    """
    Return a list of matched values from the given cpdict,
    in ascending order by atom specificity. The rationale
    for this order is that package.* config files are
    typically written in ChangeLog like fashion, so it's
    most friendly if the order that the atoms are written
    does not matter. Therefore, settings from more specific
    atoms override those of less specific atoms. Without
    this behavior, settings from relatively unspecific atoms
    would (somewhat confusingly) override the settings of
    more specific atoms, requiring people to make adjustments
    to the order that atoms are listed in the config file in
    order to achieve desired results (and thus corrupting
    the ChangeLog like ordering of the file).
    """
    if not hasattr(pkg, "repo") and repo and repo != Package.UNKNOWN_REPO:
        pkg = pkg + _repo_separator + repo

    results = []
    keys = list(cpdict)

    while keys:
        bestmatch = best_match_to_list(pkg, keys)
        if bestmatch:
            keys.remove(bestmatch)
            results.append(cpdict[bestmatch])
        else:
            break

    if results:
        # reverse, so the most specific atoms come last
        results.reverse()

    return results


def prune_incremental(split):
    """
    Prune off any parts of an incremental variable that are
    made irrelevant by the latest occurring * or -*. This
    could be more aggressive but that might be confusing
    and the point is just to reduce noise a bit.
    """
    for i, x in enumerate(reversed(split)):
        if x == "*":
            split = split[-i - 1 :]
            break
        elif x == "-*":
            if i == 0:
                # Preserve the last -*, since otherwise an empty value
                # would trigger fallback to a default value.
                split = ["-*"]
            else:
                split = split[-i:]
            break
    return split
