#!/usr/bin/env python
#
# Copyright (C) 2013 W. Trevor King <wking@tremily.us>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this program.  If not, see
# <http://www.gnu.org/licenses/>.

import glob as _glob
import logging as _logging

import portage as _portage
import portage.dep as _portage_dep
import portage.versions as _portage_versions


def get_db():
    """Get a database of installed packages
    """
    db = _portage.db
    for key in ['/', 'vartree']:
        if key not in db:
            raise KeyError('{0} not found (choices: {1})'.format(
                    key, list(db.keys())))
        db = db[key]
    return db

def get_license_lists():
    """Iterate through installed packages with licenses

    Yields (category-package-version, license-list) tuples
    """
    db = get_db()
    for cpv in db.dbapi.cpv_all():
        licenses,use = db.dbapi.aux_get(cpv, ['LICENSE', 'USE'])
        category = _portage_versions.catsplit(cpv)[0]
        if category == 'virtual':
            if licenses:
                _logging.warn('license for {0}: {1}'.format(cpv, licenses))
            continue
        elif not licenses:
            _logging.warn('no license for {0}'.format(cpv))
            continue
        license_list = _portage_dep.use_reduce(
            licenses, uselist=use, opconvert=True)
        yield (cpv, license_list)

def incorperate_or_dependencies(license_set, or_dependencies):
    while or_dependencies:
        or_dependencies = set(
            or_set for or_set in or_dependencies
            if not license_set.union(or_set))
        if or_dependencies:
            raise NotImplementedError('select best subset of or_dependencies')
    return license_set

def get_all_licenses():
    license_set = set()
    or_dependencies = set()
    for cpv,license_list in get_license_lists():
        for token in license_list:
            if isinstance(token, str):
                license_set.add(token)
            elif token[0] == '||':
                or_dependencies.add(tuple(token[1:]))
            else:
                raise NotImplementedError((licenses, token))
    license_set = incorperate_or_dependencies(license_set, or_dependencies)
    return license_set


if __name__ == '__main__':
    licenses = get_all_licenses()
    print('\n'.join(sorted(licenses)))