#!/usr/bin/env python3
#
# Copyright (C) VyOS Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
#

# Use lxml xpath capability to detect multiple properties elements at the
# same path with differing content.


import sys
import glob
import logging
import io
from lxml import etree


debug = False

logger = logging.getLogger(__name__)
logs_handler = logging.StreamHandler()
logger.addHandler(logs_handler)

if debug:
    logger.setLevel(logging.DEBUG)
else:
    logger.setLevel(logging.INFO)


def canonical_form(e):
    # pylint: disable=c-extension-no-member
    out = io.BytesIO()

    etree.ElementTree(e).write_c14n(out)
    return out.getvalue()


def check_properties_collision(dir_name):
    # pylint: disable=too-many-locals,too-many-branches,c-extension-no-member
    """
    Collect elements with help tag into dictionary indexed by name
    attributes of ancestor path.
    """
    buffer = io.StringIO()
    for fname in glob.glob(f'{dir_name}/*.xml'):
        tree = etree.parse(fname)
        defv = {}

        xpath_str = '//properties'
        xp = tree.xpath(xpath_str)

        for element in xp:
            ap = element.xpath('ancestor::*[@name]')
            ap_name = [el.get('name') for el in ap]
            ap_path_str = ' '.join(ap_name)
            defv.setdefault(ap_path_str, []).append(element)

        trivial = []
        for k, v in defv.items():
            if len(v) < 2:
                trivial.append(k)
        for i in trivial:
            del defv[i]

        for k, v in defv.items():
            collisions = []
            for i in v:
                # If properties contains more than just a help element:
                if len(list(i)) > 1:
                    collisions.append(i)
            if len(collisions) > 1:
                property_set = set()
                for j in collisions:
                    prop = canonical_form(j)
                    property_set.add(prop)
                if len(property_set) > 1:
                    buffer.write(f'Collision in file {fname}:\n')
                    for e in collisions:
                        buffer.write(
                            f'Element {e.tag} at {e.sourceline} with content:\n {canonical_form(e)}\n'
                        )

    content = buffer.getvalue()
    if content:
        logger.info(
            'Collisions detected: multiple <properties> elements at a path with differing content other than <help>.\n'
            'Information beyond the first instance will be ignored in the resulting node.def file.'
        )
        logger.info(content)

    buffer.close()


def main():
    if len(sys.argv) < 2:
        logger.critical('Must specify XML directory!')
        sys.exit(1)

    dir_name = sys.argv[1]

    check_properties_collision(dir_name)


if __name__ == '__main__':
    main()