#!/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 find multiple elements with tag help
# relative to path; copy and replace to override the initial value.

import sys
import glob
import logging
from copy import deepcopy
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 override_element(lst: list):
    """
    Allow multiple override elements; use the final one (in document order).
    """
    if len(lst) < 2:
        logger.debug('passing list of single element to override_element')
        return

    # replace element with final override
    first_element = lst[0]
    # lxml will remove on replace, hence make a copy to avoid cleaning up
    # empty elements
    final_element = deepcopy(lst[-1])
    parent = first_element.getparent()
    parent.replace(first_element, final_element)


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

        xpath_str = '//help'
        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():
            text_set = set()
            for e in v:
                text_set.add(e.text)
            if len(text_set) > 1:
                logger.debug(f'Inconsistent help elements in file {fname}:')
                for e in v:
                    logger.debug(
                        f'Element is {e.tag} with content {e.text} at {e.sourceline}'
                    )

                logger.info(f"overriding help in path '{k}'")
                override_element(v)

        revised_str = etree.tostring(root, encoding='unicode', pretty_print=True)

        with open(f'{fname}', 'w') as f:
            f.write(revised_str)


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

    dir_name = sys.argv[1]

    collect_and_override(dir_name)


if __name__ == '__main__':
    main()