# wikiget - CLI tool for downloading files from Wikimedia sites
# Copyright (C) 2018-2023 Cody Logan
# SPDX-License-Identifier: GPL-3.0-or-later
#
# Wikiget is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Wikiget 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 Wikiget. If not, see <https://www.gnu.org/licenses/>.

import hashlib
import re
from typing import Optional

from wikiget import BLOCKSIZE


def valid_file(search_string: str) -> Optional[re.Match]:
    """
    Determines if the given string contains a valid file name, defined as a string
    ending with a '.' and at least one character, beginning with 'File:' or 'Image:',
    the standard file prefixes in MediaWiki.

    :param search_string: string to validate
    :type search_string: str
    :returns: a regex Match object if there's a match or None otherwise
    :rtype: re.Match
    """
    # second group could also restrict to file extensions with three or more
    # letters with ([^/\r\n\t\f\v]+\.\w{3,})
    file_regex = re.compile(r"(File:|Image:)([^/\r\n\t\f\v]+\.\w+)$", re.I)
    return file_regex.search(search_string)


def valid_site(search_string: str) -> Optional[re.Match]:
    """
    Determines if the given string contains a valid site name, defined as a string
    ending with 'wikipedia.org' or 'wikimedia.org'. This covers all subdomains of those
    domains.

    Currently unused since any site is accepted as input, and we rely on the user to
    ensure the site has a compatible API.

    :param search_string: string to validate
    :type search_string: str
    :returns: a regex Match object if there's a match or None otherwise
    :rtype: re.Match
    """
    site_regex = re.compile(r"wiki[mp]edia\.org$", re.I)
    return site_regex.search(search_string)


def verify_hash(filename: str) -> str:
    """
    Calculates the SHA1 hash of the given file for comparison with a known value.

    :param filename: name of the file to calculate a hash for
    :type filename: str
    :return: hash digest
    :rtype: str
    """
    hasher = hashlib.sha1()  # noqa: S324
    with open(filename, "rb") as dl:
        buf = dl.read(BLOCKSIZE)
        while len(buf) > 0:
            hasher.update(buf)
            buf = dl.read(BLOCKSIZE)
    return hasher.hexdigest()