# wikiget - CLI tool for downloading files from Wikimedia sites
# Copyright (C) 2018, 2019, 2020 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 os
import sys
from urllib.parse import unquote, urlparse

from mwclient import InvalidResponse, Site, __version__ as mwclient_version
from requests import ConnectionError
from tqdm import tqdm

from . import DEFAULT_SITE
from .validations import valid_file, valid_site, verify_hash
from .version import __version__

USER_AGENT = 'wikiget/{} (https://github.com/clpo13/wikiget) ' \
             'mwclient/{}'.format(__version__, mwclient_version)


def download(dl, args):
    url = urlparse(dl)

    if url.netloc:
        filename = url.path
        site_name = url.netloc
        if args.site is not DEFAULT_SITE and not args.quiet:
            # this will work even if the user specifies 'commons.wikimedia.org'
            print('Warning: target is a URL, '
                  'ignoring site specified with --site')
    else:
        filename = dl
        site_name = args.site

    file_match = valid_file(filename)
    site_match = valid_site(site_name)

    # check for valid site parameter
    if not site_match:
        print('Only Wikimedia sites (wikipedia.org and wikimedia.org) '
              'are currently supported.')
        sys.exit(1)

    # check if this is a valid file
    if file_match and file_match.group(1):
        # has File:/Image: prefix and extension
        filename = file_match.group(2)
    else:
        # no file extension and/or prefix, probably an article
        print('Downloading Wikipedia articles is not currently supported.',
              end='')
        if file_match and not file_match.group(1):
            # file extension detected, but no prefix
            # TODO: no longer possible to get to this point since
            # file_match is None with no prefix
            print(" If this is a file, please add the 'File:' prefix.")
        else:
            print('\n', end='')
        sys.exit(1)

    filename = unquote(filename)  # remove URL encoding for special characters

    dest = args.output or filename

    if args.verbose >= 2:
        print('User agent: {}'.format(USER_AGENT))

    # connect to site and identify ourselves
    try:
        site = Site(site_name, clients_useragent=USER_AGENT)
    except ConnectionError:
        # usually this means there is no such site,
        # or there's no network connection
        print("Error: couldn't connect to specified site.")
        sys.exit(1)
    except InvalidResponse as e:
        # site exists, but we couldn't communicate with the API endpoint
        print(e)
        sys.exit(1)

    # get info about the target file
    file = site.images[filename]

    if file.imageinfo != {}:
        # file exists either locally or at Wikimedia Commons
        file_url = file.imageinfo['url']
        file_size = file.imageinfo['size']
        file_sha1 = file.imageinfo['sha1']

        if args.verbose >= 1:
            print("Info: downloading '{}' "
                  '({} bytes) from {}'.format(filename, file_size, site.host),
                  end='')
            if args.output:
                print(" to '{}'".format(dest))
            else:
                print('\n', end='')
            print('Info: {}'.format(file_url))

        if os.path.isfile(dest) and not args.force:
            print("File '{}' already exists, skipping download "
                  '(use -f to ignore)'.format(dest))
        else:
            try:
                fd = open(dest, 'wb')
            except IOError as e:
                print('File could not be written. '
                      'The following error was encountered:')
                print(e)
                sys.exit(1)
            else:
                # download the file
                with tqdm(total=file_size, unit='B',
                          unit_scale=True, unit_divisor=1024) as progress_bar:
                    with fd:
                        res = site.connection.get(file_url, stream=True)
                        progress_bar.set_postfix(file=dest, refresh=False)
                        for chunk in res.iter_content(1024):
                            fd.write(chunk)
                            progress_bar.update(len(chunk))

            # verify file integrity and optionally print details
            dl_sha1 = verify_hash(dest)

            if args.verbose >= 1:
                print('Info: downloaded file SHA1 is {}'.format(dl_sha1))
                print('Info: server file SHA1 is {}'.format(file_sha1))
            if dl_sha1 == file_sha1:
                if args.verbose >= 1:
                    print('Info: hashes match!')
                # at this point, we've successfully downloaded the file
            else:
                print('Error: hash mismatch! Downloaded file may be corrupt.')
                sys.exit(1)

    else:
        # no file information returned
        print("Target '{}' does not appear to be a valid file."
              .format(filename))
        sys.exit(1)