# wikiget - CLI tool for downloading files from Wikimedia sites
# Copyright (C) 2018-2021 Cody Logan and contributors
# 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 APIError, InvalidResponse, LoginError, Site
from requests import ConnectionError, HTTPError
from tqdm import tqdm

from . import CHUNKSIZE, DEFAULT_SITE, USER_AGENT
from .validations import valid_file, verify_hash


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)

    # 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(f"Could not parse input '{filename}' as a file. ")
        sys.exit(1)

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

    dest = args.output or filename

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

    # connect to site and identify ourselves
    if args.verbose >= 1:
        print(f'Site name: {site_name}')
    try:
        site = Site(site_name, path=args.path, clients_useragent=USER_AGENT)
        if args.username and args.password:
            site.login(args.username, args.password)
    except ConnectionError as e:
        # usually this means there is no such site, or there's no network
        # connection, though it could be a certificate problem
        print("Error: couldn't connect to specified site.")
        if args.verbose >= 2:
            print('Full error message:')
            print(e)
        sys.exit(1)
    except HTTPError as e:
        # most likely a 403 forbidden or 404 not found error for api.php
        print("Error: couldn't find the specified wiki's api.php. "
              "Check the value of --path.")
        if args.verbose >= 2:
            print('Full error message:')
            print(e)
        sys.exit(1)
    except (InvalidResponse, LoginError) as e:
        # InvalidResponse: site exists, but we couldn't communicate with the
        # API endpoint for some reason other than an HTTP error.
        # LoginError: missing or invalid credentials
        print(e)
        sys.exit(1)

    # get info about the target file
    try:
        file = site.images[filename]
    except APIError as e:
        # an API error at this point likely means access is denied,
        # which could happen with a private wiki
        print('Error: access denied. Try providing credentials with '
              '--username and --password.')
        if args.verbose >= 2:
            print('Full error message:')
            for i in e.args:
                print(i)
        sys.exit(1)

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

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

        if os.path.isfile(dest) and not args.force:
            print(f"File '{dest}' already exists, skipping download "
                  "(use -f to ignore)")
        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(s)
                if args.verbose >= 1:
                    leave_bars = True
                else:
                    leave_bars = False
                with tqdm(leave=leave_bars, total=file_size,
                          unit='B', unit_scale=True,
                          unit_divisor=CHUNKSIZE) 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(CHUNKSIZE):
                            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(f'Info: downloaded file SHA1 is {dl_sha1}')
                print(f'Info: server file SHA1 is {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(f"Target '{filename}' does not appear to be a valid file.")
        sys.exit(1)