import asyncio
import logging
import os
import re
from asyncio.exceptions import TimeoutError
from html import unescape
from time import time
from urllib.parse import unquote

import aiohttp
from aiohttp import ClientConnectorError, ServerDisconnectedError

PROTOCOL = 'https://'
BASE_URL = 'telegram.org'
# its necessary to help crawler to find more links
HIDDEN_URLS = {
    # 'corefork.telegram.org',

    'telegram.org/privacy/gmailbot',
    'telegram.org/tos',
    'telegram.org/tour',
    'telegram.org/evolution',

    'desktop.telegram.org/changelog',

    'instantview.telegram.org/rules',

    'core.telegram.org/resources/cidr.txt',
    'core.telegram.org/apple_privacy',
}
ADDITIONAL_URLS = {
    'raw.githubusercontent.com/telegramdesktop/tdesktop/dev/Telegram/Resources/tl/api.tl',
    'contest.com',
}
BASE_URL_REGEX = r'telegram.org'

# disable crawling sub links for specific domains and url patterns
CRAWL_RULES = {
    # every rule is regex
    # empty string means match any url
    # allow rules with higher priority than deny
    'translations.telegram.org': {
        'allow': {
            r'^[^/]*$',  # root
            r'org/[^/]*/$',  # 1 lvl sub
            r'/en/[a-z_]+/$'  # 1 lvl after /en/
        },
        'deny': {
            '',  # all
        }
    },
    'bugs.telegram.org': {  # crawl first page of cards sorted by rating
        'deny': {
            # r'/c/[0-9]+/[0-9]+',  # disable comments
            '',
        },
    },
    'instantview.telegram.org': {
        'deny': {
            'file/',

            r'templates/.+',
            'samples/',
            'contest',
        },
    },
    'core.telegram.org': {
        'deny': {
            'file/',

            'bots/payments',

            'tdlib/docs/classtd',

            'validatedRequestedInfo',
        },
    },
    'telegram.org': {
        'deny': {
            'file/',
            r'apps$'
        },
    },
    'webz.telegram.org': {
        'deny': {
            '',
        },
    },
    'webk.telegram.org': {
        'deny': {
            '',
        },
    },
}

DIRECT_LINK_REGEX = r'([-a-zA-Z0-9@:%._\+~#]{0,249}' + BASE_URL_REGEX + r')'
ABSOLUTE_LINK_REGEX = r'([-a-zA-Z0-9@:%._\+~#]{0,248}' + BASE_URL_REGEX + r'\b[-a-zA-Z0-9@:%_\+.~#?&//=]*)'
RELATIVE_LINK_REGEX = r'\/(?!\/)([-a-zA-Z0-9\/@:%._\+~#]{0,249})'

DOM_ATTRS = ['href', 'src']

OUTPUT_FILENAME = os.environ.get('OUTPUT_FILENAME', 'tracked_links.txt')
COMPARE_OUTPUT_WITH_FILENAME = os.environ.get('COMPARE_OUTPUT_WITH_FILENAME', OUTPUT_FILENAME)

# unsecure but so simple
CONNECTOR = aiohttp.TCPConnector(ssl=False)
TIMEOUT = aiohttp.ClientTimeout(total=30)

logging.basicConfig(format='%(message)s', level=logging.DEBUG)
logger = logging.getLogger(__name__)

VISITED_LINKS = set()
LINKS_TO_TRACK = set()


def should_exclude(url: str) -> bool:
    direct_link = re.findall(DIRECT_LINK_REGEX, url)[0]
    domain_rules = CRAWL_RULES.get(direct_link)
    if not domain_rules:
        return False

    allow_rules = domain_rules.get('allow', set())
    deny_rules = domain_rules.get('deny', set())

    exclude = False

    for regex in deny_rules:
        if re.search(regex, url):
            exclude = True
            break

    for regex in allow_rules:
        if re.search(regex, url):
            exclude = False
            break

    return exclude


def find_absolute_links(html: str) -> set[str]:
    absolute_links = set(re.findall(ABSOLUTE_LINK_REGEX, html))

    return {link for link in absolute_links if not should_exclude(link)}


def find_relative_links(html: str, cur_link: str) -> set[str]:
    direct_cur_link = re.findall(DIRECT_LINK_REGEX, cur_link)[0]
    # optimization. when we want to exclude domain
    if should_exclude(cur_link):
        return set()

    relative_links = set()
    for attr in DOM_ATTRS:
        regex = f'{attr}="{RELATIVE_LINK_REGEX}'
        links = re.findall(regex, html)

        for link in links:
            url = f'{direct_cur_link}/{link}'
            if not should_exclude(url):
                relative_links.add(url)

    return relative_links


def cleanup_links(links: set[str]) -> set[str]:
    cleaned_links = set()
    for tmp_link in links:
        # normalize link
        link = unquote(tmp_link)
        link = unescape(link)
        link = link.replace('www.', '')
        link = link.replace('http://', '').replace('https://', '')

        # skip anchor links
        if '#' in link:
            continue

        # remove get params from link
        if '?' in link:
            link = ''.join(link.split('?')[:-1])

        # skip mailto:
        link_parts = link.split('.')
        if '@' in link_parts[0]:
            continue

        cleaned_links.add(link)

    return cleaned_links


async def crawl(url: str, session: aiohttp.ClientSession):
    if url in VISITED_LINKS:
        return
    VISITED_LINKS.add(url)

    try:
        logger.info(f'[{len(VISITED_LINKS)}] Process {url}')
        async with session.get(f'{PROTOCOL}{url}', allow_redirects=False, timeout=TIMEOUT) as response:
            content_type = response.headers.get('content-type')

            if response.status == 500:
                return await asyncio.gather(crawl(url, session))

            if response.status != 200:
                if response.status != 302:
                    content = await response.text()
                    logger.debug(f'Skip {url} because status code == {response.status}. Content: {content}')
                return

            if 'text/html' in content_type:
                LINKS_TO_TRACK.add(url)

                html = await response.text()
                absolute_links = cleanup_links(find_absolute_links(html))
                relative_links = cleanup_links(find_relative_links(html, url))

                sub_links = absolute_links | relative_links
                await asyncio.gather(*[crawl(url, session) for url in sub_links])
            elif 'application/javascript' in content_type:
                LINKS_TO_TRACK.add(url)
            elif 'text/css' in content_type:
                LINKS_TO_TRACK.add(url)
            elif 'text/plain' in content_type:
                LINKS_TO_TRACK.add(url)
            elif 'application/json' in content_type:
                LINKS_TO_TRACK.add(url)
            else:
                # TODO track hashes of image/svg/video content types
                logger.info(f'Unhandled type: {content_type}')

            # telegram url can work with and without trailing slash (no redirect). P.S. not on every sub domain ;d
            # so this is a problem when we have random behavior with link will be added
            # this if resolve this issue. If available both link we prefer without trailing slash
            without_trailing_slash = url[:-1:] if url.endswith('/') else url
            if without_trailing_slash in LINKS_TO_TRACK and \
                    f'{without_trailing_slash}/' in LINKS_TO_TRACK:
                LINKS_TO_TRACK.remove(f'{without_trailing_slash}/')
    except UnicodeDecodeError:
        logger.warning('Codec can\'t decode byte. So its was a tgs file')
    except ClientConnectorError:
        logger.warning(f'Wrong link: {url}')
    except (ServerDisconnectedError, TimeoutError):
        logger.warning(f'Retrying {url}')
        VISITED_LINKS.remove(url)
        await asyncio.gather(crawl(url, session))


async def start(url_list: set[str]):
    async with aiohttp.ClientSession(connector=CONNECTOR) as session:
        await asyncio.gather(*[crawl(url, session) for url in url_list])


if __name__ == '__main__':
    HIDDEN_URLS.add(BASE_URL)
    LINKS_TO_TRACK = LINKS_TO_TRACK | ADDITIONAL_URLS

    logger.info('Start crawling links...')
    start_time = time()
    asyncio.get_event_loop().run_until_complete(start(HIDDEN_URLS))
    logger.info(f'Stop crawling links. {time() - start_time} sec.')

    try:
        with open(COMPARE_OUTPUT_WITH_FILENAME, 'r') as f:
            OLD_URL_LIST = set([l.replace('\n', '') for l in f.readlines()])

        logger.info(f'Is equal: {OLD_URL_LIST == LINKS_TO_TRACK}')
        logger.info(f'Deleted: {OLD_URL_LIST - LINKS_TO_TRACK}')
        logger.info(f'Added: {LINKS_TO_TRACK - OLD_URL_LIST}')
    except IOError:
        pass

    with open(OUTPUT_FILENAME, 'w') as f:
        f.write('\n'.join(sorted(LINKS_TO_TRACK)))