import base64
import hashlib
import contextlib
import io
import os
import re

from requests import exceptions, get
from urllib.parse import urlparse
from bs4 import BeautifulSoup as bsoup
from cryptography.fernet import Fernet
from flask import Request

ddg_favicon_site = 'http://icons.duckduckgo.com/ip2'

empty_gif = base64.b64decode(
    'R0lGODlhAQABAIAAAP///////yH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==')

placeholder_img = base64.b64decode(
    'iVBORw0KGgoAAAANSUhEUgAAABkAAAAZCAYAAADE6YVjAAABF0lEQVRIS8XWPw9EMBQA8Eok' \
    'JBKrMFqMBt//GzAYLTZ/VomExPDu6uLiaPteqVynBn0/75W2Vp7nEIYhe6p1XcespmmAd7Is' \
    'M+4URcGiKPogvMMvmIS2eN9MOMKbKWgf54SYgI4vKkTuQKJKSJErkKzUSkQHUs0lilAg7GMh' \
    'ISoIA/hYMiKCKIA2soeowCWEMkfHtUmrXLcyGYYBfN9HF8djiaglWzNZlgVs21YisoAUaEXG' \
    'cQTP86QIFgi7vyLzPIPjOEIEC7ANQv/4aZrAdd0TUtc1i+MYnSsMWjPp+x6CIPgJVlUVS5KE' \
    'DKig/+wnVzM4pnzaGeHd+ENlWbI0TbVLJBtw2uMfP63wc9d2kDCWxi5Q27bsBerSJ9afJbeL' \
    'AAAAAElFTkSuQmCC'
)


def fetch_favicon(url: str) -> bytes:
    """Fetches a favicon using DuckDuckGo's favicon retriever

    Args:
        url: The url to fetch the favicon from
    Returns:
        bytes - the favicon bytes, or a placeholder image if one
        was not returned
    """
    response = get(f'{ddg_favicon_site}/{urlparse(url).netloc}.ico')

    if response.status_code == 200 and len(response.content) > 0:
        tmp_mem = io.BytesIO()
        tmp_mem.write(response.content)
        tmp_mem.seek(0)

        return tmp_mem.read()
    return placeholder_img


def gen_file_hash(path: str, static_file: str) -> str:
    file_contents = open(os.path.join(path, static_file), 'rb').read()
    file_hash = hashlib.md5(file_contents).hexdigest()[:8]
    filename_split = os.path.splitext(static_file)

    return f'{filename_split[0]}.{file_hash}{filename_split[-1]}'


def read_config_bool(var: str, default: bool=False) -> bool:
    val = os.getenv(var, '1' if default else '0')
    # user can specify one of the following values as 'true' inputs (all
    # variants with upper case letters will also work):
    # ('true', 't', '1', 'yes', 'y')
    return val.lower() in ('true', 't', '1', 'yes', 'y')


def get_client_ip(r: Request) -> str:
    if r.environ.get('HTTP_X_FORWARDED_FOR') is None:
        return r.environ['REMOTE_ADDR']
    return r.environ['HTTP_X_FORWARDED_FOR']


def get_request_url(url: str) -> str:
    if os.getenv('HTTPS_ONLY', False):
        return url.replace('http://', 'https://', 1)

    return url


def get_proxy_host_url(r: Request, default: str, root=False) -> str:
    scheme = r.headers.get('X-Forwarded-Proto', 'https')
    http_host = r.headers.get('X-Forwarded-Host')

    full_path = r.full_path if not root else ''
    if full_path.startswith('/'):
        full_path = f'/{full_path}'

    if http_host:
        prefix = os.environ.get('WHOOGLE_URL_PREFIX', '')
        if prefix:
            prefix = f'/{re.sub("[^0-9a-zA-Z]+", "", prefix)}'
        return f'{scheme}://{http_host}{prefix}{full_path}'

    return default


def check_for_update(version_url: str, current: str) -> int:
    # Check for the latest version of Whoogle
    has_update = ''
    with contextlib.suppress(exceptions.ConnectionError, AttributeError):
        update = bsoup(get(version_url).text, 'html.parser')
        latest = update.select_one('[class="Link--primary"]').string[1:]
        current = int(''.join(filter(str.isdigit, current)))
        latest = int(''.join(filter(str.isdigit, latest)))
        has_update = '' if current >= latest else latest

    return has_update


def get_abs_url(url, page_url):
    # Creates a valid absolute URL using a partial or relative URL
    urls = {
        "//": f"https:{url}",
        "/": f"{urlparse(page_url).netloc}{url}",
        "./": f"{page_url}{url[2:]}"
    }
    for start in urls:
        if url.startswith(start):
            return urls[start]

    return url


def list_to_dict(lst: list) -> dict:
    if len(lst) < 2:
        return {}
    return {lst[i].replace(' ', ''): lst[i+1].replace(' ', '')
            for i in range(0, len(lst), 2)}


def encrypt_string(key: bytes, string: str) -> str:
    cipher_suite = Fernet(key)
    return cipher_suite.encrypt(string.encode()).decode()


def decrypt_string(key: bytes, string: str) -> str:
    cipher_suite = Fernet(g.session_key)
    return cipher_suite.decrypt(string.encode()).decode()