import re
from time import strftime, gmtime
from string import ascii_letters

HTTP_VERSION = 'HTTP/1.1'
SUCCESS = f'{HTTP_VERSION} 200 OK'
BAD_REQUEST = f'{HTTP_VERSION} 400 Bad Request'
NOT_FOUND = f'{HTTP_VERSION} 404 Not Found'
METHOD_NOT_ALLOWED = f'{HTTP_VERSION} Method Not Allowed'

HTTP_METHODS = ['GET', 'POST', 'OPTIONS', 'HEAD', 'PUT', 'PATCH', 'DELETE', 'TRACE', 'CONNECT']

URL_REGEX_PATTERN = re.compile(r'/((.*?/?)+)?')
FIRST_LINE_PATTERN = re.compile(rf'{"(" + "|".join(HTTP_METHODS) + ")"} {URL_REGEX_PATTERN.pattern} HTTP/1\.[01]')


def add_text_headers(status, html: str):
    """
    Добавляет заголовки к ответной html-странице
    """

    return '\r\n'.join([
        status,
        f'Date: {strftime("%a, %d %b %Y %H:%M:%S GMT", gmtime())}',
        'Server: BrandNewServer',
        'Content-Type: text/html; charset=utf-8',
        'Connection: keep-alive',
        '', html
    ])


def validate_url(url):
    return bool(URL_REGEX_PATTERN.fullmatch(url))


def validate_first_line(line):
    return bool(FIRST_LINE_PATTERN.fullmatch(line))


def parse_cookies(cookies_line: str):
    cookies_line = cookies_line.strip().strip(';')
    pairs = cookies_line.split(';')
    d = {}
    for pair in pairs:
        try:
            key, value = pair.split('=', maxsplit=1)
            d[key] = value
        except ValueError:
            raise ValueError('Wrong format of cookies')
    return d


def format_cookies(cookies: dict):
    """
    Формирование cookie-строки из переданного словаря.
    """

    pairs = []
    for key, value in cookies:
        pairs.append(f'{key}={value}')

    return ';'.join(pairs)


def parse_headers(request_line: str):
    request = request_line.split('\r\n')

    first_line = request.pop(0)
    if validate_first_line(first_line):
        method, url, http_ver = first_line.split()
    else:
        # Я не знаю зачем в условии необходимо завершать работу сервера, если пришел не-HTTP запрос,
        # поэтому оставлю эту строку здесь.
        # raise ValueError('Wrong format of HTTP request')
        raise ConnectionError('Wrong format of HTTP request')

    headers = {}
    for line in request:

        try:
            field, value = line.split(': ', maxsplit=1)
        except ValueError:
            # raise ValueError('Wrong format of HTTP header')
            raise ConnectionError('Wrong format of HTTP request')

        headers[field] = value

    return method, url, http_ver, headers


def parse_query(query_line: str):
    pairs = query_line.strip().split('&')
    d = {}
    for pair in pairs:
        try:
            key, value = pair.split('=', maxsplit=1)
            d[url_decoder(key)] = url_decoder(value)
        except ValueError:
            # raise ValueError('Wrong format of query')
            raise ConnectionError('Wrong format of query')

    return d


def url_decoder(url_line: str):
    url_line = url_line.replace('+', ' ')
    encoded = b''
    i = 0
    while i < len(url_line):
        if url_line[i] == '%':
            hex_value = url_line[i + 1: i + 3]
            encoded += bytes([int(hex_value, 16)])

            i += 3
            continue
        else:
            encoded += bytes([ord(url_line[i])])
            i += 1

    return encoded.decode()


def url_encoder(line: str):
    s = ''
    for char in line:
        if char == ' ':
            s += '+'
        elif char not in ascii_letters:
            for byte in char.encode():
                s += '%' + hex(byte)[2:].upper()
        else:
            s += char

    return s