import re
from time import strftime, gmtime

_URI_RESERVED = {
    '21': '!', '23': '#', '24': '$', '26': '&',
    '27': '\'', '28': '(', '29': ')', '2A': '*',
    '2B': '+', '2C': ',', '2F': '/', '3A': ':',
    '3B': ';', '3D': '=', '3F': '?', '40': '@',
    '5B': '[', '5D': ']'
}

BAD_REQUEST = 'HTTP/1.1 400 Bad Request'
NOT_FOUND = 'HTTP/1.1 404 Not Found'
SUCCESS = 'HTTP/1.1 200 OK'
METHOD_NOT_ALLOWED = 'HTTP/1.1 405 Method Not Allowed'
URL_REGEX_PATTERN = re.compile(r'/((.*?/?)+)?')
HTTP_METHODS = ['GET', 'POST', 'OPTIONS', 'HEAD', 'PUT', 'PATCH', 'DELETE', 'TRACE', 'CONNECT']


def add_headers(status, html: str):
    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):
    methods_groups = f"({'|'.join(HTTP_METHODS)})"
    first_line_pattern = re.compile(rf'{methods_groups} {URL_REGEX_PATTERN.pattern} HTTP/1\.[01]')
    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 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]
            if hex_value in _URI_RESERVED:
                integer = ord(_URI_RESERVED[hex_value])
            else:
                integer = int(hex_value, 16)

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

    return encoded.decode()