import logging
import re
from urllib.parse import urlparse

from httplib.exceptions import InvalidStatusLine, InvalidResponse, BadRequest
from httplib.httpsocket import HTTPSocket


def _get_start_line(client: HTTPSocket):
    line = client.read_line()
    split = list(filter(None, line.split(" ")))
    if len(split) < 3:
        raise InvalidStatusLine(line)  # TODO fix exception

    return line, split


def _is_valid_http_version(http_version: str):
    if len(http_version) < 8 or http_version[4] != "/":
        return False

    (name, version) = http_version[:4], http_version[5:]
    if name != "HTTP" or not re.match(r"1\.[0|1]", version):
        return False


def get_status_line(client: HTTPSocket):
    line, (http_version, status, reason) = _get_start_line(client)

    if not _is_valid_http_version(http_version):
        raise InvalidStatusLine(line)
    version = http_version[:4]

    if not re.match(r"\d{3}", status):
        raise InvalidStatusLine(line)
    status = int(status)
    if status < 100 or status > 999:
        raise InvalidStatusLine(line)

    return version, status, reason


def parse_request_line(client: HTTPSocket):
    line, (method, target, version) = _get_start_line(client)

    if method not in ("CONNECT", "DELETE", "GET", "HEAD", "OPTIONS", "POST", "PUT", "TRACE"):
        raise BadRequest()

    if not _is_valid_http_version(version):
        raise BadRequest()

    if len(target) == "":
        raise BadRequest()
    parsed_target = urlparse(target)

    return method, parsed_target, version


def retrieve_headers(client: HTTPSocket):
    raw_headers = []
    # first header after the status-line may not contain a space
    while True:
        line = client.read_line()
        if line[0].isspace():
            continue
        else:
            break

    while True:
        if line in ("\r\n", "\n", " "):
            break

        if line[0].isspace():
            raw_headers[-1] = raw_headers[-1].rstrip("\r\n")

        raw_headers.append(line.lstrip())
        line = client.read_line()

    result = []
    header_str = "".join(raw_headers)
    for line in header_str.splitlines():
        pos = line.find(":")

        if pos <= 0 or pos >= len(line) - 1:
            continue

        (header, value) = line.split(":", 1)
        result.append((header.lower(), value.lower()))

    return result


def parse_request_headers(client: HTTPSocket):
    raw_headers = retrieve_headers(client)
    headers = {}

    key: str
    for (key, value) in raw_headers:
        if any((c.isspace()) for c in key):
            raise BadRequest()

        if key == "content-length":
            if key in headers:
                logging.error("Multiple content-length headers specified")
                raise BadRequest()
            if not value.isnumeric() or int(value) <= 0:
                logging.error("Invalid content-length value: %r", value)
                raise BadRequest()
        elif key == "host":
            if value != client.host or key in headers:
                raise BadRequest()

        headers[key] = value
    
    return headers


def get_headers(client: HTTPSocket):
    headers = []
    # first header after the status-line may not contain a space
    while True:
        line = client.read_line()
        if line[0].isspace():
            continue
        else:
            break

    while True:
        if line in ("\r\n", "\n", " "):
            break

        if line[0].isspace():
            headers[-1] = headers[-1].rstrip("\r\n")

        headers.append(line.lstrip())
        line = client.read_line()

    result = {}
    header_str = "".join(headers)
    for line in header_str.splitlines():
        pos = line.find(":")

        if pos <= 0 or pos >= len(line) - 1:
            continue

        (header, value) = map(str.strip, line.split(":", 1))
        check_next_header(result, header, value)
        result[header.lower()] = value.lower()

    return result


def check_next_header(headers, next_header: str, next_value: str):
    if next_header == "content-length":
        if "content-length" in headers:
            logging.error("Multiple content-length headers specified")
            raise InvalidResponse()
        if not next_value.isnumeric() or int(next_value) <= 0:
            logging.error("Invalid content-length value: %r", next_value)
            raise InvalidResponse()