"""URL."""

# standard
from functools import lru_cache
import re
from typing import Optional
from urllib.parse import parse_qs, unquote, urlsplit

# local
from .hostname import hostname
from .utils import validator


@lru_cache
def _username_regex():
    return re.compile(
        # extended latin
        r"(^[\u0100-\u017F\u0180-\u024F]"
        # dot-atom
        + r"|[-!#$%&'*+/=?^_`{}|~0-9a-z]+(\.[-!#$%&'*+/=?^_`{}|~0-9a-z]+)*$"
        # non-quoted-string
        + r"|^([\001-\010\013\014\016-\037!#-\[\]-\177]|\\[\011.])*$)",
        re.IGNORECASE,
    )


@lru_cache
def _path_regex():
    return re.compile(
        # allowed symbols
        r"^[\/a-z0-9\-\.\_\~\!\$\&\'\(\)\*\+\,\;\=\:\@\%"
        # emoticons / emoji
        + r"\U0001F600-\U0001F64F"
        # multilingual unicode ranges
        + r"\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]+$",
        re.IGNORECASE,
    )


def _validate_scheme(value: str):
    """Validate scheme."""
    # More schemes will be considered later.
    return (
        value
        # fmt: off
        in {
            "ftp", "ftps", "git", "http", "https",
            "irc", "rtmp", "rtmps", "rtsp", "sftp",
            "ssh", "telnet",
        }
        # fmt: on
        if value
        else False
    )


def _confirm_ipv6_skip(value: str, skip_ipv6_addr: bool):
    """Confirm skip IPv6 check."""
    return skip_ipv6_addr or value.count(":") < 2 or not value.startswith("[")


def _validate_auth_segment(value: str):
    """Validate authentication segment."""
    if not value:
        return True
    if (colon_count := value.count(":")) > 1:
        # everything before @ is then considered as a username
        # this is a bad practice, but syntactically valid URL
        return _username_regex().match(unquote(value))
    if colon_count < 1:
        return _username_regex().match(value)
    username, password = value.rsplit(":", 1)
    return _username_regex().match(username) and all(
        char_to_avoid not in password for char_to_avoid in ("/", "?", "#", "@")
    )


def _validate_netloc(
    value: str,
    skip_ipv6_addr: bool,
    skip_ipv4_addr: bool,
    may_have_port: bool,
    simple_host: bool,
    consider_tld: bool,
    private: Optional[bool],
    rfc_1034: bool,
    rfc_2782: bool,
):
    """Validate netloc."""
    if not value or value.count("@") > 1:
        return False
    if value.count("@") < 1:
        return hostname(
            (
                value
                if _confirm_ipv6_skip(value, skip_ipv6_addr) or "]:" in value
                else value.lstrip("[").replace("]", "", 1)
            ),
            skip_ipv6_addr=_confirm_ipv6_skip(value, skip_ipv6_addr),
            skip_ipv4_addr=skip_ipv4_addr,
            may_have_port=may_have_port,
            maybe_simple=simple_host,
            consider_tld=consider_tld,
            private=private,
            rfc_1034=rfc_1034,
            rfc_2782=rfc_2782,
        )
    basic_auth, host = value.rsplit("@", 1)
    return hostname(
        (
            host
            if _confirm_ipv6_skip(host, skip_ipv6_addr) or "]:" in value
            else host.lstrip("[").replace("]", "", 1)
        ),
        skip_ipv6_addr=_confirm_ipv6_skip(host, skip_ipv6_addr),
        skip_ipv4_addr=skip_ipv4_addr,
        may_have_port=may_have_port,
        maybe_simple=simple_host,
        consider_tld=consider_tld,
        private=private,
        rfc_1034=rfc_1034,
        rfc_2782=rfc_2782,
    ) and _validate_auth_segment(basic_auth)


def _validate_optionals(path: str, query: str, fragment: str, strict_query: bool):
    """Validate path query and fragments."""
    optional_segments = True
    if path:
        optional_segments &= bool(_path_regex().match(path))
    try:
        if (
            query
            # ref: https://github.com/python/cpython/issues/117109
            and parse_qs(query, strict_parsing=strict_query, separator="&")
            and parse_qs(query, strict_parsing=strict_query, separator=";")
        ):
            optional_segments &= True
    except TypeError:
        # for Python < v3.9.2 (official v3.10)
        if query and parse_qs(query, strict_parsing=strict_query):
            optional_segments &= True
    if fragment:
        # See RFC3986 Section 3.5 Fragment for allowed characters
        optional_segments &= bool(
            re.fullmatch(r"[0-9a-z?/:@\-._~%!$&'()*+,;=]*", fragment, re.IGNORECASE)
        )
    return optional_segments


@validator
def url(
    value: str,
    /,
    *,
    skip_ipv6_addr: bool = False,
    skip_ipv4_addr: bool = False,
    may_have_port: bool = True,
    simple_host: bool = False,
    strict_query: bool = True,
    consider_tld: bool = False,
    private: Optional[bool] = None,  # only for ip-addresses
    rfc_1034: bool = False,
    rfc_2782: bool = False,
):
    r"""Return whether or not given value is a valid URL.

    This validator was originally inspired from [URL validator of dperini][1].
    The following diagram is from [urlly][2]::


            foo://admin:hunter1@example.com:8042/over/there?name=ferret#nose
            \_/   \___/ \_____/ \_________/ \__/\_________/ \_________/ \__/
             |      |       |       |        |       |          |         |
          scheme username password hostname port    path      query    fragment

    [1]: https://gist.github.com/dperini/729294
    [2]: https://github.com/treeform/urlly

    Examples:
        >>> url('http://duck.com')
        # Output: True
        >>> url('ftp://foobar.dk')
        # Output: True
        >>> url('http://10.0.0.1')
        # Output: True
        >>> url('http://example.com/">user@example.com')
        # Output: ValidationError(func=url, ...)

    Args:
        value:
            URL string to validate.
        skip_ipv6_addr:
            When URL string cannot contain an IPv6 address.
        skip_ipv4_addr:
            When URL string cannot contain an IPv4 address.
        may_have_port:
            URL string may contain port number.
        simple_host:
            URL string maybe only hyphens and alpha-numerals.
        strict_query:
            Fail validation on query string parsing error.
        consider_tld:
            Restrict domain to TLDs allowed by IANA.
        private:
            Embedded IP address is public if `False`, private/local if `True`.
        rfc_1034:
            Allow trailing dot in domain/host name.
            Ref: [RFC 1034](https://www.rfc-editor.org/rfc/rfc1034).
        rfc_2782:
            Domain/Host name is of type service record.
            Ref: [RFC 2782](https://www.rfc-editor.org/rfc/rfc2782).

    Returns:
        (Literal[True]): If `value` is a valid url.
        (ValidationError): If `value` is an invalid url.
    """
    if not value or re.search(r"\s", value):
        # url must not contain any white
        # spaces, they must be encoded
        return False

    try:
        scheme, netloc, path, query, fragment = urlsplit(value)
    except ValueError:
        return False

    return (
        _validate_scheme(scheme)
        and _validate_netloc(
            netloc,
            skip_ipv6_addr,
            skip_ipv4_addr,
            may_have_port,
            simple_host,
            consider_tld,
            private,
            rfc_1034,
            rfc_2782,
        )
        and _validate_optionals(path, query, fragment, strict_query)
    )
