from __future__ import annotations

import re

_IRC_CONTROL_START = 0x00
_IRC_CONTROL_END = 0x1F
_IRC_DEL = 0x7F

_LITERAL_ESCAPE_PATTERN = re.compile(r"\\x[0-9a-fA-F]{2}")


def is_irc_control_char(ch: str) -> bool:
    if len(ch) != 1:
        return False
    cp = ord(ch)
    return cp < 0x20 or cp == 0x7F


def has_irc_control_chars(text: str) -> bool:
    return any(is_irc_control_char(c) for c in text)


def strip_irc_control_chars(text: str) -> str:
    return "".join(c for c in text if not is_irc_control_char(c))


def decode_literal_escapes(text: str) -> str:
    """Strip literal escape sequences (\\xNN) from inbound text.

    Prevents attackers from injecting IRC control characters via literal
    backslash-x escape representations (e.g. \\x01 for CTCP delimiter).
    """
    return _LITERAL_ESCAPE_PATTERN.sub("", text)


def has_literal_escapes(text: str) -> bool:
    return bool(_LITERAL_ESCAPE_PATTERN.search(text))


def sanitize_outbound_text(text: str) -> str:
    text = text.replace("\n", " ").replace("\r", " ")
    return strip_irc_control_chars(text)


def sanitize_inbound_text(text: str) -> str:
    text = decode_literal_escapes(text)
    return strip_irc_control_chars(text)


def sanitize_irc_target(target: str) -> str:
    cleaned = strip_irc_control_chars(target)
    cleaned = cleaned.replace(" ", "_")
    return cleaned