"""Pure input validation and supported host-list line formats."""
import ipaddress
import re
from urllib.parse import urlparse

def should_ignore_domain(domain):
    return domain.startswith(".") or any(
        ch in domain for ch in ["~", "=", "$", "'", "^", "_", ">", "<", ":"]
    )

def should_ignore_line(line):
    return any(sym in line for sym in ["<", ">", "##", "###", "div", "span"])

def is_valid_domain(domain):
    return bool(re.compile(r"^(?:[a-zA-Z0-9-]+\.)+[a-zA-Z]{2,}$").match(domain))

def convert_host_line(line: str, target_ip: str):
    # szybkie odrzucenia
    if not line:
        return None
    line = line.strip()

    if not line or line.startswith(("!", "#", "/", ";")):
        return None

    for sep in (" #", " ;"):
        idx = line.find(sep)
        if idx != -1:
            line = line[:idx].rstrip()

    if not line:
        return None

    m = re.match(r"^\|\|([a-z0-9.-]+)\^", line, re.IGNORECASE)
    if m:
        domain = m.group(1).strip(".")
        if not should_ignore_domain(domain) and is_valid_domain(domain):
            return f"{target_ip} {domain}"
        return None

    parts = line.split()

    if len(parts) >= 2 and (
        re.match(r"^\d{1,3}(?:\.\d{1,3}){3}$", parts[0]) or ":" in parts[0]
    ):
        domain = parts[1].strip().split("#", 1)[0].strip().strip(".")
        if not should_ignore_domain(domain) and is_valid_domain(domain):
            return f"{target_ip} {domain}"
        return None

    m = re.match(r"^(?:address|server)=/([a-z0-9.-]+)/", line, re.IGNORECASE)
    if m:
        domain = m.group(1).strip(".")
        if not should_ignore_domain(domain) and is_valid_domain(domain):
            return f"{target_ip} {domain}"
        return None

    token = parts[0].split("#", 1)[0].strip().strip(".")
    if token and not should_ignore_domain(token) and is_valid_domain(token):
        return f"{target_ip} {token}"

    return None

def validate_and_normalize_url(url):
    url = (url or "").strip()

    # prosta sanity-check: usuń CR/LF
    if any(c in url for c in ("\r", "\n")):
        raise ValueError("Invalid characters in URL")

    parsed = urlparse(url)
    if not parsed.scheme:
        url = f"https://{url}"
        parsed = urlparse(url)

    # akceptuj tylko http/https
    if parsed.scheme not in {"http", "https"}:
        raise ValueError(f"Unsupported scheme: {parsed.scheme}")

    if not parsed.netloc:
        raise ValueError("Missing host in URL")

    return parsed.geturl()

def validate_ip(value: str) -> str:
    v = (value or "").strip()
    try:
        return str(ipaddress.ip_address(v))
    except Exception:
        raise ValueError("Invalid IP address")