import asyncio
import ipaddress
import socket
from collections.abc import Awaitable, Callable
from urllib.parse import urlsplit

Resolver = Callable[[str, int], Awaitable[list[str]]]


class UnsafeTarget(ValueError):
    pass


async def system_resolver(host: str, port: int) -> list[str]:
    loop = asyncio.get_running_loop()
    records = await loop.getaddrinfo(host, port, type=socket.SOCK_STREAM)
    return sorted({record[4][0] for record in records})


async def validate_target(url: str, resolver: Resolver = system_resolver) -> None:
    parsed = urlsplit(url)
    if parsed.scheme not in {"http", "https"} or not parsed.hostname:
        raise UnsafeTarget("unsupported_target")
    if parsed.username or parsed.password:
        raise UnsafeTarget("credentials_not_allowed")
    port = parsed.port or (443 if parsed.scheme == "https" else 80)
    try:
        addresses = await resolver(parsed.hostname, port)
    except (OSError, socket.gaierror) as exc:
        raise UnsafeTarget("dns_resolution_failed") from exc
    if not addresses:
        raise UnsafeTarget("dns_resolution_failed")
    try:
        safe = all(ipaddress.ip_address(address).is_global for address in addresses)
    except ValueError as exc:
        raise UnsafeTarget("dns_resolution_failed") from exc
    if not safe:
        raise UnsafeTarget("non_public_target")