from __future__ import annotations

from dataclasses import dataclass
from ipaddress import ip_address, ip_network

from app.config import KnownSenderConfig, Settings
from app.dmarc_parser import ParsedRecord


@dataclass(frozen=True)
class SenderMatch:
    id: str | None
    name: str | None
    is_known: bool


def _domain_equal(a: str | None, b: str | None) -> bool:
    return (a or "").lower().rstrip(".") == (b or "").lower().rstrip(".")


def _ip_matches(source_ip: str, sender: KnownSenderConfig) -> bool:
    try:
        ip = ip_address(source_ip)
    except ValueError:
        return False
    for cidr in sender.ip_allowlist:
        try:
            if ip in ip_network(cidr, strict=False):
                return True
        except ValueError:
            continue
    return False


def classify_record(settings: Settings, domain: str, record: ParsedRecord) -> SenderMatch:
    senders = settings.known_senders.get(domain, [])
    for sender in senders:
        if _ip_matches(record.source_ip, sender):
            return SenderMatch(sender.id, sender.name, True)
        if sender.ip_allowlist:
            continue
        for auth in record.auth_results:
            if auth.auth_type == "dkim" and any(_domain_equal(auth.domain, item) for item in sender.dkim_domains):
                return SenderMatch(sender.id, sender.name, True)
            if auth.auth_type == "spf" and any(_domain_equal(auth.domain, item) for item in sender.spf_domains):
                return SenderMatch(sender.id, sender.name, True)
    return SenderMatch(None, None, False)