from __future__ import annotations

import re
from dataclasses import dataclass

ADDRESS = re.compile(r"^@([a-z0-9][a-z0-9._-]*):(?:[ \t]*)(.+)$", re.IGNORECASE)


@dataclass(frozen=True)
class RoutedMessage:
    target_repo: str
    body: str


def parse_address_line(line: str) -> RoutedMessage | None:
    """Parse one complete direct-address line; ordinary input returns None."""
    match = ADDRESS.match(line.rstrip("\r\n"))
    if not match:
        return None
    return RoutedMessage(target_repo=match.group(1), body=match.group(2))