from __future__ import annotations

import re
from dataclasses import dataclass

ADDRESS = re.compile(r"^To:([a-z0-9][a-z0-9._-]*):[ \t]*(.+)$")
COMMAND = re.compile(r"^Cmd:[ \t]*(\S(?:.*\S)?)?[ \t]*$")


@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))


def parse_command_line(line: str) -> str | None:
    """Return an operator command body; worker output must never call this."""
    match = COMMAND.match(line.rstrip("\r\n"))
    if not match or not match.group(1):
        return None
    return match.group(1)