signal-bot/signal_bot/counting.py

# Copyright (c) 2026 Krzysztof Rudnicki. MIT licence.
"""Which messages count toward the daily tally, and which chats we listen to."""

from __future__ import annotations

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from signal_bot.discovery import GroupDirectory
    from signal_bot.models import IncomingMessage


def watched_group(message: IncomingMessage, directory: GroupDirectory) -> str | None:
    """Return the canonical id of the watched group a message came from.

    The bot answers in every group it has been added to, and in nothing
    else. Direct messages are rejected here by an explicit lookup rather
    than a falsy check: a DM carries no group id at all, and one must never
    reach a handler no matter how the surrounding code is later rearranged.

    It returns the id rather than a bool so that the gate and the reply
    router are the same decision. Answering "may this run?" and "where does
    the answer go?" separately is how a bot ends up replying to the wrong
    group.

    Args:
        message: The parsed inbound message.
        directory: The live set of groups the bot is a member of.

    Returns:
        The canonical group id, or None for a direct message or any group
        the bot is not scoped to.
    """
    if message.group_id is None:
        return None
    return directory.resolve(message.group_id)


def should_count(message: IncomingMessage) -> bool:
    """True when a message should add to its sender's tally.

    Reactions and stickers are not messages for tally purposes, and a frame
    with no text body carries nothing to count.
    """
    if message.is_reaction or message.has_sticker:
        return False
    return bool(message.text)


def format_tally(rows: list[tuple[str, int]]) -> str:
    """Render the daily report, or a placeholder when nobody spoke."""
    if not rows:
        return "Brak wiadomosci dzisiaj."
    width = max(len(name) for name, _ in rows)
    lines = [f"{name.ljust(width)}  {count}" for name, count in rows]
    return "\n".join(lines)