from collections.abc import Mapping

CHAT_MESSAGE_MAX_LENGTH_KEY = "chat.message.max_length"
CHAT_MESSAGE_TRANSPORT_MAX_LENGTH = 10_000


def validate_chat_settings(values: Mapping[str, str]) -> None:
    raw = values.get(CHAT_MESSAGE_MAX_LENGTH_KEY)
    if raw is None:
        return
    try:
        value = int(raw)
    except (TypeError, ValueError) as error:
        raise ValueError(f"{CHAT_MESSAGE_MAX_LENGTH_KEY}: integer value expected") from error
    if str(value) != raw:
        raise ValueError(f"{CHAT_MESSAGE_MAX_LENGTH_KEY}: canonical integer value expected")
    if not 1 <= value <= CHAT_MESSAGE_TRANSPORT_MAX_LENGTH:
        raise ValueError(
            f"{CHAT_MESSAGE_MAX_LENGTH_KEY}: value must be between 1 "
            f"and {CHAT_MESSAGE_TRANSPORT_MAX_LENGTH}"
        )