"""Session routing for Synology Chat conversations.

Routes incoming messages to agent sessions based on chat type (direct/group),
user identity, and account for multi-account isolation.

DM sessions are keyed by userId to prevent cross-user session confusion
in shared DM channels. Group sessions are keyed by chat_id since group
context is shared among all members in the same group.

Identity links allow mapping between different representations of the
same user (e.g. webhook user_id ↔ DSM API user_id).
"""

from __future__ import annotations

from yuxi.channels.models import ChannelMessage, ChatType

DEFAULT_ACCOUNT_ID = "default"


def resolve_session_route(
    msg: ChannelMessage,
    default_agent_id: str = "default",
    account_id: str = DEFAULT_ACCOUNT_ID,
) -> str:
    user_id = msg.identity.channel_user_id
    chat_id = msg.identity.channel_chat_id
    chat_type = msg.chat_type

    if chat_type == ChatType.DIRECT:
        return f"agent:{default_agent_id}:synologychat:{account_id}:direct:{user_id}"
    else:
        return f"agent:{default_agent_id}:synologychat:{account_id}:group:{chat_id}"


def build_identity_link(
    user_id: str,
    account_id: str = DEFAULT_ACCOUNT_ID,
    username: str = "",
    chat_id: str = "",
) -> dict:
    return {
        "channel": "synologychat",
        "account_id": account_id,
        "user_id": user_id,
        "username": username,
        "chat_id": chat_id,
    }


def resolve_identity_links(
    msg: ChannelMessage,
    account_id: str = DEFAULT_ACCOUNT_ID,
) -> list[dict]:
    links = [
        build_identity_link(
            user_id=msg.identity.channel_user_id,
            account_id=account_id,
            username=msg.metadata.get("dsm_user_name", "") if msg.metadata else "",
            chat_id=msg.identity.channel_chat_id,
        )
    ]
    forwarded_from = msg.metadata.get("forwarded_from") if msg.metadata else None
    if forwarded_from:
        links.append(
            build_identity_link(
                user_id=str(forwarded_from),
                account_id=account_id,
                chat_id=msg.identity.channel_chat_id,
            )
        )
    return links