from app.services.session_service import get_session
from app.services.ws_manager import manager


async def attempt_match(own_token: str, detected_token: str) -> dict:
    """
    Check if two nearby users share interests and both consent.
    Sends a WebSocket nudge to both if matched.
    """
    own_session = await get_session(own_token)
    other_session = await get_session(detected_token)

    if own_session is None or other_session is None:
        return {"match": False, "shared_interests": [], "nudge_sent": False}

    own_interests = set(own_session.get("interests", []))
    other_interests = set(other_session.get("interests", []))
    shared = list(own_interests & other_interests)

    if not shared:
        return {"match": False, "shared_interests": [], "nudge_sent": False}

    nudge = {
        "type": "nudge",
        "shared_interests": shared,
        "message": f"Someone nearby shares your interest in {_format_interests(shared)}.",
    }

    await manager.send(own_token, nudge)
    await manager.send(detected_token, nudge)

    return {"match": True, "shared_interests": shared, "nudge_sent": True}


def _format_interests(interests: list[str]) -> str:
    if len(interests) == 1:
        return interests[0]
    return ", ".join(interests[:-1]) + " and " + interests[-1]