from fastapi import APIRouter, Depends
from sqlmodel import Session, select, func

from app.database import get_session
from app.models.user import User
from app.models.zone import Zone
from app.models.score import Score
from app.models.friendship import Friendship
from app.schemas.score import LeaderboardEntry
from app.auth.dependencies import get_current_user

router = APIRouter(prefix="/leaderboard", tags=["leaderboard"])


@router.get("", response_model=list[LeaderboardEntry])
def get_leaderboard(
    current_user: User = Depends(get_current_user),
    session: Session = Depends(get_session),
):
    """Friend leaderboard sorted by total points.

    Includes the current user and all their friends.
    """
    # Get friend IDs + self
    friend_ids = list(
        session.exec(
            select(Friendship.friend_id).where(Friendship.user_id == current_user.id)
        ).all()
    )
    user_ids = friend_ids + [current_user.id]

    entries: list[LeaderboardEntry] = []
    for uid in user_ids:
        user = session.get(User, uid)
        if not user:
            continue

        # Latest score
        latest_score = session.exec(
            select(Score).where(Score.user_id == uid).order_by(Score.date.desc())  # type: ignore[union-attr]
        ).first()
        total_pts = latest_score.total_pts if latest_score else 0

        # Total area
        total_area = session.exec(
            select(func.coalesce(func.sum(Zone.area_m2), 0.0)).where(
                Zone.owner_id == uid
            )
        ).one()

        # Zone count
        zone_count = session.exec(
            select(func.count()).select_from(Zone).where(Zone.owner_id == uid)
        ).one()

        entries.append(
            LeaderboardEntry(
                user_id=uid,
                username=user.username,
                avatar_url=user.avatar_url,
                total_pts=total_pts,
                total_area_m2=float(total_area),
                zone_count=zone_count,
                rank=0,  # calculated below
            )
        )

    # Sort by total_pts descending, assign rank
    entries.sort(key=lambda e: e.total_pts, reverse=True)
    for i, entry in enumerate(entries):
        entry.rank = i + 1

    return entries