import uuid

from fastapi import APIRouter, Depends, HTTPException, status
from sqlmodel import Session, select

from app.database import get_session
from app.models.user import User
from app.models.friendship import Friendship
from app.schemas.user import UserRead
from app.auth.dependencies import get_current_user

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


@router.post("", status_code=status.HTTP_201_CREATED)
def add_friend(
    username: str,
    current_user: User = Depends(get_current_user),
    session: Session = Depends(get_session),
):
    """Add a friend by username. Creates bidirectional friendship."""
    friend = session.exec(select(User).where(User.username == username)).first()
    if not friend:
        raise HTTPException(status_code=404, detail="User not found")
    if friend.id == current_user.id:
        raise HTTPException(status_code=400, detail="Cannot add yourself")

    # Check if already friends
    existing = session.exec(
        select(Friendship).where(
            Friendship.user_id == current_user.id,
            Friendship.friend_id == friend.id,
        )
    ).first()
    if existing:
        raise HTTPException(status_code=400, detail="Already friends")

    # Bidirectional
    session.add(Friendship(user_id=current_user.id, friend_id=friend.id))
    session.add(Friendship(user_id=friend.id, friend_id=current_user.id))
    session.commit()

    return {"detail": f"Now friends with {friend.username}"}


@router.get("", response_model=list[UserRead])
def list_friends(
    current_user: User = Depends(get_current_user),
    session: Session = Depends(get_session),
):
    """List all friends of the current user."""
    friend_ids = session.exec(
        select(Friendship.friend_id).where(Friendship.user_id == current_user.id)
    ).all()

    if not friend_ids:
        return []

    friends = session.exec(
        select(User).where(User.id.in_(friend_ids))  # type: ignore[union-attr]
    ).all()
    return friends


@router.delete("/{friend_id}", status_code=status.HTTP_204_NO_CONTENT)
def remove_friend(
    friend_id: uuid.UUID,
    current_user: User = Depends(get_current_user),
    session: Session = Depends(get_session),
):
    """Remove a friend (bidirectional)."""
    f1 = session.exec(
        select(Friendship).where(
            Friendship.user_id == current_user.id,
            Friendship.friend_id == friend_id,
        )
    ).first()
    f2 = session.exec(
        select(Friendship).where(
            Friendship.user_id == friend_id,
            Friendship.friend_id == current_user.id,
        )
    ).first()

    if not f1:
        raise HTTPException(status_code=404, detail="Friendship not found")

    session.delete(f1)
    if f2:
        session.delete(f2)
    session.commit()