import uuid

from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import select, update
from sqlalchemy.ext.asyncio import AsyncSession

from app.auth.users import current_active_user
from app.db import get_async_session
from app.models.character import Character
from app.models.game import GameParticipant
from app.models.message import Message
from app.models.user import User
from app.schemas.character import CharacterRead

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


@router.get("", response_model=list[CharacterRead])
async def list_my_characters(
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> list[Character]:
    characters = (
        await session.execute(
            select(Character)
            .where(Character.owner_id == user.id)
            .order_by(Character.created_at.desc())
        )
    ).scalars().all()
    return list(characters)


@router.get("/{character_id}", response_model=CharacterRead)
async def get_character(
    character_id: uuid.UUID,
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> Character:
    character = await session.get(Character, character_id)
    if character is None:
        raise HTTPException(status_code=404, detail="Character not found")
    if character.owner_id != user.id:
        raise HTTPException(status_code=403, detail="Not your character")
    return character


@router.delete("/{character_id}", status_code=204)
async def delete_character(
    character_id: uuid.UUID,
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> None:
    character = await session.get(Character, character_id)
    if character is None:
        raise HTTPException(status_code=404, detail="Character not found")
    if character.owner_id != user.id:
        raise HTTPException(status_code=403, detail="Not your character")

    # game_participants.character_id and messages.character_id have no ON DELETE cascade
    # (a character can outlive its games and vice versa) — detach them first so the delete
    # doesn't hit a FK violation. Games and message history stay intact either way.
    await session.execute(
        update(GameParticipant)
        .where(GameParticipant.character_id == character_id)
        .values(character_id=None)
    )
    await session.execute(
        update(Message).where(Message.character_id == character_id).values(character_id=None)
    )
    await session.delete(character)
    await session.commit()