from datetime import datetime, timezone

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

from ..database import get_session
from ..models import Novel, Character
from ..schemas import (
    CharacterCreate,
    CharacterUpdate,
    CharacterRead,
    CharacterList,
)

router = APIRouter(prefix="/api/novels/{novel_id}/characters", tags=["characters"])


def _get_novel_or_404(novel_id: int, session: Session) -> Novel:
    novel = session.get(Novel, novel_id)
    if not novel:
        raise HTTPException(status_code=404, detail="小说不存在")
    return novel


def _get_character_or_404(
    character_id: int, novel_id: int, session: Session
) -> Character:
    character = session.get(Character, character_id)
    if not character or character.novel_id != novel_id:
        raise HTTPException(status_code=404, detail="角色不存在")
    return character


@router.get("", response_model=CharacterList)
def list_characters(
    novel_id: int,
    session: Session = Depends(get_session),
):
    _get_novel_or_404(novel_id, session)
    total = session.exec(
        select(func.count(Character.id)).where(Character.novel_id == novel_id)
    ).one()
    items = session.exec(
        select(Character)
        .where(Character.novel_id == novel_id)
        .order_by(Character.created_at)
    ).all()
    return CharacterList(
        items=[CharacterRead.model_validate(c, from_attributes=True) for c in items],
        total=total,
    )


@router.post("", response_model=CharacterRead, status_code=201)
def create_character(
    novel_id: int,
    data: CharacterCreate,
    session: Session = Depends(get_session),
):
    _get_novel_or_404(novel_id, session)
    character = Character(novel_id=novel_id, **data.model_dump())
    session.add(character)
    session.commit()
    session.refresh(character)
    return character


@router.get("/{character_id}", response_model=CharacterRead)
def get_character(
    novel_id: int,
    character_id: int,
    session: Session = Depends(get_session),
):
    return _get_character_or_404(character_id, novel_id, session)


@router.patch("/{character_id}", response_model=CharacterRead)
def update_character(
    novel_id: int,
    character_id: int,
    data: CharacterUpdate,
    session: Session = Depends(get_session),
):
    character = _get_character_or_404(character_id, novel_id, session)
    update_data = data.model_dump(exclude_unset=True)
    for key, value in update_data.items():
        setattr(character, key, value)
    character.updated_at = datetime.now(timezone.utc)
    session.add(character)
    session.commit()
    session.refresh(character)
    return character


@router.delete("/{character_id}", status_code=204)
def delete_character(
    novel_id: int,
    character_id: int,
    session: Session = Depends(get_session),
):
    character = _get_character_or_404(character_id, novel_id, session)
    session.delete(character)
    session.commit()