from datetime import datetime, timezone

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

from ..database import get_session
from ..models import Novel, Outline
from ..schemas import (
    OutlineCreate,
    OutlineUpdate,
    OutlineRead,
    OutlineList,
    OutlineReorder,
)

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


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_outline_or_404(
    outline_id: int, novel_id: int, session: Session
) -> Outline:
    outline = session.get(Outline, outline_id)
    if not outline or outline.novel_id != novel_id:
        raise HTTPException(status_code=404, detail="大纲不存在")
    return outline


@router.get("", response_model=OutlineList)
def list_outlines(
    novel_id: int,
    session: Session = Depends(get_session),
):
    _get_novel_or_404(novel_id, session)
    total = session.exec(
        select(func.count(Outline.id)).where(Outline.novel_id == novel_id)
    ).one()
    items = session.exec(
        select(Outline)
        .where(Outline.novel_id == novel_id)
        .order_by(Outline.sort_order)
    ).all()
    return OutlineList(
        items=[OutlineRead.model_validate(o, from_attributes=True) for o in items],
        total=total,
    )


@router.post("", response_model=OutlineRead, status_code=201)
def create_outline(
    novel_id: int,
    data: OutlineCreate,
    session: Session = Depends(get_session),
):
    _get_novel_or_404(novel_id, session)
    # 自动设置 sort_order 为当前最大值 + 1
    max_order = session.exec(
        select(func.max(Outline.sort_order)).where(Outline.novel_id == novel_id)
    ).one()
    next_order = (max_order or 0) + 1

    outline = Outline(novel_id=novel_id, sort_order=next_order, **data.model_dump())
    session.add(outline)
    session.commit()
    session.refresh(outline)
    return outline


@router.put("/reorder", response_model=OutlineList)
def reorder_outlines(
    novel_id: int,
    data: OutlineReorder,
    session: Session = Depends(get_session),
):
    _get_novel_or_404(novel_id, session)
    now = datetime.now(timezone.utc)
    for idx, oid in enumerate(data.ordered_ids):
        outline = _get_outline_or_404(oid, novel_id, session)
        outline.sort_order = idx + 1
        outline.updated_at = now
        session.add(outline)
    session.commit()

    items = session.exec(
        select(Outline)
        .where(Outline.novel_id == novel_id)
        .order_by(Outline.sort_order)
    ).all()
    total = len(items)
    return OutlineList(
        items=[OutlineRead.model_validate(o, from_attributes=True) for o in items],
        total=total,
    )


@router.get("/{outline_id}", response_model=OutlineRead)
def get_outline(
    novel_id: int,
    outline_id: int,
    session: Session = Depends(get_session),
):
    return _get_outline_or_404(outline_id, novel_id, session)


@router.patch("/{outline_id}", response_model=OutlineRead)
def update_outline(
    novel_id: int,
    outline_id: int,
    data: OutlineUpdate,
    session: Session = Depends(get_session),
):
    outline = _get_outline_or_404(outline_id, novel_id, session)
    update_data = data.model_dump(exclude_unset=True)
    for key, value in update_data.items():
        setattr(outline, key, value)
    outline.updated_at = datetime.now(timezone.utc)
    session.add(outline)
    session.commit()
    session.refresh(outline)
    return outline


@router.delete("/{outline_id}", status_code=204)
def delete_outline(
    novel_id: int,
    outline_id: int,
    session: Session = Depends(get_session),
):
    outline = _get_outline_or_404(outline_id, novel_id, session)
    session.delete(outline)
    session.commit()