"""管理端：屏幕 CRUD、绑定节目。"""
import uuid
from datetime import datetime, timedelta

from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import select
from sqlalchemy.orm import Session, selectinload

from ..auth import get_current_user
from ..database import get_db
from ..models import Playlist, Screen, ScreenBinding
from ..schemas import (
    BindRequest,
    PlaylistOut,
    ScreenCreate,
    ScreenDetail,
    ScreenOut,
    ScreenUpdate,
)

router = APIRouter(prefix="/api/screens", tags=["screens"], dependencies=[Depends(get_current_user)])

ONLINE_WINDOW = timedelta(seconds=90)  # 与客户端心跳间隔保持一致


def _apply_online_status(screen: Screen) -> Screen:
    """根据最后心跳时间动态刷新在线状态（不落库，仅展示层）。"""
    if screen.last_seen and datetime.now() - screen.last_seen <= ONLINE_WINDOW:
        screen.status = "online"
    else:
        screen.status = "offline"
    return screen


def _get_screen_or_404(db: Session, screen_id: int) -> Screen:
    screen = db.get(Screen, screen_id)
    if not screen:
        raise HTTPException(status_code=404, detail="屏幕不存在")
    return screen


@router.get("", response_model=list[ScreenDetail])
def list_screens(db: Session = Depends(get_db)):
    screens = db.scalars(
        select(Screen)
        .options(selectinload(Screen.bindings).selectinload(ScreenBinding.playlist))
        .order_by(Screen.id)
    ).all()
    result = []
    for s in screens:
        _apply_online_status(s)
        d = ScreenDetail.model_validate(s)
        active = next((b for b in s.bindings if b.active), None)
        if active and active.playlist:
            d.playlist = PlaylistOut.model_validate(active.playlist)
        result.append(d)
    return result


@router.get("/{screen_id}", response_model=ScreenDetail)
def get_screen(screen_id: int, db: Session = Depends(get_db)):
    screen = db.get(
        Screen,
        screen_id,
        options=[selectinload(Screen.bindings).selectinload(ScreenBinding.playlist).selectinload(Playlist.items)],
    )
    if not screen:
        raise HTTPException(status_code=404, detail="屏幕不存在")
    _apply_online_status(screen)
    detail = ScreenDetail.model_validate(screen)
    active = next((b for b in screen.bindings if b.active), None)
    if active and active.playlist:
        detail.playlist = PlaylistOut.model_validate(active.playlist)
    return detail


@router.post("", response_model=ScreenOut)
def create_screen(body: ScreenCreate, db: Session = Depends(get_db)):
    """手动创建屏幕（可选指定 device_id 用于客户端注册匹配）。"""
    device_id = body.device_id
    if not device_id:
        # 未指定设备 ID 时：先写临时 UUID 满足 NOT NULL 约束，flush 拿到 id 后改为 pre-{id}
        screen = Screen(name=body.name, location=body.location, device_id=f"tmp-{uuid.uuid4().hex}")
        db.add(screen)
        db.flush()
        screen.device_id = f"pre-{screen.id}"
    else:
        exists = db.scalars(select(Screen).where(Screen.device_id == device_id)).first()
        if exists:
            raise HTTPException(status_code=409, detail=f"device_id 已存在（屏幕: {exists.name}）")
        screen = Screen(name=body.name, location=body.location, device_id=device_id)
        db.add(screen)
    db.commit()
    db.refresh(screen)
    return screen


@router.put("/{screen_id}", response_model=ScreenOut)
def update_screen(screen_id: int, body: ScreenUpdate, db: Session = Depends(get_db)):
    screen = _get_screen_or_404(db, screen_id)
    if body.name is not None:
        screen.name = body.name
    if body.location is not None:
        screen.location = body.location
    db.commit()
    db.refresh(screen)
    return screen


@router.delete("/{screen_id}")
def delete_screen(screen_id: int, db: Session = Depends(get_db)):
    screen = _get_screen_or_404(db, screen_id)
    db.delete(screen)
    db.commit()
    return {"ok": True}


@router.post("/{screen_id}/bind", response_model=ScreenDetail)
def bind_playlist(screen_id: int, body: BindRequest, db: Session = Depends(get_db)):
    """绑定节目到屏幕（置为 active，其它绑定取消 active）。"""
    screen = _get_screen_or_404(db, screen_id)
    playlist = db.get(Playlist, body.playlist_id)
    if not playlist:
        raise HTTPException(status_code=404, detail="节目不存在")

    for b in screen.bindings:
        b.active = False
    existing = next((b for b in screen.bindings if b.playlist_id == body.playlist_id), None)
    if existing:
        existing.active = True
    else:
        db.add(ScreenBinding(screen_id=screen.id, playlist_id=body.playlist_id, active=True))
    db.commit()

    detail = get_screen(screen_id, db)
    return detail


@router.delete("/{screen_id}/bind")
def unbind_playlist(screen_id: int, db: Session = Depends(get_db)):
    """解除屏幕当前绑定。"""
    screen = _get_screen_or_404(db, screen_id)
    for b in screen.bindings:
        if b.active:
            db.delete(b)
    db.commit()
    return {"ok": True}