from typing import Optional
from uuid import UUID
from datetime import time
from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy import and_, extract, func, or_, select
from sqlalchemy.ext.asyncio import AsyncSession
from backend.app.core.dependencies import require_any_permissions, require_permissions
from backend.app.db.session import get_db
from backend.app.models import Shift
from backend.app.schemas.pagination import PaginatedResponse
from backend.app.schemas.shift import ShiftCreate, ShiftResponse, ShiftUpdate


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


@router.get(
    "",
    response_model=list[ShiftResponse] | PaginatedResponse[ShiftResponse],
    dependencies=[Depends(require_any_permissions(["shifts.view", "schedule.view"]))],
)
async def list_shifts(
    db: AsyncSession = Depends(get_db),
    keyword: Optional[str] = Query(default=None),
    status: Optional[str] = Query(default=None),
    shift_type: Optional[str] = Query(default=None, alias="type"),
    page: Optional[int] = Query(default=None, ge=1),
    page_size: Optional[int] = Query(default=None, ge=1, le=200, alias="pageSize"),
    size: Optional[int] = Query(default=None, ge=1, le=200),
):
    query = select(Shift)
    if keyword:
        like = f"%{keyword.strip()}%"
        query = query.where(or_(Shift.name.ilike(like), Shift.remark.ilike(like)))
    if status == "enabled":
        query = query.where(Shift.enabled.is_(True))
    elif status == "disabled":
        query = query.where(Shift.enabled.is_(False))
    if shift_type == "cross":
        query = query.where(Shift.end_time < Shift.start_time)
    elif shift_type == "night":
        query = query.where(
            or_(
                Shift.end_time < Shift.start_time,
                extract("hour", Shift.start_time) >= 18,
                extract("hour", Shift.start_time) < 6,
            )
        )
    elif shift_type == "day":
        query = query.where(
            and_(
                Shift.end_time >= Shift.start_time,
                extract("hour", Shift.start_time) >= 6,
                extract("hour", Shift.start_time) < 18,
            )
        )

    if page is None and page_size is None and size is None:
        result = await db.execute(query.order_by(Shift.name))
        return result.scalars().all()

    page_value = page or 1
    size_value = page_size or size or 10
    total = await db.scalar(select(func.count()).select_from(query.subquery()))
    result = await db.execute(
        query.order_by(Shift.name)
        .offset((page_value - 1) * size_value)
        .limit(size_value)
    )
    return {
        "items": result.scalars().all(),
        "total": total or 0,
        "page": page_value,
        "pageSize": size_value,
    }


@router.post("", response_model=ShiftResponse, dependencies=[Depends(require_permissions(["shifts.create"]))])
async def create_shift(payload: ShiftCreate, db: AsyncSession = Depends(get_db)):
    start_time = time.fromisoformat(payload.start_time)
    end_time = time.fromisoformat(payload.end_time)
    shift = Shift(
        name=payload.name,
        start_time=start_time,
        end_time=end_time,
        enabled=payload.enabled,
        remark=payload.remark
    )
    db.add(shift)
    await db.commit()
    await db.refresh(shift)
    return shift


@router.put("/{shift_id}", response_model=ShiftResponse, dependencies=[Depends(require_permissions(["shifts.edit"]))])
async def update_shift(shift_id: UUID, payload: ShiftUpdate, db: AsyncSession = Depends(get_db)):
    result = await db.execute(select(Shift).where(Shift.id == shift_id))
    shift = result.scalar_one_or_none()
    if not shift:
        raise HTTPException(status_code=404, detail="班次不存在")
    update_data = payload.model_dump(exclude_unset=True)
    if "start_time" in update_data and update_data["start_time"]:
        update_data["start_time"] = time.fromisoformat(update_data["start_time"])
    if "end_time" in update_data and update_data["end_time"]:
        update_data["end_time"] = time.fromisoformat(update_data["end_time"])
    for key, value in update_data.items():
        setattr(shift, key, value)
    await db.commit()
    await db.refresh(shift)
    return shift


@router.patch("/{shift_id}/toggle", response_model=ShiftResponse, dependencies=[Depends(require_permissions(["shifts.edit"]))])
async def toggle_shift(shift_id: UUID, enabled: bool, db: AsyncSession = Depends(get_db)):
    result = await db.execute(select(Shift).where(Shift.id == shift_id))
    shift = result.scalar_one_or_none()
    if not shift:
        raise HTTPException(status_code=404, detail="班次不存在")
    shift.enabled = enabled
    await db.commit()
    await db.refresh(shift)
    return shift