from datetime import date
from fastapi import APIRouter, Depends, Query
from sqlalchemy import func, select, case
from sqlalchemy.ext.asyncio import AsyncSession
from backend.app.core.dependencies import require_permissions, get_current_user
from backend.app.db.session import get_db
from backend.app.models import ScheduleItem, User


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


def is_limited_scope(user: User) -> bool:
    return user.role and user.role.name not in {"管理员", "排班员"}


@router.get("/schedule", dependencies=[Depends(require_permissions(["statistics.view"]))])
async def get_schedule_stats(
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
    dept_id: str | None = Query(default=None),
    start: date | None = Query(default=None),
    end: date | None = Query(default=None),
):
    conditions = []
    if is_limited_scope(current_user):
        if not current_user.dept_id:
            return {"byDept": {}, "byStaff": {}, "byShift": {}, "total": 0}
        conditions.append(ScheduleItem.dept_id == current_user.dept_id)
    elif dept_id:
        conditions.append(ScheduleItem.dept_id == dept_id)
    conditions.append(ScheduleItem.tag != "stopClinic")
    if start:
        conditions.append(ScheduleItem.date >= start)
    if end:
        conditions.append(ScheduleItem.date <= end)

    total_result = await db.execute(
        select(func.count()).select_from(select(ScheduleItem).where(*conditions).subquery())
    )
    total = total_result.scalar_one() or 0

    by_dept = await db.execute(
        select(ScheduleItem.dept_id, func.count())
        .where(*conditions)
        .group_by(ScheduleItem.dept_id)
    )

    by_shift = await db.execute(
        select(ScheduleItem.shift_id, func.count())
        .where(*conditions)
        .group_by(ScheduleItem.shift_id)
    )

    by_staff = await db.execute(
        select(
            ScheduleItem.staff_id,
            func.count(case((ScheduleItem.tag == "substitute", 1))).label("substitute"),
            func.count(case((ScheduleItem.tag != "substitute", 1))).label("normal"),
        )
        .where(*conditions)
        .group_by(ScheduleItem.staff_id)
    )

    return {
        "byDept": {str(row[0]): row[1] for row in by_dept.fetchall()},
        "byShift": {str(row[0]): row[1] for row in by_shift.fetchall()},
        "byStaff": {str(row[0]): {"normal": row[2], "substitute": row[1]} for row in by_staff.fetchall()},
        "total": total
    }