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

from app.auth import hash_password, require_admin
from app.database import get_db
from app.grader_scope import get_grader_subjects, set_grader_subjects, validate_subject_names
from app.models import User
from app.schemas import GraderCreate, GraderOut, GraderUpdate, GradersResponse

router = APIRouter(prefix="/api/admin/graders", tags=["admin-graders"])


def _get_grader(db: Session, grader_id: int) -> User:
    user = db.get(User, grader_id)
    if not user or user.role != "grader":
        raise HTTPException(404, detail="考评员不存在")
    return user


def _to_out(db: Session, u: User) -> GraderOut:
    return GraderOut(
        id=u.id,
        username=u.username,
        display_name=u.display_name or "",
        is_active=u.is_active,
        created_at=u.created_at.isoformat() if u.created_at else "",
        subjects=get_grader_subjects(db, u.id),
    )


@router.get("", response_model=GradersResponse)
def list_graders(
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
):
    rows = db.scalars(select(User).where(User.role == "grader").order_by(User.id)).all()
    return GradersResponse(items=[_to_out(db, u) for u in rows])


@router.post("", response_model=GraderOut, status_code=201)
def create_grader(
    body: GraderCreate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
):
    username = body.username.strip()
    if db.query(User).filter(User.username == username).first():
        raise HTTPException(409, detail="用户名已存在")
    validate_subject_names(db, body.subjects)
    user = User(
        username=username,
        password_hash=hash_password(body.password),
        display_name=body.display_name.strip(),
        role="grader",
        is_active=True,
    )
    db.add(user)
    db.flush()
    set_grader_subjects(db, user.id, body.subjects)
    db.commit()
    db.refresh(user)
    return _to_out(db, user)


@router.put("/{grader_id}", response_model=GraderOut)
def update_grader(
    grader_id: int,
    body: GraderUpdate,
    db: Session = Depends(get_db),
    _: User = Depends(require_admin),
):
    user = _get_grader(db, grader_id)
    if body.username is not None:
        username = body.username.strip()
        if not username:
            raise HTTPException(400, detail="用户名不能为空")
        other = db.query(User).filter(User.username == username, User.id != grader_id).first()
        if other:
            raise HTTPException(409, detail="用户名已存在")
        user.username = username
    if body.display_name is not None:
        user.display_name = body.display_name.strip()
    if body.password is not None:
        user.password_hash = hash_password(body.password)
    if body.is_active is not None:
        user.is_active = body.is_active
    if body.subjects is not None:
        set_grader_subjects(db, user.id, body.subjects)
    db.commit()
    db.refresh(user)
    return _to_out(db, user)


@router.delete("/{grader_id}", status_code=204)
def delete_grader(
    grader_id: int,
    db: Session = Depends(get_db),
    admin: User = Depends(require_admin),
):
    if grader_id == admin.id:
        raise HTTPException(400, detail="不能删除当前登录账号")
    user = _get_grader(db, grader_id)
    db.delete(user)
    db.commit()