"""
用戶管理 API 端點
"""
from typing import Optional
from fastapi import APIRouter, Depends, HTTPException, status, Query
from sqlalchemy.orm import Session
from sqlalchemy import func

from app.db.session import get_db
from app.core.security import get_password_hash
from app.models import User, Role
from app.schemas.user import (
    UserCreate, UserUpdate, UserResponse, UserListResponse, PaginationResponse
)
from app.api.v1.endpoints.auth import get_current_user, require_roles

router = APIRouter()


@router.get("", response_model=UserListResponse)
def list_users(
    page: int = Query(1, ge=1),
    limit: int = Query(20, ge=1, le=100),
    role: Optional[str] = None,
    auth_type: Optional[str] = None,
    search: Optional[str] = None,
    current_user: User = Depends(require_roles("admin"))
):
    """取得用戶列表（僅管理員）"""
    db = next(get_db())
    
    query = db.query(User)
    
    # 篩選條件
    if role:
        query = query.join(Role).filter(Role.code == role)
    if auth_type:
        query = query.filter(User.auth_type == auth_type)
    if search:
        # 清理輸入，移除特殊字元，防止注入
        safe_search = search.strip()[:100]  # 限制長度
        # SQLAlchemy 的 ilike 已經使用參數化查詢，相對安全
        # 但為了額外安全，轉義 SQL 萬用字元
        safe_search = safe_search.replace('%', '\\%').replace('_', '\\_')
        query = query.filter(
            (User.username.ilike(f"%{safe_search}%")) |
            (User.display_name.ilike(f"%{safe_search}%"))
        )
    
    # 總數
    total = query.count()
    
    # 分頁
    users = query.offset((page - 1) * limit).limit(limit).all()
    
    return UserListResponse(
        data=[UserResponse.model_validate(u) for u in users],
        pagination=PaginationResponse(
            page=page,
            limit=limit,
            total=total,
            total_pages=(total + limit - 1) // limit
        )
    )


@router.post("", response_model=UserResponse, status_code=status.HTTP_201_CREATED)
def create_user(
    user_in: UserCreate,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_roles("admin"))
):
    """新增用戶（僅管理員）"""
    # 檢查帳號是否重複
    existing = db.query(User).filter(User.username == user_in.username).first()
    if existing:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="帳號已存在"
        )
    
    # 檢查角色
    role = db.query(Role).filter(Role.id == user_in.role_id).first()
    if not role:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="角色不存在"
        )
    
    # 本地帳號必須有密碼
    if user_in.auth_type == "local" and not user_in.password:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="本地帳號必須設定密碼"
        )
    
    user = User(
        username=user_in.username,
        display_name=user_in.display_name,
        email=user_in.email,
        auth_type=user_in.auth_type,
        role_id=user_in.role_id,
        password_hash=get_password_hash(user_in.password) if user_in.password else None
    )
    
    db.add(user)
    db.commit()
    db.refresh(user)
    
    return user


@router.get("/{user_id}", response_model=UserResponse)
def get_user(
    user_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_roles("admin"))
):
    """取得單一用戶（僅管理員）"""
    user = db.query(User).filter(User.id == user_id).first()
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="用戶不存在"
        )
    return user


@router.put("/{user_id}", response_model=UserResponse)
def update_user(
    user_id: int,
    user_in: UserUpdate,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_roles("admin"))
):
    """更新用戶（僅管理員）"""
    user = db.query(User).filter(User.id == user_id).first()
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="用戶不存在"
        )
    
    # 更新欄位
    if user_in.display_name is not None:
        user.display_name = user_in.display_name
    if user_in.email is not None:
        user.email = user_in.email
    if user_in.role_id is not None:
        role = db.query(Role).filter(Role.id == user_in.role_id).first()
        if not role:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="角色不存在"
            )
        user.role_id = user_in.role_id
    if user_in.is_active is not None:
        user.is_active = user_in.is_active
    if user_in.password is not None:
        if user.auth_type.value != "local":
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="AD 帳號無法修改密碼"
            )
        user.password_hash = get_password_hash(user_in.password)
    
    db.commit()
    db.refresh(user)
    
    return user


@router.delete("/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
def delete_user(
    user_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_roles("admin"))
):
    """刪除用戶（僅管理員）"""
    user = db.query(User).filter(User.id == user_id).first()
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="用戶不存在"
        )
    
    # 不能刪除自己
    if user.id == current_user.id:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="無法刪除自己的帳號"
        )
    
    db.delete(user)
    db.commit()