from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.orm import Session
from database import get_db
from models import User, UserStats
from schemas import TokenData
from config import get_settings

settings = get_settings()

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="api/auth/login")


def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Проверка пароля"""
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password: str) -> str:
    """Хеширование пароля"""
    # Обрезаем пароль до 72 байт для bcrypt
    if len(password.encode('utf-8')) > 72:
        password = password[:72]
    return pwd_context.hash(password)


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    """Создание JWT токена"""
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt


def authenticate_user(db: Session, username: str, password: str):
    """Аутентификация пользователя"""
    user = db.query(User).filter(User.username == username).first()
    if not user:
        return False
    if not verify_password(password, user.hashed_password):
        return False
    return user


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: Session = Depends(get_db)
) -> User:
    """Получение текущего пользователя из токена"""
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = TokenData(username=username)
    except JWTError:
        raise credentials_exception
    
    user = db.query(User).filter(User.username == token_data.username).first()
    if user is None:
        raise credentials_exception
    return user


async def get_current_active_user(
    current_user: User = Depends(get_current_user)
) -> User:
    """Проверка активности пользователя"""
    if not current_user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user


async def get_current_admin_user(
    current_user: User = Depends(get_current_active_user)
) -> User:
    """Проверка прав администратора"""
    if not current_user.is_admin:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Not enough permissions"
        )
    return current_user


def create_user(db: Session, username: str, email: str, password: str, is_admin: bool = False) -> User:
    """Создание нового пользователя"""
    # Проверка существования пользователя
    if db.query(User).filter(User.username == username).first():
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Username already registered"
        )
    if db.query(User).filter(User.email == email).first():
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Email already registered"
        )
    
    # Создание пользователя
    hashed_password = get_password_hash(password)
    user = User(
        username=username,
        email=email,
        hashed_password=hashed_password,
        is_admin=is_admin
    )
    db.add(user)
    db.commit()
    db.refresh(user)
    
    # Создание статистики пользователя
    user_stats = UserStats(user_id=user.id)
    db.add(user_stats)
    db.commit()
    
    return user


def init_admin_user(db: Session):
    """Инициализация администратора при первом запуске"""
    admin = db.query(User).filter(User.username == settings.ADMIN_USERNAME).first()
    if not admin:
        create_user(
            db=db,
            username=settings.ADMIN_USERNAME,
            email=settings.ADMIN_EMAIL,
            password=settings.ADMIN_PASSWORD,
            is_admin=True
        )
        print(f"Admin user created: {settings.ADMIN_USERNAME}")