from datetime import datetime, timedelta, timezone

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from passlib.context import CryptContext
from sqlalchemy.orm import Session

from app.config import settings
from app.database import get_db
from app.models import AdminUser

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


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


def hash_password(password: str) -> str:
    return pwd_context.hash(password)


def create_access_token(data: dict) -> str:
    to_encode = data.copy()
    expire = datetime.now(timezone.utc) + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm="HS256")


def authenticate_admin(db: Session, username: str, password: str) -> AdminUser | None:
    user = db.query(AdminUser).filter(AdminUser.username == username).first()
    if not user or not verify_password(password, user.hashed_password):
        return None
    return user


def get_current_admin(
    token: str = Depends(oauth2_scheme),
    db: Session = Depends(get_db),
) -> AdminUser:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="توکن نامعتبر یا منقضی شده است",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=["HS256"])
        username: str | None = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        raise credentials_exception

    user = db.query(AdminUser).filter(AdminUser.username == username).first()
    if user is None:
        raise credentials_exception
    return user