import base64
import hashlib
from elastic.es_connect import get_user_by_username as es_get_user_by_username


def _salt_for_username(username: str) -> bytes:
    return hashlib.sha256(username.encode('utf-8')).digest()


def _derive_password(password_plain: str, salt: bytes) -> bytes:
    return hashlib.pbkdf2_hmac('sha256', password_plain.encode('utf-8'), salt, 100_000, dklen=32)


def get_user_by_username(username: str):
    """
    从Elasticsearch获取用户数据
    """
    # 首先尝试从ES获取用户数据
    es_user = es_get_user_by_username(username)
    salt = _salt_for_username(username)
    derived = _derive_password(es_user.get('password', ''), salt)
    if es_user:
        # 如果ES中有用户数据，使用ES中的密码
        return {
            'user_id': es_user.get('user_id', 0),
            'username': es_user.get('username', ''),
            'password': base64.b64encode(derived).decode('ascii'),
            'premission': es_user.get('permission', 1),
            'salt': base64.b64encode(salt).decode('ascii'),
        }


    return None