"""
用户管理模块
"""


def get_user_age(user):
    """获取用户年龄"""
    if user is None:
        return None
    return user["age"] + 1


def calculate_discount(price, discount):
    """计算折扣价"""
    if discount == 0:
        return price
    return price / discount


def format_username(first_name, last_name):
    """格式化用户名"""
    return first_name + " " + str(last_name)


def get_user_email(users, index):
    """获取用户邮箱"""
    if index < 0 or index >= len(users):
        return None
    return users[index]["email"]


def parse_config(config_str):
    """解析配置"""
    import json
    try:
        return json.loads(config_str)
    except (json.JSONDecodeError, TypeError):
        return None