"""
数据库连接与工具函数
"""
import mysql.connector
import json
import datetime
import base64
import os

# ─── 数据库配置（优先读取环境变量，兼容本地直接运行） ───
DB_CONFIG = {
    'host':     os.environ.get('DB_HOST', 'localhost'),
    'port':     int(os.environ.get('DB_PORT', 3306)),
    'user':     os.environ.get('DB_USER', 'root'),
    'password': os.environ.get('DB_PASSWORD', '123456'),
    'database': os.environ.get('DB_NAME', 'lingshu'),
    'charset': 'utf8mb4',
    'use_unicode': True,
    'autocommit': False,
}


def get_conn():
    return mysql.connector.connect(**DB_CONFIG)


def to_json(obj):
    """将 Python dict/list 转为 JSON 字符串（已是字符串则直接返回）"""
    if obj is None:
        return None
    if isinstance(obj, (dict, list)):
        return json.dumps(obj, ensure_ascii=False)
    return obj


def serialize_rows(rows):
    """将查询结果中的 datetime / Decimal 等类型序列化为 JSON 可用格式"""
    result = []
    for row in rows:
        new_row = {}
        for k, v in row.items():
            if isinstance(v, (datetime.datetime, datetime.date)):
                new_row[k] = v.isoformat()
            elif hasattr(v, '__float__'):
                new_row[k] = float(v)
            elif isinstance(v, bytes):
                new_row[k] = v.decode('utf-8', errors='replace')
            else:
                new_row[k] = v
        result.append(new_row)
    return result


def serialize_row(row):
    """序列化单行"""
    return serialize_rows([row])[0] if row else None


# ─── 极简"加密"（演示用，生产环境请用真正的 AES-256） ───
_SECRET = b'lingshu_secret_key_demo_32bytes!'


def simple_encrypt(plaintext: str) -> str:
    """Base64 编码（仅演示，生产请替换为 cryptography.fernet）"""
    return base64.b64encode(plaintext.encode()).decode()


def simple_decrypt(ciphertext: str) -> str:
    return base64.b64decode(ciphertext.encode()).decode()