import ctypes
import json
from pathlib import Path
import time


class MysqlDLLClient:
    """
    MySQL DLL 调用客户端
    用于调用 mysql_dll2.dll 执行 SQL

    Example
    -------
    db = MysqlDLLClient()

    data = db.query(
        7,
        "select * from min15_a_jq where times>=? and times<=?",
        ["2025-12-24 00:00:00", "2025-12-26 00:00:00"]
    )

    print(data)
    """

    def __init__(self, dll_path=None):
        """
        初始化 DLL

        Parameters
        ----------
        dll_path : str | Path
            dll路径，默认当前目录 mysql_dll2.dll
        """

        if dll_path is None:
            root = Path(__file__).resolve().parent.parent
            dll_path = root / "lib/mysql_dll/mysql_dll2.dll"

        self.dll = ctypes.WinDLL(str(dll_path))

        self._init_functions()

        time.sleep(1)

        ret = self.dll.InitDBConfig()
        if ret != 1:
            raise RuntimeError("服务器授权失败")

    # ---------------------------------------------------------
    # 初始化 DLL 函数声明
    # ---------------------------------------------------------
    def _init_functions(self):

        # 初始化数据库配置
        self.dll.InitDBConfig.argtypes = []
        self.dll.InitDBConfig.restype = ctypes.c_int

        # 关闭 DLL
        self.dll.ShutdownDLL.argtypes = []
        self.dll.ShutdownDLL.restype = None

        # QuerySQL_Auto
        self.dll.QuerySQL_Auto.argtypes = [
            ctypes.c_int,                       # db_index
            ctypes.c_char_p,                    # sql
            ctypes.c_char_p,                    # params
            ctypes.POINTER(ctypes.c_void_p),    # out_buf
            ctypes.POINTER(ctypes.c_int)        # out_size
        ]

        self.dll.QuerySQL_Auto.restype = ctypes.c_int

        # FreeBuffer
        self.dll.FreeBuffer.argtypes = [ctypes.c_void_p]
        self.dll.FreeBuffer.restype = None

    # ---------------------------------------------------------
    # 参数转换
    # ---------------------------------------------------------
    def _build_params(self, params):
        """
        参数列表转 DLL 参数格式

        ["2025-01-01","2025-01-02"]

        ->

        b"s:2025-01-01|s:2025-01-02"
        """

        if not params:
            return b""

        arr = []

        for p in params:
            if isinstance(p, str):
                arr.append(f"s:{p}")
            elif isinstance(p, int):
                arr.append(f"i:{p}")
            elif isinstance(p, float):
                arr.append(f"f:{p}")
            else:
                raise TypeError(f"不支持的参数类型: {type(p)}")

        return "|".join(arr).encode()

    # ---------------------------------------------------------
    # 查询
    # ---------------------------------------------------------
    def query(self, db_index, sql, params=None):
        """
        执行 SQL 查询

        Parameters
        ----------
        db_index : int
            数据库编号

        sql : str
            SQL语句

        params : list
            SQL参数

        Returns
        -------
        str
            查询结果（JSON 或文本）
        """

        if isinstance(sql, str):
            sql = sql.encode()

        params_bytes = self._build_params(params)

        out_buf = ctypes.c_void_p()
        out_size = ctypes.c_int()

        ret = self.dll.QuerySQL_Auto(
            db_index,
            sql,
            params_bytes,
            ctypes.byref(out_buf),
            ctypes.byref(out_size)
        )

        if ret != 0:
            raise RuntimeError("SQL执行失败")

        try:
            data = ctypes.string_at(out_buf.value, out_size.value)
            return json.loads(data.decode())
        finally:
            self.dll.FreeBuffer(out_buf)

    # ---------------------------------------------------------
    # 关闭
    # ---------------------------------------------------------
    def close(self):
        """关闭 DLL"""
        if self.dll:
            self.dll.ShutdownDLL()

    # ---------------------------------------------------------
    # with 支持
    # ---------------------------------------------------------
    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.close()