# -*- coding: utf-8 -*-
"""
SQLite客户端
"""

from pathlib import Path
import sqlite3
import threading
from typing import Any, Dict, List, Optional, Tuple


class SQLite:
    """
    SQLite客户端，支持：
    query_one：根据SQL语句执行查询并返回一行查询数据
    query_all：根据SQL语句执行查询并返回所有查询数据
    execute：根据SQL语句执行操作
    """

    def __init__(self, database: Path):
        """
        初始化
        :param database: 数据库地址
        """
        self.database = database
        # 初始化本地线程存储
        self.threads = threading.local()

    def query_one(
        self, sql: str, parameters: Tuple[Any, ...] = ()
    ) -> Optional[Dict[str, Any]]:
        """
        在当前线程，根据SQL语句执行查询并返回一行查询数据
        :param sql: SQL语句
        :param parameters: SQL参数
        :return: 查询数据
        """
        try:
            # 为当前线程创建数据库连接和游标
            self._connect()
            # 检查当前线程游标，若游标为空值则抛出异常
            if not hasattr(self.threads, "cursor") or self.threads.cursor is None:
                raise RuntimeError("创建游标发生异常")

            # 为当前线程执行SQL
            self.threads.cursor.execute(sql, parameters)
            return (
                None
                if (result := self.threads.cursor.fetchone()) is None
                else dict(result)
            )
        # 若发生异常则回滚事务并抛出异常
        except Exception as exception:
            # 检查当前线程有数据库连接，若有则回滚
            if (
                hasattr(self.threads, "connection")
                and self.threads.connection is not None
            ):
                self.threads.connection.rollback()
            raise RuntimeError(f"执行查询发生异常：{str(exception)}") from exception

    def query_all(
        self, sql: str, parameters: Tuple[Any, ...] = ()
    ) -> List[Dict[str, Any]]:
        """
        在当前线程，根据SQL语句执行查询并返回所有查询数据
        :param sql: SQL语句
        :param parameters: SQL参数
        :return: 查询数据
        """
        try:
            # 为当前线程创建数据库连接和游标
            self._connect()
            # 检查当前线程游标，若游标为空值则抛出异常
            if not hasattr(self.threads, "cursor") or self.threads.cursor is None:
                raise RuntimeError("创建游标发生异常")

            # 为当前线程执行SQL
            self.threads.cursor.execute(sql, parameters)
            result = []
            # 分批处理
            while batch := self.threads.cursor.fetchmany(1000):
                result.extend([dict(row) for row in batch])
            return result
        # 若发生异常则回滚事务并抛出异常
        except Exception as exception:
            # 检查当前线程有数据库连接，若有则回滚
            if (
                hasattr(self.threads, "connection")
                and self.threads.connection is not None
            ):
                self.threads.connection.rollback()
            raise RuntimeError(f"执行查询发生异常：{str(exception)}") from exception

    def execute(self, sql: str, parameters: Tuple[Any, ...] = ()) -> bool:
        """
        在当前线程，根据SQL语句执行操作
        :param sql: 新增、删除和修改SQL语句
        :param parameters: SQL参数
        :return: 执行结果
        """
        try:
            self._connect()
            # 检查当前线程无游标，若无则抛出异常
            if not hasattr(self.threads, "cursor") or self.threads.cursor is None:
                raise RuntimeError("为当前线程创建游标发生异常")

            # 为当前线程执行SQL
            self.threads.cursor.execute(sql, parameters)
            # 为当前线程提交事务
            self.threads.connection.commit()
            return True
        # 若发生异常则回滚事务并抛出异常
        except Exception as exception:
            # 检查当前线程有数据库连接，若有则回滚
            if (
                hasattr(self.threads, "connection")
                and self.threads.connection is not None
            ):
                self.threads.connection.rollback()
            raise RuntimeError(f"执行SQL发生异常：{str(exception)}") from exception

    def _connect(self):
        """为当前线程创建数据库连接和游标"""
        # 检查当前线程有数据库连接，若有则继续否则创建数据库连接
        if hasattr(self.threads, "connection") and self.threads.connection is not None:
            return
        # 为当前线程关闭数据库连接和游标
        self._disconnect()

        try:
            # 为当前线程创建数据库连接
            self.threads.connection = sqlite3.connect(
                database=self.database.as_posix(),
                check_same_thread=True,
                timeout=30,  # 数据库锁超时时间（单位：秒），默认为30秒，避免并发锁死
            )
            # 开启行映射，支持按照字段名取值
            self.threads.connection.row_factory = sqlite3.Row
            # 为当前线程创建游标
            self.threads.cursor = self.threads.connection.cursor()
        except Exception as exception:
            self.threads.connection = None
            self.threads.cursor = None
            raise RuntimeError(
                f"为当前线程创建数据库连接和游标发生异常，{str(exception)}"
            ) from exception

    def _disconnect(self) -> None:
        """为当前线程关闭数据库连接和游标"""
        # 检查当前线程有游标，若有则关闭游标
        if hasattr(self.threads, "cursor") and self.threads.cursor is not None:
            try:
                # 为当前线程关闭游标
                self.threads.cursor.close()
                self.threads.cursor = None
            except Exception as exception:
                raise RuntimeError(
                    f"为当前线程关闭游标发生异常，{str(exception)}"
                ) from exception

        # 检查当前线程有数据库连接，若有则关闭数据库连接
        if hasattr(self.threads, "connection") and self.threads.connection is not None:
            try:
                # 为当前线程提交事务
                self.threads.connection.commit()
                # 为当前线程关闭数据库连接
                self.threads.connection.close()
                self.threads.connection = None
            except Exception as exception:
                raise RuntimeError(
                    f"为当前线程关闭数据库连接发生异常，{str(exception)}"
                ) from exception

    def __enter__(self):
        """进入上下文管理时为当前线程创建数据库连接和游标"""
        self._connect()
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        """退出上下文管理时为当前线程关闭数据库连接和游标"""
        self._disconnect()
        return False

    def __del__(self):
        """析构时为当前线程关闭数据库连接和游标"""
        self._disconnect()