import socket
import threading


class VoltageReceiver():
    def __init__(self):
        self.data = ""  # 数据存储
        self.active = False  # 控制线程的开关
        self.dataready = 0  # 数据是否准备好的标志位
        self.thread = None  # 线程存储
        self.sock = None  # 套接字存储

    def receive_data(self):
        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.sock.bind(('127.0.0.1', 9996))
        self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.sock.listen(1)

        while self.active:  # 只有当 self.active 为 True 时，才开始监听
            conn, addr = self.sock.accept()
            while conn:
                try:
                    data = conn.recv(1024)
                except socket.error as e:
                    print("Remote host has disconnected.")  # 打印提醒
                    break
                if not data or not self.active:  # 如果没有数据或 self.active 为 False， 则跳出循环
                    break
                data = data.decode()
                if self.dataready:
                    # 新的数据已经准备好，而旧的数据还没被取走，发出警告
                    self.alert()
                with threading.Lock():    # 使用锁确保线程安全
                    self.data = data
                    self.dataready = 1
            conn.close()

    def start(self):  # 开始监听
        if not self.thread or not self.thread.is_alive():  # 如果线程未创建或已结束，那么创建一个新线程
            self.active = True
            self.thread = threading.Thread(target=self.receive_data)
            self.thread.start()

    def stop(self):  # 停止监听
        self.active = False
        if self.sock:  # 关闭套接字，使得 sock.accept() 退出阻塞
            self.sock.close()

    def get_data(self):  # 获取数据
        with threading.Lock():  # 使用锁确保线程安全
            self.dataready = 0
            return self.data

    def alert(self):  # 报警函数
        print("Warning: New data has arrived but the old data has not been taken away.")


def write_to_file(data, filename):
    """
    This function write data to a local .txt file

    :param data: str, data to be written to the file
    :param filename: str, name of the file
    """
    with open(filename, 'w') as file:
        file.write(data)


def read_from_file(filename):
    """
    This function read data from a local .txt file

    :param filename: str, name of the file
    :return: str, data read from the file
    """
    with open(filename, 'r') as file:
        data = file.read().replace('\n', '')
    return data


if __name__ == "__main__":  # 测试代码
    receiver = VoltageReceiver()  # 创建一个 VoltageReceiver 的实例
    receiver.start()  # 开始监听
    while receiver.active:
        if receiver.dataready:  # 当数据准备好时，打印数据
            data = read_from_file('test.txt')
            if data == '#' or data == '':
                print(receiver.get_data())
                write_to_file(receiver.get_data(), "test.txt")
            else:
                pass
    receiver.stop()  # 停止监听