import threading
from threading import Thread
from typing import Callable

from serial import Serial

class SerialReader:

    serial : Serial = None
    __thread : Thread | None = None
    __listeners : list[Callable] = None

    def __init__(self, port, baudrate):
        self.serial = Serial(port, baudrate)
        self._run_event = threading.Event()
        self.__listeners = []

    def start(self) -> None:
        self._run_event.set()
        if self.__thread is None or not self.__thread.is_alive():
            self.__thread = Thread(target=self._read, daemon=True)
            self.__thread.start()

    def stop(self) -> None:
        if self._run_event.is_set():
            self._run_event.clear()

    def subscribe(self, listener : Callable) -> None:
        self.__listeners.append(listener)

    def _notify(self, data : str):
        for listener in self.__listeners:
            listener(data)

    def _read(self):
        while self._run_event.is_set():
            line = self.serial.readline()
            if line:
                data = line.decode('utf-8', errors='ignore')
                self._notify(data)


if __name__ == "__main__":

    def callback(data):
        print(data)

    reader = SerialReader("/dev/ttyUSB1", 57600)
    reader.subscribe(callback)
    reader.start()