import serial
import os
import pty
import tty
import termios
import atexit
import threading

# Open virtual serial port

# Close it when the program exits
def _cleanUp() -> None:
    pass
atexit.register(_cleanUp)

class MockJDS6600Device():
    def __init__(self):
        self._master, self._slave = pty.openpty()
        self._masterFile = os.fdopen(self._master, mode="r+b", closefd=False, buffering=0)

        self._portName = os.ttyname(self._slave)
        self._channels = [False, False]
        
        self._mainThread = threading.Thread(target=self._mainLoop)
        self._mainThread.start()

    def _mainLoop(self) -> None:
        while True:
            try:
                print("Device reading request....")
                request = self._masterFile.readline().decode().strip()
                response = self._handleRequest(request)
                print("Device sending response")
                self._masterFile.write(response.encode())
            except OSError as e:
                print("Exception caught, breaking out of loop")
                break
        print("Main loop returning")

    def _handleRequest(self, request: str) -> str:
        print(f"Device received request: {request}")
        return ":ok\r\n"

    def stop(self) -> None:
        print("STOP")
        self._masterFile.close()

        os.close(self._master)
        print("master closed")
        os.close(self._slave)
        print("slave closed")
        self._mainThread.join()
        print("stop returning")

    def checkPortConfiguration(self) -> None:
        iflag, oflag, cflag, lflag, ispeed, ospeed, cc = termios.tcgetattr(self._slave)

        # JDS6600 configuration taken from manual
        assert ispeed == termios.B115200
        assert ospeed == termios.B115200
        assert (cflag & termios.CSIZE) == termios.CS8
        assert (cflag & termios.CSTOPB) == 0
        assert (cflag & (termios.PARENB | termios.PARODD)) == 0

    def getPortName(self) -> str:
        return self._portName

    def isOn(self, ch: int) -> bool:
        return self._channels[ch - 1]